Comparing the presence of different genes in Salmonella subspecies I-IV and development of a diagnostic multiplex PCR method for identification of Salmonella subspecies.

Reptile-associated salmonellosis in humans has become a growing problem worldwide. Reptiles are frequently asymptomatic carriers of Salmonella and therefore, they are considered as an important reservoir for these bacteria. The classical biochemical method for Salmonella subspecies detection is time consuming, especially in samples from reptiles since they frequently carry more than one Salmonella subspecies. The aim of this study was therefore to develop a multiplex PCR assay for a rapid and accurate differentiation of Salmonella subspecies I, II, IIa, IIIb and IV. In the present study, the occurrence of the genes invA, ttrCA, iroB, STM4075, sciA, STM3690, sadA, gatD, foxA, pagN, fljB, iucD, spvB, lacZ, iutA, mdcA and irp2 was examined in 41 Salmonella strains from Middle Eastern animals (mainly reptiles) by monoplex PCR. According to the results a multiplex PCR assay was developed based on the genes ttrCA, sciA, foxA, iutA. Compared to biochemical analysis this method allowed a fast identification of the subspecies from all the Middle Eastern Salmonella strains (n = 41), as well as 79 strains from German children (n = 18) with reptile associated salmonellosis and other humans and animals (n = 61) with salmonellosis.These results revealed the multiplex PCR as a fast assay for a specific identification of Salmonella subspecies I, II, IIIa, and IIIb.