Proton-Pump Inhibitors Cause False Negative H. pylori tests.

Proton-pump inhibitors (PPIs) are widely used in patients with peptic symptoms in whom urea breath testing is used to diagnose Helicobacter pylori infection or confirm its eradication. But PPIs suppress H. pylori growth. To assess the effect of PPI use on urea breath testing, investigators studied 93 patients with H. pylori infection (diagnosed initially by serum antibody or endoscopic biopsy and confirmed by a positive urea breath test) who were about to begin PPI therapy for dyspepsia or gastroesophageal reflux.

After taking lansoprazole (30 mg) daily for four weeks, with no bismuth, antibiotics, or other antisecretory medications, 33 percent of patients had negative urea breath tests. One week after PPI therapy was discontinued, 97 percen…