Microbiology Homework 4

Which of the following conclusions are supported by the current research data? Select all that apply.

- Genomovars III and II appear to be the most virulent or transmissible to humans. - Burkholderia cepacia complex appears to be very diverse in its habitat and distribution. - It would appear that the environment may serve as a reservoir for acquiring Burkholderia cepacia complex strains.

Consider the different mechanisms through which antibiotics inhibit microbial growth, and consider what changes in the microbe might enable it to resist the inhibitory effects of antibiotics. Select all of the statements that describe a mechanism that would enable a microorganism to resist the action of an antibiotic.

A microbe develops a transport mechanism in the plasma membrane that rapidly pumps antibiotic out of the bacterial cell. Target site is modified, so that an antibiotic is unable to bind to its target. Altered porins in the cell wall block passage of antibiotic through the cell wall. An enzyme that destroys the antibiotic is produced.

Why does the physician start Caleb on the antibiotic azithromycin before laboratory results come back?

Antibiotic therapy is started with a broad-spectrum antibiotic because broad-spectrum antibiotics are effective against many gram-positive and many gram-negative bacteria.

The name Propionibacterium is derived from the fact that the organism produces propionic acid during fermentative metabolism. Which of the following statements about fermentative metabolism is true?

Fermentation produces significantly less ATP than aerobic respiration; however it generates NAD+, which can be used in glycolysis.

Which of the following is mismatched?

Florey and Chain identification of Penicillium as the producer of penicillin

Your DFA results come back positive for rabies. You have already started your patient on PEP; however, she continues to deteriorate. Her kidneys show signs of failure, and her respiration, heart rate, and blood pressure are gradually decreasing. You place her on mechanical ventilation and dialysis. What options do you have left to treat her condition?

Induce an extended coma.

What disease does Paul suspect Ron might have contracted?

Rocky Mountain spotted fever

Before you can treat you patient, there is a very important factor you must consider.

Selecting the best drug to treat Staphylococcus aureus infections can be difficult because some strains of the bacteria have developed drug resistance .

Which description of melioidosis is correct?

The disease may appear as pneumonia, as septic shock, or as abscesses that resemble necrotizing fasciitis. The organism is commonly found in soil.

Which of the following statements about meningitis is TRUE?

Viral meningitis, while less severe than bacterial meningitis, is more common in occurrence.

Given the above results, is it safe to say your patient has a MRSA infection? Yes or No?

No

Which of the following statements concerning Pneumocystis jirovecii is FALSE?

P. jirovecii trophozoites produce sexually by fission

There are several different forms of the plague. Which form is of the greatest concern as a potential bioweapon?

Pneumonic plague

The common cold __________.

can result from deposition of a single rhinovirus on the nasal mucosa

Which of the following fungal infections results in a white, curdy discharge?

candidiasis

Genes for beta-lactamase are present in Burkholderia cepacia but are not normally expressed unless they are induced. Exposure to which of the following agents most likely induced the expression of beta-lactamase resistance in Burkholderia cepacia? (Select the one best answer.)

cephalexin

"What is the matter?!" one of the doctors asks. You take another glance at your chart, and then respond that your patient could be infected with a disease that: Select one of the following answers in response to the doctor's question:

is caused by an agent of bioterrorism

Which of the following symptoms is LEAST characteristic of Clostridium perfringens food poisoning?

moderate vomiting and fever

It is time to confirm your diagnosis. Select the best samples to accurately confirm a diagnosis of rabies in your patient. Select all that apply.

neck tissue biopsy CSF saliva

Your second set of results and cultures come back positive for Streptococcus pyogenes. You now have all the information you need to diagnose your patient with streptococcal toxic shock syndrome; however, you are concerned that there may be other complicating factors in addition to septic shock... Review your the results from your patient's blood and urine tests (Part E) and determine which of the following complications is an additional concern, especially for patients diagnosed with streptococcal toxic shock syndrome?

necrotizing fasciitis

What is the treatment that Dr. Clark will most likely recommend?

Praziquantel or albendazole, drugs that target eukaryotic parasites with minimal side effects in the host.

Which statement regarding normal microbiota of the urinary and reproductive systems is true?

Pregnancy and menopause are associated with higher rates of urinary tract infections.

Treatment for an NTD will depend on whether it is caused by a prokaryote or a eukaryote. In this section, place each organism in the appropriate bin.

Prokaryote - Mycobacterium ulcerans Chlamydia trachomatis Eukaryote - Onchocerca volvulus Typanosoma cruzi Neither - Dengue virus Rabies virus

What sort of organisms would you instruct investigators to test for plague? Select all that apply.

Rats and mice Household pets (cats and dogs) Ground squirrels and rabbits Wild predators

Which of the following is NOT characteristic of chronic fatigue syndrome (CFS)?

Relief can be obtained through exercise

As mentioned previously, African sleeping sickness is transmitted via a biological vector. Which of the following vectors is responsible for transmitting Trypanosoma brucei?

tsetse fly

The Big Picture Activity mentions multiple strategies for reducing the incidence of NTD. Which of the following would you recommend as a successful strategy for preventing the transmission of African sleeping sickness?

preventing contact with insects such as mosquitoes, kissing bugs, fleas, etc., through the use of chemicals

All of the following are protective factors of the skin and its secretions EXCEPT

pyocyanin production.

Which of the following types of infection can result in infertility?

salpingitis

Why should children younger than 1 year of age NOT be fed honey?

They may contract botulism.

The Big Picture Activity mentioned that because no vaccine is available, prevention is the next method for keeping the number of infections to a minimum. One of the methods recommended by the CDC is to prevent infected individuals from receiving mosquito bites during the first week of their infection. How does this help prevent further spread of infection?

Additional bites would increase the chances of an uninfected vector acquiring the virus.

Which disease, resulting in damage to the heart muscle or the nerves controlling peristalsis in the gastrointestinal tract, is transmitted by the reduviid bug?

Chagas' disease

Claire's symptoms are characteristic of many different infections. Why does Dr. Peterson suspect that Claire may have meningitis?

- The closed, mixed environment of the college dorm allows for infection of susceptible students. - There have been documented cases of meningitis in Claire's dorm.

What is meant by selective toxicity?

Chemotherapeutic agents should act against the pathogen and not the host.

Quinolones and fluoroquinolones act against what bacterial target?

DNA gyrase

Given the preliminary diagnosis of furious rabies, how should you proceed with the nurse who your patient bit?

Initiate PEP

Microscopic examination of cerebrospinal fluid reveals gram-positive rods. What is the organism?

Listeria

Infants may acquire a serious form of conjunctivitis during birth if they are born to a mother infected with __________.

Neisseria gonorrhoeae

Based on Claire's medical history and the Gram stain results, which is the most likely causative organism?

Neisseria meningitidis

You would like to determine which species of Staphylococcus your patient is infected with. Which test will allow you to eliminate some possibilities?

One of the most important phenotypic features that can be used to differentiate among Staph species is their ability to produce coagulase , an enzyme that causes blood clot formation.

Which of the following statements concerning the blood-brain barrier is FALSE?

Penicillin is useless against infections of the brain because it is completely incapable of crossing the barrier.

Your first instinct is that your patient has ______. Use your patient's medical history and symptoms to form a hypothesis about your patient's disease. Select as many answers as are applicable.

Rabies

The bacteria appear to be in clusters, as opposed to chains. This suggests that your patient has ______.

a staphylococcal infection

Which region of the skin supports the largest bacterial population?

armpits

If Caleb's strain of M. tuberculosis is sensitive to antibiotic treatment, which of the following could be used to treat his infection? Select all that apply.

streptomycin isoniazid and ethambutol rifampin

Why is it more difficult to treat viral infections than it is to treat bacterial infections?

Viruses use the host cell's processes to carry out their own reproduction.

Which of the following bacterial pneumonias would you NOT treat with tetracycline?

Haemophilus influenzae pneumonia

What is the most likely sequence of events involved in the pathogenesis of meningococcal meningitis? Arrange the following statements in chronological order.

Beginning to End 1. N. meningitidis enters and attaches to the nasopharyngeal epithelium 2. The organism passages through the mucosa and enters the blood 3. N. meningitidis crosses the blood-brain barrier 4. A massive influx of polymorphonuclear cells leads to increased pressure in the brain 5. Hearing, vision, motor skills impaired

In which of the following North American locations would you expect to find the highest incidence of infection with Borrelia burgdorferi?

Atlantic coast

Why is polymyxin only used on the skin?

It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead.

What does the culture above tell you about the organism isolated from your patient?

It is beta-hemolytic.

Listeriosis is contracted through ingesting food contaminated with Listeria monocytogenes. How does this bacterium leave the gastrointestinal tract to cross the blood-brain-barrier and reach the CNS? Select the best answer.

L. monocytogenes spreads from cell-to-cell

Which statement regarding the emerging viral hemorrhagic fevers is FALSE?

Later symptoms of hemorrhagic viral infection include low-grade fever and severe, crippling joint pains.

There are basically four mechanisms of microbial resistance. This activity asks that you drag the statement describing each mechanism to the appropriate area of the image that represents the mechanism. Drag each statement to the appropriate area of the diagram.

Starting at the top box and filling in the boxes clockwise Entry of antibiotic into the cell is blocked. Cellular enzyme inactivates an antibiotic. Efflux mechanism pumps antibiotic out of the cell. Target site to which antibiotic binds is altered.

After reviewing your patient's medical history, you decide to list out the factors that you think will be most important to your diagnostic process. Review the following list and select the factors that you believe are most relevant to a diagnosis.

the patient's symptoms the fact that more than one person had similar symptoms the fact that the bite did not respond to treatment with antibiotic ointment the patient's activities before and during the infection

Cats have been identified as an essential part of the life cycle for the protozoan that causes which disease?

toxoplasmosis

Which of the following is NOT caused by infection of the upper respiratory tract?

whooping cough

Bacterial encephalitis and meningitis are difficult to treat because

many antibiotics cannot penetrate the blood-brain barrier.

Arrange in the correct order the following pathologic events in cystic fibrosis lung disease.

1. CFTR defect results in production of dehydrated, thick mucus. 2. Thick mucus results in impaired ciliary clearance. 3. Bacteria become trapped in mucus, resulting in a chronic bacterial infection. 4. As a result of bacterial infection, a chronic neutrophilic inflammatory response ensues. 5. Inflammation results in bronchiectasis and fibrosis of lung bronchial walls.

Which is the correct sequence of events regarding the stages of tooth decay? 1. Dentin decay 2. Enamel decay 3. Plaque 4. Pulp decay

3. Plaque -> 2. Enamel decay -> 1. Dentin decay -> 4. Pulp decay

The patient is a female, age 36. She is an assistant professor in philosophy. The patient is married (6 years), sexually active, and monogamous. She does not have any children. She has a history of hypertension on her mother's side of the family. She is allergic to tree nuts. She does not report using any drugs of abuse. She and her husband and pets (a cat, and two dogs) were driving cross-country from San Diego, CA to New York City, NY as part of a move to accept her academic position. During the trip, the couple had planned to stay for a week at her husband's parent's ranch in White Rock, New Mexico. While there, her husband fell ill with fever, fatigue, and a painful lump in his groin (inguinal region). Since the patient had several appointments in New York to keep, she decided to keep driving, while her husband would stay with his parents until he felt well enough to fly to New York with their dogs. The patient reports starting to feel "ill" during her first couple of days in New York. She had noticed a mild fever; however she did not seek medical attention until she developed a painful inguinal swelling similar to her husband. Soon after, she developed fever and chills. Review the patient's medical history, and then identify risks and concerns that are relevant to your diagnosis (and the patient's treatment). Indicate "YES" with a red checkmark, and "NO" with a blue checkmark.

Age-related risk of disease? Blue/No Occupational risk of disease? Blue/No Risk of sexually transmitted infection (STI)? Blue/No Risk of vector-borne disease? Red/Yes Risk of drug-related disease exposure? Blue/No Risk of travel-related disease exposure? Red/Yes Risk of genetic/familial disease? Blue/No Allergic concerns for treatment? Blue/No Risk of immunocompromise? Blue/No

Nicole is very upset after receiving news that her ex-boyfriend Paul had tested positive for syphilis and gonorrhea. She makes an appointment with her physician. Nicole receives her test results, which indicate that she is positive for syphilis, but not for gonorrhea. What treatment will her doctor most likely prescribe?

Antibiotics

A patient exhibits hemorrhagic colitis and is treated via intravenous rehydration. The pathogen is a gram-negative rod. It is isolated and differentiated from related organisms based on its inability to ferment sorbitol. Which of the following is a likely diagnosis?

Escherichia coli gastroenteritis

Candida is a normal flora found in the majority (greater than 50%) of women. True or False

False

A patient comes in with a possible Chikungunya infection. Rank the following in order. Drag and drop the steps below in the appropriate order from left to right.

First Step 1. uninfected mosquito feeds on an infected person 2. replication of the virus inside the vector 3. infected mosquito feeds on uninfected person 4. patient has fever, headaches, and joint pain 5. treatment with supportive therapy Last Step

Preliminary laboratory results rule out bacterial, viral, and protozoan infections and indicate that Michael is most likely Which of the following represents the MOST LIKELY route of transmission for Michael's infection?

Foodborne - Eating undercooked, unwashed, or otherwise contaminated food that contained parasitic propagules

What do you think is wrong with your patient's husband?

He has septicemic plague.

__________ antibodies are found in mucosal secretions and help to protect the respiratory system from infection.

IgA

Michael's blood work reveals an increase in eosinophils, which are granular white blood cells, and his IgE antibodies. Along with the microscopic analysis of the stool specimen, these lab results confirm the diagnosis of a tapeworm infection. Why do we see an increase in the levels of IgE antibody in Michael's serum?

IgE is the class of antibodies involved in hypersensitivities such as allergies and parasitic infections.

What pathogen is responsible for your patient's condition?

Listeria monocytogenes

What diagnosis will you make for this patient?

Listeriosis meningitis

How will you treat your patients?

Penicillin G

Which of the following is a characteristic of biological transmission from Dermacentor to a human host?

R. rickettsii is transmitted to the human host during a bite, when tick saliva enters the wound.

Which of the following organisms is most likely the causative agent of Michael's tapeworm infection?

Taenia solium

Compare the anatomy of the tapeworm (Image C) to the anatomy of the roundworm (Image D). Given that both are parasitic worms, which of the following reasons best explains why the tapeworm is flat?

Tapeworms utilize diffusion to absorb nutrients from the host's digestive system.

Which of the following statements concerning mumps virus infection is FALSE?

The testes can become inflamed about 2 to 3 weeks after the onset of symptoms.

All lymph that returns to the heart must pass through at least one lymph node. True or False

True

Botulism and tetanus are caused by bacterial endospores commonly found in the soil. True or False

True

Based upon these results, which of the following can you conclude about your patient?

Your patient has a CNS infection.

The most common route of central nervous system invasion by pathogens is through

circulatory system

Of the two forms of rabies, you believe that your patient has ____________ rabies.

furious

The IV regimen administered by Ron's doctors is consistent with the CDC's recommendation that doxycycline be administered when RMSF is suspected. Apply your knowledge of RMSF to choose the most likely reasons behind this recommendation. Select all that apply.

- A delay in treatment can lead to complications that include respiratory, cardiac, and renal failure. - Without prompt treatment, RMSF can have a mortality rate as high as 20%. - Most tests that can definitively identify R. rickettsii are not very effective early in infection. - The symptoms of RMSF are similar to those of several other infections, making definitive diagnosis difficult.

Use this new information to help you refine your hypothesis. Are there diseases that are more likely based upon this evidence? Make sure to consider your patient's history, symptoms, and your diagnostics (and their validity) when making your case. Select all that apply.

- A form of bacterial meningitis (meningococcal, pneumococcal meningitis...etc.) - Listeriosis (CNS infection)

Given your current information, select the best candidates for the cause of your patient's symptoms. Select all conditions that could reasonably apply to your patient.

- A form of bacterial meningitis (meningococcal, pneumococcal meningitis...etc.) - Listeriosis (CNS infection) - Arboviral encephalitis - Cryptococcosis

Which diagnostics would you like to use?

- Bacterial culture of CSF fluid - CSF Gram-stain

The two most common STI organisms associated with PID in the United States are Chlamydia trachomatis and Neisseria gonorrhoeae. There are many similarities between these STIs. Which of the following statements comparing chlamydia and gonorrhea are true? Select all statements that are TRUE.

- Chlamydia and gonorrhea can infect a patient and be transmitted without causing obvious symptoms. - Chlamydia is found more often in women, whereas gonorrhea is found more often in men. - Patients may be coinfected with both gonorrhea and chlamydia.

Michael was excited when his boss sent him to work on a 6-month project with the Vice President of International Affairs at their corporation in Beijing, China. Before leaving the United States, he visited his family doctor for a complete physical and to receive his immunizations. The physician reviewed Michael's medical history and current lab results and declared that he was a healthy 32-year-old. Michael adjusted well to the move and made many new friends. They would often get together on the weekends to go swimming at a nearby lake, to play volleyball at the local park, or to watch movies and cook dinner. He quickly found that his favorite meal was a stir-fry containing a mixture of pork, fresh raw vegetables, and noodles. He would eat this combination of foods three to four times a week. To his surprise, within 3 months of moving to China, Michael started losing weight. He was not trying to lose weight and when asked about his diet, Michael would say that he ate all the time. At first, he thought the weight loss was just a result of his metabolism adjusting to his new Asian diet and was not a cause for concern. However, after 2 months of continuous weight loss, the non-stop eating was replaced by nausea and slight abdominal pain. At this time, Michael began to think something might be wrong. Michael scheduled an appointment with Dr. Clark at the local medical center. During his appointment, the two of them discussed where Michael had traveled since he had been in China, the types of foods he had eaten, the specifics of his exercise regimen, and his extracurricular activities. They also discussed the lack of symptoms other than the weight loss and recent bouts of nausea. After talking with Michael, Dr. Clark requested that multiple stool specimen be sent to the laboratory for examination. He also ordered serological testing of Michael's blood to determine his antibody titer levels. He was concerned that Michael may have an intestinal parasite infection, even though many are asymptomatic. Why does Dr. Clark request stool samples for examination? Select all that apply.

- He will have the laboratory prepare the samples for an ova and parasite (O&P) exam. Fresh or preserved stool samples can be observed microscopically for the presence of parasites or their eggs/cysts. - Tapeworms are pathogens of the gastrointestinal tract; as a natural progression of digestion some of the tapeworm pieces will be expelled along with fecal matter.

As soldiers returned home to the United States in the fall of 1918, they brought the deadly flu with them. The first cases were noted in August of 1918. By September of that year, influenza epidemics were reported in California, Texas, North Dakota, and Florida. The disease would continue to spread throughout the fall and winter of 1918 and into the spring of 1919. It is estimated that the 1918-1919 influenza pandemic resulted in approximately 675,000 deaths in the United States and more than 20 million worldwide. Today, approximately 30,000 to 50,000 people die each year from influenza infection. Several factors play a role in this relatively low mortality rate. One factor is the availability of an influenza vaccine. But although the vaccine does offer protection, its design and production are not without their challenges. What are some of the current challenges to production of the influenza vaccine? Select all that apply

- In order to yield a vaccine, the virus must be produced in eggs. - The virus undergoes antigenic changes on a regular basis.

Molecular action of Clostridium perfringens enterotoxin: The symptoms of C. perfringens type A food poisoning usually begin within 6 to 18 hours after the ingestion of contaminated food. The time depends upon the number of bacteria in the food and the amount ingested; thus, the time of onset is dose dependent. Very large doses of bacteria are required to initiate food poisoning because gastric acid kills most bacteria. Organisms surviving the stomach continue to the small intestine, where the presence of bile salts is thought to stimulate sporulation. It is during the in vivo sporulation that the enterotoxin is produced. Rather than being secreted, as are many microbial exotoxins, Clostridium perfringens enterotoxin (CPE) is released into the intestinal lumen by lysis of the vegetative cells during the end stages of sporulation. Most strains of C. perfringens type A food poisoning carry the enterotoxin gene on the bacterial chromosome. Expression of the cpe gene is regulated by sporulation. Large amounts of toxin can be produced during sporulation. Once released into the intestinal lumen, CPE binds to integral membrane proteins called claudins associated with the tight junctions (TJ) of the epithelial cells making up the intestinal villi. The TJ serve as barriers defining the apical and base membrane compartments and function as a gate in regulating permeability across the epithelial layer. Binding of CPE inhibits the absorption of fluid and ions across the epithelium. The CPE forms a complex with claudin on the cell membrane surface, called a small complex. Six of the small complexes on the cell membrane then aggregate to form a larger complex known as a pre-pore that inserts into the cell membrane to make an active pore. Active pore formation results in calcium influx, which leads to cell death due to activation of a proteolytic enzyme known as calpain. The death of intestinal epithelial cells leads to progressive loss of epithelial lining of the villi, causing fluid to be secreted into the lumen of the intestine. An additional effect of CPE is increased myoelectrical activity of the intestine, which leads to the abdominal cramping associated with C. perfringens food poisoning. Which of the findings listed below support the hypothesis? Select all that apply.

- Increasing levels of sodium, potassium, bicarbonate, and chloride ions, as well as water, are secreted as toxin concentrations are increased from 25, 50, 100, and 150 units. - Protein levels within the ileum loop fluid are increased up to 1000 units of toxin. - Histological observation indicates that morphological alteration and sloughing of epithelial cells occurs up to a maximum of 1000 units.

It is thought that in Europe, the influenza virus changed in such a way to make it more virulent in the human population, resulting in increased severity of disease and increased mortality. What changes could have led to the differences in pathology observed in Camp Funston and in Europe? Research in recent years has led to our understanding that these changes were due to the process known as antigenic shift. Which of the following statements regarding antigenic shift are true? Select all that apply.

- Little immunity to virus strains resulting from antigenic shift exists in the population. - Antigenic shift results in a major change in the genetic composition of the virus. - Viral strains resulting from antigenic shift contain RNA segments from different species.

Laboratory and Patient follow-up: The Burkholderia cepacia complex is a group of genomic species, or genomovars. Genomovar is a term used to describe strains of related organisms that are genetically different but share common traits or characteristics. Microorganisms belonging to a specific genomovar are classified as a species when genetic and or biochemical tests allow specific groups to be differentiated from other related strains. Typically this complex is made up of low-grade nosocomial pathogens most often associated with pneumonia in CF patients. All species within the complex have been isolated from CF patients. However, patients infected with genomovar III tend to have the highest mortality rates and may develop cepacia syndrome, which is a fatal, untreatable necrotizing pneumonia. Burkholderia cepacia may develop resistance rapidly during antibiotic treatment of the patient. The Cystic Fibrosis Foundation laboratory confirms the identification of the Burkholderia cepacia isolate as genomovar III by 16S ribosomal DNA sequence analysis. Tests are performed to determine whether the organism is susceptible to cephalexin, tobramycin and ticarcillin/clavulanate; the tests yield conflicting results. Dr. Turner switches the antimicrobial regimen to trimethoprim-sulfamethoxazole, ceftazidime, and ciprofloxacin. Chloe has become febrile, and by the seventh day of hospitalization her condition has not improved or stabilized. Dr. Turner orders another set of blood cultures. Chloe's oxygen requirements have progressively increased, and her breathing has become more labored. Dr. Turner transfers Chloe to the pediatric intensive care unit (PICU) so that she can be placed on respiratory support. Why does Dr. Turner change Chloe's initial antimicrobial therapy? Which of the following are valid reasons why Chloe's antimicrobial therapy should be changed? Select all that apply.

- Results of antimicrobial susceptibility testing were conflicting. - The isolate is confirmed to be Burkholderia cepacia.

You caution the microbiologist screening your samples that you suspect toxic shock syndrome, which you know can result from more than one type of infecting organism. Which of the following genera of bacteria would you most commonly expect to find in a case of toxic shock syndrome? Select all that apply.

- Staphylococcus - Streptococcus

All of the patients who were diagnosed with listeriosis ate the following food items: fruit and cottage cheese: contains cottage cheese, cantaloupe. turkey sandwich: contains wheat bread, turkey, tomatoes, Swiss cheese. side salad: contains iceberg lettuce, tomatoes, blue cheese dressing soft-serve ice cream: contains ice cream. Which could be responsible for the listeriosis outbreak? Select all that apply.

- The cottage cheese - The cantaloupe - The turkey meat - The tomatoes - The Swiss cheese - The iceberg lettuce - The blue cheese dressing - The soft-serve ice cream

Restaurant inspection and case follow-up: Dr. Thompson's inspection of Bubba-Qs reveals a problem in the storage of the roasted meat. The pork served at the restaurant was stored in a large walk-in cooler. Even though the temperature of the coookler is 35 degrees F, the cooler could not have maintained large quantities of meat at or below 45 degrees F because of the insulating effects of large volumes of food and inadequate movement of air. The meat found in the cooler at the time of the inspection has an internal temperature of 85 degrees F although it was placed in the cooler 4 hours previously. Dr. Thompson notes other problems, as well: The sauce (which was made from meat drippings, plus brown sugar and spices) was prepared on an overcrowded steam table, and its temperature at the time of inspection is 112 degrees F. The meat was transported to the July 4 celebration in foil-covered pans stacked in the back of the catering van. The sauce was transported in plastic-lined Styrofoam buckets. No provision was made for reheating food items delivered to the event. Food was maintained at ambient temperatures. The restaurant is cited for food safety violations, and the following recommendation is made. Foods associated with C. perfringens food intoxications, such as meats, poultry, and sauces or gravies, should be cooked to an internal temperature of at least 145 to 165 degrees F and maintained at a temperature above 140 degrees F or cooler than 41 degrees F after cooking. Meat dishes should be served hot right after cooking, and any leftovers should be reheated to at least 165 degrees F before they are served. Any leftover foods should be refrigerated after they are removed from heating units and serving tables. So that appropriate cooling temperatures are reached, the food items should be divided into small quantities for refrigeration. Which of the following findings are key to the cause of the outbreak? Select all that apply.

- The sauce was prepared on an overcrowded steam table and, as a result, did not reach an appropriate temperature to kill any organisms - Large quantities of meat were prepared and kept warm for a long time before they were served.

After treatment, Dr. Clark wanted to monitor Michael's progress to make sure the tapeworm infection was completely cleared. He also ordered Michael to get a computed tomography (CT) scan and a magnetic resonance imaging (MRI) scan. These scans confirmed that Michael's infection was localized to the digestive tract and the tapeworms had not spread beyond that point. Why was Dr. Clark worried about tapeworm infection in other body sites?

- When tapeworm larvae escape the stomach, they can travel to other parts of the body such as muscles, the liver, the eye, and even the brain to form cysticerci. - The presence of T. solium in the brain can result in neurocysticercosis, a serious condition which has symptoms resembling those of brain tumors or epilepsy.

You know that Streptococcus pyogenes is both beta-hemolytic and capable of causing toxic shock syndrome; however, you also know that Staphylococcus aureus can be beta-hemolytic, and also cause its own variant of the same syndrome. What are some ways you can differentiate between these two genera? Select all that apply.

- ability to produce coagulase - arrangement of cocci - presence of M protein

In addition to the vaccine, several antiviral drugs are available to treat influenza infection. One of the most prescribed treatments for influenza is Tamiflu (osteltamivir). Tamiflu works by inhibiting the action of neuraminidase (NA). Predict which of the following would be outcomes of treatment with Tamiflu. Select all that apply.

- an increase in the ability of the immune system to combat the infection - overall decrease in the replication rate of influenza - a decrease in the release of viral particles from the cell

Acne is the result of the inflammatory response. In this case, the inflammation is resulting in acne that is very painful (physically and emotionally) for Scott. However, inflammation is a critical component of a normal immune response. What are the main functions of the inflammatory response?

- destroying and eliminating the invading pathogen - repairing tissue damage resulting from inflammation - "walling off" the site of injury or infection

Dr. Smith prescribes oral erythromycin for Scott. She also recommends that he consider using an over-the-counter gel or cream containing benzoyl peroxide. Although this regimen should be effective at treating Scott's acne, there are some possible side effects. Which of the following are possible side effects of Scott's treatment?

- gastrointestinal problems resulting from a reduction/elimination of normal intestinal flora - excessive drying of the skin

Research conducted in recent years on the 1918 flu indicated that the high mortality rate and the severe pathology associated with the disease were likely due to a cytokine storm that was stimulated during infection. Recall that when they are released, cytokines stimulate the production of more cytokines (positive feedback). Sometimes, this feedback spins out of control, leading to an overproduction of cytokines known as a cytokine storm. Predict which of the following are reasonable outcomes of the cytokine storm during the 1918 flu pandemic. Select all that apply.

- increased fluid in the lungs and labored breathing - an excessive inflammatory response leading to extensive tissue damage

Chlamydia PID is just part of the overall spectrum of disease caused by Chlamydia organisms. Even though we now understand more about STIs and their complications, we are still exploring how the organisms "branch out" beyond just a single infection. Which of the following diseases have Chlamydia infection as an etiology? Select all diseases associated with Chlamydia.

- infertility - trachoma - cervical cancer - inclusion conjunctivitis - lymphogranuloma venereum (LGV) - pneumonia

Test Results: Chloe's chest radiographs reveal areas of bronchiectasis. Her red blood cell (RBC) counts are normal, but she has an elevated white blood cell (WBC) count with an overall increase in neutrophils. The test for fecal fat is positive, and her pancreatic elastase levels are reduced. Her admission blood cultures are negative. However, sputum cultures grow an oxidase-positive, gram-negative rod that is tentatively identified as Burkholderia cepacia. The culture is sent to the Cystic Fibrosis Foundation for confirmatory identification. Dr. Turner orders pills of pancreatic enzyme supplements to be given to Chloe before meals. He also prescribes tobramycin and ticarcillin/clavulanate to be added to her daily cephalexin treatment regimen. Because Chloe is complaining of stomachache and is refusing food, Dr. Turner orders tests to evaluate Chloe for pancreatic insufficiency. Which of the following test results would indicate pancreatic insufficiency? Select all that apply.

- reduced pancreatic elastase levels - detection of fat in the feces, which indicates that fats are not being digested and appropriately absorbed in the intestine

Now that you have considered the evidence at hand, you should start to build a hypothesis about what disease your patient has. In the beginning of your diagnostic process you should try to think broadly and consider any and all reasonable possibilities. You can then narrow down these possibilities by performing diagnostics that can support or refute your hypothesis. Select all conditions that could reasonably apply to your patient.

- staphylococcal skin infection (folliculitis, impetigo, scalded skin syndrome, toxic shock syndrome) - streptococcal skin infection (necrotizing fasciitis, erysipelas)

Dr. Smith assures Scott that although inflammation may sound scary, there are several possible options for treating Scott's moderate acne. Which of the following would be the most appropriate for Scott's case?

- topical treatment with a product containing benzoyl peroxide - an oral antibiotic such as erythromycin - Clear Light, a nonchemical, light-based system

Chloe Smith is a 10-year-old white female with cystic fibrosis. Cystic fibrosis (CF) is an autosomal recessive inherited disease. To contract the disease, a child must receive a defective gene from each parent. If both parents are carriers, the child has a 1 in 4, or 25%, chance of developing cystic fibrosis and having two copies of the defective gene; a 25% chance of being unaffected by the disease and having no copies of the defective gene; and a 2 in 4, or 50%, chance of being unaffected but carrying one copy of the defective gene. Cystic fibrosis affects multiple organs. The most common presenting symptoms involve the respiratory and gastrointestinal systems. Typical features include mucus plugging, chronic inflammation, and infection. Symptoms include persistent cough or wheezing and recurrent pneumonia. Respiratory failure is the most common cause of death. Chloe has been admitted to Parkside Hospital. For the past two weeks, she has been experiencing a dry cough with no production of sputum (mucus expelled from the lungs by coughing). On the day of admission, she is intermittently febrile (feverish), complains of chest pain, and is producing small amounts of thick sputum. Chloe also complains of a stomachache and refuses to eat. Upon admission, she is turned over to Dr. Turner, chief pulmonologist for the Parkside Cystic Fibrosis Center. In reviewing Chloe's history, Dr. Turner notes that Chloe's last hospitalization occurred 3 years ago. She has been evaluated regularly and has not had any weight loss. Her lung function tests had been stable up to 2 weeks prior to her admission but have worsened on the day of admission. Dr. Turner orders a chest radiograph, CBC (complete blood count), and cultures of sputum and blood. In addition, Dr. Turner orders a test for fecal fat and elastase. (Elastase is a protein-splitting enzyme secreted by the pancreas.) After the cultures are collected, the doctor prescribes cephalexin a daily antimicrobial regimen. Chloe's mother wants to have another child. However, she is concerned that a second child might also have CF, so she encourages Chloe's stepfather to be tested. Tests reveal that he does NOT carry the CF gene. What is the chance that a second child born to Chloe's mother and stepfather will have CF?

0% chance of having CF

You immediately take blood and a urine samples from your patient and rush them to the lab for a complete blood count (CBC) and screening for all likely causal pathogens. You also perform a lumbar puncture to analyze your patient's CSF. Your initial results show that your patient's blood has elevated numbers of immature leukocytes (this is often termed left shift or blood shift) and a relative decrease in hematocrit. She also has a low serum platelet count (thrombocytopenia), as well as decreased levels of albumin and calcium. She has increased levels of serum creatine kinase (an enzyme that is released into the blood when muscle is damaged), as well as creatinine and blood urea nitrogen (BUN) (both of which are normally filtered out of the blood by the kidneys). Results from her lumbar puncture were normal. What do these results indicate? Match each set of results with a reasonable interpretation of your patient's condition.

1. Decreased hematocrit: blood loss, red blood cell destruction (hemolysis) 2. Left shift: active inflammation or infection 3. Low serum platelet count: possible coagulation pathology 4. Low serum albumin and calcium, increased creatinine and BUN: possible organ failure 5. Increased serum creatine kinase: possible tissue damage

What is the correct sequence of events for the life cycle of the pork tapeworm, T. solium? Arrange the following statements in chronological order

1. Eggs are produced by adult tapeworms living in the definitive host. 2. Eggs are released to the environment in the feces. 3. Pigs eat grass contaminated, or fertilized, with human feces. 4. Inside the intermediate host, the eggs mature into larvae and encyst in the hosts muscles. 5. The definitive host ingests the larvae and becomes infected.

You believe that it is significant that your patient cannot seem to drink the liquid medium. You decide to make a list of different ways to interpret this symptom and the disease each interpretation is associated with. Match each symptom with the disease it best fits. Each disease is used only once.

1. Epiglottitis: H. influenzae meningitis 2. Lockjaw: tetanus 3. Flaccid paralysis, difficulty swallowing: botulism 4. Mouth and pharynx spasms to response to liquid or gust of air: rabies 5. Gradual loss of motor control: transmissible spongiform encephalopathies

During the spring and summer of 1918, cases of influenza began to emerge throughout Europe. Soldiers on both sides of the front were struck down by this invisible pathogen. In contrast to the cases seen at Camp Funston, these infections were much more severe, with symptoms resembling those of pneumonia. As the months went on, the death toll continued to rise. The successful infection of a host, and subsequent spread to another, results from a specific sequence of events known as the replication cycle. Each of the statements below describes an important step in the replication cycle of influenza. Arrange the following statements in the order that best describes the sequence of events involved in the replication of influenza.

1. Hemagglutinin (HA) spikes attach to host cells. 2. Influenza enters the host cell. 3. Nucleic acid enters the host cytoplasm. 4. Influenza proteins are synthesized. 5. Influenza nucleic acid is packaged in capsid. 6. Influenza particles bud from the cell, releasing the virus into the surrounding environment.

Arrange the statement of events below in the order that best describes the sequence of events in the pathology of Clostridium perfringens poisoning once contaminated food has been ingested.

1. Sporulation and lysis of vegetative cells result in the release of CPE. 2. CPE binds to claudin receptors of the tight junctions of intestinal epithelia. 3. Absorption of fluid and ions across the epithelia is inhibited. 4. Formation of the CPE-claudin complex results in active pore formation. 5. Calcium ion influx results in activation of calpain. 6. Cellular death and loss of epithelial layer of intestinal villi result in fluid secretion into lumen and diarrhea. 7. Increased myoelectrical activity of intestine leads to severe cramping.

On the evening of July 4, 150 people attend the Independence Day celebration and fireworks display hosted by Collintown council co-chairs Cindy and Luke Clark. The celebration is largest that the members of the community can remember. A local restaurant, Bubba-Qs, has catered the event. Attendees have their choice of Texas-style barbecue (pork: dry rub or with Bubba-Qs sauce), coleslaw, baked beans, green salad, beef tacos (with onions, tomatoes, lettuce, cheese, salsa, sour cream, and tortillas), chili, chicken tortilla soup, potato salad, jalapeno cornbread, peaches, homemade vanilla ice cream, and apple pie. Around midnight, both Cindy and Luke begin to experience abdominal cramps and diarrhea. Their symptoms are so severe that they both seek immediate medical attention. Dr. Parker, who is the attending doctor in the emergency room that night, hospitalizes Cindy for severe dehydration. Luke is treated for mild dehydration and released to go home. From midnight to 8:00 in the morning, an additional 38 patients are admitted to the emergency room for symptoms similar to those that Cindy and Luke experience. All of the patients seen by Dr. Parker had attended the Fourth of July celebration. Dr. Parker immediately notifies the director of the Collin County Health Department, Dr. Thompson, to initiate an investigation and collect food samples for microbiological analysis. In addition, Dr. Parker ordered stool cultures on Cindy Clark as well as a reverse passive agglutination (RPLA) test for detecting Clostridium perfringens enterotoxin A. Dr. Thompson's investigation reveals that a total of 40 individuals were given emergency treatment at Collintown Community Hospital. Interviews with these individuals lead to the identification of an additional 65 people who were ill with compatible signs and symptoms but did not seek medical attention. His investigation revealed that all of the ill persons and 45 who did not become ill attended the Independence Day celebration. As an epidemiologist, Dr. Thompson is interested in determining the frequency with which a specified event occurs within a particular population at a certain instant or during a particular period. This measure is known as a rate. In epidemiologic practice, an attack rate is the most commonly used method of determining the extent or frequency with which a disease is experienced by a population of individuals. In this instance, Dr. Thompson is interested in knowing what percentage of the individuals who attended the July 4 celebration became ill. The attack rate is the number of individuals treated and/or had symptoms divided by the number of attending individuals. What is the attack rate of food poisoning among the group who attended the July 4 celebration?

105/150(100)= 70.0%

To help you better understand your patient's condition, you would like to collect some samples for analysis. You decide to take a blood sample, but you would like to take one other type of sample as well. Select the sample that will be most informative if you suspect that your patient has a disease of the central nervous system.

A CSF sample

Which of the following is NOT a characteristic of tuberculosis infection?

A TB diagnosis can be rapidly confirmed because the organism that causes this disease grows quickly.

A driving force of this sort of evolution is _________ , which is sometimes colloquially referred to as the "survival of the fittest."

A driving force of this sort of evolution is natural selection , which is sometimes colloquially referred to as the "survival of the fittest."

What diagnostic test would be most useful at this stage of Dr. Peterson's diagnosis?

A lumbar puncture to obtain a sample of cerebrospinal fluid (CSF).

STI home test kits are still relatively new on the market. Given their newness, it is necessary to weigh the benefits and the risks to doing the tests at home. Place each statement below in the appropriate bin. Drag and drop the items into the appropriate bin.

Advantage - anyone can purchase and use increased treatment improved communication Disadvantage - kits can make mistakes increased costs information leaks

John mentioned that while in the Caribbean, he had been very careful to wear bug spray when outside and to use a mosquito net around the bed at night. Why were these protective measures not enough to keep him from being infected?

Aedes mosquitoes prefer to live inside buildings, are more resistant to bug spray, and feed during the day.

Rickettsia rickettsii is a gram-negative, obligate intracellular pathogen. Which of the following statements about the R. rickettsii life cycle is FALSE?

After entering a host, R. rickettsii multiplies to levels high enough to successfully invade cells and establish an infection.

The patient is a 30-year old woman from Charleston, South Carolina. She was admitted to the clinic for a sore throat and vomiting that she attributes to a medication she was recently prescribed following a laparoscopic hernia operation. The patient is an equestrian who earns her living teaching riding and performing at a local renaissance fair. She is in a monogamous relationship (3 years), and is sexually active (she uses oral contraceptives and condoms). She smokes cigarettes (roughly half a pack/day), but does not drink alcohol very often and denies any drug use. She keeps a dog and a cat at her home, and routinely cares for five horses and a goat at the stable she works at. She is allergic to shellfish, and has a family history of schizophrenia (father's side). Five months ago, she traveled to South Africa, where she spent eight days at Kruger National Park. One week ago, she underwent a laparoscopic operation for a hernia, and was prescribed a liquid laxative to prevent straining and/or constipation during her recovery. Since she began taking the laxative, she has developed a worsening sore throat, and within the last few days has been vomiting following ingestion of the medicine. She reports feeling "weak" with a headache, and has not been able to keep down many foods or liquids. Initial examination shows that the patient is dehydrated and appears to be nervous. When questioned about her emotional state, she responds that she has been under a lot of stress recently and has not been sleeping well for the past week. You administer intravenous fluids to treat her dehydration, and switch her laxative prescription. You discharge your patient; however, you ask her to come back in for a check-up in two days. The next day she calls you in a state of high alarm. Her right arm has been getting more and more painful and she insists that she is having a heart attack. You ask her to come in immediately. Review the patient's medical history, and then identify risks and concerns that are relevant to your diagnosis (and the patient's treatment). Indicate "YES" with a red checkmark, and "NO" with a blue checkmark.

Age-related risk of disease? Blue/No Occupational risk of disease? Blue/No Risk of sexually transmitted infection (STI)? Blue/No Risk of vector-borne disease? Red/Yes Risk of drug-related disease exposure? Blue/No Risk of travel-related disease exposure? Red/Yes Risk of genetic/familial disease? Blue/No Special concerns for treatment? Blue/No Risk of immunocompromise? Blue/No

The patient is a 74-year old man who lives in an retirement community in Rancho Cucamonga, California. He was diagnosed with prostate cancer a year ago, and is currently undergoing radiation therapy. He is divorced, and not currently sexually active. He does not own any pets. He took a trip with his son's family to the Great Smoky Mountains within the last year. During this trip, he stayed in a family cabin, which was not used very often. He noted that the screen enclosing the cabin's porch had a hole in it, which permitted several animals to take up residence in the eaves of the porch. As a result, he and his family had to clean up mouse and bird droppings, which had accumulated. He also recalled being bitten by mosquitoes several times. He has a history of hypertension on his mother's side of the family. He does not have any allergies. He does not use drugs of abuse. His chart shows that last week, during a check-up related to his radiation therapy, he complained of a headache and a stiff neck (nuchal rigidity). Since then, the patient says he has developed a fever, which had gotten progressively more severe. The patient was admitted to the hospital for fever and tremors (involuntary shaking movements) Review the patient's medical history, and then identify risks and concerns that are relevant to your diagnosis (and the patient's treatment). Indicate "YES" with a red checkmark, and "NO" with a blue checkmark.

Age-related risk of disease? Blue/Yes Occupational risk of disease? Blue/No Risk of sexually transmitted infection (STI)? Blue/No Risk of vector-borne disease? Red/Yes Risk of drug-related disease exposure? Blue/No Risk of travel-related disease exposure? Red/Yes Risk of genetic/familial disease? Blue/Yes Allergic concerns for treatment? Blue/No Risk of immunocompromise? Blue/Yes

Which of the following choices correctly matches the class of antibiotic and its mode of action? Select all that apply.

Aminoglycosides and tetracyclines are inhibitors of protein synthesis. Sulfonamides inhibit the synthesis of essential metabolites.

Identify the statements below that accurately describe the mechanisms through which organisms acquire antibiotic resistance. Select all of the statements that accurately describe the origins and spread of antibiotic resistance.

Antibiotic-resistance genes can be passed from one bacterium to another by bacterial transformation. Antibiotic-resistance genes can be passed horizontally via bacterial conjugation. Antibiotic-resistance genes can be passed horizontally via transduction. Antibiotics select for those microbes that have developed resistance, increasing their frequency in the bacterial population. Mutations are the ultimate source of antibiotic-resistance genes. Antibiotic resistance is readily transmitted to the next generation during binary fission.

After completing the prescribed antibiotics, Robert's eye was still red, painful, and draining excessively. Why were the antibiotics prescribed for Robert not effective against the organism causing his eye infection?

Antibiotics are only effective against bacterial pathogens.

You carefully think over these results. You ultimately decide to drain the pus from the carbuncle and dress the wound. You instruct the boy and his family about proper wound care and decontamination to prevent the spread and recurrence of the infection. Why did you not prescribe antibiotics in this case?

Antibiotics may increase opportunistic infections. Antibiotics will kill off beneficial bacteria. Antibiotics have side effects. Using antibiotics can accelerate drug resistance in Staph.

Which statement regarding Influenzavirus is true?

Antigenic shift can occur because the genome is in several pieces.

Scott's pimples result from the inflammatory response generated in his hair follicles. The statements below describe events that occur during this response. Place the following statements in the chronological order that best describes the sequence of events leading to the appearance of acne.

Beginning to End 1. Overproduction of sebum leads to an accumulation in the follicle. 2. P. acnes metabolizes glycerol in sebum, forming free fatty acids. 3. Free fatty acids stimulate the release of proinflammatory cytokines within the follicle. 4. The blood vessels surrounding the follicle dilate and become more permeable. 5. Immune cells such as neutrophils and phagocytes move into the follicle to try to eliminate P. acnes. 6. The buildup of dead cells, bacteria, and body fluids causes a raised pustule to appear on the skin surface.

Case conclusion: After her transfer to pediatric intensive care, Chloe is successfully placed on respiratory support. Her condition stabilizes for a short time, but thereafter her respiratory function declines progressively, and she develops bradycardia (slow heart rate) and hypotension (reduced blood pressure). She dies 3 days later. Blood cultures collected on the seventh day of her hospital stay grow Burkholderia cepacia genomovar III that is resistant to all antimicrobials. Postmortem biopsy of the lungs reveals extensive tissue necrosis characteristic of cepacia syndrome. The pathology of cepacia syndrome is often complex and due to multiple factors. All of the following factors may contribute to the development of cepacia syndrome EXCEPT which one?

Burkholderia cepacia produces an inducible beta-lactamase.

The development of which disease is promoted by mosquito-borne malarial infections?

Burkitt's lymphoma

Which of the following is NOT caused by HSV-1?

Canker sores

Now that you have considered the evidence at hand, you should start to build a hypothesis about what disease your patient has. As you ponder her symptoms, you find yourself particularly troubled by her groin swelling. Groin (or inguinal) swellings can be a common symptom of a variety of sexually transmitted infections including herpes (genitalis and simplex), syphilis, chancroid, and lymphogranuloma venereum, among others. Your patient has been in a monogamous relationship for 6 years however, and does not report using any drugs of abuse. While it is still possible that your patient has contracted a sexually transmitted infection, you also would like to consider other disease possibilities. Select all conditions that could reasonably apply to your patient.

Cat-scratch disease Tularemia Plague Chagas' disease

All penicillins, or "cillins," share several structural features but differ in others. This activity asks that you identify several features common to all "cillin" antibiotics. Drag the labels to the appropriate locations on the image.

Common nucleus - box on the top Side chain - box on the left side ββ-lactam ring - box on the bottom; pointing at yellow square

The following results were obtained from a disk-diffusion test for microbial susceptibility to antibiotics. Staphylococcus aureus was the test organism. Antibiotic: A, B, C, D Zone of Inhibition: 3 mm, 7 mm, 0 mm, 10 mm In the table, the most effective antibiotic tested was

D

MEDICAL HISTORY (Hx) The patient is a female, age 68. She is from Minneapolis, MN. She was admitted to emergency room for a sudden onset of vomiting, fever, and chills. Upon admittance, hospital staff noted that she had several large, erythematous (red) patches on her body. The patient is unmarried and not presently sexually active. She works part time in her local community center, and volunteers at a dog rescue organization. She lives in an apartment by herself and does not have any pets. She has not traveled recently, and does not report any use of illicit drugs. She has a family history of chronic rheumatoid arthritis and is currently on a course of steroids for the same. A little more than a month ago, she had a bad crash while biking. She broke her nose and wrist, and required surgery to correct both breaks. Post-surgery, the patient reported soreness and pain associated with the site of injury, and a generalized feeling of malaise. She had checked in with her surgeon at several points throughout her convalescence, and was reassured that her symptoms were not out of the range of normal recovery. Last week she noticed that several small, flat, red lesions on her wrist had developed. Upon admittance to the emergency room, she had large, diffuse red patches (similar to macules, but much larger) resembling sunburn across her neck, chest, and abdomen, as well as desquamation (peeling skin) on the tip of her nose and the palms and soles of her feet. You ask the patient to remove her sweater, and as she does, you notice several large (~1.5 cm across), raised purplish lesions that resemble blood blisters on the underside of her right arm and wrist. Review the patient's medical history and the dermatological symptoms relevant to her diagnosis. Indicate "YES" with a red checkmark, and "NO" with a blue checkmark.

Dermatological Description Exanthem - Red/Yes Enanthem - Blue/No Vesicles - Blue/No Bullae - Red/Yes Macules - Blue/No Papules - Blue/No Pustules - Blue/No

Which of the following can best explain the symptoms and deterioration of your patient's husband? Select all that apply.

Disseminated intravascular coagulation Endotoxic shock Gram-negative sepsis

Why does Dr. Bell start Caleb on HIV therapy in addition to the antibiotics used to treat the tuberculosis?

Dr. Bell prescribes Caleb HIV therapy because the virus is not affected by the antibiotics used to treat tuberculosis.

There are numerous examples of microorganisms displaying each of the four major resistance mechanisms. In this activity, you are asked to identify the mechanism that each example best illustrates. Drag each item into the appropriate bin.

Enzymatic inactivation of the antibiotic - Many strains of Neisseria gonorrhoeae are resistant to penicillin because of the production of ββ-lactamases. Prevention of penetration to the target site within the microbe - Resistance to tetracycline may result from modified pore proteins in the outer membrane that form a porin too small for the tetracycline to pass through. Alternation of the drug's target site - - Resistance to clindamycin develops when mutations in bacteria alter the ribosomal binding site to which clindamycin would normally bind. - MRSA (methicillin-resistant Staphylococcus aureus) is resistant to all ββ-lactam drugs because of a mutation in its penicillin-binding protein (PBP). Rapid efflux of the antibiotic - - Pseudomonas aeruginosa has membrane pumps that export a number of different antibiotics from its cells.

Penicillin and streptomycin are commonly used in synergism because they display the same mode of action. True or False

False

The majority of the staphylococci isolated from human skin are coagulase-positive. True or False

False

The normal flora of the skin is predominantly gram-negative rods. True or False

False

Robert went from being fine to having a full-blown eye infection. Thinking about how his eye infection could have developed, rank the following in order from the first to the last step of this disease. Drag and drop the steps below in the appropriate order from left to right.

First Step 1. Fusarium cells attach to the eye 2. fungal mat and/or biofilm form(s) 3. inflammation of the cornea 4. eye becomes red, painful, and drains 5. antifungal therapy with natamycin Last Step

Since you suspect your patient could have the plague, you must confirm your diagnosis as soon as possible! Select the most appropriate samples to establish that you patient does or does not have the plague, and if these samples come back positive; which sort of plague. Select as many sample as are useful:

Fluid from your patient's inguinal swelling Blood Sputum (mucus from lower airways)

Following a county fair, 160 persons complained of gastrointestinal symptoms. Symptoms included diarrhea (84 percent), abdominal cramps (96 percent), nausea (84 percent), vomiting (82 percent), body aches (50 percent), fever (60 percent; median body temperature = 38.3°C); median duration of illness 6 days (range 10 hr to 13 days). In the situation, fecal samples should be cultured for all of the following EXCEPT

Giardia lamblia.

Why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug?

Humans and other animal hosts lack peptidoglycan cell walls.

The at-home tests work similarly to pregnancy tests and are based on antigen-antibody reactions between the infectious agent and the patient's antibodies. Which class of antibody is most likely to give a result in the assay?

IgG

Why would conjugation to a protein carrier improve the efficacy (i.e. improve the immune response generated by the vaccine) of a polysaccharide vaccine?

In contrast to polysaccharide vaccines, protein-conjugated vaccines elicit a strong T-cell dependent response.

An indirect immunofluorescence assay is described as the CDC "gold standard serological test" for RMSF. Keeping in mind the principles behind indirect fluorescent-antibody (indirect FA) testing, which of the following characteristics contributes to its choice as the gold standard? Select all that apply.

Indirect FA will detect R. rickettsii-specific antibodies present in the patient's serum. Indirect FA is more sensitive than direct immunofluorescent testing. Indirect FA uses an antibody that reacts with any human antibody. Indirect FA is rapid, sensitive, and specific.

From the preliminary analysis, it would appear that individuals who consumed barbecue with Bubba-Qs sauce had the highest attack rate, followed by the dry-rubbed barbecue. Some of the individuals who said they ate the barbecue with the sauce did not become ill. Which one of the following is the most likely explanation for such an occurrence?

Individuals who became ill may have consumed larger quantities of the food than individuals who did not become ill.

In this case study, the main focus has been on the organism Vibrio cholerae and the toxin it produces. Many organisms are capable of producing toxins that allow for pathogenesis, while others are able to infect the host directly and cause disease. In this activity, you will place the organism in a bin based on its ability to cause an infection, an intoxication, or both. Drag and drop the items into the appropriate bin.

Infection - Vibrio cholerae Shigella sonnei Escherichia coli Salmonella enterica Intoxication - Staphylococcus aureus

In this activity, you will identify the general mechanism of inhibition for the antimicrobial actions listed. Drag each item into the appropriate bin.

Inhibiting cell wall synthesis - Inhibiting synthesis of peptide cross-links Inhibiting bonding of N-acetyl glucosamine to N-acetylmuramic acid Inhibiting lipopolysaccharide synthesis Inhibiting mycolic acid synthesis Injuring the plasma membrane - Inhibiting fatty acid synthesis Interfering with DNA replication - Interfering with DNA polymerase Inhibiting DNA gyrase Interfering with RNA synthesis (transcription) - Interfering with RNA polymerase Interfering with protein synthesis - Interfering with attachment of tRNA to mRNA Interfering with peptide bond formation, catalyzed by the ribosome Interfering with activity of 50S ribosomal subunit Interfering with activity of 30S ribosomal subunit

The activity asks you to identify potential targets of antimicrobial drugs by dragging labels to the target. Drag the following labels to the appropriate antimicrobial target in the diagram.

Inhibition of cell wall synthesis - the top box pointing at the brown outer membrane, cell wall Interference with translation - is the box in between mRNA and Protein (read left to right) Interference with transcription - is the box in between DNA and mRNA (read left to right) Interference with DNA replication - is the box found on the left side pointing at the down arrow where DNA turns (replicates) into two Inhibition of synthesis of essential metabolites - the box pointing at the enzyme Injury to plasma - the bottom box pointing at the yellow membrane

Choose the FALSE statement from those listed below.

Intestinal gas includes microbially produced oxygen.

Which of the following is NOT true of acne?

It can be treated by eliminating fatty foods from the diet.

Which of the following statements correctly describes the disease schistosomiasis?

It can cause a variety of different problems, including urinary, intestinal, and neurological symptoms, depending on the particular species.

As a child, Jamie suffered from rheumatic fever, which caused some major damage to one of her heart valves. She is OK, in general. However, she's been advised against getting body piercings, and her dentist gives her antibiotics before performing some dental procedures. What is the concern?

Jamie is more likely to develop subacute bacterial endocarditis.

The structure of the influenza virus is central to its ability to cause disease in susceptible hosts. The structure of the virus is relatively simple (compared to that of a prokaryotic or eukaryotic cell); however, each component has an important role to play in the infectious cycle of influenza. Part B Part complete Drag each one of the labels onto the figure to identify the function of each structure.

Left Side Top to Bottom 1. Assists the virus in exiting the cell after reproduction 2. protects the viral nucleic acid 3. recognizes and attaches to host cells 4. contains antigenic determinants Right Side 1. contains the viral genetic information

A 20-year-old woman comes to the local clinic complaining of lower abdominal pain and sharp burning pain on urination (dysuria) that has gone on for 1 week. She also complains of mild fever and chills. Her history and physical reveal that she has had eight sexual partners in the previous year and has used condoms only on occasion because she has been taking birth control pills. She has not visited her physician or gynecologist for 2 years. The clinic physician performs a pelvic exam and sample collection to determine the causative agent, telling the patient that she likely has contracted a sexually transmitted infection (STI). Sexually transmitted infections (STIs) are a significant problem in the world. The symptoms described in the case thus far are fairly general and may apply to multiple STIs. However, many STIs can be discerned by other visual signs that accompany the general symptoms. Drag each of the organism labels onto the picture that best matches the MOST identifiable trait/symptom associated with each disease appearance.

Left Side Top to Bottom - 1. Neisseria gonorrhoeae 2. Herpes simplex virus (HSV) 3. Human papillomavirus (HPV) Right Side Top to Bottom - 1. Treponema pallidum 2. Chlamydia trachomatis 3. Candida albicans

RMSF results from the interactions that occur between the R. rickettsii pathogen and the host. The infection results from a coordinated series of events that ultimately result in disease. Apply your knowledge of bacterial pathogenesis and the symptoms of RMSF to predict the order of events that occur during RMSF.

Left to Right 1. Tick bites transmit R. rickettsii into bloodstream. 2. R. rickettsii travels throughout the body via the blood and lymph systems. 3. R. rickettsii invades endothelial cells of blood vessels. 4. R. rickettsii multiplies within host cells. 5. Blood begins to escape from vessels as a result of increased vascular permeability. 6. Symptoms, such as a macular rash, develop.

Which of the following contribute to drug resistance in M. tuberculosis? Select all that apply.

Many individuals fail to complete their entire regimen of antibiotics. Some physicians prescribe the wrong medication, the wrong dosage, or the wrong length of time for treating tuberculosis. In many areas, tuberculosis antibiotics are unavailable or of poor quality.

Which of the following cause(s) ringworm?

Microsporum and Epidermophyton

What is the likely cause for the drop in glucose levels?

N. meningitidis uses the glucose as a source of energy to fuel its growth.

Nicole received her diagnosis at her physician's office. Which of the following procedures was most likely used by the physician to confirm her infection?

Nucleic Acid Amplification Testing (NAAT)

Part of the reason for Scott's acne is the overproduction of sebum. Scott's initial instinct is that shutting down production of sebum would be the quickest route to eliminating his acne; however, sebum actually plays an important role in maintaining the skin as a first line of defense against pathogens. Which of the following best describes the role of sebum as a component of the first line of defense?

Sebum forms a protective layer over the skin. Sebum helps to keep the pH of the skin low, which inhibits the growth of microorganisms.

John went to a picnic. He took home some leftover chicken and rice, heated it on the stove, ate it, and got sick two hours later. John thought the heating made his food safe because it would have killed any bacteria present. He didn't know that __________ produces a heat-stable toxin.

Staphylococcus aureus

These results support the idea that your patient's infection was caused by ______.

Staphylococcus aureus

Which of the following statements regarding African trypanosomiasis is true?

T.b. rhodesiense not only causes disease, but also severely affects food production because it infects domestic animals, which could otherwise be used for agriculture.

Which of the following is an accurate statement concerning the Sabin and Salk vaccines?

The Sabin vaccine is slightly more dangerous because it is made from live, attenuated virus, and the virus occasionally reverts back to its pathogenic form.

Improved water sanitation and hygiene services are listed in the Big Picture activity as a method of prevention for NTDs. Why is water sanitation a possible method of prevention?

The ability to bathe in clean water can help in the reduction of disease transmission.

Based on the information from Part B, the causative agent of Robert's eye infection is most likely the fungus Fusarium. Some species of Fusarium are known to produce biofilms. Which of the following is NOT a way in which the biofilm helps in the fungal pathogenesis involved in keratitis?

The biofilm allows for the breakdown of cellulose by producing the enzyme cellulase.

The pathogenesis of Vibrio cholerae is due to the organism's ability to produce cholera toxin. This is an A-B toxin that affects host cells in the small intestine. Which of the following correctly describes the mechanism of the toxin?

The cholera toxin causes the host cells to secrete large amounts of fluids and electrolytes.

You contact the New York City Department of Health and Mental Hygiene, as well the New Mexico Department of Health, and update them on the cases you have diagnosed. Both agencies are eager to locate where and how the infections were first contracted. Where will you recommend that investigators FIRST look for the source of infection? Select the BEST answer.

The couple's parent's ranch in New Mexico

Why is bacterial meningitis considered more life threatening than viral meningitis?

The immune response generated against bacteria leads to a massive influx of immune cells in the meninges; this response is much less extreme in viral meningitis.

Postexposure treatment for rabies includes vaccination and injection of immunoglobulin; why does postexposure vaccination work?

The infection progresses so slowly that there is time for postexposure vaccination to generate immunity.

An individual presents with a pinkish-red rash and a red sore throat. Gram-positive cocci are cultured from a throat swab. The cocci are growing in chains. Which of the following is the most likely conclusion?

The patient has scarlet fever.

Your screening results come back from the lab and they are negative for all possible pathogens. You order a second screening immediately. What is one possible reason for certain organisms to be prematurely (and sometimes wrongly) dismissed from pathogen screens when a microbial disease of the skin is suspected?

The presence of certain organisms may not seem significant because they are part of the normal skin microbiota.

In untreated individuals, the mortality rate of cholera can be as high as 50%, but in individuals that are given oral rehydration therapy, fatalities are rare. Oral rehydration therapy involves treating the patients with an oral suspension of salt, sugar, and water. Which of the following choices explains why this suspension is used instead of pure water to treat cholera infections?

The salt and sugar in the rehydration solution will replace lost electrolytes and the water replaces the lost water.

Which of the following statements concerning viral sexually transmitted infections (STIs) is true?

The viral infections that cause genital warts and herpes can be treated but not cured.

Which of the following is FALSE concerning Clostridium species?

Their main reservoir is rabbits.

What is a likely result of the elevated WBC level in Claire's CSF?

There will be an extreme inflammatory response which will eventually lead to shock and ultimately to Claire's death.

There are a large number of antibiotics that inhibit protein synthesis at 70S ribosomes found in bacterial cells but do not interfere with protein synthesis at the 80S ribosomes found in eukaryotic cells. Some of these antibiotics bind to the smaller ribosomal subunit and interfere with the reading of the mRNA code, whereas others bind to the larger ribosomal subunit and inhibit the formation of peptide bonds. Unfortunately, some of the antibiotics that inhibit protein synthesis in bacteria exhibit some toxicity to the eukaryotic host cells as well. What is the most likely reason for this toxicity to the host cell? Select the correct answer.

These antibiotics interfere with protein synthesis within eukaryotic mitochondria.

Which of the following statements about drugs that competitively inhibit DNA polymerase or RNA polymerase is FALSE?

They cause cellular plasmolysis.

Natural selection is a gradual, nonrandom process by which biological traits become more or less frequent within a population. Which of the following are necessary conditions for natural selection to occur within a population of Staphylococcus aureus?

Traits are hereditary. Traits that permit an individual to survive at least until reproduction will increase in frequency over time. Individuals in the population vary from one another. Some individuals in the population reproduce more than others.

Nicole knew that these were both sexually transmitted infections caused by bacteria. Which of the following is correct regarding the causative agents for these diseases?

Treponema pallidum causes syphilis, while Neisseria gonorrhoeae causes gonorrhea.

Which of the following organisms is likely to be transmitted via undercooked pork and horse?

Trichinella spiralis

Pathogens of the skin often enter via hair follicles and ducts of the sweat glands. True or False

True

Whitney went on a mission trip to Africa with her church group. They visited for two weeks and worked with doctors in the area to provide information about tropical diseases and the availability of treatment and vaccines. About a month after returning home, she started having headaches, fever, and severe joint pain. She went to the doctor and was diagnosed with African sleeping sickness. What is the causative agent of this disease?

Trypanosoma brucei

Cholera is a waterborne pathogen that causes severe gastrointestinal disease. The organism is a slightly curved, gram-negative rod that likes to grow in the small intestine and causes watery stools and violent vomiting. Complete the following statement: Cholera is caused by the bacterium, __________ and produces __________ that result in severe diarrhea.

Vibrio cholera; exotoxins

Why is it difficult to find good chemotherapeutic agents against viruses?

Viruses depend on the host cell's machinery, so it is hard to find a viral target that would leave the host cell unaffected.

Your laboratory results are shown here: Does your patient have the plague? Can you say which form?

Yes, she has bubonic plague

You have a culture of bacteria that you suspect is either Staphylococcus aureus or Streptococcus pyogenes. Is there any morphological difference between the two?

Yes. S. aureus tends to grow in clusters, whereas S. pyogenes tends to grow in chains.

What does this evidence show? Select the best answer.

Your patients could have bacterial meningitis or listeriosis.

Post-mortem brain tissue biopsy shows the following: What is indicated by the arrow?

a Negri body

Our patient needs antibiotics to overcome this infection and prevent any further complications. Which of the following would be the best choice?

a combination therapy of cephalosporin-class AND macrolide-class.

John's physician said that he might be suffering from Chikungunya fever, an emerging disease that once was limited to Asia, Africa, and Europe, but is now making appearances in the Caribbean and the United States. How did John most likely get infected?

a mosquito bite

When the antibiotics failed to work against Robert's infection, the doctor was concerned that it might be caused by a fungal pathogen. The lab technician collected a sample from the pair of contacts he was wearing when he first started having symptoms, as well as the cleaning solution that he was using. The lab technician plated the samples on Sabaroud-Dextrose agar and incubated it for 5 days at 26 degrees C. After growth appeared on the agar, a microscope slide was made, stained with Lactophenol Cotton Blue, and observed. Which of the following would the lab technician most likely see?

blue filaments and conidiospores

The physician performs a pelvic exam, which reveals the presence of an abnormal thin, watery vaginal discharge and inflammation of the cervix. The physician then palpates the abdomen (examines by touch and pressure) and finds that the uterus, fallopian tubes, and ovaries are enlarged and tender. The physician takes a swab sample of the cervix and sends it to the laboratory to determine the causal organism. Light microscopy and simple staining of the sample in the lab reveal an organism with a very unique life cycle. The organism is classified as gram-negative, but it stains very poorly compared to other classic gram-negative STI pathogens. The stain shows both a nonreplicating, extracellular infectious elementary body and a replicating, noninfectious reticulate body inside mucosal cells from the cervical epithelium swab. Based on the symptoms and these new laboratory findings, which of the following would be the most likely diagnosis for the patient?

chlamydia

These signs are ______.

consistent with the symptoms of toxic shock

In cystic fibrosis, a defective gene and its protein product lead to the production of thick and dehydrated mucus because of __________.

defective secretion of chloride ions and excess absorption of sodium

Fill in ONE diagnostic method that will allow you to accurately confirm your diagnosis. You order the ___________ to be performed on a sample of your patient's saliva.

direct fluorescent-antibody

In the 1940s, penicillin began to be widely used to treat a variety of bacterial infections. At that time, penicillin-resistant strains of S. aureus were virtually unknown. Twenty years later, 80% of hospital-acquired S. aureus were penicillin-resistant, leading to the introduction of methicillin in 1961 to combat penicillin-resistant strains. Within one year, doctors began to encounter methicillin-resistant strains of S. aureus. Since the development of methicillin-resistance, strains of S. aureus have become resistant to beta-lactam drugs (including all the penicillins), as well as some cephalosporins, leaving vancomycin (typically a "drug of last resort") as the favored treatment for antibiotic-resistant Staph infection.In the late 1990s, vancomycin-resistant strains of Staph began to appear. Around that time, oxazolidinones also became available, and linezolid, also a drug of last resort, was introduced as a treatment for S. aureus. Linezolid-resistant strains of Staph were subsequently reported in 2003.The development of multi-drug resistance in Staphylococcus aureus is a classic example of ______.

evolution

It was the spring of 1918, and the world was at war. In Haskell County, Kansas, an epidemic of influenza was underway. Public health officials in Washington, D.C. were notified; however, no investigators were sent. Meanwhile, soldiers from all across Kansas were reporting to Camp Funston in training for the war. In hindsight, it appears that a soldier from Haskell County brought influenza with him to Camp Funston. By the middle of March, there was an epidemic in the camp. Ultimately, about 1100 soldiers were infected and 38 died during the outbreak. Unfortunately, the reporting methods at that time were not particularly good. The epidemic at Camp Funston essentially went unnoticed by public health officials. Within only a few months, the country would be caught in an epidemic that no one could ignore. During the initial epidemic at Camp Funston, the infection was characterized by several of the typical symptoms of influenza infection. Which of the following are symptoms of influenza infection? Select all that apply.

fever muscle pain headache

Recurring vesicles on the surface of human skin are symptoms of

genital herpes.

A patient presents with diarrhea that has lasted for weeks and is accompanied by malaise, flatulence, weight loss, and abdominal cramps. You detect the odor of sulfur on his breath. Based on the signs and symptoms, you suspect __________, a protozoan. It is not easily found in stool samples, so you do a string test.

giardiasis

Gums bleeding while brushing one's teeth is most commonly associated with

gingivitis.

You take a sample of pus from your patient's abscess for analysis. Results from Gram-staining are shown here: What does this result show?

gram-positive, spherical bacteria

Vaccines can be used to protect at-risk individuals from all of the following liver diseases EXCEPT __________.

hepatitis C

Research has indicated that during the inflammatory response to P. acnes, both the classical and the alternative complement pathways are activated. Which of the following are outcomes of activating complement pathways?

inflammation opsonization cytolysis

Necrotizing fasciitis is an aggressive and dangerous infection, and although it can occur as a result of several types of bacteria, it is most frequently associated with S. pyogenes infection. On a molecular level, S. pyogenes has several virulence factors that contribute to the speed and severity of necrotizing fasciitis (and other streptococcal conditions). S. pyogenes is a beta-hemolytic bacterium that is categorized with the group A streptococci (GAS) based upon the antigenic carbohydrates of its cell wall. The GAS have a virulence factor known as an M protein, which helps them evade phagocytosis and colonize mucous membranes. In addition to the M protein, the GAS can produce several other substances that promote the rapid spread of an infection. These substances include hyaluronidases, streptokinases, deoxyribonucleases, and streptolysins, which each perform different duties as the infection spreads (liquefying pus, breaking down cell's DNA, weakening connective tissue, lysing blood cells, etc.). In addition to these substances, S. pyogenes also produces a substance known as exotoxin A. Exotoxin A is considered to be a superantigen because ______.

it can provoke an intense immune response

Penicillin was considered a "miracle drug" for all of the following reasons EXCEPT

it was the first antibiotic.

Which of the following is caused by Chlamydia?

lymphogranuloma venereum

If a patient is diagnosed with trichomoniasis, which treatment should be prescribed?

metronidazole

Which of the following is an antiprotozoan drug that interferes with anaerobic metabolism?

metronidazole

The prodromal (i.e. pre-acute disease stage) symptoms of bacterial meningitis is/are

mild cold symptoms

Treating fungal infections can be challenging. Fungi are classified as eukaryotic organisms, the same as their human host. The idea that antimicrobial drugs should only affect the microbe without harming the host is an important principle in microbiology. It is referred to as the principle of __________.

selective toxicity

Which of the following does NOT affect eukaryotic cells?

semisynthetic penicillins

During his presentation to the Microbiology Club, Cody mentions that the cholera epidemic in 2010 came shortly after an earthquake. He also mentions that other cholera epidemics had occurred following natural disasters such as flooding. Which of the following has the greatest impact on the number of cholera cases after a natural disaster?

sewage contamination in drinking water

Which of the following is/are associated with secondary stage syphilis?

skin rashes of varying appearance

Now that you have considered the evidence at hand, you should start to build a hypothesis about what disease your patient has. In the beginning of your diagnostic process you should try to think broadly and consider any and all reasonable possibilities. You can then narrow down these possibilities by performing diagnostics that can support or refute your hypothesis. Select all conditions that could reasonably apply to your patient.

staphylococcal skin infection (folliculitis, impetigo, scalded skin syndrome, toxic shock syndrome) acne streptococcal skin infection (necrotizing fasciitis, erysipelas)

What part of the United States is endemic for RMSF?

the Appalachian region (North Carolina, Kentucky)

Use of antibiotics in animal feed leads to antibiotic-resistant bacteria because

the antibiotics kill susceptible bacteria, but the few that are naturally resistant live and reproduce, and their progeny repopulate the host animal.

As you speak to your patient about her medical history, you notice that she is beginning to slur her speech, and that she seems to be breathing heavier than she was during intake. You immediately become concerned that something very serious could be going on! Which of the following conditions is the most dangerous possibility for her symptoms?

toxic shock syndrome

Now that we have looked at ways to prevent breeding in mosquitos, another possible prevention is to limit the vector geographically, but recent climate changes have led to changes in location where the mosquito can now be found. Which of the following climate change scenarios has allowed for this increase in vector habitat?

warmer temperatures in northern regions with increased rainfall

Drug resistance occurs

when antibiotics are used indiscriminately.

If a person in the United States is exposed to rabies, which animal is the most likely culprit?

wild bats