Increasing primary antibiotic resistance and ethnic differences in eradication rates of Helicobacter pylori infection in New Zealand--a new look at an old enemy

Abstract

Aims: To determine the current prevalence, primary antibiotic resistance and eradication rate with standard triple therapy of Helicobacter pylori (H. pylori) infection in South Auckland, New Zealand (NZ).

Methods: Consecutive patients undergoing gastroscopy in 2012 were prospectively enrolled. The prevalence of primary H. pylori infection was determined from all Campylobacter-like organism (CLO) tests performed. Antibiotic susceptibility testing was performed for a range of relevant antibiotics and the success of eradication therapy was determined by stool antigen clearance.

Results: The prevalence of H. pylori infection by ethnic group; European (7.7%), Maori (34.8%), Pacific People (31.3%) and Orientals (23.8%). Metronidazole resistance was found in 49.3% of isolates, clarithromycin resistance in 16.4%, and moxifloxacin resistance in 9.5%. No isolates were resistant to tetracycline. Clarithromycin resistance (greater than and equal to 15%) was prevalent among Maori, Pacific People and Orientals. Metronidazole resistance has increased significantly from 32.7% in 1999 to 49.3% in 2012 (p=0.011), and clarithromycin resistance from 7% in 1999 to 16.4% in 2012 (p=0.021). The eradication rate (intention to treat) with standard omeprazole, amoxicillin and clarithromycin (OAC) therapy in ethnic groups where clarithromycin resistance was <15% was 85.7% versus 64.9% in groups where clarithromycin resistance was greater than and equal to 15% (p=0.024).

Conclusion: H. pylori infection is very common among certain ethnic groups living in South Auckland. Resistance to clarithromycin and metronidazole have increased significantly among treatment naive patients compared to historical NZ data. Ethnic groups with clarithromycin resistance of greater than and equal to 15% were associated with lower eradication rates with OAC therapy. This suggests a need to review the current NZ H. pylori eradication guidelines to accommodate ethnic differences in the response to first-line regimens.