504. Change in Clostridium difficile Strain-Type Distribution After Implementation of Diagnostic Stewardship

Abstract

BackgroundThe aim of this study was to evaluate the change in strain-type distribution after eliminating testing of formed and laxative induced diarrheal stool.MethodsBeginning in July 2013, all Clostridium difficile-positive stool samples by Cepheid’s GeneXpert were routinely typed using Multi-Locus Sequence Typing (MLST). MLST was performed as previously described (1). After implementation of rejection policy and re-education of staff, strain type (ST) distribution among tested samples were analyzed and compared with historic data.ResultsAfter evaluation of our historical typing data the 10 most frequent ST were identified. Diagnostic stewardship led to 40.0% reduction in testing volume, the positivity rate increased from 12.0% to 12.6%. The frequency distribution of threemost prevalent strain types (MLST-2, 8, and 42) declined by 38%, 60%, and 42%, respectively. The absolute number of epidemic strains, ST-1 and ST-11, remained unchanged and the frequency distribution increased from 9.6% to 14.0%. No clonal outbreaks were detected during this time.ConclusionImplementation of diagnostic stewardship led to a reduction in recovery of endemic strains without substantial impact on detection of hypervirulent or epidemic strains.Disclosures All authors: No reported disclosures.