Detection of InvA Gene in Non typhoidal salmonellae isolated from food products and clinical cases

Salmonellae are well-known pathogens, highly adaptive and potentially pathogenic for humans and/or animals. Salmonellae are capable of producing serious infections that are often food borne and present as gastroenteritis. The main reservoirs for non-typhoidal Salmonella are animals such as poultry, livestock, pets and reptiles. Salmonella typhi and Salmonella paratyphi colonize only in humans, so they can be acquired only from close contact with a person who has typhoid fever, from a chronic carrier, or from water or food contaminated by human feces. Determine the virulence of the Salmonella serovars obtained from human and animal sources by investigating the presence of chromosomal virulence gene, invA gene as it triggers the internalization of the organism required for invasion of deeper tissue. A total 480 clinical samples: 120 milk samples were collected from faculty of agriculture farm and Markets, 115 eggs were received from different farms and markets, 125 fresh slaughtered chicken and 120 stool sample were collected from Assiut Children University Hospital. Invasion gene operon, invA was detected in all 50 clinical isolates representing multiple serotypes from different sources. Identification of S. enterica and screening of invA gene through PCR based procedures can have major benefit in public health specifically for rapid diagnosis, epidemiological investigations, ideal vaccine, development of treatment, and prophylactic strategies for salmonellosis

Detection of non typhoidal salmonella isolated from food products and clinical cases by PCR and conventional methods: a comparative study

Non typhoidal Salmonella [NTS] are important food-borne pathogens. Infection with NTS may not lead to fatal disease, hut it may remain localized in the gastrointestinal tract resulting in gastroenteritis or may take a septicemic form that can affect several organs systems causing gastroenteritis, bacteremia and subsequent focal infection. To compare PCR with different conventional methods for identification of non-typhoidal Salmonella species, and to determine the virulence of the Salmonella serovars obtained from human and animal sources by investigating the presence of virulence gene, InvA in the chromosomal DNA. A total of 480 clinical samples were collected. These included: 120 milk, 115 eggs and 125 fresh slaughtered chicken from farms, slaughterhouses, markets, in addition to 120 stool samples from Assiut Children University Hospital. They were subjected to conventional methods for bacteriological and biochemical examination. Conventional cultural examination, API 20 E system and PCR amplification assay of virulence gene invA were investigated in animal and human isolates. By comparing the results of PCR using SI 39 and SI 41 primers and those of culture examination, it was found that PCR had similar results to culture examination. PCR could detect 50 positive cultures of Salmonella species, while API 20 E could detect only 47 of these positive cultures.: PCR amplification assay has the ability to detect a wide range of Salmonella species depending on the design of primers targeted to invasion gene operon [InvA gene] of salmonella. PCR technique may provide a valuable, rapid, specific and sensitive laboratory diagnostic test for detection of salmonella DNA in cultures