Examination of microbial contaminants of emergency showers and eyewash stations

To evaluate the effects of regular flushing, water from fifty emergency eyewash and shower stations was cultured for the presence of potentially pathogenic protozoa, heterotrophic bacteria, and Legionella species. This study also provided the opportunity to evaluate a commercially available molecular assay for the direct detection of Legionella sp in environmental samples. The Perkin Elmer Legionella EnviroAmp polymerase chain reaction (PCR) kit and culture on buffered charcoal yeast extract agar were used to detect Legionella species in water samples. Chemical and physical parameters of station water measured included: pH, hardness, alkalinity, turbidity, conductivity, total chlorine and assimilable organic carbon. Protozoal isolates were identified by classical identification methods, and isolates from the stations were identified as Hartmannella sp, Vexillifera sp, Vahlkampfia sp, Acanthamoeba sp, and Vanella sp. Heterotrophic plate counts ranged from 10² to 10⁶ CFU ml⁻¹ and acridine orange total counts ranged from 10³ to 10⁶ cells ml⁻¹ after regular flushing. PCR and gene probe analysis showed that 89% of the stations (eyewash and shower) were positive for Legionella species by PCR, while 6% of the samples were culture positive. These results indicate that routine flushing alone is not sufficient to control microbial contamination and disinfection must also be included in a routine maintenance program. In addition, regular maintenance, disinfection, and monitoring of emergency eyewash and shower stations is important in preventing potential secondary microbial infections by either direct inoculation or aerosol transmission.