Abstract #T37

# T37
Investigation of toxin genes in strains of Staphylococcus spp. antimicrobial resistant isolated from bovine mastitis.
J. R. P. Arcaro*1, J. C. R. da Cruz1, J. E. P. Braga1, L. Castelani1, 1Instituto de Zootecnia, Nova Odessa, São Paulo, Brazil.

Staphylococcus spp. are one of the main etiological agents of bovine mastitis, and exhibit high-level antimicrobial resistance. These microorganisms are reported as significant contaminants of raw milk and dairy products, being able to produce various toxins causing food poisoning outbreaks and toxic shock syndrome in humans. The aim of this study was to detect the presence of genes sea, sec, and tst, responsible for the production of staphylococcal enterotoxins A, C and TSST-1, respectively, in strains of Staphylococcus spp. antimicrobial resistant, isolated from bovine mastitis. Twenty-seven S. aureus and 40 CoNS (i.e., S. capitis, S. chromogenes, S. epidermidis, S. hominis, S. sciuri, S. simulans, and S. warneri), exhibiting a resistance profile (ampicillin, ciprofloxacin, clindamycin, enrofloxacin, erythromycin, florfenicol, gentamicin, kanamycin, linezolid, neomycin, oxacillin, penicillin, streptomycin and tetracycline, and mecA gene negative), isolated from heifers and cows with mastitis, were used. The samples were from commercial farms in São Paulo State, Brazil. The extraction of genomic DNA was performed using DNA Kit RTP Bacterium - Invitek. The genes amplification was performed by PCR and the reaction product was visualized on 2% agarose gel electrophoresis in 1× TBE buffer (1 M Tris base, 0.9 M boric acid, 0.01 M EDTA) stained 0.5% red gel. For positive control they were used to S. aureus ssp. aureus ATCC 29213 and NRS111. Descriptive statistical analysis was performed by calculating relative frequencies (PROC FREQ; SAS Institute, 2011) of resistant strains containing enterotoxins genes. The presence of the sea and tst genes was not found in any of the 67 strains, and the sec gene was detected in 20 of S. aureus strains (29.85%). The bacterial resistance to antibiotics associated with the production of enterotoxins in strains of Staphylococcus spp. isolated from bovine mastitis, adds risk to public health. Once the enterotoxins are thermostable and remain active in the foods even after processing, the use of the good hygiene practices is required to reduce the microbial load of milk and dairy products, and therefore the chance of causing food poisoning.

Key Words: coagulase negative staphylococcus, enterotoxins, mastitis