Physiology & Biochemistry · single question
Which bacterium is considered part of normal human intestinal flora — distinct from the organism that causes antibiotic-associated pseudomembranous colitis?
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Correct answer: A. Escherichia coli (normal colonic flora)
E. coli is a normal, usually harmless inhabitant of the colon. C. difficile, by contrast, is the classic cause of antibiotic-associated pseudomembranous colitis when broad-spectrum antibiotics disrupt normal protective gut flora, allowing C. diff to overgrow and produce its toxins — an important consideration when prescribing antibiotics (e.g., clindamycin is a classic culprit).
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