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1. The NAP1 strain of Clostridium difficile is known to produce large quantities of which of the following toxins?
Toxin A
Toxin B
Both toxins A and B
Neither toxin A nor B
2. Although multiple strains of C. difficile may be present in a long-term care facility (LTCF) at any given time, most colonized patients in these facilities remain asymptomatic.
True
False
3. In the absence of adequate eradication methods, C. difficile spores have the potential to survive on the surfaces of inanimate objects for a maximum of which of the following durations?
Hours
Days
Weeks
Months
4. Recent use of which of the following antimicrobials is not commonly associated with an increased risk of C. difficile infection (CDI)?
Aminoglycosides
Ampicillin
Cephalosporins
Fluoroquinolones
5. Which of the following is the most sensitive test for C. difficile?
Assay for detection of glutamate dehydrogenase
Enzyme immunoassay for toxins A and B
Stool culture
Tissue culture cytotoxicity
6. Testing for C. difficile or its toxins should be performed only on unformed stool unless ileus is suspected.
True
False
7. Which of the following is not a marker for severe CDI?
Increased serum creatinine concentration
Increased serum albumin concentration
Presence of colonic thickening on CT scan
Presence of pseudomembranes on endoscopy
8. Recent prospective trials have shown that metronidazole is superior to vancomycin for treatment of severe initial episodes of CDI.
True
False
9. Approximately what percentage of patients who receive treatment for CDI will go on to experience at least one recurrence of symptoms?
10%
20%
30%
40%
10. Which of the following infection control strategies have been found to effectively reduce rates of C. difficile transmission?
Soap and water hand hygiene
Cohorting of patients with known CDI
Restricted use of cephalosporins and fluoroquinolones
All of the above

Answers:

The NAP1 strain of Clostridium difficile is known to produce large quantities of which of the following toxins?
Answer: Both toxins A and B
The severity of infections caused by the BI/NAP1/027 strain may possibly be explained by its capacity to produce large quantities of both toxins A and B.
Although multiple strains of C. difficile may be present in a long-term care facility (LTCF) at any given time, most colonized patients in these facilities remain asymptomatic.
Answer: True
Multiple strains of C. difficile may be present in LTCFs, due in part to the large number of patients who are either colonized at the time of admission or become colonized during their stay; however, relatively few of these patients become symptomatic.
In the absence of adequate eradication methods, C. difficile spores have the potential to survive on the surfaces of inanimate objects for a maximum of which of the following durations?
Answer: Months
Epidemiologic studies have found that C. difficile spores can survive for several months on such surfaces as toilet seats, bedpans, and telephones.
Recent use of which of the following antimicrobials is not commonly associated with an increased risk of C. difficile infection (CDI)?
Answer: Aminoglycosides
One of the main risk factors for CDI remains use of antimicrobial therapy within the previous 6 to 8 weeks. Fluoroquinolones have been most frequently associated with CDI, but other classes that have been implicated include cephalosporins, sulfonamides, macrolides, and some penicillins. To date, the use of aminoglycosides has not been commonly associated with an increased risk for CDI.
Which of the following is the most sensitive test for C. difficile?
Answer: Stool culture
The enzyme immunoassay is less sensitive than the tissue culture cytotoxicity and glutamate dehydrogenase assays. When performed properly, the stool culture is the most sensitive of the tests available for widespread use.
Testing for C. difficile or its toxins should be performed only on unformed stool unless ileus is suspected.
Answer: True
Persistent diarrhea is the most prominent symptom of CDI, so testing patients for C. difficile is recommended when clinical suspicion is high and when the patient has three or more unformed stools within 24 hours for 2 days or longer. However, on rare occasions, a patient with ileus may have CDI without having loose stools or diarrhea.
Which of the following is not a marker for severe CDI?
Answer: Increased serum albumin concentration
In addition to severe diarrhea and marked leukocytosis, markers for severe CDI include increased serum creatinine concentration, decreased serum albumin concentration (less than 2.5 g/dL), colonic thickening and ascites on CT scan, and pseudomembranes on endoscopy.
Recent prospective trials have shown that metronidazole is superior to vancomycin for treatment of severe initial episodes of CDI.
Answer: False
Data reported by Zar et al. suggested that vancomycin may be superior to metronidazole for treatment of cases of severe CDI. For mild cases, response rates for metronidazole and vancomycin were found to be similar.
Approximately what percentage of patients who receive treatment for CDI will go on to experience at least one recurrence of symptoms?
Answer: 20%
Approximately 20% of patients treated for CDI will go on to experience a recurrent episode. Of those who have recurrence of symptoms, 45% are likely to have at least one more future episode.
Which of the following infection control strategies have been found to effectively reduce rates of C. difficile transmission?
Answer: All of the above
Soap and water have been shown to be more effective than alcohol-based sanitizing gels for removing C. difficile spores from hands. Patients with suspected or confirmed CDI should be isolated in private rooms when possible or cohorted if private rooms are not available. Reducing the use of cephalosporins and fluoroquinolones has also been shown to control high rates of CDI in hospitals and LTCFs.

January 14th, 2009 | Posted in Uncategorized |