Effect of Lactobacillus rhamnosus GG and Bifidobacterium longum treatment on colonic proliferation in sepsis. Colonic epithelial proliferation was determined by quantifying proliferating cell nuclear antigen (PCNA)-positive cells in 100 consecutive crypts. Septic mice had a significantly decreased number of proliferating cells compared with shams (1,456 ± 174 vs. 2,010 ± 347; P = 0.0128), whereas septic mice treated with L. rhamnosus GG (LGG) or B. longum (BL) showed normalization to sham levels (LGG: 2387 ± 137, P = 0.0001; BL: 2,326 ± 224 vs. septic 1,456 ± 174, P = 0.0003). Shams, n = 5 per group; septic, n = 5; LGG, n = 4; and BL, n = 4. Data are expressed as the mean ± SD.