| Congresso Brasileiro de Microbiologia 2023 | Resumo: 570-1 | ||||
Resumo:Bovine mastitis, an inflammation of the mammary glands, can be caused by various factors, making it difficult to control. This disease leads to significant economic losses in the dairy industry and poses potential risks to public health due to the presence of microorganisms carrying antimicrobial resistance genes against drugs used to treat both animal and human diseases. Escherichia coli and Klebsiella pneumoniae are major pathogens responsible for environmental bovine mastitis and are of particular concern in public health and epidemiological surveillance due to their role as reservoirs of antimicrobial resistance genes. These pathogens possess multiple virulence factors that impede the host's immune response. The rise of antimicrobial resistance is a significant concern for human and animal health. Beta-lactams, tetracyclines, and aminoglycosides are commonly used to treat clinical mastitis. However, the emergence of extended-spectrum beta-lactamases (ESBLs), a group of enzymes that confer resistance to most beta-lactams, has rendered these antimicrobials ineffective, except for cephamycins, carbapenems, and other beta-lactamase inhibitors. Carbapenemases, initially identified in K. pneumoniae, are enzymes capable of hydrolyzing various beta-lactam antibiotics. This study aimed to characterize ESBL-producing and carbapenemase-producing E. coli and K. pneumoniae isolates from bovine mastitis cases in ten high-production dairy farms in São Paulo and Minas Gerais states. Three isolates of each species (E. coli and K. pneumoniae), in each degree of mastitis severity (mild, moderate, and severe), totaling eighteen isolates, underwent phenotypic tests to evaluate ESBL and carbapenemase production. ESBL production was confirmed in all isolates according to CLSI (2020) guidelines, using ceftriaxone, cefotaxime, ceftazidime, and aztreonam (Cefar Disks). Isolates resistant to these drugs were further subjected to a confirmatory test using amoxicillin-clavulanic acid to detect ESBL production. Additionally, all isolates were tested for carbapenemase production according to ANVISA Technical Note Nº. 01/2013, using ertapenem, imipenem, and meropenem. Furthermore, the isolates were assessed for β-lactam resistance encoding genes (blaTEM, blaSHV, blaCTX-M2, blaCTXM8, and blaCTX-M15), carbapenemases (blaKPC and blaNDM), as well as colistin resistance (mcr-1 and mcr-2). The results revealed that one isolate of each species exhibited the "ghost zone" or distorted halo, confirming ESBL production, and the presence of blaCTX-M15 and blaCTX-M2 genes, respectively. None of the samples tested positive for carbapenemase production. The detection of ESBL-producing isolates in milk samples is concerning because dairy products could serve as a transmission vehicle for these pathogens to humans. Palavras-chave: Bovine mastitis, Carbapenemases, ESBL Agência de fomento:Processo n° 2021/09902-3, Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) | |||||