| Congresso Brasileiro de Microbiologia 2023 | Resumo: 513-2 | ||||
Resumo:The Staphylococcus aureus is one of the main agents responsible for causing mastitis in dairy cows. This pathogen causes significant economic losses due to the reduction in the quality and quantity of milk produced. In addition to these losses, these bacteria have pathogenic potential,are widely resistant to antimicrobials and are capable of producing biofilm on the bovine udder
and on equipment. In addition, the indiscriminate and unnecessary use of antibiotics in the treatment of this disease can result in residual effects in the milk, causing risks to public health.The aim of this study was to analyze the molecular and phenotypic profile in relation to antimicrobial resistance, biofilm production and the presence of an efflux pump in 28 S. aureus isolates obtained from raw milk samples of clinical and subclinical mastitis in the Federal District. To this end, the samples were confirmed biochemically and by molecular biology for the presence of the specific genes nuc and aroA. Antimicrobials were evaluated by the disk diffusion method and also by PCR for the blaZ, mecA, tetK, tetM, vanA and vanB genes. For the investigation of biofilm production, Congo Red Agar, Microplate Adhesion Assay (MAS)and PCR for the icaA, icaD genes and Mueller Hinton medium with the addition of ethidium
bromide were used to assess the presence of an efflux pump. The results showed that in the Congo Red test 21.42% were able to produce biofilm. Using the plate adhesion method, 100% of the isolates produced biofilm and were classified into 3 categories: 32.14% were able to produce biofilm strongly (maximum OD 0.397), 32.14% moderately and 35.71% weakly. The icaA gene was present in 28% and the icaD gene in 92.85% of the samples evaluated. Regardless to the presence of the efflux pump, only 3.5% were phenotypically positive.Analysis of the antimicrobial resistance profile showed higher resistance to the pharmacological bases clarithromycin (100%), doxycycline (92.9%), linezolid (92.9%) and clindamycin (89.3%). Nitrofurantoin showed the highest sensitivity profile, reaching 89.3%,followed by gentamicin and vancomycin with 82.1%. The mecA gene was not detected in any sample, while the blaZ β-lactam resistance gene was present in 89.7% of the samples. The tetK,tetM, vanA and vanB genes were present in 10/28 (34.5%), 10/28 (34.5), 5/28 (17.2%) and 9/28 (31%), respectively. The ability to produce biofilm and the high resistance to antimicrobials observed in some isolates in this study are characteristics that contribute to the difficulty of treating mastitis and also the persistence of this bacterium in dairy herds and in the food industry. Palavras-chave: Biofilm, foodborne diseases, mastitis, resistance Agência de fomento:Fundação de Apoio à Pesquisa do Distrito Federal | |||||