Characterization of staphylococcus spp. isolates and β-lactam resistance in broiler chicken production

Abstract

Methicillin-resistant Staphylococcusspp. are important in both human and veterinary medicine due to its resistance to all β-lactam antimicrobials. The mec genes (mecA, mecA variant and mecC) and blaZgenes are responsible for this phenotype, β-lactam resistance, and are widely spread between staphylococci from animal and human origin. Otherwise, detected that point mutations at the alignment sites could impair the conventional primers for mecA gene amplification in some isolates from animal origin. This study aimed to analyze strains of Staphylococcus spp. isolated from broiler chicken to evaluate its resistance profile to β-lactams. Sixty cloacal and sixty tracheal swab's were collected at two broiler chicken farms located in the Rio de Janeiro mountain region. The biochemical tests and MALDI-TOF performed bacterial identification. Resistance was evaluated by disk diffusion test and PCR for detecting conventional mecA, variant mecA and blaZ gene. Of 88 staphylococcal isolates, 35,2% (31/88) was identified as S. gallinarum, 17%(15/88) ofS. simulans, 10.2%(9/88) ofS. sciuri, 4.5% (4/88) ofS. lentusand S. cohnii, and 2.2% of S. xylosus and S. aureus (only coagulase-positive Staphylococcus specie identified). The antimicrobials evaluated were penicillin, cefoxitin, oxacillin and vancomycin. Considering the antibiotype profile of Staphylococcus spp. isolates evaluated, six patterns were observed, and the antibiotype 1 were the prevalent presenting 62.5% (55/88). Phenotypic oxacillin-resistance was detected in 26,1% (23/88) of the isolates, and this parameter were used to analyze mecA mediated resistance. The conventional primer did not amplify any the mecA gene while the universal primer allowed the detection of the variant mecA in six strains, being its first report in broilers.