Multidrug-resistant Enterococcus and coagulase-negative Staphylococcus isolates from poultry farms and nearby wells in Ibadan, Nigeria and their resistant genes

Abstract

Objective: To determine the antibiotic resistance patterns and resistance genes in enterococci and coagulase-negative staphylococci (CoNS) isolated from poultry farms and nearby wells in Ibadan, Nigeria. Methods: Poultry litter and well water samples were collected from three farms. Isolation of bacterial isolates were done using bile esculin azide agar and presumptive identification was done using conventional methods and confirmed by 16S rRNA using PCR. Antibiotic susceptibility testing was by disk diffusion method, while antibiotics resistance genes (ARGs) was detected by PCR. Results: Of the 86 Gram-positive cocci isolated, 71 (82.6%) were CoNS comprising Staphylococcus (S.) sciuri (69.0%) and S. xylosus (31.0%), while the remaining 15 (17.4%) were Enterococcus spp. comprising Enterococcus (E.) faecalis (60.0%) and E. faecium (40.0%). Antibiotics resistance of the isolates showed that 91.5% (CoNS) and 93.0% (enterococci) were resistant to penicillin, 90.1% and 86.7% to tetracycline and 94.4% and 66.7% to erythromycin, respectively. Also, all the 15 (100%) Enterococcus spp. and 68 (95.8%) CoNS were multidrug resistant. The ARGs detected in the CoNS include: tetM (45.4%), tetL (9.0%) and ermB (27.3%), while tetM (9.1%), tetL (4.5%) and ermB (4.5%) were found in Enterococcus spp. Conclusions: This study revealed that poultry litters in the study area are pools of antimicrobial resistant enterococci and CoNS, as well as, the corresponding ARGs. Therefore, necessary monitoring and ample treatment of poultry waste should be done before their release into the environment.

Keywords

• poultry litter
• well water
• enterococci
• coagulase-negative staphylococci
• antibiotic resistance