Assessment of stn, sipB and sopB Virulence Genes in Various Salmonella Serovars.

Salmonella is a zoonotic bacterium that is considered to be one of the most common causes of foodborne infections worldwide. Bearing in mind the genes involved in its virulence, identifying these genes can enable experts to better understand bacterial pathogenicity, which could subsequently help develop more efficient means to control and prevent infections. This study aimed to analyze stn, sipB, and sopB genes in various Salmonella serovars. To carry out this study, 103 Salmonella serovars were extracted from livestock, poultry, and humans from existing samples at the Department of Microbiology of the Razi Serum and Vaccine Research Institute in Karaj, Iran. These samples were cultured in selection and differential media, and their serovars were identified using specific antibodies based on Kaufman-White Tables. Utilizing PCR and specific primers, stn, sopB, and sipB genes were detected among these serovars. In this investigation, the most common human serovars were Salmonella paratyphi A, Salmonella paratyphi B, and Salmonella enteritidis; the most common serovars among livestock consisted of Salmonella dublin and Salmonella typhimurium and the most common Salmonella serovars among poultry consisted of Salmonella infantis and Salmonella enteritidis. The results of PCR on stn, sipB, and sopB genes demonstrated segments with 617bp, 875 bp, and 220 bp on agar gel, respectively. Based on the obtained findings, stn, sipB, and sopB genes were detected in 96.11%, 99.02%, and 98.05% of Salmonella serovars, respectively. Considering the fact that the aforementioned genes play significant roles in bacterial virulence, they can be used to develop diagnostic ELISA kits and recombinant vaccines.

An epidemiological comparative study on diagnosis of rodent leptospirosis in Mazandaran Province, northern Iran / 한국역학회지

OBJECTIVES: Leptospirosis is a zoonosis caused by leptospires, in which transmission occurs through contact with contaminated biological fluids from infected animals. Rodents can act as a source of infection for humans and animals. The disease has a global distribution, mainly in humid, tropical and sub-tropical regions. The aim of this study was to compare culture assays, the microscopic agglutination test (MAT), polymerase chain reaction (PCR), and nested PCR (n-PCR), for the diagnosis of leptospirosis in rodents in Mazandaran Province, northern Iran. METHODS: One hundred fifty-one rodents were trapped alive at 10 locations, and their urine and kidney samples were collected and used for the isolation of live Leptospira. The infecting serovars were identified and the antibody titres were measured by MAT, using a panel of 20 strains of live Leptospira species as antigens. The presence of leptospiral DNA was evaluated in urine and kidney samples using PCR and n-PCR. RESULTS: No live leptospires were isolated from the kidney and urine samples of the rodents. Different detection rates of leptospirosis were observed with MAT (21.2%), PCR (11.3%), and n-PCR (3.3%). The dominant strain was Leptospira serjoehardjo (34.4%, p=0.28), although other serotypes were also found. The prevalence of positive leptospirosis tests in rodents was 15.9, 2.6, and 2.6% among Rattus norvegicus, R. rattus, and Apodemus sylvaticus, respectively. CONCLUSIONS: Leptospirosis was prevalent in rodents in Mazandaran Province, northern Iran. MAT was able to detect leptospires more frequently than culture or PCR. The kidney was a more suitable site for identifying leptospiral DNA by n-PCR than urine. Culture was not found to be an appropriate technique for clinical diagnosis.