Pathogenic Escherichia coli Found in Sewage Treatment Plants and Environmental Waters

Abstract

cWe previously demonstrated that some Escherichia coli strains with uropathogenic properties survived treatment stages of sewage treatment plants (STPs), suggesting that they may be released into the environment. We investigated the presence of such strains in the surrounding environmental waters of four STPs from which these persistent strains were isolated. In all, 264 E. coli isolates were collected from 129 receiving water sites in a 20-km radius surrounding STPs. We also included 93 E. coli strains collected from 18 animal species for comparison. Isolates were typed using a high-resolution biochemical fingerprinting method (the PhPlate system), and grouped into common (C) types. One hundred forty-seven (56%) environmental isolates were identical to strains found in STPs' final effluents. Of these, 140 (95%) carried virulence genes (VGs) associated with intestinal pathogenic E. coli (IPEC) or uropathogenic E. coli (UPEC) and were found in a variety of sites within areas sampled. Of the remaining 117 environmental strains not identical to STP strains, 105 belonged to 18 C types and 102 of them carried VGs found among IPEC or UPEC strains. These strains belonged mainly to phylogenetic groups A (A0 and A1) and B1 and to a lesser extent B2 2 , B2 3 , D1, and D2. Eight of 18 environmental C types, comprising 50 isolates, were also identical to bird strains. The presence of a high percentage of environmental E. coli in waters near STPs carrying VGs associated with IPEC and UPEC suggests that they may have derived from STP effluents and other nonpoint sources.

Antibiotic resistance and virulence genes in coliform water isolates

“…Similarly, presence of EPEC, EAEC, EIEC, EHEC and ETEC pathotypes has also been reported in sub-tropical surface water collected in Brisbane, Australia (Sidhu et al, 2013). Another Australian study found 56 % out of 264 E. coli isolates collected from the surrounding environmental waters of sewage treatment plants identical to strains isolated from sewage treatment plant's final effluent (Anastasi et al, 2012). Among these isolates the appearance of virulence genes like the siderophore gene iroNE.…”

“…Among these isolates the appearance of virulence genes like the siderophore gene iroNE. coli and the toxin genes eaeA, hylA, cnf1, estII was common (Anastasi et al, 2012). A Polish study showed that the occurrence of heat-stable toxin gene of ETEC, S. fimbriae subunit gene sfaS, and siderophore receptor genes, fyuA and intA in E. coli isolated from Warta River was associated with the presence of class 1 integrons (Koczura et al, 2013).…”

Relating Watershed Characteristics to Elevated Stream Escherichia coli Levels in Agriculturally Dominated Landscapes: An Iowa Case Study

“…The concentration of fecal coliforms in treatment plant effluent depends on flow, treatment type, and the target bacterial population [9,10]. In addition, some strains of E. coli that possess the virulence characteristics of uropathogenic strains can survive the wastewater treatment process [11,12]. In areas without wastewater treatment plants, leaking septic systems may release FIB [6,13].…”

Ecological and Public Health Implications of the Discharge of Multidrug-Resistant Bacteria and Physicochemical Contaminants from Treated Wastewater Effluents in the Eastern Cape, South Africa

“…E. coli, Shigella, Salmonella and Vibrio spp. have been the predominant pathogens linked to waterborne outbreaks in Africa [21,22], whereas certain clonal strains of these pathogens have been reported to survive conventional wastewater treatment processes [23][24][25][26].…”