Some Acid Reflux Drugs Linked to C. diff

Sept. 21, 2011 (Chicago) -- The popular class of acid reflux medication that includes Aciphex, Dexilant, Nexium, Prevacid, Prilosec, and Protonix is associated with an increased risk of diarrhea caused by the bug Clostridium difficile(C. diff).

Japanese researchers followed about 500 hospitalized patients, over half of whom were taking these drugs, called proton pump inhibitors (PPIs).

Those who were taking PPIs were more than three times as likely to develop C. diff diarrhea as those who were not taking them.

Still, the risk of any individual patient developing the infection was relatively low, says researcher Takatoshi Kitazawa, MD, of Teiko University in Tokyo.

Overall, 19 of 487 PPI users developed C. diff diarrhea, compared with four of 329 people who didn't take the acid-lowering drugs.

That's potentially tens of thousands of cases a year, Kitazawa says.

The findings were reported here at the Interscience Conference on Antimicrobial Agents and Chemotherapy.

Proton Pump Inhibitors and C. diff

This isn't the first study to link PPIs to C. diff infection. But this study had a more robust design, following patients over time to see if they developed the infection, Kitazawa tells WebMD.

The study is limited, however, by the fact it only involved 793 patients admitted to one Japanese hospital.

Also, such studies don't show cause and effect -- just an association between PPIs and C. diff diarrhea, says Lindsay Grayson, MD, head of infectious diseases at Austin Health in Melbourne, Australia. He was head of the committee that chose which studies to highlight at the meeting.

"Why were the people on the PPIs in the first place? [They could have shared some other characteristic] making them more prone to C. diff," he tells WebMD.

On the other hand, it makes sense that PPI use would allow C. diff bacteria to increase and spread, says Craig Rubens, MD, PhD, of the Seattle Children's Hospital Research Institute, who was also a member of the program committee.

PPIs lower stomach acidity, allowing C. diff in the gut to survive when it wouldn’t otherwise, he tells WebMD. The bugs travel downstream, where they release toxins that cause diarrhea.

C. diff Outside the Hospital

The study didn't look at people who take PPIs outside the hospital. They're the third highest-selling class of drugs in the U.S., accounting for over 1 million prescriptions each year.  Prevacid, Prilosec, and Zegerid are available without prescription.

At the same time, C. diff infections outside of the hospital are on the rise.

One can't draw any conclusions about whether PPIs play a role in the rise of community C. diff infections based on this study, the experts say.

The drugs do a great job of reducing stomach acid, and for some people, the benefits outweigh the risks.

But PPIs are supposed to be used only for serious conditions, not to be popped for simple heartburn or indigestion, they note. If you have questions, ask your doctor.

These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.