Molecular Epidemiology of Clostridioides difficile Colonization in Families with Infants

Once an infection that was confined to hospitalized patients, C. difficile now is a principal cause of diarrhea among older children and adults in the community. The reservoirs of community-associated C. difficile infection (CA-CDI), however, are not known. Infants less than 1 year of age excrete C. difficile asymptomatically in their stool in high concentration, but their role in CA-CDI is not known. As a step toward answering this question, the current project tested whether strains of C. difficile excreted by the infants could be transmitted to their parents.30 healthy families (adults and infants) were recruited at a general pediatric office in suburban Cleveland, Ohio at the babies 4-month well-child visit. Stool (from the baby) and rectal wipes (from the parents) were collected every two weeks over a total of 4 months; these samples then were sent by the USPS to a research microbiology laboratory and cultivated for C. difficile. Isolated organisms then were strain-typed by PCR-ribotyping and by whole genome sequence core genomic multilocus sequence typing (WGS cgMLST). Of the 30 enrolled families, C. difficile was cultivated from at least one family member in 28 and of these 28, there was evidence of stain-sharing in 17 of them. Almost all strain-sharing involved the infant, who usually was culture-positive first. These findings suggested that asymptomatically-excreting infants can share the organism with their healthy parents and thus may play a role in spreading the organism to older contacts (primary, secondary, and beyond) in the community. The WGS data obtained as part of the WGC-cgMLST assignments are being submitted for public access.