Identification and antimicrobial resistance prevalence of pathogenic Escherichia coli strains from treated wastewater effluents in Eastern Cape, South Africa

• Published in: MicrobiologyOpen (Weinheim) 2016-02, Vol.5 (1), p.143-151
• Main Authors: Adefisoye, Martins A., Okoh, Anthony I.
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; Antibiotic resistance; Antibiotics; Antibiotic‐resistance gene; Antiinfectives and antibacterials; Antimicrobial agents; Antimicrobial resistance; Bacteria; Bacterial infections; Drug resistance; Drug Resistance, Multiple, Bacterial - genetics; E coli; E. coli; Effluent treatment; Effluents; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - isolation & purification; Escherichia coli - pathogenicity; Escherichia coli Infections - drug therapy; Genes; Genomes; Identification; Infections; MARI; MARP; Meningitis; Microbial Sensitivity Tests; Molecular Typing; Multidrug resistance; Multidrug resistant organisms; Municipal wastewater; Mutation; Neonates; Original Research; Pathogens; Phenotypes; Polymerase Chain Reaction; Public health; South Africa; Veterinary medicine; Virulence; Waste Water - microbiology; Wastewater treatment; Water Microbiology; Water Purification; Water treatment; Water treatment plants; Watersheds
• ISSN: 2045-8827; 2045-8827
• DOI: 10.1002/mbo3.319

Antimicrobial resistance (AMR) is a global problem impeding the effective prevention/treatment of an ever‐growing array of infections caused by pathogens; a huge challenge threatening the achievements of modern medicine. In this paper, we report the occurrence of multidrug resistance (MDR) in Escherichia coli strains isolated from discharged final effluents of two wastewater treatment facilities in the Eastern Cape Province of South Africa. Standard disk diffusion method was employed to determine the antibiotic susceptibility profile of 223 polymerase chain reaction (PCR)‐confirmed E. coli isolates against 17 common antibiotics in human therapy and veterinary medicine. Seven virulence associated and fourteen antibiotic resistance genes were also evaluated by molecular methods. Molecular characterization revealed five pathotypes of E. coli in the following proportions: enterotoxigenic ETEC (1.4%), enteropathogenic EPEC (7.6%), enteroaggregative EAEC (7.6%), neonatal meningitis (NMEC) (14.8%), uropathogenic (41.7%), and others (26.9%). Isolates showed varying (1.7–70.6%) degrees of resistance to 15 of the test antibiotics. Multidrug resistance was exhibited by 32.7% of the isolates, with the commonest multiple antibiotic‐resistant phenotype (MARP) being AP‐T‐CFX (12 isolates), while multiple antibiotic‐resistant indices (MARI) estimated are 0.23 (Site 1) and 0.24 (Site 2). Associated antibiotic resistance genes detected in the isolates include: strA (88.2%), aadA (52.9%), cat I (15%), cmlA1 (4.6%), blaTEM (56.4%), tetA (30.4%), tetB (28.4%), tetC (42.2%), tetD (50%), tetK (11.8%), and tetM (68.6%). We conclude that municipal wastewater effluents are important reservoirs for the dissemination of potentially pathogenic E. coli (and possibly other pathogens) and antibiotic resistance genes in the aquatic milieu of the Eastern Cape and a risk to public health. Discharged final effluents of wastewater treatment plants are potential point source of multidrug‐resistant pathogen in receiving surface waters. Antibiotic‐resistant genes from discharged effluents can be transferred to other pathogens in the receiving water environment, thus, constituting significant public health threat. The combination of deadly duo of drug resistance and emerging virulence in pathogenic bacteria brings about a worrisome situation of possible lack of therapeutic options particularly in immunocompromised individuals.