A new study finds it may be possible to eradicate an infection responsible for an often-fatal cancer.
The research also illustrates the complexities of that approach, especially when different treatments seem to work differently in different parts of the world.
H. pylori is an extremely common bacteria. Worldwide, about half of us have it in our gut. Most of the time, it doesn't bother us. But sometimes it causes ulcers, and H. pylori is implicated in stomach cancer, the second-deadliest cancer worldwide.
A three-drug treatment spread out over two weeks had been considered the preferred therapy. However, recent studies in Europe, Asia, and North America have found that a four-drug treatment given over five to 10 days was more effective.
But that's not the case, according to a new study, for patients in Latin America.
"And we found that the three-drug regimen - somewhat to my surprise - actually did better than the four-drug regimen," said Robert Greenberg of the Fred Hutchinson Cancer Research Center in Seattle, Washington.
Greenberg and his colleagues randomly assigned about 1,500 participants to different treatments. They found that the four-drug regimen - which worked so well elsewhere - was less effective than the standard triple therapy.
The study was conducted at seven locations in six countries - Mexico, Nicaragua, Honduras, Costa Rica, Colombia, and Chile.
In a research paper published in The Lancet, Greenberg and his colleagues explain that the responses to the different drug combinations might be explained by regional variations in resistance that H. pylori has developed to the specific antibiotics and other medicines in each combination regimen.
More than 87 percent of those in the three-drug group who took their medicine were cured of their infection, a success rate that suggests the possibility of eradicating H. pylori. But researcher Greenberg says it's not a simple decision.
"I think, although we were positive in saying we think it's feasible to eradicate [H. pylori], we ourselves are undecided as to whether and how an eradication program should be implemented."
Because H. pylori is more common in developing countries, eradication might make more sense in those areas, although Greenberg and his colleagues take no position on whether it should be done.
In a commentary published with Greenberg's paper, a trio of Brazilian experts argue against mass eradication for several reasons, including the fear that the widespread use of antibiotics could prompt drug-resistant mutations not only of H. pylori but of other pathogens, too.