Evaluation and remediation of bulk soap dispensers for biofilm

Abstract

Recent studies evaluating bulk soap in public restroom soap dispensers have demonstrated up to 25% of open refillable bulk-soap dispensers were contaminated with ~6 log10(CFU ml-1) heterotrophic bacteria. In this study, plastic counter-mounted, plastic wall-mounted and stainless steel wall-mounted dispensers were analyzed for suspended and biofilm bacteria using total cell and viable plate counts. Independent of dispenser type or construction material, the bulk soap was contaminated with 4–7 log10(CFU ml-1) bacteria, while 4–6 log10(CFU cm-2) biofilm bacteria were isolated from the inside surfaces of the dispensers (n=6). Dispenser remediation studies, including a 10 min soak with 5000 mg 1-1 sodium hypochlorite, were then conducted to determine the efficacy of cleaning and disinfectant procedures against established biofilms. The testing showed that contamination of the bulk soap returned to pre-test levels within 7–14 days. These results demonstrate biofilm is present in contaminated bulk-soap dispensers and remediation studies to clean and sanitize the dispensers are temporary.