H pylori eradication and allergy to metronidazole or fluoroquinolones

Paul Moayyedi, MB, is a professor of medicine and assistant dean of research in the Faculty of Health Sciences at McMaster University.

What treatment regimen should be used for Helicobacter pylori eradication in patients with allergy to metronidazole or with allergy to fluoroquinolones (as the first choice and in case of initial treatment failure)?

Initial treatment failure. In that example, when the patient is allergic to a lot of things, you may have to go straight to rifabutin with amoxicillin. Obviously, as they’re allergic to penicillin as well, which wasn’t in the question, you’re suddenly stuck because you really don’t have a good therapy. But I would say that with second line I would go with the proton pump inhibitor (PPI), rifabutin, and amoxicillin for the question asked as the approach.

The other thing is whether they really need it. If they’ve got a lot of antibiotic allergies and the indication is for, let’s say, functional dyspepsia, the number needed to treat there is around 14, so your benefit is definitely there but it is small. Probably the risk is not worth the possible benefit when it’s likely that it’s going to be tough to get rid of the infection.

But in cases of things like peptic ulcer disease, where you really need to get rid of it if you can, I would actually test for this antibiotic resistance to see if they’re really allergic to these antibiotics or whether it’s just, you know, a doctor said, “Your rash was an allergy.” So, consult your allergist, get them tested—this applies for penicillin allergies, too—document what they’re really allergic to, and then use therapies that you can based on objective testing.