Retail chicken giblets contaminated with extended-spectrum cephalosporin- and carbapenem-resistant Salmonella enterica carrying bla CMY-2.

Background and Aim: Chickens are considered as the main source of Salmonella , with infection potentially spreading to the public through outlets. The study aimed to investigate poultry shops for Salmonella enterica resistant to extended-spectrum cephalosporins-resistant (ESCR) and carbapenems-resistant (CR).
Materials and Methods: Samples were collected from chicken giblets, water tanks, and workers at retail shops. Salmonella was isolated and serotyped; the presence of invA , stn , ompA , and ompF was determined using polymerase chain reaction (PCR). The isolates were tested for ESCR and CR by a disk-diffusion test; a confirmatory extended-spectrum β-lactamase (ESBL) test was performed by combinational disk-diffusion test with clavulanic acid. The resistant isolates were screened for ESBL ( bla TEM, bla SHV, bla CTX-M, and bla OXA-1), AmpC bla CMY-2, and carbapenemase ( bla KPC, bla NDM, and bla OXA-48) genes using PCR.
Results: S. enterica was isolated from chicken giblets (13/129) and the 13 isolates were ESCR. Based on the confirmatory ESBL test and CR, the 13 isolates were classified into the following resistance phenotypes: ESBL-producing and CR (n=4), ESBL-producing (n=1), non-ESBL-producing and CR (n=6), and non-ESBL-producing (n=2). All the five isolates with ESBL-producing phenotype carried predominantly bla TEM, bla SHV, and bla CMY-2. Regardless of being phenotypically CR, none of these isolates carried any of the tested carbapenemase genes. Surprisingly, the isolates with non-ESBL phenotype were found to carry bla TEM, bla SHV, and bla CMY-2. The bla KPC was present mainly in the isolates with non-ESBL and CR phenotypes. Interestingly, two isolates of the non-ESBL and CR phenotype showed resistance to cefepime, the fourth generation cephalosporins. Salmonella was also recovered from the water tanks (2/7) and the workers (2/16). The four isolates were ESCR and showed a non-ESBL-producing and CR phenotype; they harbored bla TEM, bla SHV, bla OXA-1, and bla KPC. The bla CMY-2 was found in one isolate from water and one from humans. All Salmonella isolates carried invA , stn , ompA , and ompF .
Conclusion: Virulent ESCR S. enterica were identified in retail shops. The isolates carried bla CMY-2 and ESBL-genes, with a high proportion showing CR. Transmission of such strains to humans through food leads us to recommend regular inspection of retail outlets for antibiotic-resistant bacteria.
Competing Interests: The authors declare that they have no competing interests.
(Copyright: © Abdel-Kader, et al.)