| Congresso Brasileiro de Microbiologia 2023 | Resumo: 725-2 | ||||
Resumo:Staphylococcus aureus is responsible for approximately 40% of mastitis cases in bovine herds and is also associated with animal and environmental contamination. Additionally, S. aureus is one of the bacteria that causes the most infections in humans due to its rapid adaptability and antibiotic resistance. Considering the importance of this microorganism in public health, the study aimed to assess the sensitivity of S. aureus isolates from bovine mastitis to the ethanolic extract of Ocimum campechianum (basil) to define possible resistance profiles. Microbiological analyses were performed on 20 raw milk samples from cows with clinical suspicion of mastitis to detect S. aureus. Gram staining was conducted for bacterial characterization, along with catalase, coagulase, and oxidase tests. Out of the 20 collected samples, 6 were considered gram-positive cocci, confirmed as catalase and coagulase positive on mannitol salt agar, thus identified as Staphylococcus aureus. After this step, the strains were standardized and subjected to susceptibility testing to beta-lactam antibiotics (ampicillin, oxacillin, and penicillin G) and third-generation cephalosporins (cefotaxime and ceftriaxone) using the disc-diffusion method on agar, with results interpreted according to the Clinical and Laboratory Standards Institute (CLSI) manual. Additionally, Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of basil extract were evaluated using the microdilution technique in broth. The assays were performed in biological triplicates, and sterility control of the medium and extract, as well as bacterial viability and antimicrobial potential of the diluent used, were conducted for enhanced test safety. The results showed that 67% of the isolates were resistant to cephalosporins and penicillin G, 50% to ampicillin, while all were sensitive to
oxacillin. However, when tested against basil, all isolates showed sensitivity to the extract. Therefore, O. campechianum demonstrated good bacteriostatic and bactericidal action, with relatively low MIC and MBC values (3.125 µg/mL for both), reinforcing its potential as an alternative to conventional antibiotics. In conclusion, these results suggest that the use of basil extract may represent a viable and effective alternative to conventional antibiotic treatment. Moreover, its observed sensitivity profile indicates that basil may be particularly valuable in combating strains resistant to cephalosporins and penicillin G, which are common in clinical cases. Although our findings are promising, it is essential to proceed with additional in vivo studies to better understand the mechanisms of action of basil extract and its impacts on animal health. Palavras-chave: antibiotic resistance, mastitis, public health, S. aureus Agência de fomento:Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) - Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco (FACEPE). | |||||