Table 1.

Relationship between presence of persistent S. Typhimurium isolated from internal organs vs colonic histological score of mice intragastrically infected and treated for 3 weeks with enrofloxacin.

Experimental group	Days post-infection	Total mice	% of persistent mice	Colon score Persistent bacteria	Colon score No persistent bacteria
C57BL/6 + STM WT	39	6	50	2.3	1.9
IL-10−/− + STM WT	42	9	33.3	1.9	1.5
IL-10−/− + STM ΔTTSS-1	42	10	10	1.33	2.3
IL-10−/− + STM ΔTTSS-2	42	9	0	0	1.7
IL-10−/− unimmunized	63	7	57.1	1.9	1
IL-10−/− immunized	63	8	50	0.4	0.5

WT or IL-10^−/− mice were intragastrically infected with 1 × 10⁵ or 1 × 10⁶ CFU of S. Typhimurium, respectively and bacterial loads were quantified at the end of the experiments (39, 42, or 63 days post-infection, respectively) in spleen, liver, and mLNs. The homogenized tissues were cultured into MacConkey agar, as described in Section “Materials and Methods.” The histopathological score of colon (ascending, transverse, and descending colon) did not show differences with respect to non-persistent mice.

S. Typhimurium, Salmonella enterica serovar Typhimurium; WT, wild type; TTSS, type three secretion system; mLNs, mesenteric lymph nodes; IL, interleukin.