Low rate of emergence of clarithromycin-resistant Helicobacter pylori with amoxycillin co-therapy.
BACKGROUND
Patients with persistent Helicobacter pylori infection following treatment with clarithromycin or omeprazole plus clarithromycin often develop clarithromycin resistance.


OBJECTIVE
To assess pre- and post-treatment antibiotic resistance in three double-blind trials of triple therapy with omeprazole, amoxycillin and clarithromycin.


METHODS
Patients with H. pylori and duodenal ulcer (studies 1 and 2) or history of duodenal ulcer (study 3) were randomly assigned to 10 day courses of omeprazole 20 mg b.d., amoxycillin 1 g b.d. and clarithromycin 500 mg b.d. (OAC) or placebo, amoxycillin 1 g b.d. and clarithromycin 500 mg b.d. (AC). Endoscopy was performed at baseline and 4 weeks after completion of therapy in studies 1 and 2, and at 4-6 weeks after therapy in study 3. At baseline, H. pylori was diagnosed by CLO test with confirmation by histology, or by culture. Eradication was defined as no positive biopsy test and > or = 2 negative tests. Susceptibility testing was performed using the Etest.


RESULTS
In the 91 patients with pre-treatment susceptible isolates who had persistent infection after AC, 10 developed resistance, eight had intermediate susceptibility and 73 continued to have clarithromycin-susceptible H. pylori isolates. In the 10 patients with pre-treatment susceptible isolates who had persistent infection after OAC, three developed clarithromycin resistance and seven still had susceptible isolates.


CONCLUSIONS
Use of amoxycillin co-therapy results in a low rate of clarithromycin resistance developing in patients with persistent H. pylori infection following therapy with a clarithromycin-containing regimen.
Laine
L
L
U.S.C. School of Medicine, Los Angeles, California 90033, USA. llaine@usc.edu
Suchower
L
L
Frantz
J
J
Connors
A
A
Neil
G
G
D000658:Amoxicillin / Q000627:therapeutic use*; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D017291:Clarithromycin / Q000627:therapeutic use*; D004311:Double-Blind Method; D004352:Drug Resistance, Microbial; D004359:Drug Therapy, Combination / Q000627:therapeutic use*; D004381:Duodenal Ulcer / Q000150:complications / Q000188:drug therapy / Q000382:microbiology; D016481:Helicobacter Infections / Q000150:complications / Q000188:drug therapy*; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D010406:Penicillins / Q000627:therapeutic use
D000900:Anti-Bacterial Agents; D010406:Penicillins; D000658:Amoxicillin; D017291:Clarithromycin