2427. A Laboratory Simulation and Field Study of Simplified Qualitative and Quantitative Environmental Cultures for Clostridioides difficile

Abstract Background Reliable, simple methods to assess environmental contamination with Clostridioides difficile are needed for studies of terminal disinfection effectiveness and transmission of C. difficile from fomites. We compared two novel sampling methods for assessment of C. difficile contamination: (1) isopropanol wipe sampling with broth enrichment (IW), where alcohol wipes are used to sample surfaces followed by immersion in CDBB-TC broth and (2) ethanol-shock hand imprint sampling (HI), where surfaces are sampled by gloved hands moistened with ethanol hand sanitizer followed by imprinting hands on selective agar (CDBA-TC). Both methods allow for sampling of complex surfaces common in hospital environments. Methods We performed a laboratory simulation study using six 10-fold dilutions (101–106) of C. difficile spores from two strains sampled from fiberglass surfaces by IW and HI. We then performed a field study of 10 sites in 11 hospital rooms of patients with C. difficile infection (CDI) diagnosed < 48 hours prior to sampling. Results for the HI and IW method were quantitative and qualitative, respectively. We compared room contamination prevalence (total CFU per room by HI and sites positive/total sites per room) to the cycle crossing threshold (CT) from the diagnostic C. difficile PCR test (Cepheid) from the room occupant. Results The IW laboratory limit of detection was 101 spores compared with 104 spores for HI. In the field study, IW and HI detected C. difficile contamination in 9/11 (82%) rooms at 22/110 (20%) sites and 5/11 (45%) rooms at 22/110 (20%) sites, respectively (Table 1). Six rooms with no detection by the HI method had a lower median number of sites positive per room compared with the 5 rooms with ≥1 cfu (1 vs 6, P < 0.05) (Table 1). The most commonly contaminated sites were linens (53%), call bells (43%), toilets (40%), blood pressure cuffs (40%), over-bed tables (38%), and bedrails (30%) (Table 2). Higher tcdB CT was associated with a lower total room contamination prevalence (Figures 1 and 2). Conclusion Our data suggest that the IW method is more sensitive for detection of C. difficile in the hospital environment, but the HI method offers quantitation. The prevalence of hospital room contamination for CDI patients appears to correspond with their toxin burden as estimated by PCR. Disclosures All authors: No reported disclosures.