Thermal resistance of antibiotic-resistant and antibiotic-sensitive Salmonella spp. on chicken meat

The aim of this research was to investigate the potential relationship, if any, between the acquisition/possession of antibiotic resistance genes in strains of Salmonella and its resistance to heat stress. Chicken pieces were inoculated with antibiotic sensitive (AS) strains of S. Enteritidis and S. Typhimurium, its laboratory-acquired antibiotic-resistant (AR) mutant strains (nalidixic acid and streptomycin), or a multiresistant strain of S. Typhimurium DT104. Half of these samples were heat-shocked (48C for 30 min) and all were heat-challenged at 55C for up to 30 min. Samples were then plated on xylose lysine desoxycholate (XLD) and tryptone soya agar (TSA) overpoured with XLD. Heat-shocked cultures of S. Typhimurium DT104 had significantly higher D-values (the time required for a 1 log reduction in the number of bacteria) than their non-heat-shocked counterparts (P < 0.05). No significant differences were observed between AR and their AS. However, the D-values for S. Typhimurium DT104 were significantly higher than the D-values for S. Typhimurium (AS) and S. Enteritidis (AS) (P < 0.05). This study concluded that laboratory-acquired antibiotic-resistant mutation did not affect heat resistance of the Salmonella strains studied and suggested a potential link between multiantibiotic resistance and heat resistance in S. Typhimurium DT104.