First: check that the result is reliable
Before assuming treatment has failed, it is worth ruling out something more common than people think: that the test of cure was done incorrectly.
The breath test has two conditions that are often broken. It must be performed at least four weeks after finishing antibiotics, and with proton pump inhibitors stopped for the preceding two weeks.
Done earlier, or while taking acid suppression, the result can be falsely negative. Conversely, repeating it too soon can be positive because of bacterial remnants not yet cleared.
Before writing treatment off
Check how long passed between finishing treatment and the test, and whether you were taking acid suppression. It is the first error I rule out in clinic, and it resolves a proportion of cases without any further treatment.
Why it really fails
When the result is reliable, the causes are fairly specific.
- Antibiotic resistance. The main one. In Spain resistance to clarithromycin and levofloxacin is high, and a regimen that ignores this starts at a disadvantage.
- Short courses or inadequate doses. Seven-day regimens are behind us. Longer courses with higher doses of acid suppression are now used.
- Stopping treatment early. Side effects are common and patients are not always warned. Abandoning the course after four days is equivalent to not having taken it.
- Prior exposure to those antibiotics. A course of clarithromycin for bronchitis years ago may have selected resistance.
- Smoking. It measurably reduces the likelihood of eradication.
What to do after a first failure
The rule is simple and constantly broken: do not repeat the same treatment. The chance of success second time round with the same antibiotics is low, and resistance accumulates.
The second attempt must be chosen on the basis of what has already been taken. So when someone comes to clinic for this, the first thing I ask for is the exact detail: which antibiotics, at what dose and for how many days. Almost nobody brings it, because almost nobody has been asked.
With that information, a rescue regimen is chosen that avoids the previous antibiotics and takes allergies into account.
When two or more treatments have failed
Beyond the second or third failure, continuing to guess makes little sense. It is time to establish directly what your bacterium is sensitive to.
This is done with a gastroscopy taking samples for culture and sensitivity testing, or with molecular resistance testing. Treatment is then chosen on objective data rather than by exclusion.
Confirmation is not optional
Every course must be confirmed with a subsequent test, respecting the required intervals. Treatment without a test of cure is only half a treatment, and it is why many patients believe they are cured when they are not.
And if it is never eradicated
This happens in a minority of cases. At that point the decision stops being automatic and becomes individual: age, symptoms, family history of gastric cancer and gastroscopy findings all weigh in.
In some patients it is worth continuing; in others, surveillance is the right approach. What makes no sense is stringing together antibiotic courses indefinitely without a plan.
If you have completed one or more courses and remain positive, it is worth reviewing the case from the beginning before treating again.