Disease 3

Identify which of the following genera have members that are disease-causing facultative anaerobes.

- Corynebacterium - Escherichia - Staphylococcus

Required information Skip to question Legionnaires' disease (also known as Legionellosis) is a serious, potentially fatal respiratory disease. Signs and symptoms include fever, muscle aches, confusion, cough, and shortness of breath. The disease is caused by inhaling small droplets of water containing the fastidious, Gram-negative bacterium Legionella pneumophila. The number of cases of this disease has been on the rise in the United States since 2000, with approximately 6,000 cases occurring in 2015. In Arizona, there were two reports of this disease in newborn infants in 2016. Both babies were delivered at home in birthing tubs (water births). The delivery of Baby A was overseen by a midwife and took place in a tub filled with tap water. The infant's Apgar score was recorded and was 5/10 at 1 minute and 9/10 at 5 minutes. The Apgar score is a measure of a newborn's physical condition and is obtained by adding points for skin coloration (appearance), heart rate (pulse), response to stimuli (grimace), muscle tone (activity), and respiratory effort (respiration). The next day, the infant was taken to the emergency department (ED) with severe respiratory distress, tachypnea (abnormally fast breathing), and hypoxemia (abnormally low blood oxygen levels). The infant was diagnosed with congenital heart disease and was admitted to the hospital where further tests were performed. Chest X-rays showed left lobe opacity (cloudiness) which was thought to indicate a collapsed lung. However, opacity can also suggest pneumonia. A bronchoscopy with a bronchoalveolar lavage (flushing a small part of the lung with liquid that is then collected for culture purposes) were performed on the child at a different hospital. L. pneumohpila was cultured from the fluid and the infant was diagnosed with Legionnaires' disease. The child was treated with azithromycin and recovered. Investigation of the tub in which Baby A had been delivered showed that it was new, had been cleaned with vinegar and water, and then filled with tap water using a new hose immediately before the birth. The mother delivered the infant within an hour of entering the tub, and the infant was not observed to have inhaled any of the tub water. Baby B was also delivered in a water birth but the birth was overseen by a different midwife from the previous case. Three days after the delivery, the baby developed a high fever (102.6o F) and was brought to the ED. A chest X-ray showed lung opacities and pneumonia was suspected; the child was admitted to the hospital for treatment. Culture of respiratory secretions revealed L. pneumophila. Like the first case, the baby was treated with azithromycin and recovered. Investigation into the case revealed that this infant had been born in a rented jetted Jacuzzi hot tub. The tub had been filled with tap water through a newly purchased hose, and had been maintained at 98o F for a week before the birth (the optimum growth range of L. pneumophila is 77o F - 108o F). The mother went through her labor outside the tub, only getting into it to deliver the baby. The infant was not observed to have inhaled any water. In both cases, the tube water was discarded directly after the births, so it was not possible to culture the tub water. In each case however, tap water (which is not sterile) was used to fill the tubs. The ability of L. pneumophila to thrive in biofilms in man-made water systems, including plumbing, is well documented, suggesting that in both cases, the tap water had been contaminated with this pathogen. These cases led to the development of guidelines for home deliveries, including using new, disposable birthing tubs or lined, disinfected reusable tubs, running hot water through the filling hoses for three minutes before filling the tub, and changing the water into the tub every 6 hours. Select all the true statements regarding Legionella pneumophila.

- It has a thin peptidoglycan cell wall and an outer membrane. - It requires special media for culture. - It can create a biofilm in water pipes. - It is transmitted in aerosol droplets that are inhaled by a person.

Which of the following statements regarding the Enterobacteriaceae are TRUE?

- They are Gram-negative rods that form part of the normal microbiota. - Their name derives from the fact that they reside in intestinal tracts of humans and animals. - They are facultative anaerobes that ferment glucose. - Enterobacteriaceae called coliforms ferment lactose.

How does H. pylori survive stomach acidity?

- it burrows into the stomach's mucus coating - it produces ammonia from urea

Which of the following invade(s) intestinal cells? 1. Shigella species 2. Vibrio cholerae 3. Helicobacter pylori 4. Giardia lamblia

1

Which of the following produce functionally similar/identical toxins? 1. Shigella dysenteriae 2. E. coli O157:H7 3. Vibrio cholerae 4. Giardia

1 and 2

Required information Skip to question You are a nurse on a post-surgical ward. One of your patients is an elderly woman who has just had her gallbladder removed. When you go into her room to check on her, you find that she has significant diarrhea, as well as fever and abdominal pain. You suspect that she has Clostridioides difficile infection (CDI), and send a sample of her feces down to the hospital lab for analysis. The test result indicates that your patient does indeed have CDI. You make your patient comfortable and answer her questions about her illness. 1. You tell your patient that her CDI is caused by a bacterium belonging to the genus Clostridium. Which of the following is true of all Clostridia? 2. Clostridioides difficile produces toxins that are involved in the pathogenesis of CDI. Which toxins are associated with ALL strains of this organism?

1. They are Gram-positive, rod-shaped, endospore-forming obligate anaerobes. 2. Toxin A and toxin B

Required information Skip to question Clostridioides difficile is a Gram-positive, spore-forming, obligate anaerobe that is found in the normal microbiota of some people and is acquired by others via the fecal-oral transmission route. This organism can cause Clostridioides difficile infection (CDI*), the signs and symptoms of which range from mild diarrhea to severe colitis that in rare cases may be fatal. There are several strains of C. difficile; those that cause illness produce exotoxins, including toxin A and toxin B. Detection of these toxins in a person's stool is used for CDI diagnosis. CDI primarily occurs in older people in healthcare facilities or hospitalized patients on antibiotic therapy. Antibiotics can disrupt the person's normal intestinal microbiota, allowing C. difficile to thrive. Treatment of CDI involves taking the patient off the antibiotic that caused the patient to develop CDI initially. This allows the person's normal microbiota to recover, and to out-compete the C. difficile. If the patient is not cured by this measure, they are given a different antibiotic, typically vancomycin and/or metronidazole. Community-acquired CDI cases (CA-CDI) are now becoming increasingly common, affecting healthy people with no apparent risk factors. The Pennsylvania Department of Public Health (PDPH) reported two such cases. Patient A, a 34-year old woman 14 weeks pregnant with twins, went to her local emergency department (ED) complaining of 3 weeks of sporadic diarrhea. For three days before going to the ED, she had experienced cramping, and had passed watery, black stools 4 to 5 times every day. The patient's stool tested positive for C. difficile toxin. Her only history of antimicrobial use before the onset of the diarrhea was trimethoprim-sulamethoxazole that she had been given for a urinary tract infection three months before her current illness. The patient was hospitalized and given metronidazole for the CDI. She was discharged after a day, but the following day she was readmitted with severe colitis. She remained in the hospital for 18 days, where she was given metronidazole, cholestyramine and oral vancomycin. She improved and was discharged again. However, 4 days later she was readmitted with diarrhea and hypotension; she miscarried her fetuses. The patient was given a colectomy (subtotal) and inotropic medication; she was also intubated. Despite all the medical assistance, the patient died after three days in the hospital. An autopsy revealed that she had megacolon with pseudomembranous colitis. Patient B, a 10-year old female went to a children's ED with severe diarrhea, projectile vomiting and abdominal pain. The patient's stool tested positive for C. difficile toxin. Patient B was unrelated to patient A and had no contact with her; she had not taken any antimicrobials in the preceding year. However, patient B's brother had experienced a febrile diarrheal illness a few days before patient B herself became ill. The boy's symptoms resolved after 2-3 days without treatment; he was not taking any antimicrobial medication when he became sick. Patient B had been healthy until her brother became ill but became symptomatic a few days after he showed signs and symptoms. Initially, patient B had been examined by a clinician who diagnosed streptococcal pharyngitis and prescribed amoxicillin but she was unable to take the antibiotic because of stomach cramps and diarrhea. By the time she went to the ED, her signs and symptoms had worsened and she was having liquid stools up to 14 times a day. Patient B was admitted to the hospital where she received intravenous fluids and electrolytes, as well as metronizadole. She recovered and was discharged. Following these cases, the CDC carried out a survey on CA-CDI. Of 33 identified cases, 8 reported no history of antimicrobial use within three months of developing CDI, although three of the 8 cases did report close contact with a person who had a diarrheal illness (two with confirmed CDI). Nine additional cases occurred after the person had taken three or fewer doses of an antimicrobial, most commonly clindamycin. The results indicated the need for clinicians to consider CDI as a possible diagnosis in patients with severe diarrhea, even if those patients do not have the typical risk factors of being in the hospital and/or taking antimicrobial medications. * Previously, CDI was known as Clostridium difficile-associated disease or CDAD Source: Chernack, E., Johnson, C.C., Weltman, A. et al. Severe Clostridium difficile-Associated Disease in Populations Previously at Low Risk - Four States, 2005. MMWR Morb Mortal Wkly Rep Dec. 2, 2005, vol. 54 (47); 1201-1205 Why does the report note whether the two patients had recently been getting antibiotic therapy?

CDI usually occurs in patients receiving antibiotics, because the medication causes dysbiosis, facilitating overgrowth of the causative agent, C. difficile.

Pseudomembranous colitis is associated with infections caused by which of the following?

Clostridioides difficile

Clostridium tetani, an obligate anaerobe, is placed onto the same type of solid culture medium but incubated under two different conditions: aerobic and anaerobic. Which of the following best predicts what would be observed after 48 hours?

Colony growth on the culture plate in anaerobic conditions; no colony growth on culture plate in aerobic conditions.

Which of the following pairs about dental diseases is FALSE?

Dental caries - associated primarily with Treponema species.

What is the definitive host of Toxoplasmosis gondii?

Felines

Required information Skip to question You examine a patient who is complaining of belching (burping), bloating, and some vomiting. She also has some abdominal discomfort which she describes as a dull, burning pain that is worse when she is hungry and is often relieved when she takes antacids. You suspect that she may have Helicobacter pylori gastritis, and send her for a urea breath test. The breath test is positive; based on this, you get the patient's stool tested for blood, and you send her for an endoscopy, during which a biopsy is taken. Your diagnosis is confirmed by the results of these tests—she does indeed have H. pylori infection. Your patient asks you how a bacterium can survive in her stomach, which she knows is very acidic. You explain that

H. pylori produces urease that converts urea into carbon dioxide and ammonia; the ammonia neutralizes the pH of the stomach, allowing the bacteria to survive.

Chronic infections caused by which of the following are associated with stomach cancer?

Helicobacter pylori

Which of the following statements regarding hepatitis is TRUE?

Hepatitis A spreads via the fecal-oral route.

How does Helicobacter pylori survive in the stomach?

It converts urea into ammonia, creating a neutral environment.

Which is true about C. botulinum?

It forms endospores.

Clostridium paradoxum grows optimally at 55°C, pH 9.3; it will not grow in the presence of O2. Please select the TRUE statement about this organism.

It is an obligate anaerobe.

Required information Skip to question A cluster of cases of legionellosis have occurred in your neighborhood. People with the illness have cough, fever, shortness of breath, chest pain and sometimes diarrhea. The illness is caused by the bacterium Legionella pneumophila, a facultative intracellular parasite that survives in certain ameba. The organism has an absolute requirement for L-cysteine. L. pneumophila is widespread and is found in various water sources, including hot tubs, water cooling towers, swimming pools, grocery store misters, and shower water. Select the FALSE statement regarding the organism, given this information.

It is an obligate anaerobe.

Intracellular Gram-negative diplococci found in a urethral sample from a male is indicative of

Neisseria gonorrhoeae.

Required information Skip to question You work as an RN in the emerency department (ED) at a large regional hospital. A 37-year-old man is admitted exhibiting dizziness, dry mouth, blurred vision, and slurred speech. He also reports abdominal symptoms, including pain, nausea, vomiting, and diarrhea. The patient's family tells you that he was recently at a church potluck, where he ate bread, homemade tomato-beef stew and home-canned green beans. Based on the patient's signs and symptoms, the physician with whom you are working suspects botulism, a neurological disease that is caused by consumption of a toxin produced by the Gram-positive, spore-forming, obligate anaerobic bacterium Clostridium boltulinum. The patient develops breathing difficulty and is placed on a mechanical ventilator. A stool sample from the patient is cultured on a medium called CBI. This medium contains the antibiotics cycloserine, sulfamethoxazole and trimethoprim as inhibitory agents—C. botulinum has a high level of resistance to these drugs. Some normal fecal bacteria can grow on CBI medium but they produce colonies that are easy to idenitify because they are pinpoint (tiny). The stool sample shows colony growth on the CBI agar, confirming the presence of C. botulinum. The stool sample, leftover stew and green beans are also tested for botulinum toxin; the stool sample and the green beans test positive for the toxin, but the stew is negative for the toxin. The test results confirm the diagnosis of foodborne botulism and the patient is treated appropriately. He remains in the hospital for several weeks, before being discharged. Clostridium botulinum grows optimally at 26-30oC, pH higher than 4.6 and 1% oxygen. How should it be classified?

Obligate anaerobe, neutrophile, mesophile

The principal microbe involved in dental caries is

S. mutans.

Please choose the microorganism that is the most common cause of bacterial meningitis in adults

Streptococcus pneumoniae

Gram-positive encapsulated diplococci found in sputum are likely

Streptococcus pneumoniae.

The leading cause of bacterial meningitis in adults is

Streptococcus pneumoniae.

Required information Skip to question A 24-year-old woman experienced repeated episodes of watery diarrhea, abdominal pain, and fever, and was diagnosed as having Clostridium difficile infection (CDI). Shortly before she developed the CDI, the woman had been taking an oral antibiotic for a tooth infection. Initially, her doctor advised her to stop taking the antibiotic, hoping that her intestinal normal microbiota, which had been negatively impacted by the antibiotic, would recover and outcompete the C. difficile, aiding the woman's recovery. However ,that approach failed, so the doctor then prescribed a different antibiotic for the woman: a 10-day course of vancomycin. At first it seemed that the second antibiotic had resolved the CDI, but as soon as the patient completed the course of antibiotics, her signs and symptoms returned. Eventually the woman was given a fecal transplant, which involved inserting fecal bacteria taken from a healthy person into her intestinal tract. The donor in this case was the patient's sister. The transplant was a success and the patient recovered. Which of the following explains why the woman in this case developed the signs and symptoms of CDI, an intestinal infection?

The antibiotic harmed her intestinal normal microbiota, allowing C. difficile to flourish (thrive).

You take a swab sample from a patient, stain it and culture it. You observe spherical bacteria in the staining preparation. The organism grows equally well throughout a tube of thioglycolate culture medium. It does not produce catalase. From this you can conclude it is likely

a Streptococcus species.

The lactobacilli, in their role as normal microbiota of the vagina, help the vagina resist infection by contributing to

acidity of the vagina.

Part of the ability of S. mutans to result in dental caries depends on its ability to

convert sucrose to lactic acid.

Haemophilus influenzae is a virus that causes the "flu."

false

Required information Skip to question Your patient has just returned from vacation in Asia. She has come to the clinic where you work, complaining of abdominal pain, fever, diarrhea, and nausea. She reports that the last day of her trip included a visit to a turtle sanctuary, where tourists have an opportunity to handle rescued turtles. You suspect that your patient has salmonellosis, caused the the bacterium Salmonella enterica. You get a stool sample from the patient and send it to the lab for analysis. There, the sample is inoculated into tetrathionate broth and incubated overnight. The lab reports that the broth is turbid (cloudy) after incubation, indicating bacterial growth. A sample is then inoculated onto an agar plate designed to isolate S. enterica and after 24 hours of aerobic incubation, colonies of suspected S. enterica are seen. Further tests confirm S. enterica, supporting your presumptive diagnosis. Because S. enterica is a facultative anaerobe, it would not grow well in an aerobic environment.

false

Helicobacter pylori

inhabits the stomach.

Viral gastroenteritis in infants and children is most commonly caused by

rotavirus.

Who determined that the cholera outbreak in 1850s London was due to contaminated water and approached the problem by removing the pump handle at the contaminated site?

snow

Required information Skip to question Thirteen people visited an emergency department at a military hospital for treatment of gastrointestinal signs and symptoms including nausea, vomiting, abdominal pain and diarrhea. All of the patients had attended a work lunch party 2-3 hours before becoming ill. Initial investigation by Centers of Disease Control (CDC) personnel into the cause of the illnesses suggested bacterial contamination of one of the main dishes served at the lunch. Indeed, subsequent CDC laboratory analysis revealed the presence of bacterial toxin in one of the dishes, supporting the initial findings. Improper food handing and preparation were identified as the cause of the bacterial contamination. People who attended the lunch party and who developed signs and symptoms of gastrointestinal illness within 24 hours after the party were interviewed by CDC personnel. Forty people attended the lunch party. Of these, 35 were interviewed by CDC personnel. The remaining 5 people were not available for the interview. Samples of the 4 main dishes were tested for bacterial toxins. The dishes were perlo (chicken/sausage/rice dish), chicken wings, pulled pork and green beans with potatoes. Storage, preparation and handling of the dishes are summarized in the table. Laboratory testing identified Staphylococcus aureus as the source of the toxin; the toxin was staphylococcal enterotoxin type A. Bacillus cereus and Clostridium perfringens were eliminated as possible sources of toxins in the tested foods. DishPreparation/ StorageHandling/ ServingPerloChicken and sausage thawed in microwave. Chicken and rice boiled. Sausage fried. Perlo stored in unheated oven for 8 hours (overnight).Heated in slow cooker on high for 1 hour before serving.Chicken wingsDefrosted overnight in refrigerator. Spiced, then replaced in refrigerator overnight. Fried on day of party.Transported and served within hours of frying.Pulled porkDefrosted in microwave and cooked in slow cooker on low, overnight.Transported in slow cooker to party and served.Green beans/ potatoesPotatoes chopped on day of party. Beans from cans opened on day of party.Beans and potatoes cooked on day of party in slow cooker on high. What part of the body would you expect to be affected by enterotoxin?

intestines

Streptococcus pyogenes

is beta-hemolytic.

The membranes that cover the surface of the brain and spinal cord are known as the

meninges.

An infection of the membranes covering the brain is called

meningitis.

The viral disease that characteristically infects the parotid glands is

mumps

It has been estimated that 99% of intestinal bacteria are

obligate anaerobes.