title: Diagnosis of Helicobacter pylori: what should be the gold standard?
abstract: Since the discovery of Helicobacter pylori (H. pylori) in 1983, numerous detection methods for the presence of the bacterium have been developed. Each one of them has been associated with advantages and disadvantages. Noninvasive tests such as serology, (13)C urea breath test (UBT) and stool antigen tests are usually preferred by the clinicians. Serology has its own limitation especially in endemic areas while (13)C UBT is technically very demanding. The stool antigen detection method, although specific, is usually associated with poor sensitivity. The (13)C UBT is believed to be specific, but with present revelation of the fact that stomach is colonized by many other urease producing bacteria makes it questionable. Histology, culture, rapid urease test and polymerase chain reaction (PCR) are the tests which are carried out on antral biopsies collected by invasive means. Histology has been proposed to be very sensitive and specific but the question is how by simply looking the morphology of the bacteria in the microscope, one can claim that the curved bacterium is exclusively H. pylori. Rapid urease test (RUT), the doctor's test, is also challenged because the presence of other urease producing bacteria in the stomach cannot be denied. Moreover, RUT has been reported with poor sensitivity specially, when density of the bacterium is low. Isolation of H. pylori is essential to investigate its growth requirements, antibiotic susceptibility testing, studying virulence factor to develop vaccine and many more explorations. It has also got several disadvantages i.e., special condition for transporting, media, incubation and few days waiting for the colonies to appear, apart from the speed essentially needed to process the specimens. Till date, majority of the microbiological laboratories in the world are not equipped and trained to isolate such fastidious bacterium. The option left is PCR methods to detect H. pylori's DNA in gastric mucosa, gastric juice, saliva, dental plaques and environmental specimens. There are speculations for false positivity due to detection of non-pylori Helicobacters due to genetic sharing; and false negativity due to low bacterial counts and presence of PCR inhibitors. However, specimen collection, transportation and processing do not require speed and special conditions. PCR based diagnosis may be considered as gold standard by designing primers extremely specific to H. pylori and targeting at least more than one conserved genes. Similarly specificity of PCR may be improved by use of internal Primers. Further, nested PCR will take care of false negatives by countering the effect of PCR inhibitors and low bacterial counts. Therefore, nested PCR based methods if performed properly, may be proposed as gold standard test.
authors.affiliation: Saurabh Kumar Patel, Chandra Bhan Pratap, Anil Kumar Gulati, Gopal Nath, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, UP 221005, India.
authors.forename: Saurabh Kumar
authors.initials: SK
authors.lastname: Patel
authors.affiliation: Saurabh Kumar Patel, Chandra Bhan Pratap, Anil Kumar Gulati, Gopal Nath, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, UP 221005, India.
authors.forename: Chandra Bhan
authors.initials: CB
authors.lastname: Pratap
authors.affiliation: Saurabh Kumar Patel, Chandra Bhan Pratap, Anil Kumar Gulati, Gopal Nath, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, UP 221005, India.
authors.forename: Ashok Kumar
authors.initials: AK
authors.lastname: Jain
authors.affiliation: Saurabh Kumar Patel, Chandra Bhan Pratap, Anil Kumar Gulati, Gopal Nath, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, UP 221005, India.
authors.forename: Anil Kumar
authors.initials: AK
authors.lastname: Gulati
authors.affiliation: Saurabh Kumar Patel, Chandra Bhan Pratap, Anil Kumar Gulati, Gopal Nath, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, UP 221005, India.
authors.forename: Gopal
authors.initials: G
authors.lastname: Nath
mesh_terms: D000942:Antigens, Bacterial / Q000302:isolation & purification; D001431:Bacteriological Techniques / Q000592:standards*; D015415:Biomarkers / Q000032:analysis; D001706:Biopsy / Q000592:standards; D001944:Breath Tests; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D016481:Helicobacter Infections / Q000097:blood / Q000175:diagnosis* / Q000382:microbiology / Q000473:pathology; D016480:Helicobacter pylori / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D006801:Humans; D016133:Polymerase Chain Reaction / Q000592:standards; D011237:Predictive Value of Tests; D011379:Prognosis; D015203:Reproducibility of Results; D012699:Serology / Q000592:standards; D013270:Stomach / Q000382:microbiology* / Q000473:pathology
chemical_list: D000942:Antigens, Bacterial; D015415:Biomarkers; D004269:DNA, Bacterial
keywords: Gold standard; Helicobacter pylori review; Invasive tests; Nested polymerase chain reaction; Non-invasive tests; Polymerase chain reaction detection