[Laboratory and clinical study of levofloxacin against Helicobacter pylori]

To assess antibacterial activity of levofloxacin to Helicobacter pylori (Hp) strains In Vitro and In Vivo.

The Minimum inhibitory concentration (MIC) for 52 clinical isolates was detected by agar dilution method and was compared with those of amoxicillin and clarithromycin. To examine the effects of pH variation on the susceptibility of Hp to levofloxacin, Mueller-Hinton agar with 7% defibrinated sheep blood was adjusted to a pH range of 4.0, 5.0, 7.0 by adding hydrochloric acid. 85 Hp-positive Patients with chronic active gastritis or active peptic ulcer disease were consecutively recruited in a prospective, open-label study. The enrolled patients were randomised to receive a seven-day course of omeprazole 20 mg bid plus amoxicillin 1000mg bid and levofloxacin 200mg bid. Their Hp status was assessed by (13)C-urea breath test and/or endoscopy 4 - 6 weeks after the end of treatment.

The resistant rates of strains to levofloxacin, amoxicillin and clarithromycin were 1.9%, 11.5% and 25%, respectively. A dual-resistance to amoxicillin and clarithromycin was demonstrated in five Hp strains (9.6%), which were all susceptible to levofloxacin. The prevalence of strains with resistance to levofloxacin was lower than that of strains with resistance to clarithromycin (P < 0.01), and was no statistically different with amoxicillin (P > 0.05). The activity of levofloxacin was diminished under acidic environment (P < 0.01). 84 enrolled patients completed the study. 76 patients (PP and ITT analysis, 91.7%; 90.6%) become Hp-negative. Slight side-effects occurred in 5 patients (5.9%).

In the present study, we report a high rate of resistance to amoxicillin and clarithromycin in this region. Omeprazole/levofloxacin-based triple therapy, including amoxicillin, is attractive because they combine a high eradication efficacy with an excellent tolerability and safety profile.