Biofilm Formation and Antibiotic Resistance Genes of Escherichia coli From Poultry Farms and Clinical Samples

Escherichia coli affects human health through intestinal and extraintestinal infections. Avian pathogenic E. coli (APEC) contributes to colibacillosis in poultry and can develop public health risks. Antibiotic resistance and biofilm-producer strains are challenges in infection control options.

This study aimed to characterize phenotypic and genotypic antibiotic resistance profiles as well as biofilm formation assay in E. coli isolates from clinical and poultry samples.

In the study, 42 E. coli isolates were collected and confirmed from clinical and poultry sources. The isolates were evaluated for pathotypes using polymerase chain reaction (PCR). Antibiotic resistance was evaluated using the disk diffusion technique and minimum inhibitory concentration (MIC) tests. PCR was utilized to identify antimicrobial resistance genes associated with fluoroquinolones, sulphonamides, tetracyclines and beta-lactams. Biofilm formation was evaluated using a 96-well microtiter plate.

Three clinical isolates, including enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC) and enterotoxigenic E. coli (ETEC), were identified as pathogenic strains. The highest rates of resistance were recorded against tylosin (100%), neomycin (92.85%), tetracycline (85.7%), ampicillin (73.8%), doxycycline (71.4%), ciprofloxacin (64.28%), trimethoprim/sulfamethoxazole (64.28%) and enrofloxacin (57.1%). The most prevalent resistance genes detected as blaTEM and gyrA/B (97.6% and 76.1%, respectively). The overall prevalence of blaCTX, sul1, sul2, tetA and tetB genes were 21.4%, 45.2%, 11.9%, 33.3% and 7.1%, respectively. The qnrB, qnrB4 and qnrS genes were absent in the clinical samples, whereas present in poultry isolates. All isolates were biofilm producers, and 96.4% of poultry isolates had strong biofilm formation capacity.

The alarming levels of resistance genes and biofilm formation of isolates in the present study emphasize the need for antibiotic management practices and further research on resistance transmission dynamics in the food industry.