Characterization of Extended Spectrum Cephalosporin-Resistant Escherichia coli Strains Isolated from Raw Poultry Carcasses in Catering Services in Northern Greece.

Antimicrobial resistance is considered a topic of utmost interest under the concept of "One Health", having severe implications in both human and veterinary medicine. Among the antibiotic-resistant bacteria, gram-negative bacteria, especially those belonging to the order of Enterobacterales (such as Escherichia coli ), hold a prominent position in terms of both virulence and possessing/disseminating antimicrobial resistance (AMR) traits. The aim of this study was to examine the presence of extended-spectrum β-lactamase producing E. coli isolates in raw poultry carcasses collected from a university club. Five hundred raw poultry skin samples were collected from the Aristotle University of Thessaloniki (AUTh) club in Thessaloniki, Greece. A total of 64% of the samples were positive for the presence of extended-spectrum β-lactamase (ESBL)-producing E. coli . The isolates were further examined for their susceptibility to selected antibiotics by the disc diffusion method and were characterized as true ESBL, as producing class C cephalosporinases (AmpC) or "of unknown etiology" by the combination disc test. The 86 of the 120 isolates (71.67%) were classified as true ESBL, 24 (20.00%) as AmpC, and 10 (8.33%) as "of unknown etiology". The isolates were screened for the occurrence of β-lactamase genes ( bla TEM , bla CTX-M , bla SHV, and bla OXA ). Thirty-six isolates (32 ESBL- and 4 AmpC-phenotype) harbored both bla TEM and bla CTX-M genes, twenty-two isolates (among which 19 ESBL-phenotype and 2 AmpC-phenotype) harbored bla CTX-M only, whereas twenty-six (14 ESBL- and 12 AmpC-phenotype) isolates harbored bla TEM alone. No isolate harboring bla SHV or bla OXA was detected. The results demonstrate the existence of E. coli isolates producing extended-spectrum β-lactamases in poultry carcasses from Greece, pausing a risk for antibiotic resistance transfer to humans.