Figure 10. Antibiotic induced commensal depletion enhances pathogen colonization but does not alter host pathology in Muc2^−/− mice.

A. Quantification of DAPI stained bacteria from stools of WT and Muc2−/− mice 24 hours following oral treatment with Streptomycin (20 mg) or Vehicle (dH₂0). Streptomycin (strep) led to significantly reduced numbers of total bacteria within mouse stool. Results represent the means of 3–4 mice per group. Error bars  =  SEM (***P<0.001, unpaired t test). B. Enumeration of ΔespF C. rodentium^Str (strep-resistant) in stool of strep-or vehicle-treated mice as indicated, at various times post-infection. Results represent the means of 3–4 mice per group. Error bars  =  SEM (*P≤0.05, Mann-Whitney test, one-tailed). C. Body weights following infection of strep or vehicle treated WT and Muc2^−/− mice with ΔespF C. rodentium^Str. n = 3–4 mice per group. Error bars  =  SEM. D. Representative histological sections of ceca from uninfected or infected (6 DPI) strep- or vehicle-treated WT and Muc2^−/− mice. Original magnification  = 100×. Scale bar  = 100 µm. E. H&E (Left panel) and FISH analysis (right panel) of an ulcer from ΔespF C. rodentium^Str infected vehicle-treated Muc2^−/− mouse cecum (6 DPI). Numerous commensals (EUB338⁺/GAM42⁻ cells, red) can be seen overlying the ulcer in direct contact with PMNs (arrow), and both pathogen (EUB338⁺/GAM42a⁺ cells, yellow) and commensal (red) can be seen within the PMNs (arrow heads, inset). Original magnification  = 200×. Scale bars  = 100 µm. F. H&E and FISH analysis of an ulcer in the descending colon from an ΔespF C. rodentium^Str infected strep-treated Muc2 ^−/− mouse (6 DPI). Large pathogenic microcolonies (yellow) are associated with the ulcer (arrows), while commensals (red) can be seen in the lumen. Original magnification  = 200×. Scale bar  = 100 µm.