Comparison of disease susceptibility in vaccinated mice infected with hyperinfectious and conventionally virulent salmonellae.

aBALB/c mice orally immunized with a live, attenuated dam mutant S. Typhimurium 14028 vaccine [98]. Vaccinated mice challenged with a dose of 100 LD50 of hyperinfectious salmonellae derived from stationary phase cultures under conditions that were permissive (LPM pH 5.5 medium) or nonpermissive (LB medium) for the hypervirulent phenotype. Nonvaccinated control mice (25/group) all died by day 21 post-infection. Conventionally virulent S. Typhimurium reference strain 14028 was used in all studies for comparison.
*Designates statistical significance for the number of survivors obtained after dam mutant Salmonella vaccinated animals were challenged with salmonellae grown in LB medium versus LPM pH 5.5 medium. Statistical significance for difference in proportions was calculated using Chi-square tests; a significance level (P) of less than 0.05 was considered to be statistically significant.