Prevalence and Duration of Asymptomatic Clostridium difficileCarriage among Healthy Subjects in Pittsburgh, Pennsylvania

ABSTRACTPrevious studies suggested that 7 to 15% of healthy adults are colonized with toxigenic Clostridium difficile. To investigate the epidemiology, genetic diversity, and duration of C. difficilecolonization in asymptomatic persons, we recruited healthy adults from the general population in Allegheny County, Pennsylvania. Participants provided epidemiological and dietary intake data and submitted stool specimens. The presence of C. difficilein stool specimens was determined by anaerobic culture. Stool specimens yielding C. difficileunderwent nucleic acid testing of the tcdAgene segment with a commercial assay; tcdCgenotyping was performed on C. difficileisolates. Subjects positive for C. difficileby toxigenic anaerobic culture were asked to submit additional specimens. One hundred six (81%) of 130 subjects submitted specimens, and 7 (6.6%) of those subjects were colonized with C. difficile. Seven distinct tcdCgenotypes were observed among the 7 C. difficile-colonized individuals, including tcdCgenotype 20, which has been found in uncooked ground pork in this region. Two (33%) out of 6 C. difficile-colonized subjects who submitted additional specimens tested positive for identical C. difficilestrains on successive occasions, 1 month apart. The prevalence of C. difficilecarriage in this healthy cohort is concordant with prior estimates. C. difficile-colonized individuals may be important reservoirs for C. difficileand may falsely test positive for infections due to C. difficilewhen evaluated for community-acquired diarrhea caused by other enteric pathogens.