DETECTION AND ANTIBIOTIC SUSCEPTIBILITY OF PATHOGENIC ESCHERICHIA COLI ISOLATED FROM THE FINAL EFFLUENT OF TWO WASTEWATER TREATMENT PLANTS IN THE EASTERN CAPE PROVINCE, SOUTH AFRICA

Wastewater effluent is a significant reservoir for pathogenic and antibiotic-resistant Escherichia coli, which can pose substantial acute risks if released into surface water without adequate treatment. This study examines the presence of pathogenic E. coli strains in treated effluents and determines their antibiotic profiles.. A culture-based approach was employed using E. coli differential chromogenic agar for isolation via the membrane filtration method. Confirmation of presumptive E. coli strains was achieved by PCR. The confirmed isolates were also genotyped to identify the species present. Antibiotic profiling of the confirmed isolates was performed using the CLSI-recommended first-line antibiotics for E. coli. Out of eight pathotypes screened, four were confirmed: Uropathogenic E. coli (UPEC) at 5.7%, Enteroaggregative E. coli (EAEC) at 2.3%, Neonatal Meningitis E. coli (NMEC) at 1.1%, and Enteropathogenic E. coli (EPEC) at 0.6%. The antibiotic susceptibility patterns showed that UPEC had low resistance to meropenem (100%), cefotaxime (100%), and gentamicin (88.9%), but high resistance to tetracycline (74.1%), ampicillin (74.1%), and cephalothin (66.7%). EAEC, NMEC, and EPEC exhibited high sensitivity (100%) to meropenem, gentamicin, and cefotaxime, with varying degrees of resistance to ampicillin, tetracycline, and cephalothin. The study indicates that the two treatment plants discharge effluents containing pathogenic E. coli, serving as reservoirs for these bacteria. The study highlights the inadequacy of the plants to produce effluents of acceptable quality.