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Background The number of adults afflicted with community-associated Clostridium difficile infection (CA-CDI) has increased dramatically over the past 10 years. Exposure to infants, a population known to be asymptomatically colonized by C. difficile (CD), has been identified as a risk factor for CA-CDI, implying that infants may be a reservoir for adult infection. In the present study, we determined the distribution of CD ribotypes isolated from adults with CA-CDI and compared them to the ribotypes of strains excreted asymptomatically among a cohort of healthy infants from the same geographical location. Methods Adult samples submitted to a referral university hospital microbiology laboratory as part of routine care were identified as CD+ by commercial PCR and stored at −80°; the subset of samples from patients meeting IDSA criteria for CA-CDI were selected for further analysis. A cohort of healthy infants attending a suburban, demographically diverse pediatric practice 6 miles from the hospital were enrolled at birth and prospectively followed at 2-, 6-, and 12-month well-visits. Stool collected at each infant visit was cultivated for CD using routine techniques. DNA from both sets of organisms was extracted and subjected to fluorescent PCR ribotyping. Amplicons were assigned to specific ribotypes through sequence analysis, using the nomenclature proposed previously (J Clin Microbiol 2015;53:1192). Results To date, 29 adult samples (collected between August 1, 2016 and January 31, 2018) and 32 infant samples (collected between July 1, 2016 and March 31, 2018) have been ribotyped. Eleven (18%) organisms could not be typed (3 adult; 8 infant). The most representative ribotype identified in the adult CA-CDI samples was F014-020 (54%), with small numbers scattered among six other ribotypes. The most prominent ribotypes in infants were F106 (33%), F010 (17%), and F012 (17%); two (8%) infants were colonized with ribotype F014-020. Except for F014-020, there was no concordance of ribotypes among adult CA-CDI and infant isolates. Conclusion In this population, a small proportion of asymptomatic infants were colonized by a prominent CA-CDI ribotype in adults, but other ribotypes were unique to each age group. Disclosures All authors: No reported disclosures.

Background Recent years have witnessed an explosive increase in community-associated Clostridium difficile infection (CA-CDI) in adults. Contact with infants, a population known to be asymptomatically colonized by C. difficile (CD), has been identified as a risk factor for CA-CDI, rendering it vital to explore the epidemiology and determinants of acquisition in babies. Methods In this prospective cohort study, healthy infants attending a demographically diverse suburban pediatric practice were enrolled at birth and followed through their 2-month, 6-month, and 12-month well child visit. At each visit, stool samples were collected, and questionnaires including interim exposure to potential risk factors for CD acquisition were administered. Stool was inoculated on pre-reduced CCFA agar with a graduated loop. Among CD isolates, toxin genes were identified by PCR. Results Fifty infants were recruited; 90% of samples and questionnaires were completed. The average gestational age was 39 weeks and 46% were male. Twenty-eight (56%) infants had at least one sample positive for CD during the study: cross sectional incidence was 0/50 at birth; 9/47 (19%) at 2 months; 22/43 (51%) at 6 months; 6/37 (16%) at 1 year. Of those with positive stool cultures, three(11%) tested positive at multiple visits. Of the 37 (81%) isolates, 30 were PCR-positive for CD toxin. Five stool samples harbored >4.5 log10 cfu of toxigenic CD/g of stool. Proportions of CD+ vs. CD− subjects, respectively, with interim exposure to selected CD risk factors at each visit were as follows: infant healthcare visit 45% vs. 42%; household member healthcare visit 17% vs. 23%; household member with diarrhea 14% vs. 29%; antibiotic exposure 5% vs. 4%; antacid exposure 7% vs. 3%, all P > 0.05. Regarding risks for acquisition of enteric pathogens in general: breastmilk-including nutrition 57% vs. 73% (P < 0.05 only at 2-month visit); 48% CD+ infants had interim daycare attendance vs. 25% CD− (but P > 0.05 at each visit). Conclusion Asymptomatic carriage of toxigenic CD occurred in over half of healthy infants during the first year of life, and several had a high organism burden that could increase the risk for transmission. While daycare attendance was more common among colonized infants, the majority of infants who were CD+ had no daycare exposure. Disclosures All authors: No reported disclosures.