Tests for H. pylori

Mr B needs a full-dose PPI (see below) for 4-8 weeks to heal his ulcer. Following this he should be tested for H. pylori, and if this test is positive he should have eradication treatment. Note that in patients already taking a PPI a two-week washout period is needed before a breath test or a stool antigen test is used. 

If Mr B is symptomatic following H. pylori eradication he should be re-tested for H. pylori, and if this test is positive he should be given a further course of eradication treatment, using a different antibacterial combination to the one given previously (regimens detailed in the BNF). He should also be reviewed annually and given advice on lifestyle and the management of any dyspeptic symptoms. 

This study has therefore shown that in patients infected with H. pylori who take low-dose aspirin, eradication of H. pylori is as effective as prophylactic therapy with omeprazole in preventing recurrent upper gastrointestinal bleeding. Therefore, patients taking aspirin for cardiovascular prophylaxis could be tested for H. pylori infection and treated for it if infection is confirmed. In contrast, omeprazole is superior to eradication of H. pylori for the secondary prevention of upper gastrointestinal bleeding in H. py/on-infected users of naproxen and presumably other non-aspirin NSAIDs. 

A wide range of invasive and noninvasive diagnostic tests for H, pylori has been described as shown in Box 48-1. 

Table 22.1. The ultrasound meal accommodation test (UMAX) was developed at Haukeland University Hospital on the basis of close interaction between scientific and clinical work in patients with dyspepsia. Before entering the protocol, the patients have been carefully studied with history, physical examination, blood tests, testing for H. pylori and upper endoscopy. In some cases, additional examinations are performed to rule out organic causes of their symptoms. The protocol presented here is the mainstream clinical protocol. In scientific studies, other elements are often added. A 500-ml liquid meal of commercial meat soup (Toro clear meat soup, Rieber Son A/S, Bergen, Norway) containing 1.8 g protein, 0.9 g bovine fat, and 1.1 g carbohydrate (20kcal) is ingested over a period of 4 min. The soup is preheated and then cooled to 37°C to improve imaging quality by reducing the amount of air bubbles. Psychometric evaluation is also performed...

Under these circumstances, a biopsy sample should be used to test for H. pylori, preferably by means of the rapid urease test. It is important that at least two biopsy samples be evaluated (fundic and antral), because if eradication therapy has not been completely successful, the organism may be present only in small numbers and may have migrated (a consequence of acid-suppressive therapy and the alteration of its ideal pH milieu) from its original site. In those patients who exhibit relapse or recurrence of symptomatology, the presence of H. pylori should be meticulously assessed. 

Patterson is referred to a gastroenterologist for endoscopy to examine the gastric mucosa. There are signs of inflammation in both the antrum and body of the stomach and an area of ulceration is visualized in the pylorus. Tests for Helicobacter pylori (H. pylori) are positive. Patterson was treated successfully with a course of antibiotics to eradicate the H. pylori infection and a proton pump inhibitor. 

GQ is 33-year-old alcoholic who is placed on metronidazole, clarithromycin, and omeprazole for a recently diagnosed peptic ulcer. A urease breath test is positive for H. pylori. His other medications include ibuprofen, lisinopril, and meclizine. Which of the following is most likely to interact with GQ s metronidazole ... 

The growth in endoscopic procedures, with direct visualization of the interior of the stomach, has largely removed the need for the clinical laboratory to carry out the analysis of gastric contents. Situations remain, however, in which the laboratory continues to play a significant role in the diagnosis of gastric diseases and in monitoring the effectiveness of treatment. This section describes peptic ulcer disease and tests for Helicobacter pylori H. pylori) and the measurement of basal acid output from the stomach. 

In the stool test, specific H. pylori antigens are detected in microtiter plates coated with polyclonal antibodies. Debate continues regarding its accuracy for assessing treatment outcome some of the variability in results between different studies appears to be caused by lack of standardization of the interval between completion of eradication therapy and stool testing.However, the test is currently recommended for posteradication testing if the urea breath test is not available. 

Answer Peptic ulcer disease is most frequently secondary to either Helicobacter pylori infection or use of NSAIDs. The patient does admit to NSAID use (naproxen), but should also be checked for concomitant H. pylori infection at time of endoscopy or by a serology test. If the patient was found to have H. pylori, an appropriate eradication regimen should be prescribed. The patient should also be counseled to avoid NSAIDs. The patient should be prescribed a proton pump inhibitor for 8 weeks to heal the ulcer. A repeat endoscopy should be done at that time to document ulcer healing and rule out gastric cancer. In addition, the patient should be counseled to stop smoking, which is a risk factor for more severe peptic ulcer disease. 

Consequently, treatment of H. pylori infection may improve the prognosis of people with gastric ulcers and other forms of upper GI distress (dyspepsia, gastroesophageal reflux disease). Patients with clinical signs of ulcers who also test positive for this infection should receive a treatment regimen attempting to eradicate the infection. Successful treatment of an H. pylori infection may reduce or eliminate the need for subsequent antiulcer medications in patients with gastric ulcer disease.42... 

H. pylori produces urease, and hydrolysis of endogenous urea to bicarbonate and ammonia may create a more hospitable microenvironment for the survival of the organism in the stomach. Mammalian cells do not hydrolyze urea and it was only in 1984 that gastric urease was associated with the presence of H. pylori The ability of the organism to rapidly hydrolyze urea is the basis of the urea breath tests and of the direct urease tests on gastric biopsy samples. 

Ability of H. pylori to produce urease is clinically used for detection by the [13C]-urea breath test and clofazimine (CLO) tests. Other methods of detection include biopsy (histologic identification is the gold standard) and serology. 

When combined with proton pump inhibitor (PPI) and other antimicrobials for the therapy of duodenal ulcer and chronic active gastritis, roxithromycin showed excellent activity in eradicating H. pylori. Eradication rates of 80-100% as determined by urease test, histologic analysis, and microbiologic cultures were achieved in various randomized open clinical trials [174-176]. However, lower rates of cure (50-67%) were found in larger randomized comparative studies [177,178]. 

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