Susceptibility of Helicobacter pylori to mupirocin, oxazolidinones, quinupristin/dalfopristin and new quinolones.

The in vitro activities of mupirocin, quinupristin/dalfopristin, linezolid, eperezolid, sitafloxacin, clinafloxacin, moxifloxacin, amoxycillin, metronidazole and clarithromycin were tested at pH 7.4 against 57 strains of Helicobacter pylori. The most active agents (mupirocin, sitafloxacin and clinafloxacin) were also tested for activity at pH 5.4 against the same strains. Mupirocin was very active at pH 7.4 and 5.4 (MIC90 0.25 and 0.12 mg/L, respectively). Quinupristin/dalfopristin, linezolid and eperezolid had low activity (MIC90 4, 8 and 4 mg/L, respectively). Sitafloxacin (MIC90 </= 0.008 mg/L) was the most active fluoroquinolone, while clinafloxacin (MIC90 0.12 mg/L) and moxifloxacin (MIC90 2 mg/L) were least active.