Extended-spectrum β-lactamase (ESBL)-producing enterobacteria isolated from broiler breeder chickens

Due to the use of antibiotics for the treatment and prevention of bacterial infections in intensive poultry production, it is important to study the prevalence and resistance profile of gram-negative extended-spectrum beta-lactamase (ESBL)-producing bacteria. Among the several classes of antibiotics available, beta-lactam agents are the most widely used category in human and veterinary medicine. Thus, the objective of this work was to evaluate the resistance profile and ESBL-producing capacity of strains isolated from broiler breeders. Gram-negative bacteria were isolated in selective media from a collection of 87 cloacal swabs, and they were identified by conventional biochemical methods and MALDI-TOF mass spectrometry and studied for antibiotic resistance, including ESBL production. Of the 87 samples, 52 gram-negative bacteria were isolated. There was high bacterial resistance to the main classes of antibiotics used in poultry: cephalosporins (74.2%), quinolones (73.8%) and penicillins (73.6%). A phenotype suggestive of ESBL production was also found in 42.31% of isolates, showing resistance to the beta-lactam antibiotics tested. The results demonstrate the need for the guidance of professionals working broiler breeders to reduce the presence of drug-resistant and ESBL-producing bacteria and to prevent their spread to the environment, fertile eggs and broilers, and consequently to chicken meat and humans.