The discovery of Helicobacter pylori revolutionised ulcer treatment because antibiotics could be acced to acid-lowering medications. However, this treatment doesn't work for everyone and research suggests that there may be more ulcer bacteria than Helicobacter.
Perth is also famous as the place where the peptic ulcer germ, Helicobacter pylori was discovered. Peptic ulcers are those in the stomach and the next part of the intestine, the duodenum. Helicobacter pylori revolutionised ulcer treatment because antibiotics could be added to acid-lowering medications in the hope of a cure.
But the treatment doesn't work in everyone, and research from Michigan suggests that there may be more ulcer bacteria than Helicobacter.
It's a complex story involving what may be misguided notions of why we have acid in the stomach in the first place, and the role of a hormone called gastrin.
Dr Juanita Merchant is an Associate Professor in Internal Medicine at the University of Michigan, Ann Arbor.
Juanita Merchant: Gastrin is a hormone that normally is secreted when you eat and will stimulate the acid secreting cell to secrete acid.
Norman Swan: What stimulates the gastrin?
Juanita Merchant: There's actually a textbook definition that distension in the stomach and peptides in the stomach will actually turn on acid secretion.
Norman Swan: So food hits the stomach, your stomach gets stretched, gastrin comes out and it tells the other cells 'Hey chums, you've got to produce acid to start digesting this food.'
Juanita Merchant: To start digesting, right. And so basically people think that the reason why you're making acid is because you want to begin digestion.
Norman Swan: And you don't believe that?
Juanita Merchant: Well I think that's part of the reason. You need acid around to activate some of the enzymes that begin digestion. However what our study shows is that gastrin turning on acid secretion is the first line of defence for anything that you're ingesting in terms of bacteria.
Norman Swan: So it's not just the digestive process, it's almost like partly sterilising the food before it gets into the rest of your bowel?
Juanita Merchant: Correct. It's your first line of defence against any microbes that you may ingest.
Norman Swan: What's the relationship of this to the ulcer germ to Helicobacter pylori?
Juanita Merchant: Well gastrin levels increase in patients that are infected with Helicobacter pylori.
Norman Swan: Which according to your original theories makes sense, because it's trying to get rid of an infection.
Juanita Merchant: Right. This is according to the hypothesis that we've developed from our recent study. Basically Helicobacter causing an increase in acid secretion which is overwhelming the neutralising capabilities of the duodenum, and then you get the duodenal ulcers. The feedback mechanism should really be kicking in and shutting off acid secretion but we don't see that.
Norman Swan: Now you believe that that should really cause a bit of a re-think about how you approach the whole problem of peptic ulcers?
Juanita Merchant: Right. The problem in this situation with Helicobacter is that it's not killed by the acid, it's adapted to live in acid. So therefore the stomach's still detecting that the bug is still present, continues to crank up the acid.
Norman Swan: Now you studied mice where you deliberately knocked out the gene that produces gastrin, this hormone that keeps the acid going.
Juanita Merchant: Actually a colleague of ours, Linda Samuelson, created these mice, and when we attempted to infect these animals we found that we had a difficult time infecting them, the organism did not colonise the stomach, and it was probably because there were already bacteria there occupying the niche that Helicobacter would like to occupy.
Norman Swan: Dr Juanita Merchant.
And when they examined these mice which had very low acid in their stomachs, she found they had inflammation of the stomach, gastritis, pretty much like the one that Helicobacter causes, but instead of Helicobacter, they saw a host of other bacteria. These new bacteria were taking advantage of the low acid situation and this is potentially very significant.
Juanita Merchant: In other words, Helicobacter is probably not the only game in town, and these other organisms certainly can grow much faster than Helicobacter pylori.
Norman Swan: And more resistant to the current antibiotics being used?
Juanita Merchant: In general, people that haven't really been exposed much to antibiotics, it's fairly easy to treat these organisms. However there's a rise in Helicobacter organisms as well as a variety of other organisms such as staphylococcus that are resistant to the garden variety antibiotics.
Norman Swan: The commonest treatment around the world, or at least the approved treatment if you like for duodenal ulcers, where you've got Helicobacter is that you give drugs called proton pump inhibitors, or Meprosol would be the commonest form, the trade name in Australia is Losec and antibiotics. But from what you say low acid levels are not necessarily the right thing and treating the Helicobacter might just be enough by itself.
Juanita Merchant: A lot of the symptoms that patients are having is from the acid, so initially treating with the proton pump inhibitors to decrease the amount of acid that you're producing, is not a bad thing. The issue is that once the two or three weeks of treatment is done, should you leave these patients on those drugs. More importantly there are other disorders in which we use proton pump inhibitors.
Norman Swan: Like reflux.
Juanita Merchant: Exactly, reflux disease.
Norman Swan: Heartburn.
Juanita Merchant: Exactly. These patients, especially if they never go to surgery to correct the problem will be on these drugs lifelong. And there's the issue that if you continue to suppress your acid that eventually you'll continue to have the smouldering infection or inflammation from the bacterial overgrowth, and that eventually there's the question that long-term chronic inflammation will lead to cancer.
Norman Swan: Although every time I ask a gastro-enterologist about this they pooh-pooh it and say there's no evidence of that.
Juanita Merchant: There is no evidence at the moment. However we don't have more than probably 20, 25 years of experience with these drugs. The other issue is how compliant patients are on these drugs, because all you probably would need is a little bit of breakthrough acid to decrease the bacterial load in the stomach and resolve the inflammation.
Norman Swan: In other words if people are being naughty and not taking their drugs, they actually may be helping -
Juanita Merchant: They may be helping themselves, exactly. More importantly there are now about five of these proton pump drugs on the market and each new one that comes out is more and more effective in shutting off acid so one pill can last a lot longer at smaller doses. And then there's the issue of whether these are available over the counter. So these are things that we probably need to think about in the future.
Norman Swan: We definitely do. Dr Juanita Merchant is Associate Professor of Internal Medicine at the University of Michigan, Ann Arbor.
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- Dr Juanita Merchant
- Associate Professor in Internal Medicine,
University of Michigan,
Ann Arbor, Michigan
- Dr Norman Swan
- Brigitte Seega