Metronidazole resistance reduces efficacy of triple therapy and leads to secondary clarithromycin resistance.

There has been a significant increase in the prevalence of H. pylori resistance to metronidazole in recent years, while clarithromycin resistance is still relatively rare. In this study we assessed: (1) the effect of primary H. pylori resistance to metronidazole and clarithromycin on the clinical efficacy of a one-week regimen consisting of omeprazole, metronidazole, and clarithromycin; and (2) the rate of acquisition of secondary antimicrobial resistance after treatment failure. Eighty-seven patients with duodenal ulceration or nonulcer dyspepsia were included in the study. The primary metronidazole and clarithromycin resistance rates were 35.6% and 3.4%, respectively (all three pretreatment clarithromycin resistant strains had concurrent metronidazole resistance). H. pylori was eradicated in 81.6% of patients. The eradication rate for fully sensitive isolates was 98.2% (55/56) but was significantly reduced to 57.1% (16/28) for isolates that were resistant to metronidazole alone and 0% (0/3) in cases of dual resistance (P < 0.001). Secondary resistance to clarithromycin was acquired in 58.3% of cases of treatment failure. In areas of high prevalence of primary metronidazole resistance, this is a significant cause of treatment failure with this triple therapy regimen. This leads to the selection of strains with dual resistance that are difficult to eradicate and may contribute to an increase in the prevalence of clarithromycin resistance. In such areas an alternative first-line treatment should be prescribed.

Short report: high-dose omeprazole and amoxycillin in the treatment of Helicobacter pylori-associated duodenal ulcer.

Thirteen consecutive patients with active duodenal ulcer disease were assigned to a treatment schedule with high-dose omeprazole and amoxycillin. Duodenal ulcer was diagnosed endoscopically in all patients, at which time antral biopsies were taken for culture and histology. All were positive for Helicobacter pylori and histological gastritis. Treatment was for 2 weeks: 80 mg omeprazole daily plus 500 mg amoxycillin syrup t.d.s. in the first week, followed by 40 mg omeprazole daily in the second week. Repeat gastroscopy was performed 4 weeks after completion of treatment in all patients. Duodenal ulcer healing occurred in 4/13 patients. H. pylori eradication was achieved in 2/4 patients with healed ulcers and in 3/9 patients with persistent ulceration. This study suggests that a short period of treatment with high-dose omeprazole and amoxycillin achieves low rates of ulcer healing and H. pylori eradication.