Abstract: The present invention relates to methods and compositions for treating or preventing pathological conditions associated with ferrous-dependent bacteria, such as, Helicobacter pylori in which high intracellular ferrous iron concentration is required for survival and pathogenesis. The compositions of the invention comprise endoperoxide bridge-containing compounds that specifically inhibit the growth of the ferrous-dependent bacteria and preferably promote the eradication of the bacteria. The compositions, typically also include at least one active agent for treating Helicobacter sp-related gastrointestinal disorders, such as a proton pump inhibitor, an H2 blocker or a bismuth-containing compound.