Resistance of Helicobacter pylori to antimicrobial treatment in a Seville hospital catchment area.

AIM: To determine the sensitivity to metronidazol, clarithromycin, amoxicillin and tetracycline of strains of Helicobacter pylori isolated in a prospective series of patients referred to a university hospital in Seville for endoscopic examination. METHODS: During the period from March 1998 to July 1999 we studied 117 patients with ulcer. The diagnosis of bacterial infection was based on the rapid urease test, histological study, Gram staining or culture of gastric biopsy material (from the antrum and corpus) obtained during gastroscopy. Susceptibility studies were done with the diffusion method using E-test strips. RESULTS: Helicobacter pylori infection was found in 64 patients. A total of 58 strains were grown, 40 of which were from patients who had received no previous treatment to eradicate the infection (69%), and 18 of which were from patients who had failed one or more eradication therapies (31%). In the first group, metronidazol resistance was found in 42%, clarithromycin resistance in 13%, and resistance to both in 10% of the patients. In the second group these rates were 39%, 44% and 17% respectively, and one strain was found which was also resistant to tetracyclines (2%). No strains resistant to amoxicillin were found. CONCLUSIONS: We found high rates of resistance, especially to clarithromycin, and especially in patients who had received previous eradication therapy. Empirical treatments should use effective antimicrobials and avoid regimens based on a single antibiotic. Culture of gastric biopsy samples provides information on the resistance to antimicrobials in a given setting, and this information can be used to develop the most rational treatment for the infection.