Antimicrobial activity and in vitro identification of extended-spectrum beta-lactamases (esbls) produced by escherichia coli and klebsiella spp. isolated from bovine mastitis cases

Bovine mastitis is of high significance in public health due to its potential as a source of infectious agents transferable between animals and humans. Extended-spectrum beta-lactamases (ESBLs) play a crucial role by hydrolyzing penicillins, cephalosporins (excluding cephamycins), posing a current public health problem. This study focused on detecting ESBLs in Escherichia coli and Klebsiella spp. isolated from bovine mastitis cases, using the Kirby-Bauer technique and phenotypic methods to assess antibiotic susceptibility, for which the data were collected in the microbiology area of the general laboratory of the State University of Bolivar for 12 months. Two E. coli strains were sensitive to all antibiotics, while two others showed resistance to the third-generation cephalosporins, with an increased inhibition zone in the presence of beta-lactamase inhibitors. The remaining two strains exhibited total resistance. In Klebsiella spp., all six strains were resistant to the third-generation cephalosporins, with an increased inhibition zone observed in one strain. 25% of the isolates were ESBL producers (33.33% in E. coli and 16.67% in Klebsiella spp.), with seven isolates carrying other beta-lactamases. In conclusion, bovine mastitis, as a source of infectious agents and the presence of beta-lactamases, stands out as a public health issue. The study highlights antimicrobial resistance, emphasizing the need for control and surveillance.