Background: Variation in Clostridium difficile infection (CDI) rates between healthcare institutions suggests overall incidence could be reduced if the lowest rates could be achieved more widely. Methods: We investigated whether whole-genome sequencing (WGS) of consecutive C. difficile isolates from six English hospitals over one year (2013-14) could be used to assess infection control performance. Fecal samples with a positive initial screen for C. difficile (GDH or toxin-PCR) were cultured and sequenced. Within each hospital, we estimated the proportion of cases plausibly acquired from previous cases, defined by an isolate ≤2 single nucleotide polymorphisms different from a previous isolate in the last 90-days. Results: 851/971(87.6%) sequenced culture-positive samples were toxigenic, and 451(46.4%) were fecal-toxin-positive. 128/652(20%,95%CI 17-23%) toxigenic isolates >90-days after the study started were genetically-linked to a prior patient’s isolate from the previous 90-days. Hospital-2 had the fewest linked isolates, 7/105(7%,3-13%), hospital-1 an intermediate proportion, 9/70(13%,6-23%), while hospitals 3-6 had similar proportions of linked isolates (22-26%) (p≤0.002 comparing hospital-2 vs 3-6). Results were similar adjusting for locally-circulating ribotypes. Adjusting for hospital, ribotype-027 had the highest proportion of linked isolates (57%, 95%CI 29-81%). Fecal-toxin-positive and toxin-negative patients were similarly infectious in terms of being a potential transmission donor, OR=1.01(0.68-1.49,p=0.97). There was no association between the estimated proportion of cases linked to a previous case within 90-days and testing rates (p=0.60). Conclusions: WGS can be used to identify varying rates of C. difficile transmission in different locations, and offers the potential to allow targeted efforts to reduce CDI incidence.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)