Israel Medical Association Journal

Background: Antimicrobial resistance is the main determinant for Helicobacter pylori treatment failure. Regional antimicrobial susceptibility testing is essential for appropriate antibiotic selection to achieve high eradication rates.

Objectives: To assess primary and secondary H. pylori resistance in isolates recovered from Israeli naïve and treatment failures. To identify predictors of resistance.

Methods: In this retrospective study, in vitro activity of isolated H. pylori in Israel was tested against metronidazole, clarithromycin, tetracycline, amoxicillin, and levofloxacin in 128 isolates: 106 from treatment failures and 22 from naïve untreated patients. The minimal inhibitory concentration values were determined according to the Etest instructions. Treatment failures previously failed at least one treatment regimen.

Results: No resistance to amoxicillin and tetracycline was detected. Resistance to metronidazole and clarithromycin was high in H. pylori isolates both from treated and untreated patients: 68.9%, 68.2% for metronidazole (P = 0.95); 53.8%, 59.1% for clarithromycin (P = 0.64), respectively. Dual resistance to clarithromycin and metronidazole was seen in 45.3% and 50%, respectively (P = 0.68). Resistance to levofloxacin was detected in two (1.9%) isolates from treated patients. Simultaneous resistance to clarithromycin, metronidazole, and levofloxacin was seen in an isolate from a treated patient. Age was the only predictor of resistance to metronidazole and clarithromycin.

Conclusion: The resistance rates to both single and dual metronidazole and clarithromycin in isolates recovered from both Israeli naïve and treated patients is high. Low resistance renders levofloxacin an attractive option for second or third line treatment. Therapeutic outcome would benefit from susceptibility testing after treatment failure.

Background: Empiric treatment for Helicobacter pylori is influenced by antibiotic susceptibility of infecting strains. A rise in the resistance rate to clarithromycin and metronidazole has been reported in pediatric populations.

Objectives: To assess the primary and secondary antibiotic resistance of H. pylori isolates in Israeli children and adolescents.

Methods: A retrospective review of H. pylori isolates cultured from antral biopsies of consecutive children aged 1 to 18 years, who were referred to the Pediatric Gastroenterology Unit, Kaplan Medical Center, over a 2.8 year period, was performed. Antibiotic susceptibility to clarithromycin, metronidazole, amoxicillin, tetracycline, and levofloxacin was determined by E-test. Data on the age of the patient, indication for endoscopy, and antibiotic treatment for H. pylori in previously treated children was collected.

Results: Cultures for H. pylori yielded 123 isolates. In children not previously treated (n=95), the primary global resistance was 38% with resistance to clarithromycin 9.5%, metronidazole 32.6 %, and to both 4.2%. Respective rates of resistance in previously treated children (n=28) were 71% (P = 0.002), 29% (P = 0.02), and 61% (P = 0.007). Simultaneous resistance to both drugs was found in 18% (P = 0.02). All H. pylori strains were susceptible to amoxicillin, tetracycline, and levofloxacin. Past eradication treatment was the only independent risk factor for antibiotic resistance in multivariate analysis.

Conclusions: Significantly higher resistance rates were found in previously treated patients, stressing the need to refrain from empiric treatment using the "test and treat strategy." Culture-based treatment strategy should be considered in all previously treated children.