Prevalence, antimicrobial susceptibility, and molecular characterization by PCR and pulsed field gel electrophoresis (PFGE) of Salmonella spp. isolated from foods of animal origin in San Luis, Argentina

Abstract

This study was aimed to determine the prevalence of Salmonella spp. in foods of animal origin sold at retail stores over the period 2005–2011 in San Luis, Argentina. Characterization of isolates was performed by biochemical and serological tests, antimicrobial susceptibility assays, detection of invA invasion gene by PCR and comparison of genomic profiles by XbaI DNA restriction and PFGE. Twenty seven Salmonella strains were detected in 27 (6.32%) of 427 samples of foods analysed. Sixteen S. Enteritidis and one S. Montevideo strains from chicken meat (17 positive samples/115 total samples), six S. Anatum strains from pork sausages (6/90), two S. Typhimurium strains from liquid egg (2/60) and two S. Montevideo strains from chicken giblets (2/62) were isolated. No Salmonella strains were recovered from chicken carcasses (0/100). Salmonella strains were susceptible to antimicrobials commonly used for clinical treatment. All isolates carried the invA gene. DNA restriction and PFGE analysis revealed similar genomic profiles within each Salmonella serovar regardless of the food type, sampling year, or retail store where samples were purchased, suggesting the possibility of circulation and transmission of clones of limited diversity in our region.