Antibiotic Resistance of Escherichia coli from Humans and Black Rhinoceroses in Kenya

Upsurge of antibiotic resistance in wildlife poses unprecedented threat to wildlife conservation. Surveillance of antibiotic resistance at the human-wildlife interface is therefore needed. We evaluated differences in antibiotic resistance of Escherichia coli isolates from human and the endangered black rhinoceros in Lambwe Valley, Kenya. We used standard microbiological techniques to carry out susceptibility assays using eight antibiotics of clinical and veterinary importance. Standard PCR method was used to characterize antibiotic resistance genes. There was no difference in resistance between E. coli isolates from human and those from rhinoceros (U = 25, p = 0.462). However, higher resistance in isolates from humans was noted for cotrimoxazole (p = 0.000, OR = 0.101), ceftriaxone (p = 0.005, OR = 0.113) and amoxicillin/clavulanic acid (p = 0.017, OR = 0.258), whereas isolates from rhinoceros showed higher gentamicin resistance (p = 0.001, OR = 10.154). Multi-drug resistance phenotype was 69.0% in humans and 43.3% in rhinoceros. Isolates from both species contained bla(TEM), tetA, tetB, dfrA1 and sul1 genes. Resistance profiles in the two species suggest potential for cross-transfer of resistance genes or exposure to comparable selective pressure and call for a multi-sectorial action plan on surveillance of antibiotic resistance at the human-wildlife interface. Genome-wide studies are needed to explicate the direction of transfer of genes that confer antibiotic resistance at the human-wildlife interface.