Major Article
Efficacy of laundering and tumble-drying in reducing microbial contamination of wastewater treatment plant worker coveralls

https://doi.org/10.1016/j.ajic.2018.11.007Get rights and content

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.

Section snippets

Wastewater treatment plant

The study was conducted at the Gold Bar WWTP in Edmonton, Alberta, Canada. The plant serves a population of approximately 820,000 residents. It treats 310million liters of wastewater per day, with peak flows up to 910million liters per day. The plant is a tertiary treatment plant that receives raw wastewater from the sewer system and performs the following treatment steps: (1) primary sedimentation in clarifiers, which produces a primary effluent; (2) secondary treatment by biological nutrient

Effects of decontamination stages on indicator organism and pathogen concentrations

The mean concentrations of indicator organisms and pathogens on swatches and the effectiveness of decontamination varied depending on wastewater treatment levels (Table1, Fig.1 and 2). In the case of most organisms, contamination with raw water resulted in coveralls carrying the highest microbial loads; the exceptions were E coli, P aeruginosa, and Acinetobacter spp. In addition, in most cases, organisms experienced a sharp decrease in concentration as a result of laundering, the only

Conclusions

There is a growing body of evidence implicating uniforms and other textiles in the health care industry as potential reservoirs of pathogenic and multidrug-resistant organisms.6, 8, 14, 15 We conducted a study to determine if coveralls worn by WWTP workers performing tasks that require contact with raw, partially treated, or fully treated wastewater could potentially result in occupational infection risk comparable to those in health care settings. We enumerated some commonly detected indicator

Acknowledgments

I would like to thank Kassi Cust, who helped with the experimental design and sampling for this study; Jeff Hunter, who solicited scientific input; Melissa Pawluk, who helped with coverall processing; and the utility crew members who provided the coveralls.

References (21)

There are more references available in the full text version of this article.

Conflicts of interest: None to report.

View full text
© 2018 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.