ISOLATION of Escherichia coli FROM TULUM CHEESE, PATHOTYPING, AND DETERMINATION OF ANTIBIOTIC RESISTANCE PROFILES

Abstract

Within the scope of this study, the presence of Escherichia coli, its pathotype characteristics, and antimicrobial resistance profiles were investigated in a total of 70 Tulum cheese samples obtained from local markets in the provinces of Isparta and Konya, Türkiye. A total of 25 presumptive E. coli isolates were recovered using Chromogenic Coliform agar. Morphological characterization of the isolates was performed by Gram staining, indole, and catalase tests, revealing that all isolates exhibited Gram-negative rod morphology and were positive for both indole and catalase reactions. For molecular confirmation, 16S rRNA gene-based PCR analyses were conducted, and the E. coli-specific 544 bp target fragment was detected in all isolates. Consequently, E. coli was detected in 35.71% of the cheese samples examined. In the pathotype analyses, none of the investigated isolates carried the targeted virulence genes, indicating that these strains could be considered commensal or non-pathogenic E. coli. Antimicrobial resistance testing demonstrated that all isolates were susceptible to eravacycline, trimethoprim-sulfamethoxazole, meropenem, aztreonam, amoxicillin-clavulanic acid, nitrofurantoin, cefoxitin, imipenem, and ampicillin. In contrast, the highest resistance rate was observed against norfloxacin (64%), followed by gentamicin (52%), amikacin (36%), ceftriaxone, and ciprofloxacin (28% each). A considerable proportion of the isolates exhibited resistance to two to five antibiotics. Multiple antibiotic resistance (MAR) index values ranged from 0.0 to 0.312, suggesting that some strains may have originated from high-risk sources exposed to intensive antibiotic pressure. Overall, these findings highlight the need for continuous monitoring of traditional Tulum cheeses with respect to hygienic quality and indicate that the presence of antibiotic-resistant E. coli strains may represent a potential public health concern.