Helicobacter pylori and plasma ammonia levels in cirrhotics: role of urease inhibition by acetohydroxamic acid

Abstract: Background and Aims, The role of Helicobacter pylori as a cause of hyperammonaemia in cirrhotics has still not been fully clarified. This study was aimed at evaluating the effect of acute Helicobacter pylori urease inhibition by oral acetohydroxamic acid administration on blood ammonia levels in cirrhotic patients. Methods. Twenty-nine cirrhotics (14 males, 15 females; mean age: 63 years; Child-Pugh class: 14 A, 9 B, and 6 C) undergoing upper gastrointestinal endoscopy were enrolled in the study. The presence of Helicobacter pylori infection was assessed by rapid urease test and histology. A semi-quantitative grading of bacterial density was also performed at histology. All patients received oral acetohydroxamic acid 750 mg, and blood samples for assessment of ammonia levels were taken before and at 15, 30, 60 and 90 minutes after administration. Results. Helicobacter pylori infection was detected in 20 patients, while 9 patients were uninfected. Acetoydroxamic acid administration led to a significant reduction in blood ammonia levels at 15 and 30 minutes (mean +/- SD, 113 +/- 44 vs 101 +/- 43 and 93 +/- 38 mu g/dl, respectively; p=0.002) only in patients with Helicobacter pylori infection. Moreover the reduction was statistically significant only in Child-Pugh B/C class patients and in those with moderate/marked Helicobacter pylori density in gastric mucosa. Basal ammonia levels did not differ between Helicobacter pylori positive and negative patients, nor in patients with mild and moderate/marked Helicobacter pylori density in gastric mucosa, while Child-Pugh class B/C cirrhotics had higher basal ammonia levels than class A cirrhotics, in both Helicobacter pylori positive and negative groups. Conclusions. Our data showed that Helicobacter pylori urease inhibition by acetahydroxamic acid administration significantly reduces blood ammonia levels in patients with more advanced liver cirrhosis and in those with a high bacterial density in gastric mucosa.