Different antibiotic susceptibility between antrum and corpus of the stomach, a possible reason for treatment failure of Helicobacter pylori infection.

AIM: To assess whether antibiotic resistance varies between the antrum and corpus of the stomach of patients that are either Helicobacter pylori (H. pylori) therapy-naive or pre-treated. METHODS: H. pylori strains were isolated from antrum and corpus biopsies from 66 patients that received a diagnostic gastroduodenoscopy for variant clinical indications. Antimicrobial susceptibility to amoxicillin, clarithromycin, tetracycline, metronidazole, levofloxacin and rifabutin was tested with the E-test method on Iso-Sensitest agar with 10 vol% defibrinated horse blood. In patients with a different antibiotic susceptibility pattern between the isolates from the antrum and corpus, DNA fingerprinting via random amplified polymorphic DNA analysis was performed to detect differences among DNA patterns of H. pylori isolates. RESULTS: Primary, secondary and tertiary resistance to clarithromycin was 6.9%, 53.8% and 83.3%, retrospectively. Metronidazole and levofloxacin resistance also increased according to the number of previous treatments (17.2%, 69.2%, 83.3%; 13.8%, 23.1%, 33.3%). Tertiary resistance to rifabutin was detected in 12.5% of patients. In none of the 66 patients a resistance against amoxicillin or tetracycline was detectable. Discordant antibiotic susceptibility between antrum and corpus isolates for different antibiotics was seen in 15.2% (10/66) of the patients. Two out of those ten patients were naive to any H. pylori antibiotic treatment. The remaining eight patients previously received at least one eradication therapy. DNA fingerprinting analysis revealed no substantial differences among DNA patterns between antrum and corpus isolates in the majority of patients suggesting an infection with a single H. pylori strain. CONCLUSION: Different antibiotic susceptibility between antrum and corpus biopsies is a common phenomenon and a possible explanation for treatment failure. Resistant H. pylori strains may be missed if just one biopsy from one anatomic site of the stomach is taken for H. pylori susceptibility testing.

Antibiotic susceptibility of Helicobacter pylori in central Germany and its relationship with the number of eradication therapies.

OBJECTIVES: Helicobacter pylori eradication rates show a constant decline over the last few years. The main reason for H. pylori treatment failure is the increasing antibiotic resistance.We assessed antibiotic susceptibility of H. pylori in a region of mid-Germany and analyzed the relationship of antibiotic resistance with the number of eradication therapies over a period of 7 years (2005-2012). METHODS: H. pylori strains were isolated from 436 patients who underwent gastroscopy for different clinical indications. Susceptibility to amoxicillin, clarithromycin, metronidazole, tetracycline, levofloxacin, and rifabutin was determined using the E-test. RESULTS: Primary, secondary, and tertiary resistances against clarithromycin were 7.5, 63.2, and 75.4%, respectively. Primary, secondary, and tertiary resistances to levofloxacin were 11.7, 17.6, and 36.4% and to metronidazole were 32.7, 63.2, and 80.1%, respectively. The resistance rates against tetracycline and rifabutin were comparatively low (<5%), even in patients with previous exposure to these antibiotics. Resistance to rifabutin increased to 6.2% in patients who received more than two previous eradication therapies. Amoxicillin resistance was not detectable in all patients. CONCLUSION: In our region, we observed a stable, but constantly increasing, resistance rate to antibiotics commonly used for the treatment of H. pylori infection. Knowledge of the local antibiotic resistance rates is essential for developing successful treatment strategies for H. pylori eradication.