Occurrence of Multidrug-Resistant Escherichia coli in Abuja Wastewater Treatment Plant and Wupa River

The discharge of multidrug-resistant bacteria into the environment can promote the transfer of resistance genes to clinically important bacteria, thereby posing a substantial public health risk. This study evaluated Escherichia coli isolated from the Abuja wastewater treatment plant and the Wupa River in Abuja, Nigeria, for multidrug resistance (MDR) and antibiotic resistance genes (ARGs). Isolates were characterised as presumptive using morphological and biochemical methods. Susceptibility to 10 different antibiotics was determined using the Kirby-Bauer disc diffusion technique. Confirmation of E. coli (uidA gene presence) and detection of ARGs were achieved by conventional polymerase chain reaction (PCR). Of 39 presumptive E. coli isolates, 100% were resistant to cefpodoxime, with high rates of resistance to ampicillin (79.5%) and cefuroxime (71.8%). Susceptibility to ciprofloxacin (89.7%), fosfomycin (84.6%), nitrofurantoin (84.6%), and chloramphenicol (74.4%) remained high, but up to 7.7% of the isolates showed carbapenem resistance. Multidrug resistance was observed in 87.2% (34/39) of E. coli isolates, with MAR index above the critical threshold of 0.2. Seventeen isolates, comprising 15 multidrug-resistant (MDR) and 2 extensively drug-resistant (XDR), were selected for confirmation, and the uidA gene was detected in 16 (94.1%). Of the ARGs screened for, aadA (75%), acrA (88%), blaCTX-M(69%), blaNDM-1(75%), and tetA (25%) were detected. In all, 81.3% of the confirmed isolates harboured at least three resistance genes. These findings highlight the environmental dissemination of MDR E. coli and ARGs and underscore the need for enhanced wastewater management.