Abstract
Background:
Foodborne illness outbreaks are frequently linked to pathogenic Escherichia coli O157:H7. Bacteria that are resistant to antibiotics, including E. coli O157:H7, are a worldwide issue that affects food safety and public health. Transporting meat between regions can spread antibiotic-resistant E. coli O157:H7.

Aim:
The aim of this study was to isolate and identify E. coli O157:H7 from beef and buffalo meat transshipped through Trisakti Port in Banjarmasin, to test its antibiotic resistance patterns, and to detect resistance genes.

Methods:
A total of 44 samples were collected, consisting of 31 beef samples and 13 buffalo meat samples. About 250 grams of each sample were labeled, and aseptic handling was required. Isolation and identification of E. coli were performed according to Indonesian National Standard (SNI) 2897:2008, followed by Gram staining. Serotyping of E. coli O157:H7 uses the Polymerase Chain Reaction (PCR) method. Resistance testing of E. coli O157:H7 was performed using the Kirby-Bauer disk diffusion method against six types of antibiotics, including ciprofloxacin, gentamicin, ampicillin, tetracycline, chloramphenicol, and sulfamethoxazole/trimethoprim. Antibiotic resistance gene detection was performed using the PCR method targeting the qnrS, tetA, and blaTEM genes

Results:
The results showed that 4 isolates were positive for E. coli O157:H7: 9.1% (4/44) from beef, 6.5% (2/31) from buffalo meat, and 15.4% (2/13) from other sources. Positive isolates showed resistance to ciprofloxacin, tetracycline, and ampicillin, with 2 classified as multidrug-resistant. All isolates were still susceptible to gentamicin, chloramphenicol, and sulfamethoxazole/trimethoprim. The resistance genes detected in these isolates included qnrS, tetA, and blaTEM.

Conclusion:
The occurrence of antimicrobial-resistant E. coli O157:H7 in transshipped beef and buffalo meat highlights potential food safety and public health concerns. These findings provide preliminary baseline information that may support future surveillance of foodborne pathogens and antimicrobial resistance within a One Health framework.

Key words: Antibiotic resistance; Escherichia coli O157:H7; Foodborne disease; Food transshipped; Meat.