engleski

Primary Resistence of Helicobacter pylori to Macrolides and Metronidazole

The aims of the study were to investigate primary resistance of Helicobacter pylori to metronidazole, azithromicyn and clarithomycin in Croatia in in past 4 years, as well as to determine the influence of primary resistance on the success of H. Pylori eradication therapy. Endoscopic biopsy specimens from the antrum and corpus were obtained from consecutive patients with either peptic ulcer or non-ulcer dysepsia attending the Endoscopy laboratory of University Hospital Merkur, Zagreb, Croatia. H. Pylori straints, isolated from these biopsies during the first (pre-treatment) and follow –up endoscopy (at least 4 weeks after one ot the triple therapies containing metronidazole, clarithromycinor azithromycin) were cultured. Antimicrobial susceptibility to metronidazole, clarithromycin and azithromycin was established by measurement of minimal inhibitory concetrations (MICs) according to NCCLS. The MIC was defined as the lowest concetration (mikrogram of antibiotics/ ml of agar) which inhibited visible growth, and interpreted as susceptible (S) or resistsnt (R). Values for selected antibiotics are: metronidazole S less then 8, R gt then 32, clarithromycin S less then 2, R gt then 4, and azithromycin S less then 2, R gt then 8. Results: In the period of 1996-1999, 556 H. Pylori straints were isolated from patients treated with azithromycin, 512 threated with metronidazole, and 446 patients treated with clarithromycin. Primary resistance to both macrolides was less then 10 per cent, and average primary resistance to metronidazole was aproximmately 30 per cent. The success of eradication therapy was analysed in patients with positive H. Pylori in culture. Eradication with triple therapies containing one of the macrolides was successful in 166/223 (75 per cent) patients infected with azithromycin/clarithromycin-H. Pylori sensitive strains, and in 7/23 (30 per cent) patients infected with azithromycin/clarithromycin-H. Pylori resistant strains. Eradication with triple therapies containing metronidazole was successful in 117/159 (74 per cent) patients infected with metronidazole-H. Pylori sensitive strains, and in 40/76 (53 per cent) patients infected with metronidazole-H. Pylori resistant strains. Conclusion: The primary H. Pylori resistance to metronidazole has been significantly more prevalent that to macrolides. No increase in the prevalence of primary resistance to either metronidazole or macrolides was noticed during the analysed 4 year period. The eradication therapy success was under the influence of H. Pylori starin susceptibly to antibiotics, especially when macrolides were concerned. However, eradication was achived in 1/3 of patients infected with H. Pylori resistant strains treated with azithromycin/clarithromycin. No significant differences in the susceptabiliy of analysed H. Pylori strains to azithromycin and clarithromycin were observed.

Helicobacter pylori; therapy; resistance; azithromicin

nije evidentirano