Figure 4. The effect of DFMO on H. pylori requires constant exposure.

(A) Mice were infected with H. pylori SS1 grown for 12 h with or without 1% DFMO and colonization levels were determined after one month. Each point represents bacterial load in a single mouse, and mean and standard error are indicated (n = 12 per group). (B) Growth curves were performed to determine the permanence of the effect of DFMO. Brucella broth cultures, with or without DFMO, were inoculated with H. pylori. After 6 h, the cultures were centrifuged and switched to new medium so that four conditions resulted: –DFMO → –DFMO, +DFMO → –DFMO, –DFMO → +DFMO, and +DFMO → +DFMO. Bacterial levels were monitored by OD₆₀₀. Data depicted are from a single representative experiment; similar results were obtained in two others. (C) Conditions are the same as for panel B, except that medium switching occurred after 12 h of growth. Data are from a single representative experiment of three performed.