Biological and physicochemical wastewater treatment processes reduce the prevalence of virulent Escherichia coli

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Journal titleApplied and Environmental Microbiology
Pages835844; # of pages: 10
SubjectAfter-treatment; DNA micro-array; E. coli; Freshwater environments; Pathogenic bacterium; Pathogenic E. coli; Quinolones; Resistance genes; Treatment process; Virulence factors; Virulence gene; Wastewater treatment plants; Wastewater treatment process; Activated sludge process; Effluents; Pathogens; microbial activity; physicochemical property; genetics; genotype; isolation and purification; microarray analysis; water management; DNA, Bacterial; Genotype; Microarray Analysis; Waste Water; Water Purification
AbstractEffluents discharged from wastewater treatment plants are possible sources of pathogenic bacteria, including Escherichia coli, in the freshwater environment, and determining the possible selection of pathogens is important. This study evaluated the impact of activated sludge and physicochemical wastewater treatment processes on the prevalence of potentially virulent E. coli. A total of 719 E. coli isolates collected from four municipal plants in Québec before and after treatment were characterized by using a customized DNA microarray to determine the impact of treatment processes on the frequency of specific pathotypes and virulence genes. The percentages of potentially pathogenic E. coli isolates in the plant influents varied between 26 and 51%, and in the effluents, the percentages were 14 to 31%, for a reduction observed at all plants ranging between 14 and 45%. Pathotypes associated with extraintestinal pathogenic E. coli (ExPEC) were the most abundant at three of the four plants and represented 24% of all isolates, while intestinal pathogenic E. coli pathotypes (IPEC) represented 10% of the isolates. At the plant where ExPEC isolates were not the most abundant, a large number of isolates were classified as both ExPEC and IPEC; overall, 6% of the isolates were classified in both groups, with the majority being from the same plant. The reduction of the proportion of pathogenic E. coli could not be explained by the preferential loss of one virulence gene or one type of virulence factor; however, the quinolone resistance gene (qnrS) appears to enhance the loss of virulence genes, suggesting a mechanism involving the loss of pathogenicity islands.
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AffiliationNational Research Council Canada; Energy, Mining and Environment; Human Health Therapeutics
Peer reviewedYes
NPARC number21270363
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Record identifier7450b834-891f-4dd6-8023-ebef3e1d176b
Record created2014-02-05
Record modified2016-05-09
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