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Resistance to last resort drugs such as carbapenem and colistin is a serious global health threat. This study investigated carbapenem and colistin resistance in 583 non-duplicate Enterobacteriaceae isolates utilizing phenotypic methods and whole genome sequencing (WGS). Of the 583 isolates recovered from humans, animals and the environment in Nigeria, 18.9% (110/583) were resistant to at least one carbapenem (meropenem, ertapenem, and imipenem) and 9.1% (53/583) exhibited concurrent carbapenem-colistin resistance. The minimum inhibitory concentrations of carbapenem and colistin were 2–32 μg/mL and 8 to >64 μg/mL, respectively. No carbapenem resistant isolates produced carbapenemase nor harbored any known carbapenemase producing genes. WGS supported that concurrent carbapenem-colistin resistance was mediated by novel and previously described alterations in chromosomal efflux regulatory genes, particularly mgrB (M1V) ompC (M1_V24del) ompK37 (I70M, I128M) ramR (M1V), and marR (M1V). In addition, alterations/mutations were detected in the etpA, arnT, ccrB, pmrB in colistin resistant bacteria and ompK36 in carbapenem resistant bacteria. The bacterial isolates were distributed into 37 sequence types and characterized by the presence of internationally recognized high-risk clones. The results indicate that humans and animals in Nigeria may serve as reservoirs and vehicles for the global spread of the isolates. Further studies on antimicrobial resistance in African countries are warranted.

At Shika in a subhumid environment of Nigeria, a 3-year study was carried out to select newly developed groundnut varieties for use in crop-livestock production systems. The study examined 11 groundnut varieties. Emergence time, plant stands at full emergence, forage and seed yields and yield components were examined. Whole plant samples were analysed for crude protein (CP) content. Varieties ICGV 87123 gave the lowest forage yield and cultivar M517-80I, the highest, with seven varieties recording forage yields above 5 t\ha. The CP content of forage was lowest (14n8 %) for variety M576-80I and highest (21n6 %) for variety M554-76. Mean seed yield (over 3 years) varied significantly from 0n73 to 1n68 t\ha. Only two varieties had mean seed yield 1 t\ha. The relationship between seed and forage yields was positive and significant (r l 0n529, P 0n006). Varieties RMP 12, 88-80I and M517-80 were most promising for both forage and seed production.