Untreated Wastewater as a Reservoir of Carbapenem-Resistant Escherichia Coli and Klebsiella Pneumoniae Isolates

Carbapenem-resistant Escherichia coli and Klebsiella pneumoniae are increasingly important pathogens with limited treatment options, and there is limited knowledge on the environmental factors contributing to their spread. We determined the occurrence of carbapenem-resistant E. coli and K. pneumoniae in hospital and slaughterhouse wastewater in Owerri, a city in southeast Nigeria. Samples of untreated hospital and slaughterhouse wastewater were collected monthly at the major tertiary hospital and slaughterhouse in Owerri between April and September 2023.  E coli and K. pneumoniae strains were selectively isolated and identified using conventional microbiological technique, and antibiotic susceptibility testing performed using the Kirby Bauer disk diffusion assay. A total of 193 E. coli and K. pneumoniae were isolated from the 269 wastewater samples analyzed.  Among the 193 isolates, 101 (52.3%) were identified as K. pneumoniae while 92 (45.7%) were identified as E. coli respectively. The isolates had high resistance rates (≥48.1%) to 6 antibiotics tested, and resistance to carbapenems ranged from 22.8% to 30.6% with resistance to ertapenem, 30.6 %( 59/193) being the highest carbapenem resistance observed. There was no statistical significant difference in carbapenem resistance rates between the hospital and slaughterhouse wastewater isolates (P > 0.05). This study has shown that the release of untreated wastewater into the environment may contribute to the increased spread of carbapenem-resistant E. coli and K. pneumoniae in Owerri, Nigeria. Therefore, there is pressing need to address wastewater as a crucial factor in curtailing the spread of carbapenem-resistant bacteria.