Antibiotic regimens to eradicate Helicobacter pylori (H. pylori) have been developed for most patient subgroups, however they have not been standardized for patients with a penicillin allergy, which reportedly occurs in 1-12% of populations. A regimen including clarithromycin and metronidazole is the most commonly used regimen in penicillin-allergic patients but is associated with low eradication rates. Thus the Maastricht V/Florence Consensus Report has recommended a triple regimen including a fluoroquinolone in patients allergic to penicillin.
Supporting this recommendation are results from a recent trial assessing the efficacy of a 10-day triple regimen (20 mg esomeprazole, bid; 250 mg metronidazole, bid; and 100 mg sitafloxacin, bid) in penicillin-allergic patients. This study also assessed the relationship between eradication rates and resistance profiles by measuring the MICs of sitafloxacin and metronidazole, and the gyrA mutation status of the H. pylori isolates.
A prospective, non-randomised study enrolled 78 patients between March 2014-November 2015, with 57 suitable for analysis (23 men and 34 women, mean age 57.8 years). The eradication rates for metronidazole and sitafloxacin-susceptible or -resistant H. pyloriisolates were examined with secondary analysis focussing on eradication rates of gyrA mutation- positive or -negative H. pyloristrains as well as safety.
Twelve weeks after therapy, eradication was confirmed with an overall rate of 89.5%. Looking at specific subgroups, the eradication rate of gyrA mutation-negative strains was 96.2%, compared to 83.9% for gyrA mutation-positive strains. However, in patients with H. pylori isolates resistant to both metronidazole and sitafloxacin the eradication rate was 40.0%, indicating a significant association between antibiotic resistance and efficacy.Physicians are asked to consider substituting metronidazole or sitafloxacin in patients with double-resistant strains. It is important to note however that while the eradication rate of these double-resistant strains was low, this finding was taken from a small population (2 of 5 patients). The authors drew attention to the fact that patients infected with metronidazole resistant and sitafloxacin sensitive strains achieved complete eradication (7/7).
With regard to safety analysis, adverse events were reported in 31.6% of cases, but these were all mild and self-limiting.
The authors concluded that a 10-day triple therapy regimen containing sitafloxacin and metronidazole was highly effective in eradicating H. pylori and well tolerated in penicillin-allergic patients. Double resistance to metronidazole and sitafloxacin was an important factor predicting eradication failure, but in patients with H. pylori resistant to only one of these agents the 10-day triple therapy regimen with sitafloxacin and metronidazole was highly effective.
United European Gastroenterol J. 2017 Oct;5(6):796-804. doi: 10.1177/2050640616688995. Epub 2017 Jan 19.