Caracterização epidemiológica e molecular de Slaphylococcus coagulase negativa resistentes aos beta lactâmicos isolados de leite de vacas com mastite subclínica

Abstract

The coagulase-negative Staphylococcus group has become one of the main pathogens causing subclinical mastitis in dairy cattle. The objective of this study was to identify species of coagulase negative Staphylococcus isolated from milk contaminated by subclinical mastitis using the MALDI-TOF MS technique, to evaluate the resistance to beta lactam antimicrobials and to trace the presence of blaOXA-23 and blaKPC genes by polymerase chain reaction (PCR). One hundred and eleven isolates identified as Gram-positive cocci from the UFMG library were analyzed in this study. The isolates were submitted to analysis for identification through MALDI-TOF MS. The strains identified were evaluated for susceptibility to antibiotics cefoxitin (30 g), oxacillin (1 g), vancomycin (30 g), meropenem (10 g), imepenem (10 g) and subactam-ampicillin (10 g) the species multiresistance index was used. Strains phenotypically resistant to the antimicrobial meropenem were analyzed genotypically for the presence of the resistance genes blaOXA-23 and blaKPC. The frequency of species of the coagulase-negative Staphylococcus coagulase group, resistance to beta-lactams, as well as the multidrug resistance index were evaluated by Chi-square test. Using the MALDI-TOF MS technique, the most common genotype was 56.8% and the coagulase-negative Staphylococcus group had a frequency of 27%. The species Staphylococcus epidermidis and Staphylococcus chromogenes had a higher prevalence in the herds with 35.8%, respectively. In Janaúba Nova Prima property, the mean value of the multiresistance index found was 0.6, the other properties and municipalities were 0.5. Cefoxitin (100%), oxacillin (100%), meropenem (100%) and vancomycin (100%) were the antimicrobial resistance in the herds of dairy cattle. The blaOXA-23 and blaKPC resistance genes were not screened in the species Staphylococcus epidermidis, Staphylococcus chromogenes, Staphylococcus auriculares and Staphylococcus haemolyticus. Other mechanisms of resistance are present in the strains causing inefficiency in the antimicrobial treatment in the herds, compromising the well-being of the animals and public health.