¹Astt. Technical manager, Bovian health care Pvt. Ltd, ²Professor, Department of Veterinary Public Health & Epidemiology, LLRUVAS, Hisar, Haryana, ²Professor, Department of Veterinary Medicine, LLRUVAS, Hisar, Haryana, India
*Corresponding author: tarunvet@gmail.com

ABSTRACT
A total of 51 isolates of Salmonella, including 23 isolates of Salmonella gallinarum, 13 isolates of Salmonella pullorum, 9 isolates of Salmonella enteritidis and 6 isolates of Salmonella typhimurium were isolated and characterized from outbreaks of Salmonella infection in broilers from commercial poultry farms of Haryana state, India. Isolates were characterized at their genotypic level by plasmid profiling, restriction endonuclease analysis and PCR. Plasmid profiles and antibiotic resistance pattern were correlated. Eight different plasmid profiles were obtained with presence of large plasmid of size 85 kb in maximum number of isolates (70%). Study suggested that 85 kb plasmid might carry the genes responsible for virulence. No positive correlation between plasmid profiles and antibiotic resistance pattern was found. Restriction endonuclease analysis of genomic DNA showed a high degree of genome homogeneity suggesting a common grandparent source of infection. PCR was found to be sensitive, specific and fast method to know the virulence of Salmonella isolates. Study concluded that plasmid profiling along with restriction enzyme analysis can be used as epidemiological markers in back tracing infections especially in case of outbreaks. Need of hour is to start mandatory Salmonella testing of parent flocks, positive reactors should be removed from the flock and vaccination of parent flocks should be carried out for control of this fast spreading, zoonotically important vertically transmitted pathogen. Moreover, at government level, there should be some legislation for control of such infections from hatchery.

Key Words: Molecular epidemiology; Salmonella; Plasmid Profiling; PCR; Restriction enzyme analysis