Carbapenemase Genes and Plasmid Profiles in Meropenem-Resistant Bacteria from Goats and Cattle in Ekiti State, Nigeria

Carbapenem resistance in livestock is a growing One Health concern, but data from goats and cattle in sub-Saharan Africa are limited. This study examined meropenem-resistant bacteria in 100 rectal swabs from goats and cattle in Ekiti State, Nigeria. Isolates were grown on MacConkey and blood agar and identified by biochemical tests and 16S rRNA sequencing. Meropenem MICs were measured by E-test, other antibiotics by disc diffusion, and six carbapenemase genes by multiplex PCR. Plasmids were extracted by the TENS method and sized on agarose gels. Six isolates were resistant to meropenem (MIC 4-6 μg/mL). Four came from goats (Enterococcus casseliflavus, E. gallinarum, Enterobacter huaxiensis and Bacillus cereus) and two from cattle (both B. subtilis). Carbapenemase genes were found in five isolates (83.3%), including every goat isolate. The genes blaVIM, blaOXA-48 and blaSPM were the most common (two isolates each), blaIMP was not detected, and two isolates carried more than one gene. Tigecycline was fully active (100%), followed by nitrofurantoin and fosfomycin (92.86% each), while polymyxin B showed the highest resistance (57.8%). Four isolates carried a single plasmid of about 10 kb, and two had none. Because genes and plasmids did not always coincide, some genes may be chromosomal. The findings give baseline evidence for including ruminants in antimicrobial resistance surveillance under a One Health framework.