Microbiology - Chapter 19 - Mastering
What would have been the possible source for this patient's infection?
Contaminated water in Thailand was used for drinking or cooking.
Along with intravenous rehydration, many of the medication groups listed below may be used for secondary infections. But which group must be used if the infection is to be controlled?
antiprotozoan medications
As a means to confirm diagnosis, TCBS agar (Thiosulfate-citrate-bile salts-sucrose agar) is used to grow Vibrio cholerae from patient samples The recipe for this growth media is shown below. Based on this information, which of the following statements accurately describe this media? Select all that apply. (NCLEX-HESI-TEAS style)
Bromothymol blue and thymol blue contribute to this agar's use as a differential media. This agar is selective. This media is considered a complex agar.
Which of the following provides the best definition for the term dysentery?
Diarrhea accompanied by pain, blood, and/or mucus
Which species of amoeba would be considered the causes this patient's disease?
Entamoeba histolytica
The incidence of cholera in the city has been recorded for the past decade and is shown in the graph below. (Note, more cases were eventually identified than were originally discovered in the case.) The 10-year average is indicated by the dashed red line. Using the incidence data, select the epidemiology terms that accurately describe this year's outbreak. (NCLEX-HESI-TEAS style)
Epidemic
The organism isolated from the sprouts is oxidase negative, motile, ferments glucose and lactose, and cannot utilize citrate. What organism is it?
Escherichia coli
The HE results indicate the presences of Salmonella.
False
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
Why does Dr. Clark request stool samples for examination?
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.
Which of the findings listed below support the hypothesis?
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. Histological observation indicates that morphological alteration and sloughing of epithelial cells occurs up to a maximum of 1000 units. Protein levels within the ileum loop fluid are increased up to 1000 units of toxin.
Ashleigh suspected the illnesses she saw were likely caused by norovirus. What information from the case support(s) that hypothesis? Select all that apply.
Patients were experiencing a low fever. Patients were experiencing gastrointestinal distress. The first signs/symptoms appeared within 48 hours of the patient's initial infection.
You are tending to your preschool-aged patient who presents with excessive anal itching. The child's mother notes that the child woke several times during the night due to anal irritation. Gastrointestinal symptoms are absent. You recommend performing a tape test on the child. Which of the following diseases is the pediatric patient most likely afflicted with?
Pinworm
Which of the following organisms is most likely the causative agent of Michael's tapeworm infection?
Taenia solium
Examine the photomicrograph and then drag the organism classification to correctly complete the sentence.
The organism appears to be an amoeba.
The EMB results would accurately be reported as two fecal coliforms / 100 mlml water sample.
True
Which of the following organisms can cause water-borne diarrheal disease?
Vibrio cholerae Entamoeba histolytica Cryptosporidium enteritis
If not handled promptly with the correct treatment regime, which of the following infections may develop and be considered as life threatening?
extraintestinal amebiasis
How did this couple become infected with C. jejuni?
ingestion of contaminated, raw milk
Amoebae are a group of protozoa that move and feed using __________.
lobe-shaped pseudopods
What is the recommended course of therapy?
oral fluids
If you were an epidemiologist looking for the source of the pathogen, what samples would you collect at Jane's house? Please select all applicable answer choices. There may be more than one correct answer.
- Soil sample (including clover sample) - Food preparation areas (such as kitchen countertops), food preparation tools (such as knives used to cut food), and consumed food items (including the baby jar food) - Stool sample of caretakers
Which of the following virulence factors are used by Shigella to facilitate development of disease? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer.
- Toxin production - Induction of endocytosis - Actin propulsion system
Is the pediatrician suspecting a bacterial or viral pathogen? What tests will help identify the causative pathogen?
A bacterial pathogen is suspected. Stool samples from infected individuals should be sent for growth culture analysis.
Which of the following statements is true concerning the life cycle of Giardia lamblia?
After ingestion, a Giardia lamblia cyst hatches into two trophozoites in the small intestine.
How does boiling water kill pathogens in it?
Boiling denatures proteins and cell membranes.
In a single day, two 19-year-old women and one 20-year-old man sought treatment at a university health clinic, complaining of acute diarrhea, nausea, and vomiting. No blood was found in their stools. One of the women was found to have a urinary tract infection. All three had eaten lunch at a nearby health food store the previous day. The man had a sandwich with tomato, avocado, sprouts, pickles, and sunflower seeds. One woman had a pocket sandwich with turkey, sprouts, and mandarin oranges; the other woman had the lunch special, described in the menu as a "delightful garden salad of fresh organic lettuces, sprouts, tomatoes, and cucumbers with zesty raspberry vinaigrette dressing." All had bottled water to drink.
Case 3
After ingesting contaminated spinach, your patient presents with fever, jaundice, severe abdominal pains, and hemorrhagic diarrhea. You believe that the patient has contracted Enterohemorrhagic Escherichia coli. Which of the following laboratory techniques would be the most useful for identification of the foodborne pathogen?
Cultural analysis of stool sample on sorbitol-MacConkey (SMAC) agar
Which of the following findings are key to the cause of the outbreak?
Large quantities of meat were prepared and kept warm for a long time before they were served. The sauce was prepared on an overcrowded steam table and, as a result, did not reach an appropriate temperature to kill any organisms.
Was the pediatrician negligent in not prescribing antibiotics? Why or why not?
No. Supportive therapy is the suggested treatment for mild cases of several bacterial diseases, including the one presented in the case study.
Which of the following best describes the role of mucosa-associated lymphoid tissue (MALT)?
Phagocytic protection from pathogens and mediation of immune responses
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.
What is the word used to refer to diseases transmissible from animals to humans?
zoonoses
How does the child chewing on clover leaves impact the list of suspected potential pathogens? Please select all applicable answer choices. There may be more than one correct answer.
- Fecal matter from the free-roaming chickens may have contaminated the clover leaves. Thus pathogens found naturally in chicken intestines should be of increasing concern. - Since only the ill child chewed on the clover leaves, it is now more likely that the clover leaves are the source of infection (as opposed to the raw eggs and poultry).
The next day Richard examines the plates. The EMB agar plates average two blue colonies / plate. The HE agar plates have only a few yellow/orange colored colonies.
1.) Fecal coliform 2.) Non-fecal coliform
Based on information provided, what is another piece of evidence that may support Jane's claim of safe food handling? Please select all applicable answer choices. There may be more than one correct answer.
1.)The sick twin had stuffed clover leaves into her mouth, making the clover leaves a suspected source of infection, as opposed to a contaminated food item or preparation area. 2.) Only one of the twin daughters is ill, yet both children most likely ate the same food items (the fruit and baby jar food item).
What is the best way to prevent the spread of this infection?
All food handlers are required to wash their hands thoroughly after using the restroom.
Which of the following statements accurately describes a chronic Hepatitis B viral infection?
Chronic Hepatitis B viral infections can promote cirrhosis and hepatocellular carcinomas.
Giardia undergoes a process called encystation that requires a large energy investment. Cysts are considered the parasite's infective stage. What advantages does encystation provide for the microbe? Select all that apply.
Cysts can tolerate low pH. Cysts have a survival advantage in the environment. Cysts can resist pharmacological therapies. Cysts resist water chlorination and ultraviolet treatment.
Richard loves his job working for the Tri-County Water District. In his seven years with the district, he has had many different jobs; currently he is a Waste Water Treatment Laboratory Technician. Today, he is doing his routine visit to one of the three Waste Water Treatment Facilities, where he'll collect samples of the treated water to take back to the lab. At the lab, his coworker Joey will do a chemical analysis of the water, while he does the microbiological analysis. To collect the samples at the waste water facility, Richard first dons his gloves, and then he uses the grab sample technique to fill his various containers, filling the sterile glass flasks he will use for his micro analysis last. To preserve the chemical integrity of the water sample and accurate microbial population estimates, these samples have to be chilled, and the analysis must begin within the hour. Once all of his samples are collected, he disinfects the outside of the containers, removes his gloves, and disposes of them in the biohazard bin. After washing his hands, he gets out a waterproof pen to label the containers with his name, the sample site location, and the date and time of the sample collection. Back at the lab, Richard gives the chemistry samples to Joey, and then heads to his microbiology lab. He starts setting up his tests to look for Enterobacteriaceae in the water samples.Which of the following best describes the Enterobacteriaceae group (enteric bacteria)?
Gram-negative bacillus found in many locations including animal intestines
Which of the following media is used to isolate Gram-negative organisms?
MacConkey agar plate
Two days after disembarking on a Caribbean cruise, twenty percent of the passengers aboard an American cruise ship became violently ill with profuse vomiting and diarrhea. Gastrointestinal symptoms lasted up to 3 days. Patients ranged in age from toddler to senior, and the majority of those infected were up-to-date on all vaccinations. Which of the following infections was the most likely cause of illness aboard the ship?
Norovirus gastroenteritis
Richard decides to use Hektoen Enteric Agar (HE) to detect the presence of Salmonella and differentiate it from Escherichia. He carefully notes the composition of HE agar and the expected results.HE contains the following:- bile salts to inhibit most Gram positive bacteria- lactose, sucrose, salicin sugars available for fermentation- bromothol blue as pH indicator to detect acid produced by fermentation- sodium thiosulfate available for bacterial sulfur reduction- an iron compound that will react with any H2S produced and turn blackPossible HE results in the following:- Pink/orange/yellow colonies indicate sugar fermentation.- Blue/green colonies indicate no fermentation and no sulfur reduction.- Black colonies indicate sulfur reduction and no fermentation.He pours 100 mlml of the sample water through a filtration membrane, and then he places the membrane on HE agar. He makes two duplicate plates and places these in the incubator at 37 degrees Celsius. Richard cleans up and disinfects his work area. Next, he takes a quick inventory of the media, places an order for a few reagents, and heads home for the day. Which of the following are coliforms?
Serratia Klebsiella Enterobacter
Which food is the most likely source of the infection?
Sprouts
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.
Why did the pediatrician assume Jane was mishandling raw eggs and poultry?
The girl's exhibited symptoms align with campylobacteriosis and salmonellosis, diseases caused by gastrointestinal pathogens that are known to be associated with poultry.
Your teenage patient presents with muscle weakness and is unable to move her legs. She notes that yesterday she felt a tingling sensation in her feet. Three weeks prior, the patient had a severe diarrheal illness. Which of the following is the most likely mechanism through which the patient contracted this illness?
eating undercooked chicken
Ashleigh's working diagnosis for her patients was based mainly on the signs and symptoms present, which included fever, vomiting, nausea, and diarrhea. Which of these manifestations are signs? Select all that apply.
- Diarrhea - Fever - Vomiting
Which of the following clinical signs and symptoms is characteristic of a mumps infection? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer.
- Dry mouth - Swelling of the parotid salivary glands
Which of the following are virulence factors used by Helicobacter pylori to facilitate the development of stomach ulcers? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer.
- Polar flagella - Production of VacA toxin
What is the most likely cause of this couple's disease?
Campylobacter jejuni
Which protozoan disease would be responsible for the symptoms seen in this patient?
Invasive amebic dysentery is characterized by severe diarrhea, colitis, bloody mucus-containing stools, and pain; symptoms that match those seen in this patient.
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%
Which of the following explains the mechanism of dental cavity formation?
Biofilms on the surface of the teeth ferment sugars (especially sucrose), and the resulting acid degrades the tooth enamel and damages dentin.
Two patients--a woman and her husband, ages 23 and 22, respectively--arrive at the health clinic one morning. They report having had severe abdominal cramps, grossly bloody diarrhea, nausea, and fever for 48 hours. Cultures of stool samples grown under microaerophilic, capneic conditions contain comma-shaped, Gram-negative bacilli. Both the patients are lactovegetarians and report being part of a "cow leasing" program at a local dairy in which patrons lease part of a cow's milk production so that they can drink natural, whole, raw milk. The couple devised the program so that they and several neighbors could circumvent state regulations prohibiting the sale of unpasteurized milk. Investigators obtained and cultured a milk sample from the dairy's bulk milk tank.
Case 2
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
Case 5
in water quality sampling, it is typical for the technician to look for fecal coliforms to indicate sewage contamination. Rapid carbohydrate fermentation is a reliable test for detecting the presences of fecal coliforms. Richard runs this test routinely: He pours 100 mlml of the sample water through a filtration membrane, and then he places the membrane on an eosin methylene blue (EMB) agar. He makes two duplicate plates and places the samples in the incubator at 44.5 degrees Celsius so that the bacteria can grow into colonies. These colonies will appear blue if rapid carbohydrate fermentation is occurring. Each blue colony on the filter is assumed to be the result of one fecal coliform in the original water sample. Richard is also planning to test for the presence of Salmonella in his samples, as local people had been reporting concerns about a large, new chicken ranch in the area. Richard needs to design a method to differentiate Salmonella from other similar species, so he gets out reference material that includes a dichotomous key, a tool to identity organisms through the process of eliminating characteristics that do not apply to it.
Escherichia: - Rapid Lactose Fermentation - No H2S Production Salmonella: - No Rapid Lactose Fermentation - H2S production
Your patient complains of upper abdominal pain, heartburn, and indigestion. Based on the patient's case history and clinical presentation, you believe that your patient has a stomach ulcer caused by a resident microorganism. You ask the microbiology laboratory to culture the stomach pathogen from a gastric tissue biopsy. Which of the following bacterial genera would you expect the microbiology laboratory to observe in the patient's culture?
Helicobacter
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.
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.
Patty returns later and says she found amoeba trophozoites and cysts. Since amoebae are not uncommon in fresh water and they are not generally pathogenic, she has done a serological test using antibodies and, unfortunately, has discovered that the organism is Entamoeba histolytica. Which of the following should be employed to avoid further problems with the Entamoeba histolytica?
Post warning that the water should be filtered before drinking. Advise doctors to prescribe iodoquinol to people who have been drinking the lake water and now have diarrhea. Advise people that have been drinking the lake water, but do not have symptoms, to visit their doctor and ask about a prescription for paromomycin.
If filtering and boiling water can prevent infection, how do you think most gastrointestinal illnesses are transmitted?
Through the fecal-oral route
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.
Which of the following symptoms is LEAST characteristic of Clostridium perfringens food poisoning?
moderate vomiting and fever
