Genetic diversity with potential ESBL-producing and multidrug-resistant Salmonella strains from chicken meat

TL;DR

This study analyzed Salmonella strains from chicken meat in Istanbul and found high levels of antibiotic resistance and genetic diversity.

Contribution

The study provides a comprehensive analysis of ESBL-producing and multidrug-resistant Salmonella strains from chicken meat in Istanbul.

Findings

S. Infantis was the dominant Salmonella type found in chicken meat samples.

High resistance rates were observed for pefloxacin, azithromycin, and tetracycline.

Multidrug resistance was identified in 84.6% of the Salmonella strains.

Abstract

Salmonella, a major foodborne pathogen, is a primary concern due to its role in spreading antibiotic resistance. Raw chicken meat samples (n = 210) were collected from various retail locations in Istanbul.

The food samples were isolated according to ISO 6579-1 and 13 (6.2%) of Salmonella strains confirmed through PCR, agglutination tests, and Sanger sequencing; S. Infantis (84.6%) was identified as the dominant type. The other types found included S. Enteritidis (7.7%) and S. Virchow (7.7%). Additionally, antibiotic susceptibility was tested according to EUCAST and CLSI standards in different Salmonella serotypes. The serotypes were analyzed for susceptibility to 13 antibiotics using agar-disk diffusion assays, and resistance levels were determined via E-test.

The disc diffusion method revealed resistance to cefazolin across all Salmonella serotypes. High resistance rates were also observed for pefloxacin (84.6%), azithromycin (76.9%), and tetracycline (84.6%). Multidrug resistance was identified in 11 (84.6%) strains by the disc diffusion test. The minimum inhibitory concentration testing with MIC test strips showed high tetracycline resistance at 84.6%. The blaTEM gene was found in 30.7% of strains, while blaCTX-M subgroup 1 (7.7%) and blaCTX-M subgroup 9 (30%) were detected by multiplex PCR; however, and blaCTX-M, blaOXA-2, and blaSHV genes were not present. Resistance to carbapenem and colistin was also checked via PCR, and blaOXA-48, blaVIM, blaNDM, blaKPC, and mcr genes were not detected in the Salmonella serotypes.

This pioneering study provides a comprehensive analysis of serotyping and ESBL production in Salmonella strains isolated from Istanbul.

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