Detection of extended-spectrum β-lactamase producing Escherichia coli in table eggs from Istanbul.

ESBL-producing Escherichia coli strains threaten public health and obligate the use of last-resort antibiotics. This study identified 15 E. coli isolates through 16S rRNA and gyrB genes, specific to E. coli, in 120 egg samples (12.5%). Antibiotic resistance was detected according to the EUCAST and CLSI in E. coli isolates. 2 isolates were susceptible to all antibiotics, one isolate was resistant to one antibiotic, one isolate was resistant to 2 antibiotics, and 11 E. coli isolates (73.3%) had multidrug resistance. Most frequent antibiotic resistances were detected against ampicillin (80%), tetracycline (66.6%), and chloramphenicol (66.6%). A double-disc confirmation test was used to detect ESBL production, and blaTEM, blaSHV, blaCTX-M and blaOXA genes were searched by PCR. The blaTEM (100%) gene was found in all resistant E. coli isolates, and the blaCTX-M gene was detected in only 3 (20%) E. coli isolates. None of the E. coli isolates contained the genes responsible for carbapenem and colistin resistance. Our results show that multi-drug antibiotic resistance and the blaTEM gene are frequent in E. coli from table eggs in Istanbul. This is the first preliminary study on ESBL-producing E. coli isolates in table eggs in Türkiye.