1Director, Centre for Animal Health Studies, Madhavarum Milk Colony, TANUVAS, Chennai – 600 0051, India
Poultry Disease Diagnosis and Surveillance Laboratory, Veterinary College and Research Institute Campus, Namakkal, Tamil Nadu – 637 002, India
*Corresponding author: E-mail: sarava3@rediffmail.com
A total of 1215 samples such as poultry tissue, environmental samples and poultry related products were collected from 154 layer farms and screened for the presence of Salmonella organisms. Twenty one isolates were confirmed as Salmonella enterica subsp enterica by conventional method and further subjected to molecular tests viz. multiplex PCR, allele specific PCR and real time PCR. By multiplex PCR conducted for 21 isolates, 16 isolates were categorized as Salmonella Typhimurium (which produced two fragment sizes of 363 bp and 497 bp) and five isolates identified as Salmonella Enteritidis (which produced only one fragment size of 497 bp only). Allele specific PCR was carried out for differentiating group D Salmonella from others based on amplification of rfbS gene. Out of 21 isolates, four were identified as Group D Salmonella which produced amplification fragment of 720 bp. The real time PCR assay was carried out for the specific detection of Salmonella targeting the gene invA. All the Salmonella isolates produced amplification curve by detecting the invA gene with Ct value ranged from 23.11 ± 0.104 to 38.61±0.316. Allele specific PCR is used only for differentiation of group D Salmonella from other Salmonella organisms, whereas both real-time and multiplex PCR assay can detect the Salmonella at species/serovars level. Among all the above mentioned molecular tests, multiplex PCR was found to be specific molecular diagnostic tool for rapid detection and differentiation of various serovars of Salmonella organisms in poultry and related products.
