SdiA activity and fitness during transit through different animal species.

1Animals were inoculated with a 1∶1 mixture of the wild-type and sdiA mutant Salmonella RIVET strains (a total of 9.7×108 cfu for the mice, 6.0×109 cfu for the guinea pigs and rabbits, 1.8×109 cfu for the pigs, 1.3×1011 cfu for the calves, 7.0×109 cfu for the chicks, and 3.1×109 cfu for turtles).
2The inoculum was plated for single colonies and screened for ampicillin resistance to determine the actual percent wild-type inoculated.
3The “Total colonies screened” represents a compilation of all colonies recovered (sum of all time points) from all animals of each species. The colonies were recovered by plating fecal samples, unless noted otherwise, on XLD-kan and then screened for ampicillin and tetracycline resistance. Wild-type and sdiA mutant Salmonella are differentiated by ampicillin resistance and resolution of the res1-tetRA-res1 cassette is indicated by tetracycline sensitivity.
4The competitive index equals the output ratio (cfu of mutant/cfu of wild type) divided by the input ratio (cfu of mutant/cfu of wild type). A competitive index of 1.0 indicates that the wild-type and sdiA mutant had equal fitness during transit through the animal. The log of the competitive index represents a normal distribution so the mean of this value was calculated. A value of zero indicates that the wild-type and sdiA mutant had equal fitness during transit through the animal. For those animal species in which colonies were recovered from more than one animal, the standard deviation is shown. The wild-type was statistically more fit than the sdiA mutant in turtles, while the sdiA mutant was more fit than wild-type in chicks (student's t test, p<0.05). However, the differences are so small (competitive index of less than 3) that they are not likely to be biologically significant. For those animal species where only one individual shed colonies, the standard deviation could not be calculated, but a competitive index that is less than 3-fold different than 1.0 is unlikely to be biologically significant (0.33 to 3.0).
5Of the total screened, 700 colonies were from fecal samples, 582 were from the ileum, and 67 were from the cecum.
6Of the total screened, 782 colonies were from fecal samples, 150 were from the ileum, 2 were from the cecum, and 66 were from the Peyer's patches.
7All colonies from the chicks were obtained from the cecum and distal large intestine. No colonies were from fecal samples.
8All colonies from the turtles were obtained from cloacal swabs. These data were also used to generate Figures 1 and 3.
*Statistically significant fitness difference between wild-type and sdiA mutant (p<0.05).