ABSTRACT
Salmonella enterica is one of the most important food-borne pathogens, causing a variety of diseases in humansand animals. This study aimed to detect the virulence genes in 33 S. enterica strains isolated from patients andto investigate the immunogenicity of the outer membrane proteins (OMPs) of S. enterica serovar Typhimurium.The aggregative fimbriae (agfA) gene was detected in all S. enterica isolates except one strain, SalmonellaParatyphi C strain SA7. In addition, 81.8% of the isolates harbored the sefC gene (fimbrial protein). However,all of the tested S. enterica isolates possessed the fimA, hilA, invA, stn, and misL virulence genes, regardless ofserovar. The predominant OMPs of S. enterica Typhimurium SA3 identified by 12% sodium dodecyl sulfatePolyacrylamide Gel Electrophoresis (PAGE) were used as eliciting antigens in the experimental mice. Theresults of the protection studies indicated that the selected OMPs conferred varying degrees of protection.However, the highest protection was observed using the 38-kDa OMP, which provided 100% protection tomice challenged with 50× LD50 of Salmonella Typhimurium SA3 and 75% protection to mice subjected toan even higher bacterial challenge of 100× LD50. The humoral response in mice caused by the 38-kDa OMPwas confirmed using an immunodiffusion assay. This 38-kDa OMP is a promising candidate for the vaccinedevelopment against S. enterica Typhimurium. Further research on the protein structure was recommended.
ABSTRACT
Although the prevalence of suspected tuberculosis [TB] in the Kingdom of Saudi Arabia remains high, there has been a modest decrease in recent years. In this multi-center cross-sectional study, the prevalence of TB was determined by various techniques with the aim of identifying differences and indicating where there is uniformity in findings. A total of 3404 samples were collected from Saudi TB patients from different regions in Saudi Arabia: Riyadh, Dammam, Jeddah, Madinah, Hail, Qassim, Jazan, and Taif. Different techniques including Ziehl-Neelsen [ZN], Mycobacteria growth indicator tube [MGiT], Lowenstein-Jensen [LJ], and polymerase chain reaction [PCR] were used to screen for the presence of Mycobacterium tuberculosis [MTB]. ZN stain showed that Riyadh and Dammam had the highest prevalence of MTB with 22% and 21%, respectively, while prevalence was lowest in Jazan and Hail with an incidence of 2% and 3%, respectively. MGiT culture showed that Riyadh, Dammam, and Jeddah had the highest prevalence with a rate of 26%, 22%, and 22%, respectively. LJ culture showed the highest prevalence in Riyadh and Dammam with 22% and 21%, respectively. Of all the techniques, the highest detection rate was by PCR which was 10.46% while ZN stain technique was 6.64%, for MGiT culture it was 8.34%, and for LJ culture it was 7.7%. This study is the first in which different methods have been used for detection in the various regions of Saudi Arabia. Collected data are important not only for patients and physicians but for future epidemiological studies to monitor the spread of MTB infection in Saudi Arabia