Biocide Resistance and Transmission of Clostridium difficile Spores Spiked onto Clinical Surfaces from an American Health Care Facility

Clostridium difficile is the primary cause of antibiotic-associated diarrhea globally. In unfavourable environments the organism produces highly resistant spores which can survive microbicidal insult. Our previous research determined the ability of C. difficile spores to adhere to clinical surfaces; finding that spores had marked different hydrophobic properties and adherence ability. Investigation into the effect of the microbicide sodium dichloroisocyanurate on C. difficile spore transmission revealed that sub-lethal concentrations increased spore adherence without reducing viability. The present study examined the ability of spores to transmit across clinical surfaces and their response to an in-use disinfection concentration of 1,000-ppm of chlorine-releasing agent sodium dichloroisocyanurate. In an effort to understand if these surfaces contribute to nosocomial spore transmission, surgical isolation gowns, hospital-grade stainless steel and floor vinyl were spiked with 1 × 106 spores/ml of two types of C. difficile spore preparations: crude spores and purified spores. The hydrophobicity of each spore type versus clinical surface was examined via plate transfer assay and scanning electron microscopy. The experiment was repeated and spiked clinical surfaces were exposed to 1,000-ppm sodium dichloroisocyanurate at the recommended 10-min contact time. Results revealed that the hydrophobicity and structure of clinical surfaces can influence spore transmission and that outer spore surface structures may play a part in spore adhesion. Spores remained viable on clinical surfaces after microbicide exposure at the recommended disinfection concentration demonstrating ineffectual sporicidal action. This study showed that C. difficile spores can transmit and survive between varying clinical surfaces despite appropriate use of microbicides. IMPORTANCE Clostridium difficile is a healthcare-acquired organism and the causative agent of antibiotic-associated diarrhoea. Its spores are implicated in faecal to oral transmission from contaminated surfaces in the healthcare environment due to their adherent nature. Contaminated surfaces are cleaned using high-strength chemicals to remove and kill the spores; however, despite appropriate infection control measures, there is still high incidence of C. difficile infection in patients in the US. Our research examined the effect of a high-strength biocide on spores of C. difficile which had been spiked onto a range of clinically relevant surfaces including isolation gowns, stainless steel and floor vinyl. This study found that C. difficile spores were able to survive exposure to appropriate concentrations of biocide; highlighting the need to examine the effectiveness of infection control measures to prevent spore transmission, and consideration of the prevalence of biocide resistance when decontaminating healthcare surfaces.