Antibiogram and Some Genetic Markers of Resistance in Coagulase Negative Staphylococci and Mammaliicoccus (Staphylococcus) Sciuri from Veterinary Sources in Rivers State, Nigeria

Abstract

Coagulase-negative Staphylococci (CoNS) are important reservoirs of antibiotic-resistance genes and associated mobile genetic elements, with potential relevance to the emergence of methicillin-resistant staphylococcal clones. This study determined antibiotic resistance and molecular resistance markers among coagulase-negative Staphylococcus isolates from livestock in Port Harcourt, Rivers State, Nigeria. During a four-month study, 422 samples were collected from the ears, fur, noses and mouths of rams, goats, cows and sheep and processed using standard microbiological methods. Antimicrobial susceptibility testing was performed by disc diffusion against oxacillin, cefoxitin, erythromycin, gentamicin, clindamycin, amoxicillin, vancomycin, ciprofloxacin, ofloxacin and cefuroxime. Polymerase chain reaction was used to detect mecA, ermA, ermC and SCCmec. Ninety-four coagulase-negative isolates were recovered from the sampled anatomical sites and animal species, and the majority showed resistance to several antimicrobial agents tested. Four genera, Enterococcus, Mammaliicoccus, Staphylococcus and Micrococcus, were identified. Mammaliicoccus (Staphylococcus) sciuri was the most frequent, whereas Enterococcus gallinarum, Staphylococcus aureus and Micrococcus aloeverae were evenly represented. Of 15 representative isolates analysed by PCR, 11 harboured one or more resistance markers: six carried ermA, three ermC, one mecA and nine SCCmec. The detection of these resistance markers, together with multidrug-resistant Mammaliicoccus (Staphylococcus) sciuri, indicates that livestock in the study area may harbour coagulase-negative Staphylococci with antimicrobial-resistance determinants of veterinary and public health relevance.