Failure of first-line eradication treatment significantly increases prevalence of antimicrobial-resistant Helicobacter pylori clinical isolates

Objectives: Helicobacter pylori infection is a major health problem worldwide, and effective eradication of the infection is mandatory. The efficacy of recommended eradication regimens is approximately 70%. To avoid treatment failure and the consequent development of secondary resistance(s), it is important to choose the most appropriate first-line treatment regimen. This choice should also be made based on the knowledge of the antimicrobial resistance peculiar to a given geographical area. We evaluated the prevalence of antimicrobial-resistant H pylori strains isolated from naive patients and from patients with previous unsuccessful treatments. Methods: This study examined 109 H pylori-infected subjects (Group 1) who had never received an eradication treatment and 104 H pylori-infected subjects (Group 2) who had failed one or more eradication treatments. Resistance to amoxicillin (AMO), tetracycline (TET), clarithromycin (CLA), metronidazole (MET) and levofloxacin (LEV) was determined using the epsilometer test. The significance of differences was evaluated by the chi(2) test. Results: The prevalence of antimicrobial resistance was 0% versus 3.1% to AMO, 0% versus 2% to TET, 27% versus 41.3% to MET (p < 0.05), 18% versus 45.8% to CLA (p < 0.05) and 3% versus 14.6% to LEV (p < 0.05) in Group 1 vs Group 2, respectively. In Group 2, there was an increased prevalence of H pylori strains resistant to multiple antimicrobials. Conclusions: This study confirms the high prevalence of H pylori strains resistant to CLA and MET, and indicates that unsuccessful treatments significantly increase resistance. Choosing eradication regimens other than standard triple therapy as a first- line therapy should be advisable in areas with high primary antimicrobial resistance prevalence.