RESUMO
Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) is one of the most important virulent foodborne pathogens in industrialized countries. The ability to type bacterial strains is essential for surveillance, investigation of outbreaks, and epidemiological studies. Multilocus variable number tandem repeat combined with high-resolution melting analysis (MLV-HRMA) is a fast, cost-efficient, and easy sample genotyping method. In this study, MLV-HRMA and multilocus variable number tandem repeat analysis (MLVA) were used to differentiate between the allelic variants in 5 tandem repeat (TR) loci in 117 Salmonella Typhimurium isolates derived from various farms, slaughterhouses, market, and humans in Thailand. Both MLV-HRMA and MLVA analyses resulted in the identification of a total of 43 different genotypes, but slight differences were observed in cluster analysis results between the 2 methods. The unweighted pair-group method with arithmetic mean-based cluster analysis showed the same core clades; some small differences in the placement of sister-clades and subgrouping were observed due to the inability to reliably type the polymorphic STTR3 locus in the MLV-HRMA. The results of this study show that the MLV-HRMA, following the selection of suitable TR loci, is a relatively reliable and rapid screening method capable of differentiating between Salmonella Typhimurium isolates on the basis of allelic diversity at TR loci. As such, MLV-HRMA can be potentially used to investigate and track sources of contamination in order to effectively control Salmonella contamination in the food supply chain.
