Detection of some resistance genes in Salmonella isolated from Poultry farms in Abia and Imo States, Southeastern Nigeria
Sixteen Salmonella Gallinarum and 24 Salmonella Pullorum strains isolated from chickens were screened for resistance to 11 antibacterial agents using the disc diffusion method. Five of the Salmonella Gallinarum and five of S. Pullorum strains resistant to streptomycin, gentamicin, tetracycline and sulfamethoxazole /trimethoprim were screened for presence of strA/strB, aac (3)-II, aac (3)-1V, tetA and tetB and sul 1 (dfr/A) and sul 3 (dfr/G) resistance genes. A singleplex PCR with resistance gene specific primers was used to ascertain the presence of the target resistance gene. All the Salmonella isolates studied were resistant to ampicillin while 95% were resistant to tetracycline and streptomycin. None of the isolates were resistant to ofloxacin and ciprofloxacin. Three of the sulphamethaxazole/trimethoprim-resistant isolates haboured dfrA and dfrG genes while one of the gentamicin-resistant isolates was positive for aac (3)-II genes. None out of the 10 streptomycin and tetracycline resistant isolates harbored any strA/strB, tetA and tetB genes. In addition, none of the 10 gentamicin resistant isolates harbored aac (3)-IV genes. The high resistance rates recorded in this study may be attributed to indiscriminate use of antibacterial agents.
Keywords: Salmonella, antimicrobials, resistance genes, Polymerase chain reaction, Southeastern Nigeria