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Metallo-β-lactamases (MBLs) are broad spectrum β-lactam degrading enzymes with the „last resort antibiotics‟, carbapenems, in their hydrolytic spectrum. Their emergence and rapid global spread have become a threat to the antibiotics armamentarium. This study was conducted to determine the prevalence of carbapenem non-susceptible Escherichia. coli isolates harbouring MBL enzymes in major meat sources within Nsukka, Enugu State, Nigeria. A total of 250 randomized non-duplicate rectal swab samples of birds and cattle at different poultry and ranches, as well as meat vendors‟ tables were cultured for E. coli isolates. Susceptibility of the properly characterized E. coli isolates to carbapenems and other commonly administered antibiotics was evaluated using disk diffusion method according to Clinical & Laboratory Standard Institute (CLSI) 2018 guideline. MBL production and Multiple Antibiotics Resistance (MAR) Index of the isolates were determined using standard formula and Combined Disc Test (CDT) technique respectively. A total of 138 E. coli were identified, out of which 57% (n = 78) were resistant to carbapenems, while 60% (n = 47) of the carbapenem-non-susceptible isolates were phenotypically confirmed as MBLs-producers. Their MAR Indices and level of resistance to other antibiotics ranged from 0.2 to 1.0 and 20 to 100% respectively. The work identified high levels of carbapenem resistance mediated by MBL enzymes in meat sources among occupants of Nsukka metropolis, necessitating an urgent need for sensitization of livestock and meat handlers, as well as the institutionalization and implementation of proper infection control measures to contain their spread. Further molecular studies are also needed for the full characterization of other carbapenem resistance mechanisms that could be associated.
Keywords: E. coli, Carbapenem, Resistance, MBL, CDT, CLSI