High Prevalence of ESBL and Plasmid-Mediated Quinolone Resistance Genes in Salmonella enterica Isolated from Retail Meats and Slaughterhouses in Egypt

The emergence and spread of multidrug-resistant Salmonella enterica (S. enterica) to humans through food of animal origin are considered a major global public health concern. Currently, little is known about the prevalence of important antimicrobial resistance genes in S. enterica from retail food in Africa. Therefore, the screening and characterization of the extended-spectrum β-lactamase (ESBL) and plasmid-mediated quinolone resistance (PMQR) genes in S. enterica isolated from retail meats and slaughterhouses in Egypt were done by using PCR and DNA sequencing techniques. Twenty-eight out of thirty-four (82.4%) non-duplicate S. enterica isolates showed multidrug-resistance phenotypes to at least three classes of antimicrobials, and fourteen (41.2%) exhibited an ESBL-resistance phenotype and harbored at least one ESBL-encoding gene. The identified β-lactamase-encoding genes included bla_CTX-M-1, bla_CTX-M-3, bla_CTX-M-13, bla_CTX-M-14, bla_CTX-M-15, and bla_SHV-12 (ESBL types); bla_CMY-2 (AmpC type); and bla_TEM-1 and bla_OXA-1 (narrow-spectrum types). PMQR genes (included qnrA, qnrB, qnrS, and aac(6')-Ib-cr) were identified in 23 (67.6%) isolates. The presence of ESBL- and PMQR-producing S. enterica with a high prevalence rate in retail meats and slaughterhouses is considered a major threat to public health as these strains with resistance genes could be transmitted to humans through the food chain.