The discovery of Helicobacter pylori in 1982 was the starting point of a revolution concerning the concepts and management of gastroduodenal diseases. It is now well accepted that the most common stomach disease, peptic ulcer disease, is an infectious disease, and all consensus conferences agree that the causative agent, H. pylori, must be treated with antibiotics. Furthermore, the concept emerged that this bacterium could be the trigger of various malignant diseases of the stomach, and it is now a model for chronic bacterial infections causing cancer. Most of the many different techniques involved in diagnosis of H. pylori infection are performed in clinical microbiology laboratories. The aim of this article is to review the current status of these methods and their application, highlighting the important progress which has been made in the past decade. Both invasive and noninvasive techniques will be reviewed.

Helicobacter pylori Detection and Antimicrobial Susceptibility Testing

Objective To generate a classification of methods to evaluate medical tests when there is no gold standard. Methods Multiple search strategies were employed to obtain an overview of the different methods described in the literature, including searches of electronic databases, contacting experts for papers in personal archives, exploring databases from previous methodological projects and cross-checking of reference lists of useful papers already identified. Results All methods available were classified into four main groups. The first method group, impute or adjust for missing data on reference standard, needs careful attention to the pattern and fraction of missing values. The second group, correct imperfect reference standard, can be useful if there is reliable information about the degree of imperfection of the reference standard and about the correlation of the errors between the index test and the reference standard. The third group of methods, construct reference standard, have in common that they combine multiple test results to construct a reference standard outcome including deterministic predefined rules, consensus procedures and statistical modelling (latent class analysis). In the final group, validate index test results, the diagnostic test accuracy paradigm is abandoned and research examines, using a number of different methods, whether the results of an index test are meaningful in practice, for example by relating index test results to relevant other clinical characteristics and future clinical events. Conclusions The majority of methods try to impute, adjust or construct a reference standard in an effort to obtain the familiar diagnostic accuracy statistics, such as sensitivity and specificity. In situations that deviate only marginally from the classical diagnostic accuracy paradigm, these are valuable methods. However, in situations where an acceptable reference standard does not exist, applying the concept of clinical test validation can provide a significant methodological advance. All methods summarised in this report need further development. Some methods, such as the construction of a reference standard using panel consensus methods and validation of tests outwith the accuracy paradigm, are particularly promising but are lacking in methodological research. These methods deserve particular attention in future research.

Evaluation of diagnostic tests when there is no gold standard. A review of methods.

AGA technical review: Evaluation of dyspepsia ☆ ☆☆

Background: Over the past few years, the profile of Helicobacter pylori infection has changed in Japan. In particular, the relationship between H. pylori and gastric cancer has been demonstrated more clearly. Accordingly, the committee of the Japanese Society for Helicobacter Research has revised the guidelines for diagnosis and treatment of H. pylori infection in Japan. Materials and Methods: Four meetings of guidelines preparation committee were held from July 2007 to December 2008. In the new guidelines, recommendations for treatment have been classified into five grades according to the Minds Recommendation Grades, while the level of evidence has been classified into six grades. The Japanese national health insurance system was not taken into consideration when preparing these guidelines. Results: Helicobacter pylori eradication therapy achieved a Grade A recommendation, being useful for the treatment of gastric or duodenal ulcer, for the treatment and prevention of H. pylori-associated diseases such as gastric cancer, and for inhibiting the spread of H. pylori infection. Levels of evidence were determined for each disease associated with H. pylori infection. For the diagnosis of H. pylori infection, measurement of H. pylori antigen in the feces was added to the tests not requiring biopsy. One week of proton-pump inhibitor-based triple therapy (including amoxicillin and metronidazole) was recommended as second-line therapy after failure of first-line eradication therapy. Conclusion: The revised Japanese guidelines for H. pylori are based on scientific evidence and avoid the administrative restraints that applied to earlier versions.

Guidelines for the management of Helicobacter pylori infection in Japan: 2009 revised edition.

Breath tests are among the least invasive methods available for clinical diagnosis, disease state monitoring, and environmental exposure assessment. In recent years, interest in breath analysis for clinical purposes has increased. This review is intended to describe the potential applications of breath tests, including clinical diagnosis of diseases and monitoring of environmental pollutant exposure, with emphasis on oxidative stress, lung diseases, metabolic disorder, gastroenteric diseases, and some other applications. The application of breath tests in assessment of exposure to volatile organic compounds is also addressed. Finally, both the advantages and limitations of breath analysis are summarized and discussed.

Breath Analysis: Potential for Clinical Diagnosis and Exposure Assessment

Diagnostic tests for Helicobacter pylori: a prospective evaluation of their accuracy, without selecting a single test as the gold standard.

Background: Microscopic colitis presents with chronic diarrhoea with or without abdominal pain. Microscopic colitis is an important cause of chronic diarrhoea. It can be distributed throughout the colon, as well as limited to the right colon. Microscopic colitis is associated with coeliac disease. We studied the prevalence and distribution of microscopic colitis in patients with diarrhoea and normal colonoscopy and we studied the association with coeliac disease. Methods: Colonoscopy was performed. Biopsies were taken from every segment of the colon. Lymphocytic colitis was defined as the presence of more than 20 lymphocytes per 100 epithelial cells and collagenous colitis was defined as thickening of the basal membrane of more than 10 m. Upper endoscopy was performed if upper intestinal symptoms were present. If this was the case, small bowel biopsies were taken. Results: Microscopic colitis was found in 13 out of 103 patients. The distribution was diffuse throughout the colon in ten and restricted to the right colon in three patients. In seven patients, upper endoscopy was performed. Marsh I/II lesions were found in six out of seven patients. Conclusion: Microscopic colitis was limited to the right colon in 23% of patients. Biopsies of macroscopically normal colonic mucosa in patients with diarrhoea is mandatory.

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Microscopic colitis: prevalence and distribution throughout the colon in patients with chronic diarrhoea.

Background and Study Aims: In the past, small-bowel biopsies for diagnosis of celiac disease were taken from the jejunum with a suction capsule, but nowadays most physicians take endoscopic biopsies from the distal duodenum. To validate that practice we compared the diagnostic yield of endoscopic duodenal biopsies with that of endoscopic jejunal biopsies. In addition, we describe a method of orienting biopsy specimens optimally. Patients and Methods: Upper endoscopy was performed with a colonoscope. Four jejunal and four duodenal biopsies were taken and oriented immediately thereafter. The pathologist rated the orientation as poor, adequate, or good, and histopathological results were expressed according to the Marsh classification. Jejunal and duodenal biopsy results were compared. Results: 146 patients were included. Jejunal biopsies were taken in 142 patients, and Marsh I-II lesions were found in 56 and Marsh III lesions in 15 patients. In three patients duodenal biopsies were normal while jejunal biopsies showed Marsh I-II lesions. No discrepancies were found in patients with Marsh III lesions. Orientation was good in all biopsies. Conclusion: Duodenal biopsies are sufficient to diagnose full-blown celiac disease (Marsh III), but Marsh I-II lesions may be missed in some cases.

WJ Thijs

Papers

Diagnostic tests for Helicobacter pylori: a prospective evaluation of their accuracy, without selecting a single test as the gold standard.

Microscopic colitis: prevalence and distribution throughout the colon in patients with chronic diarrhoea.

Duodenal versus jejunal biopsies in suspected celiac disease

Diagnostic tests for H-pylori: A prospective evaluation of their accuracy, without selecting a single test as the gold standard - Response

Diagnostic tests for H. pylori: A prospective evaluation of their accuracy with an independent “gold standard”