Clostridium difficile whole genome sequencing reveals limited transmission among symptomatic children: A single-center analysis

Background Although pediatric Clostridium difficile infections (CDIs) are increasing, C. difficile transmission patterns among children are poorly understood. Methods We performed whole genome sequencing (WGS) on C. difficile isolates collected from children diagnosed with CDI between December 2012 and December 2013 at a single academic medical center. Genome sequences of isolates from CDIs diagnosed ≥8 weeks after study initiation were compared to all study isolate genome sequences. Among patients with isogenic isolates (≤2-3 core genome single nucleotide variants [SNVs] identified by pairwise SNV analyses), common inpatient and/or outpatient healthcare exposures were investigated. Results Among 131 CDIs in 107 children, WGS identified 104 genetically distinct isolates. Of 84 incident CDIs occurring ≥8 weeks after study initiation, only 10 (11.9%) were caused by a strain isogenic to another cohort CDI isolate (putative transmission events). Proportions of each CDI class putatively associated with transmission were hospital-onset healthcare facility-associated (HCFA), 2/16 (12.5%); community-onset HCFA, 1/17 (5.9%); indeterminate, 1/11 (9.1%); community-associated (CA), 5/40 (12.5%); and recurrent, 1/21 (4.8%). Transmission events among CA and HCFA CDIs were similarly infrequent (5/40 [12.5%] vs 3/33 [9.1%]; P =.64). Shared healthcare facility exposures were only identified among 7/10 putative transmission events. Potential community transmission (same postal code) was not identified. Conclusions WGS identified a highly diverse group of C. difficile isolates among children with CDI, including those with HCFA CDI. Clostridium difficile transmission among symptomatic children was very uncommon. Among putatively transmitted cases, investigation of shared healthcare exposures often did not identify a potential transmission source.