Abstract

Background:
Food safety is essential for public health. Food products from animals and farm environments can serve as vehicles for the transmission of antibiotic-resistant bacteria and resistance genes to humans.

Aim:
This study aimed to identify the phenotypic and genotypic resistance profiles of multidrug-resistant Escherichia coli isolated from dairy buffalo farms.

Methods:
A total of 103 E. coli isolates were recovered from soil samples from a previous survey of dairy buffalo farms. Phenotypic characterization of these isolates was performed using antibiotic susceptibility test through microbroth dilution, while molecular analysis employed polymerase chain reaction (PCR) and multilocus sequence typing (MLST).

Results:
Antibiotic sensitivity testing revealed that 19.41% (20/103) of the environmental E. coli isolates exhibited variable resistance to antibiotics such as tetracycline (TET), ampicillin (AMC), ticarcillin (TIC), piperacillin (PIP), chloramphenicol (CHL), and minocycline (MNO). Of these resistant isolates, four were identified as multidrug-resistant (MDR), with AMC-TIC-PIP-TET-CHL as the most common resistance pattern. Molecular assays also confirmed the presence of resistance determinants, including blaTEM for β-lactam resistance, and tetA for TET resistance, in these MDR E. coli. These MDR environmental isolates also belong to the same E. coli clones found in humans based on their unique MLST sequence types.

Conclusion:
The detection of MDR environmental E. coli in dairy buffalo farms in the country highlights a multifaceted hazard that can spread through livestock production systems, enter the food supply chain, and pose zoonotic disease risks.

Key words: AST; Buffalo farms; MDR E. coli; tetA; blaTEM.