Figure 1.

Mutation frequency to rifampicin resistance for H. pylori isolates. The dotted lines indicate the approximate mutation frequencies to rifampicin resistance for wild-type and mutator Enterobacteriaceae and P. aeruginosa (23, 24). Indicated are strains isolated from peptic ulcer patients (stippled), non-ulcer dyspepsia patients (open), and gastric cancer patients (vertical lines). The number of peptic ulcer and dyspepsia non-ulcer strains with mutation frequencies <10⁻⁶ were 3 and 11, respectively, and for strains with mutation frequencies >10⁻⁶ were 7 and 5, respectively. This difference is not statistically significant as calculated by Fischer's Exact test (P > 0.05).