Diagnosis of Helicobacter Pylori Infections
Helicobacter pylori is a spiral-shaped gram-negative rod. H. pylori is associated with antral gastritis, duodenal (peptic) ulcer disease, gastric ulcers and gastric carcinoma. Other Helicobacter species that infect the gastric mucosa exist but are rare.
H. pylori is one of the commonest bacterial pathogens in humans. The prevalence of infection varies, but is falling in most developed countries. Seropositivity increases with age and low socioeconomic status.
Direct fecal antigen detection of H. pylori has been approved by the US Food and Drug Administration for diagnosis and follow-up testing.
H. pylori antigens from fresh human faecal specimens are detected by polyclonal antibodies. The sensitivity and specificity of faecal antigen detection is 89% and 94% - 95%, respectively, in multiple studies. Faecal antigen detection is a recommended noninvasive approach for confirmation of H. pylori infection in paediatric patients because serologic tests are less reliable (especially in children younger than 5 years) and are useful only for screening in this population.
Several assays have been developed to detect serum antibodies specific for H. pylori. The serum antibodies persist even if the H. pylori infection is eradicated and the role of antibody tests in diagnosing active infection or following therapy is therefore limited.
Urea Breath Tests
The breath tests are performed by asking the patient to swallow carbon- labelled urea which is metabolized by H. pylori produced urease to produce labelled carbon dioxide. This is absorbed into the blood stream and then exhaled in the breath of infected individuals.
An overnight fast is required. False negative breath test results can occur through suppression of urease activity if the breath tests are performed too soon after antibiotic or acid suppression therapy. Contact the local laboratory to confirm the availability of the urea breath test.
Culture remains a reference method, but its limited sensitivity and difficulty precludes its routine use. Patient factors which could affect culture results include high gastric activity, low bacterial load and alcohol.
Giemsa staining on oesophagogastroduodenoscopy specimens is also useful in the histological diagnosis of H. pylori related gastritis.
Different treatment regimens have been summarised in the table below.²
|Length of treatment (Days)||Component Drugs|
|Regimens based on clarithromycin|
|14||Ranitidine bismuth citrate 400 mg twice daily||Clarithromycin 500 mg twice daily|
|7 - 10||Ranitidine bismuth citrate 400 mg twice daily||Amoxicillin 1000 mg twice daily||Clarithromycin 500 mg twice daily|
|7 - 10||Proton pump inhibitor twice daily||Amoxicillin 1000 mg twice daily||Clarithromycin 500 mg twice daily|
|Regimens based on metronidazole (or tinidazole)|
|14||bismuth compound 4 times/day||Tetracyline 500 mg 4 times/day||Metronidazole 400 - 500 mg 3 - 4 times/day|
|7 - 10||Proton pump inhibitor twice daily||Amoxicillin 500 mg 2 - 3 times/day||Metronidazole 400 - 500 mg 2 - 3 times/day|
|4 - 7||Proton pump inhibitor twice daily||Colloidal bismuth subcitrate 4 times/day||Tetracyline 500 mg 4 times/day||Metronidazole 400 - 500 mg 3 - 4 times/day|
|Regimens based on clarithromycin plus metonidazole (or tinidazole)|
|7||Ranitidine bismuth citrate 400 mg twice daily||Clarithromycin 500 mg twice daily||Metronidazole 400 - 500 mg twice daily|
|7||Proton pump inhibitor twice daily||Clarithromycin 500 mg twice daily||Metronidazole 400 - 500 mg twice daily|
- Atherton JC, Spiller RT. The urea breath test for Helicobacter pylori. Gut 1994, 35:723-725
- De Boer WA, Tytgat GNJ. Treatment of Helicobacter pylori infection. BMJ 2000, 320:31?4
- http://www.uptodate.com/contents/helicobacter-pylori-infection-and-treatment-beyond-thebasics, accessed December 2012.
- McNulty et al. Diagnosis of Helicobacter pylori Infection. Helicobacter 2011, 16 (Suppl. 1): 10-