RESISTANCE TO ANTIBIOTICS OF HELICOBACTER PYLORI STRAINS FROM PATIENTS AFTER TREATMENT FAILURE

The presence of mutant resistant bacteria can be due to the prolonged and continuous exposure to antimicrobial agents during the infection with consequent treatment failure. The observed high resistance rates in our study may be related to the high number of therapy cycles (up to 9) that the population under consideration has done suggesting that the following treatments might increase antibiotic resistance, even if data on resistance before and after eradication failure in the same group of patients are not available. K-B and E-test provide comparable results for Hp when testing for the antibiotics studied with reduced reliability for MZ. In fact the E-test may over-estimate MZ-resistance because the presence of intermediate MIC levels. Dual resistance to both MZ and CLA was found in 16 strains (50%). LEV appears a promising alternative for Hp refractory infections. A distinct pattern of antibiotic sensitivity of isolates belonging to different districts of the stomach (heteroresistance) was noticed in 36.3% of cases (4/11 patients with pangastritis). The presence in the same patient of Hp strains either S or R to various antimicrobial agents, may interfere with the outcome of the therapy