Impact of UV and Peracetic Acid Disinfection on the Prevalence of Virulence and Antimicrobial Resistance Genes in Uropathogenic Escherichia coli in Wastewater Effluents

Abstract

bWastewater discharges may increase the populations of pathogens, including Escherichia coli, and of antimicrobial-resistant strains in receiving waters. This study investigated the impact of UV and peracetic acid (PAA) disinfection on the prevalence of virulence and antimicrobial resistance genes in uropathogenic Escherichia coli (UPEC), the most abundant E. coli pathotype in municipal wastewaters. Laboratory disinfection experiments were conducted on wastewater treated by physicochemical, activated sludge, or biofiltration processes; 1,766 E. coli isolates were obtained for the evaluation. The target disinfection level was 200 CFU/100 ml, resulting in UV and PAA doses of 7 to 30 mJ/cm 2 and 0.9 to 2.0 mg/liter, respectively. The proportions of UPECs were reduced in all samples after disinfection, with an average reduction by UV of 55% (range, 22% to 80%) and by PAA of 52% (range, 11% to 100%). Analysis of urovirulence genes revealed that the decline in the UPEC populations was not associated with any particular virulence factor. A positive association was found between the occurrence of urovirulence and antimicrobial resistance genes (ARGs). However, the changes in the prevalence of ARGs in potential UPECs were different following disinfection, i.e., UV appears to have had no effect, while PAA significantly reduced the ARG levels. Thus, this study showed that both UV and PAA disinfections reduced the proportion of UPECs and that PAA disinfection also reduced the proportion of antimicrobial resistance gene-carrying UPEC pathotypes in municipal wastewaters.

Chemical and Microbiological Quality of Effluents from Different On-Site Wastewater Treatment Systems across Finland and Sweden

“…Both UV and peracetic acid can be effective disinfection methods [30,31]. If there is a need to only disinfect effluents during brief periods, such as when it will be used for agricultural irrigation or bathing periods, or during epidemic periods, peracetic acid might be a good alternative since there are low capital costs.…”

Peracetic acid disinfection kinetics for combined sewer overflows: indicator organisms, antibiotic resistance genes, and microbial community

“…17 Exposure to PAA was associated with 1.6–3.7 log reductions in uropathogenic E. coli concentrations with 30, 50 and 60 mg∙min/L PAA (applied dose × time). 17 …”

“…PAA disinfection significantly decreased detection of cultivable ARG carrying uropathogenic E. coli isolates (detected via microarray following cultivation) in treated WW effluent at a dose of 0.9–2 mg/L and a contact time of 30 min to meet a goal of 200 CFU/100 mL. 17 Exposure to PAA was associated with 1.6–3.7 log reductions in uropathogenic E. coli concentrations with 30, 50 and 60 mg∙min/L PAA (applied dose × time). 17 …”

“…15, 16 Flow cytometry analysis with live-dead staining demonstrated damage to cell walls indicating that a portion of detected ARGs were extracellular or present in nonviable cells. 15 Little data is available reporting disinfection kinetics for ARG carrying cells in WW, 17 and none is available for CSO effluent. Understanding the partitioning of ARGs between viable and non-viable sources is critical for understanding the mechanisms and therefore the risk of ARG proliferation in the environment.…”

Antibiotic-Resistant Bacteria and Resistance Genes in the Water–Food Nexus of the Agricultural Environment

“…Antibiotic-resistant bacteria and resistance genes that are disseminated into the environment from the treated wastewater can be inactivated by ultraviolet (UV) irradiation (Biswal et al, 2014;Guo et al, 2013b;Huang et al, 2013;McKinney and Pruden, 2012) or adsorbed onto natural organic matters (Lu et al, 2012). Antibiotic-resistant bacteria and resistance genes that are disseminated into the environment from the treated wastewater can be inactivated by ultraviolet (UV) irradiation (Biswal et al, 2014;Guo et al, 2013b;Huang et al, 2013;McKinney and Pruden, 2012) or adsorbed onto natural organic matters (Lu et al, 2012).…”