Multidrug-resistance in Escherichia coli and Klebsiella pneumoniae isolated from broiler chickens in Eastern Thailand

Abstract

Broiler chickens have been suggested as an important source of antibiotic resistance Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae). The coinfection of multiple species of bacteria provides a specific ecological niche for the plasmid-mediated exchange of antibiotic-resistance genes. However, there is limited information about antimicrobial resistance (AMR) phenotypes of E. coli and K. pneumoniae isolates from broiler chickens. This study aimed to isolate E. coli and K. pneumoniae from broiler chicken farms in Thailand by observing the antibiotic resistance profiles and detecting the coexistence of these two bacteria. A total of 26 E. coli and 29 K. pneumoniae isolates were collected from 116 chicken cloacal swabs from four broiler chicken farms. Biochemistry tests and conventional polymerase chain reaction (PCR) were performed to identify the strains. All isolates were tested for antimicrobial susceptibility by disc diffusion against 11 antibiotics. Extended-spectrum β-lactamase (ESBL) production was confirmed using the double disc synergy test. The most detected antibiotic resistance from E. coli and K. pneumoniae isolates was erythromycin (100%), followed by chloramphenicol (96%) for E. coli and amoxycillin (93%) for K. pneumoniae. Most isolates of E. coli (100%) and K. pneumoniae (89.65%) were classified as multi-drug resistance (MDR) bacteria. Ten simultaneous E. coli and K. pneumoniae isolates were found. The ESBL production was detected from most E. coli, whereas it was not detected from K. pneumoniae, concurrently. Co-resistance against enrofloxacin was the majority of them. Possibly coexisting resistance genes in plasmids, they transmit between species from the same host. This is the first report on detecting simultaneously isolated multidrug-resistant E. coli and K. pneumoniae from broiler chickens in Thailand. Surveying the spread of multidrug-resistant bacteria and further studies of genetic communication events are necessary to determine human health risks.