Anti-Salmonella Monoclonal antibody, Clone C458N

Little progress has been made in decreasing the incidence rate of salmonellosis in the US over the past decade. Mitigating the contribution of contaminated raw meat to the salmonellosis incidence rate requires rapid methods for quantifying Salmonella, so that highly contaminated products can be removed before entering the food chain. Here we evaluated the use of Time-to-Positivity (TTP) as a rapid, semi-quantitative approach for estimating Salmonella contamination levels in ground beef. Growth rates of 14 Salmonella strains (inoculated at log 1 to -2 CFU/g) were characterized in lean ground beef mTSB enrichments and time-to-detection was determined using culture and molecular detection methods. Enrichments were sampled at five timepoints and results were used to construct a prediction model of estimated contamination level by TTP (superscript indicates time in hours) defined as TTP4: >= 5 CFU/g; TTP6: <= 5, >= 1 CFU/g; TTP8: <= 1, >= 0.01 CFU/g; with samples negative at 8 h estimated <= 0.01 CFU/g. Model performance measures showed high sensitivity (100%) and specificity (83% and 93% for two detection methods) for samples with a TTP4, with false negative rates of 0%.

Background Salmonella Paratyphi A causes paratyphoid A, a severe systemic disease of people and remains a major public health problem in many parts of the world. In the interest of researching the roles of sptP on Salmonella Paratyphi A and developing a live-attenuated vaccine candidate, an sptP mutant of Salmonella Paratyphi A SPA017 (SPA017 Delta sptP) was constructed, and then its characterization, immunogenicity, and protective ability were evaluated. Results The deletion of sptP had no effect on growth and biochemical properties. Adhesion and invasion assays showed that the lack of sptP did not affect the adhesion of Salmonella Paratyphi A, but the invasive ability of the mutant strain was significantly decreased, the half-lethal dose (LD50) of the mutant strain was 1.43 x 10(4) times of the parent strain in intraperitoneally injected mice. Single intraperitoneal vaccination with SPA017 Delta sptP (1 x 10(5) CFU) in mice did not affect the body weight or elicit clinical symptoms relative to the control group, SPA017 Delta sptP bacteria were isolated from livers and spleens of vaccinated mice at 14 days postvaccination. Notably, specific humoral and cellular immune responses were significantly induced. The protective assessment showed that the mutant strain could provide high-level protection against subsequent challenge with the wild-type SPA017 strain. Conclusions These results demonstrated that SptP plays an essential role in the pathogenicity of Salmonella Paratyphi A, and Salmonella Paratyphi A lacking sptP is immunogenic and protective in mice.