Abstract

Background:
Extended-spectrum β-lactamases (ESBLs), particularly those encoded by the cefotaxime (CTX-M) gene family, represent a significant threat to antimicrobial resistance. Ducks sold in traditional markets have been identified as active reservoirs of ESBL-producing bacteria, including those harboring CTX-M genes.

Aim:
This study aimed to molecularly detect the CTX-M gene, which encodes ESBL-producing bacteria, in ducks sold in traditional markets in Surabaya, Indonesia.

Methods:
A total of 144 samples were used. The isolation and identification of Escherichia coli bacteria were 83.33% (120/144) using eosin methylene blue agar media (Oxoid, England), biochemical tests, including triple sugar iron agar, Simmons citrate agar, and Indole, Methyl Red, Voges–Proskauer, and Citrate utilization tests media, such as sulfide indole motility, methyl red, and Voges–Proskauer. Isolates were positive for multidrug resistance and then subjected to the double disk synergy test. Strains that were ESBL in the double disc synergy test (DDST) test were then subjected to molecular testing of the CTX-M gene.

Results:
The multidrug resistant (MDR) test obtained results from 14 MDR isolates from 144 tested samples. ESBL detection was performed using the DDST, which showed that 50% (7/14) of the samples were positive for ESBL. pPolymerase chain reaction test confirmation showed that 71.4% (5/7) of the samples were positive for the CTX-M gene. The resistance profile indicates high resistance to ciprofloxacin, gentamicin, and erythromycin.

Conclusion:
This study confirmed the presence of the CTX-M gene encoding ESBL-producing bacteria in duck cloacal swabs from traditional markets in Surabaya, highlighting the actual role of these ducks as reservoirs of antimicrobial resistance.

Key words: CTX-M; Ducks; E. coli; ESBL; Public health.