ESBL-producing and virulent enteric bacteria from goats in Northeastern Brazil

The aim of this study was to identify Enterobacteriaceae in healthy milk, mastitic milk, and rectal swab samples from dairy goats and kids in herds located in the state of Pernambuco, Brazil, and to evaluate the phenotypic profile of ESBL-producing isolates, as well as to detect the genotypic expression of ESBL resistance genes and virulence factors. Rectal swab and milk samples were collected from 56 goats and 14 kids. Gram-negative bacillary colonies were identified using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS). The double-disk synergy test (DDST) for the detection of extended-spectrum β-lactamases (ESBL) was performed using the antibiotic discs ceftazidime, ceftriaxone, cefotaxime, aztreonam, and amoxicillin/clavulanic acid. Genotypic profiling for ESBL and virulence factor genes targeted blaSHV, blaTEM, blaCTX-M, stx1, stx2, eaeA, and hlyA. Escherichia coli, Enterobacter spp., Klebsiella spp., and Cronobacter sp. were identified. The phenotypic test revealed that 27% (25/92) of the isolates were ESBL-positive. In the genotypic analysis, one isolate carried the blaSHV gene and one carried the blaTEM gene, while blaCTX-M was not detected. At least one virulence-associated gene (hlyA, stx1, and stx2) was detected in 32% (30/92) of the isolates. The detection of antimicrobial resistance and virulence factors in enteric bacteria from healthy goat herds highlights potential risks to human health and animal welfare, as well as possible economic losses in rural farming systems.