Staphylococcus aureus isolados de leite de vacas com mastite em diferentes regiões do Rio Grande do Sul: enterotoxigenicidade, capacidade de formação de biofilme, resistência a antimicrobianos e classificação nos grupos agr

Abstract

Bovine mastitis is a serious problem for the dairy herd in the world, with S. aureus main microrganism that causes the disease, as it is one of the most important microrganisms involved in foodborne disease (FBD) throughout the world. The objective of this study was to evaluate the identity of 31 isolates of coagulase positive staphylococci (SCP) from bovine mastitis clinical and subclinical through phenotypic and molecular analyzes, and check your enterotoxigenic potential, biofilm formation capacity, antimicrobial resistance and classify them in agr groups. To evaluate the enterotoxigenicity, was analyzed the presence of the classic enterotoxin genes (sea, seb, sec, sed and see) using the polymerase chain reaction and to verify the biofilm production capacity was evaluated adherence capacity in polystyrene microplates as well as the presence of icaA and icaD genes, using PCR. Antimicrobial resistance was tested according to CLSI (2012). For classification in agr groups used a biplex- PCR. All isolates were identified as S. aureus. We observed the resistance to one or more antibiotics in 93% of the isolates and 54% of the isolates were multidrugresistant. In relation to biofilm formation, it was found that 45% of isolates adhered to polystyrene, and the presence of icaA gene was observed in 71% of the isolates and icaD gene in 74% of the isolates. Regarding the presence of the classical enterotoxin genes was observed the prevalence of the enterotoxin A gene (13%), followed by the enterotoxin C gene with 6.4% and enterotoxin B gene with 3.2%. There was no presence of enterotoxin gene D and E. In relation to the classification in agr groups, there was prevalency of agr III and I (32.2% and 22.5% respectively), however, there was overlap of these agr groups in two isolates. It was found that all isolates belonged to the species S. aureus between SCP isolates from mastitis from different regions of Rio Grande do Sul, Brazil. Some isolates have enterotoxin genes and have the capacity to form biofilm in polystyrene, Because of this, the isolates have the capacity of persist in environments milking and the food industry. The isolates are resistant to most antibiotics tested, and belong to different agr groups, that are responsible for regulating the antimicrobial resistance and biofilm formation, worrying factors for the incidence of the disease and the persistence of this microrganism in the milking and in the milk processing environment.