Open refillable bulk soap dispensers in public restrooms: A public health risk?

Soap in public restrooms from open refillable dispensers is known to be prone to bacterial contamination. The objectives of this study were to assess the factors contributing to contamination and to test for the presence of organisms of public health concern. Bacteria in the soap samples were quantified using standard microbiological methods, E. coli enrichment was performed according to water quality standard methods, and antibiotic resistance was assessed using selective media. Contamination was found in 21% (32/155) of facilities and averaged 6.3x10⁶ bacteria/ml. E. coli was detectable in 28% (7/25) of the contaminated soaps tested. Resistance to quinilones or ceftazidime was observed in 28% (22/78) of the isolates, most frequently in species of Pseudomonas, 68% (15/22), but also in Klebsiella, Serratia, Burkholderia and Enterobacter species. Five percent (4/78) of the isolates were resistant to both antibiotics. Contamination was found in both bland and antimicrobial soaps and in all types of bulk dispensers tested (including both plastic and metal wall-mounted as well as the through the counter types). Contamination of bulk liquid soap in public restrooms appears to be a fundamental and widespread problem associated with the open design of the dispensers as it is not limited to any particular soap or dispenser type. The organisms found in this study included several species of Gram-negative opportunistic pathogens such as E. coli as well as antibiotic resistant bacteria. Further research is warranted to determine the extent to which contaminated bulk soap in public restrooms poses an unnecessary public health risk.