New infectious diseases emerge with worrisome frequency. Some accompany natural events such as changes in climate, while others surface with human help. Of great importance among the latter are the infections caused by Clostridium difficile (casually called C. diff). The prevalence of these infections is related to the use of certain gut-cleaning antibiotics such as clindamycin. In the pre-antibiotic era, C. diff infections were unknown, although they probably occurred once in a while.
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