The notion that Clostridioides difficile infection (CDI) is a hospital-acquired infection transmitted between symptomatic patients is questionable following the isolation of clinically important C. difficile strains in production animals, food and the environment, and the lack of evidence of transmission based on whole genome sequencing studies. Driven by the use of antimicrobials in production animals, and subsequent use of contaminated animal manure in composted gardening products, the environment outside of hospitals is contaminated with C. difficile spores. We suspect environmental C. difficile is being carried into the hospital on the soles of contaminated shoes and subsequently contributes to CDI in the hospital.
The initial stage of this study was to determine the prevalence and circulating strains of C. difficile on the hospital floor and the shoes of visitors, patients and hospital personnel.
Selective direct and enrichment cultures were performed on shoe and floor samples collected using MWE Polywipe sponges between January and March 2019. Toxin profiling and PCR ribotyping were used to characterize all isolated C. difficile strains.
C. difficile was isolated from 77.3% (58/75) of floor samples and 76.7% (46/60) of shoe samples. The floor samples (58/58) tested positive by enrichment culture only. For the shoe samples, 43/46 (93.5%) were positive by enrichment only. Of the 3 shoe samples that were positive by direct culture, 20 spores/shoe were present on all 3. Non-toxigenic ribotype (RT) 010 predominated in both the floor (98.0%) and shoe (96.3%) samples. Toxigenic C. difficile RT043 was isolated from the shoe of 1 staff member.
In Australia, C. difficile RT010 is one of the most common RTs found in compost, lawn and asymptomatically-colonized people. While non-toxigenic, its presence implies it is being transported into the hospital. On-going surveillance of C. difficile on hospital floors and shoes is continuing to look for any seasonality. Later, comparative genomic analysis will be performed on environmental C. difficile and clinical cases of CDI.