Isolation of amoebae and Pseudomonas and Legionella spp. from eyewash stations

Abstract

Forty eyewash units were sampled for protozoa, bacteria, and fungi. Total heterotrophic bacterial counts on nutrient agar and R2A agar (Difco Laboratories, Detroit, Mich.) ranged from 0 to 10(5) CFU/ml, with Pseudomonas spp. being the most frequently isolated. Total counts of 10(4) and 10(8) cells per ml were obtained with the acridine orange staining procedure. All samples were examined for Legionella spp. by direct fluorescent-antibody staining and by culturing on buffered charcoal-yeast extract agar containing alpha-ketoglutarate and glycine and supplemented with cycloheximide, vancomycin, and polymyxin B. DNA-DNA hybridization was used to confirm identification of the Legionella isolates. Legionellae were detected in 35 of 40 (87.5%) samples by direct fluorescent-antibody staining, with 3 samples yielding both Legionella spp. and amoebae. Amoebae identified as Hartmannella, Vahlkampfia, Acanthamoeba, and Cochliopodium spp. were detected in 19 of 40 (47:5%) samples. Sabouraud dextrose agar was used to obtain a crude estimate of viable fungal populations, pH, hardness, and ammonia, alkalinity, chlorine, copper, and iron contents were recorded for all water samples collected from eyewash stations; 33% of the samples had greater than or equal to 10 mg of CO2 per liter. It is concluded that eyewash stations not regularly flushed and/or cleaned and used to flush traumatized eye tissue may be a source of infection and can contaminate laboratory environments via aerosol transmission.