Urea breath test for Helicobacter pylori detection: present status.

Helicobacter pylori (H. pylori) is the commonest bacterial pathogen found worldwide and more than half the world population aged 40 years and above is colonized with it. The infection rate is >95 % in some African countries. In 1994, the International Agency for Research on cancer classified H. pylori as a class I carcinogen in humans. It causes chronic active gastritis, duodenal and gastric ulcer and gastric malignancy, and is thought to be associated with coronary artery disease, cerebral stroke, vitamin B12 and iron-deficiency anaemia, etc. Therefore, non-invasive test-and-treatment strategies are widely recommended in primary care settings. Conventionally, H. pylori infection can be diagnosed by invasive techniques using an upper gastrointestinal endoscope for obtaining multiple biopsies from different sites of the stomach for RUT, culture, histological examination, polymerase chain reaction (PCR), etc. and by non-invasive tests such as Urea breath test (UBT), stool antigen test and blood serology. At present, 13/14C-UBT is considered the test of choice for confirmation of H. pylori infection. The UBT is based on the principle, that isotopically labelled urea ingested by an H. pylori--infected patient is rapidly hydrolysed by the microbial urease. The released 13/14CO2 is absorbed across the mucous layer to the gastric mucosa and hence, excreted via the systemic circulation in the breath which is collected and measured. The non-hydrolysed urea is excreted completely in the urine within 3-4 days. 13C-UBT being non-radioactive, 13C-UBT can be used in pregnant women and children, and a user's license is not required. There is still no standard protocol accepted and followed internationally for this test. Although the methods are almost similar, various laboratories/clinics use variable tracer doses, test meals, timings and methods for breath collection, and different cut-off values, which make formal validation studies necessary. This review describes the present status of the UBT and its application in the detection of H. pylori infection.

Effect of eradication of Helicobacter pylori on gastric antrum histology.

BACKGROUND: Helicobacter pylori is a leading cause of gastritis. Some of the histological changes revert after eradication of H. pylori. There is paucity of reports from India. AIM: To study the effect of H. pylori eradication on the histopathological changes. METHODS: Endoscopically obtained antral biopsies from 164 consecutive H. pylori positive cases of dyspepsia were analysed before and 4 weeks after completion of treatment. RESULTS: Treatment for H. pylori resulted in eradication of the organism as confirmed histologically in 123 out of 164 (76.22%) cases. Analysis of histopathological changes in pre and post treatment biopsies from the same patient revealed a significant reduction in neutrophils, eosinophils, chronic inflammatory cells, acute epithelial changes and regenerative foveolar hyperplasia (p < 0.001) There was no difference in these findings in cases where H. pylori eradication failed when compared with their pre-treatment biopsies (p > 0.05). Similarly the pre and post treatment biopsies revealed, no difference in frequency of intestinal metaplasia and gastric atrophy in cases where H. pylori was eradicated or persisted after treatment. CONCLUSION: There was significant reduction in neutrophils, eosinophils, chronic inflammatory cells, acute epithelial changes and regenerative foveolar hyperplasia, following eradication of H. pylori.

Normal limits of 14C-urea breath test.

BACKGROUND/AIMS: 14C-urea breath test has been widely used for diagnosis of Helicobacter pylori (H. pylori) infection. There is no general agreement on the cutoff values for determination of H. pylori negative subjects. We studied baseline values in subjects who were proved to be H. pylori negative and calculated the cutoff value of normalcy. A comparison of this test with other tests for diagnosis of H. pylori infection was also done. PATIENTS AND METHODS: 12 patients (mean age 34 +/- 14, range 22-65 years; 8 men) of non-ulcer dyspepsia were studied, who were proved to be H. pylori negative by rapid urease test, Gram's staining, histopathology and culture of gastric mucosal biopsies obtained four each from the antrum, body and fundus of the stomach. The controls included 12 patients (mean age 40 +/- 13, range 22-65 years, 9 men), who were positive for H. pylori on culture or combination of rapid urease test and histopathology or rapid urease test and Gram's stain. 14C-urea breath test was performed using 5 uCi of 14C-urea dissolved in 300 ml of water. Breath samples were collected once before ingestion of 14C urea and subsequently at 5, 15 and 30 minutes after ingestion and 14C-contents in the breath samples measured. Results were expressed as 14 CO2/mmol CO2 exhaled as percent of administered urea. RESULTS: The mean +/- SD 14-C value in H. pylori negative vs H. pylori positive patients at 5 minutes, 15 minutes and 30 minutes were found to be 0.003 +/- 0.003 vs 0.064 +/- 0.042 (p < 0.001), 0.002 +/- 0.001 vs 0.056 +/- 0.039 (p < 0.001) and 0.001 +/- 0.002 vs 0.041 +/- 0.026 (p < 0.001) respectively. The mean values of 14C-urea breath test were significantly lower in H. pylori negative patients as compared to H. pylori positive patients. Using receiver operating characteristic (ROC) analysis of the data, the cutoff values obtained were 0.01, 0.007 and 0.009 at 5 minutes, 15 minutes and 30 minutes respectively. CONCLUSIONS: 14C-urea breath test levels at 5, 15 and 30 minutes intervals are significantly lower in H. pylori negative patients as compared to H. pylori positive patients. This test has high sensitivity and specificity in detecting H. pylori infection.