Molecular characterization of antimicrobial resistance and enterobacterial repetitive intergenic consensus-PCR as a molecular typing tool for Salmonella spp. isolated from poultry and humans

Abstract

Background and Aim: Salmonella spp. are one of the most important food-borne pathogens in the world, emerging as a major public health concern. Moreover, multidrug-resistant (MDR) strains have been isolated from salmonellosis outbreaks, which compromise its treatment success. This study was conducted to characterize the phenotypic and genotypic antibiotic resistance profile of Salmonella strains isolated from broilers and humans from the regions of Tolima and Santander (Colombia). Materials and Methods: Salmonella spp. strains (n=49) were confirmed through molecular detection by amplification of the invA gene. Phenotypic antibiotic resistance was determined by the automated method and the agar diffusion method, and the presence of resistance genes was evaluated by PCR. Genotypic characterization was conducted using the enterobacterial repetitive intergenic consensus (ERIC)-PCR method, from which a dendrogram was generated and the possible phylogenetic relationships were established. Results: Salmonella isolates were classified as MDR strains exhibiting resistance to four antibiotic classes, penicillins, aminoglycosides, sulfonamides, and cephalosporins, and the human strains were resistant to gentamicin. At the genotypic level, the isolates contained the genes blaCMY2, blaCTX-M, blaPSE-1, blaTEM, aadA1, srtB, dfrA1, sul2, and floR. The genotyping results obtained by ERIC-PCR allowed the grouping of strains according to the source of isolation. Conclusion: The Salmonella spp. strains exhibited resistance to multiple antibiotics, as well as multiple genes associated with them, and the ERIC-PCR method was a technique that was helpful in generating clusters with biological significance.