MCQs: Clinically Important Anaerobes: Answers

1) Clostridium difficile infection responds well to intra-venous vancomycin? T/F

False: Although vancomycin has good in-vitro activity against Clostridium difficile, it is too big a molecule to cross the intestinal epithelium. Therefore Intra-venous vancomycin has no effect on Clostridium difficile. Oral vancomycin (or metronidazole) is a better option.

2) Propionibacterium acnes is a common cause of infections in prosthetic shoulder joints? T/F

True: This is well recognised, however it is not so clear why shoulders in preference to knees or joints. It may be because of a higher load of Propionibacterium in the upper part of the body.

3) Fusobacterium nucleatum is more pathogenic than Fusobacterium necrophorum? T/F

False: Fusobacterium necrophorum is more pathogenic than Fusobacterium nucleatum. Fusobacterium necrophorum can cause severe infections such as Lemierre’s syndrome and unlike Fusobacterium nucleatum, tends not to colonise the oropharynx.

4) When Bacteroides fragilis is isolated from blood cultures, it often indicates intra-abdominal pathology? T/F

True: In this setting often indicates the presence of an intra-abdominal collection, or occasionally perforation.

5) Lactobacillus is the dominant bacterium in a menstruating female? T/F

True: There is a close link between the presence of estrogen and Lactobacillus predominance in the female genital tract. This predominance is usually absent in the pre-pubertal and post-menopausal period.

6) Actinomyces israelii is a facultative anaerobe? T/F

False: Actomyces israellii is a strict anaerobe.

7) Prevotella species commonly produce beta-lactamase? T/F

True: This may have implications for treatment of infections caused by Prevotella.

8) Peptostreptococcus can occasionally be a contaminant in blood cultures. T/F

True: Peptostreptococcus can colonise skin and therefore can be a blood culture contaminant.

9) Veillonella is a Gram negative bacillus. T/F

False: Usually a Gram negative coccus.

10) If anaerobic culture is negative then anaerobic antibiotic cover can be discontinued? T/F

False: Anaerobic culture is not sensitive enough to allow this luxury. Whether anaerobic cover can be stopped is very much a clinical judgement.


Here is an article describing anaerobic infections in a bit more detail.

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