2428. Whole-genome Sequencing to Determine Clostridium difficile Transmission

BACKGROUND: Clostridium difficile is a major problem in healthcare institutions due to its substantial attributable morbidity, mortality and costs. Although traditionally recognized as a nosocomial infection, there is increasing evidence that hospital-based transmission may not be as common as previously thought. Whole-genome sequencing (WGS) has superior discriminatory ability than other previously used techniques for C. difficile typing. This study aimed to investigate whether WGS could help to elucidate C. difficile transmission patterns at The Royal Melbourne Hospital (RMH). METHODS: All C. difficile isolates (N = 138) identified in patients admitted to RMH from November 1, 2015 to October 31, 2016 had molecular typing performed by WGS, multilocus sequence typing (MLST) and PCR ribotyping. Clinical epidemiological data were collected for each episode so that patient locations could be examined together with molecular typing information to determine putative transmissions in the hospital. RESULTS: After combining molecular and clinical epidemiology, a picture of diverse C. difficile emerged. Only 7 (6%) of isolates appeared to have been transmitted from other hospital patients, according to combined WGS and patient location data. However, both PCR ribotyping (33%) and MLST (44%) had significantly higher proportions of putative transmissions in this cohort. CONCLUSION: This finding has significant implications for the Infection Prevention team as efforts toward prevention of C. difficile infection may need to be redirected away from the current focus on prevention of nosocomial transmission. Future studies are needed to broaden understanding of C. difficile transmission dynamics so that other sources can be identified and targeted for intervention. DISCLOSURES: All authors: No reported disclosures.