Clarithromycin-resistant genotypes and eradication of Helicobacter pylori

Three point mutations (A2143G, A2142G, and A2142C) have been involved in Helicobacter pylori clarithromycin resistance.

To compare the eradication rates among the different point mutations and the efficacy of triple therapy and a sequential regimen according to genotypic resistance.

Post hoc subgroup study from a multicenter, randomized trial.

Two hospitals in central and southern Italy between January and December 2001.

156 patients with H. pylori infection.

Real-time polymerase chain reaction for assessing clarithromycin resistance; histology, rapid urease test, and 13C-urea breath test at entry and after 4 to 6 weeks.

7-day triple therapy (20 mg of rabeprazole, 500 mg of clarithromycin, and 1 g of amoxicillin) in 75 patients or a 10-day sequential regimen (20 mg of rabeprazole plus 1 g of amoxicillin for 5 days and 20 mg of rabeprazole, 500 mg of clarithromycin, and 500 mg of tinidazole for the remaining 5 days) in 81 patients. All drugs were given twice daily.

Helicobacter pylori infection was eradicated in 11 of 23 patients (48%) with the A2143G mutation and in 14 of 15 patients (93%) with either A2142G or A2142C strains (difference, 45 percentage points [95% CI, 15 to 65 percentage points]; P = 0.004). The sequential regimen achieved a higher cure rate than triple therapy in A2143G mutate strains (difference, 49 percentage points [CI, 8 to 72 percentage points]; P = 0.024).

The post hoc substudy design may require further confirmation. Other limitations are the accessibility to the tool and the cost of investigations (70 euros per patient).

The A2143G mutation seemed to be associated with a very low eradication rate. The sequential regimen achieved a higher cure rate than standard therapy even in patients with these strains.