Efficacy of laundering and tumble‐drying in reducing microbial contamination of wastewater treatment plant worker coveralls

Abstract

Background: Evidence implicates textiles in health care as potential reservoirs of pathogens. No similar data exist for the wastewater treatment plant (WWTP) industry. We investigated if coveralls worn by WWTP workers could present occupational infection risk. Methods: We enumerated heterotrophic plate counts (HPCs), total coliforms, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, methicillin‐resistant Staphylococcus aureus, Clostridium difficile, and Acinetobacter spp on coverall swatches experimentally contaminated with raw, primary, secondary, and final effluent. Contaminated swatches were examined by culture‐based methods after laundering, tumble‐drying, and storing. Results: Concentrations of microorganisms and efficacy of decontamination differed depending on the contaminating wastewater matrix and the organism. Laundering was an effective decontamination method for coveralls contaminated with all microorganisms, except HPCs. Tumble‐drying resulted in statistically significant decreases for HPCs, P aeruginosa, and Acinetobacter. Increases in contamination after laundering were seen in Acinetobacter spp, in P aeruginosa when coverall swatches were contaminated with raw and final effluent, and in HPCs when contaminated with secondary effluent. Discussion: Results suggest that solely laundering at 60°C for 25 minutes as per ASTM Standard F1449 may not always be an efficient means of controlling microorganisms on coveralls. Conclusions: Clearer guidelines are needed to better protect WWTP workers.