Abstract
Methicillin-resistant Staphylococcus spp. 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 blaZ genes 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) of S. simulans, 10.2% (9/88) of S. sciuri, 4.5% (4/88) of S. lentus and 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.
Highlights
Animal production is a relevant activity of Brazilian agribusiness
TOF MS, achieving a confident score (2.0 to 2.616), of which 52 isolates needed complementary identification. They were tested for resistance to novobiocin and sugar fermentation, 59.6% (31/52) identified as S. gallinarum, and 40.4% (21/52) as other coagulasenegative Staphylococcus spp. (CoNS)
S. gallinarum was the prevalent species, presenting 32.1% (18/56) isolates, followed by S. simulans, S. hominis, S. cohnii, S. lentus, S. sciuri, S. xylosus, S. aureus and other CoNS that could not be identified at species level (Figure 1)
Summary
Animal production is a relevant activity of Brazilian agribusiness. Brazil stands out in poultry production as the second-largest producer of chicken meat globally, reaching 13.056 million tons, leaving behind only the US with a production of 18.596 million tons (Associação Brasileira de Proteína Animal, 2018). The use of antimicrobials in animal production has different purposes: to protect or improve animal health and to stimulate faster growth and maximize profits (Van Boeckel et al, 2015). The use of antimicrobials as growth promoters is of great concern as it increases the chances of developing resistant bacteria. In Brazil, the prohibition of β-lactams as additives was established in article 18 the Normative Instruction 26/2009 published by Ministry of Agriculture, Livestock and Supplies (Brasil, 2009)
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