Molecular characterization of some virulence genes of Salmonella enterica serotype sandow and saintpaul isolated from environment of dairy farms at Assiut Province, Egypt

Abstract

Dairy farm environment could become contaminated with Salmonella following outbreaks of illness, colonization of animals or by general contamination. The present study investigated a total number of 95 samples collected from 3 dairy farms in 3 different localities at Assiut Province including air (25), water (35) and manure (35) samples for detection of Salmonella species by bacteriological isolation, morphological, biochemical and serological identification followed by molecular characterization for the presence of 6 virulence genes; pefA (700 bp), mgtC (677 bp), stn (617 bp), sopB (517 bp), invA (284 bp) and avrA (422 bp) in Salmonella isolates. Bacteriological examination revealed the isolation of 3 (3.2%) Salmonella isolates from totally examined samples, which were identified serologically as 1 (2.9%) Salmonella enterica serotype Sandow isolated from water and 2 Salmonella enterica serotype Saintpaul from air and manure (one from each with 2.9% of each. Molecular characterization of the 3 Salmonella isolates revealed that all 6 tested virulence genes; except sopB (517 bp); presented in Salmonella enterica serotype Sandow isolated from water, while all 6 tested virulence genes found in Salmonella enterica serotype Saintpaul isolated from manure and found that invA (284 bp) was the only virulence gene located in Salmonella enterica serotype Saintpaul isolated from air. This study highlighted on the potential sources for Salmonella contamination moreover the epidemiology of salmonellosis in dairy farms that necessitate following of strict healthful measures to reduce the risk of Salmonella infection that still constitutes a significant world zoonosis particularly through contamination of dairy farm environments that contribute to extend the recycling of Salmonella that considered the most vital sources of animal and human infection with Salmonella.