|Year : 2011 | Volume
| Issue : 3 | Page : 206-209
A study of Helicobacter pylori infection using the 14 C UBT method
K Swaroop1, Jayachandran2, Shrikanth L Patil3, HM Somashekarappa1
1 Centre for Application of Radioisotopes and Radiation Technology, Mangalore University, Mangalagangotri, Karnataka, India
2 Radioanalytical laboratory, Board of Radiation and Isotope Technology, Navi Mumbai, Maharashtra, India
3 Department of Physiology K S Hegde Medical Academy, NITTE University, Deralakatte, Mangalore, Karnataka, India
|Date of Web Publication||27-Sep-2012|
Centre for Application of Radioisotopes and Radiation Technology, Mangalore University, Mangalagangotri, Karnataka
Source of Support: None, Conflict of Interest: None
Carbon-14 ( 14 C) is present in the environment and in all organic materials and behaves in the environment in the same manner as other carbon isotopes. In medicine, 14 C can be injected to study abnormalities of metabolism that underlie diabetes, gout, anaemia and acromegaly (adult "gigantism"), and for diagnosis of Helicobacter pylori (H. pylori). The discovery H. pylori by Warren and Marshall in 1982 changed the approach to treat peptic ulcer disease (PUD). Since then H. pylori has been the focus of clinical research and debate. The causal relationship between H. pylori infection and chronic gastritis is well established. H. pylori infection is one of the most common human infections worldwide. This organism has been shown to infect over half of the world's population. This article presents the application of 14 C Urea Breath Test ( 14 C UBT) for the diagnosis of the H. pylori bacteria which present in the stomach and duodenum. 14 C UBT relies on the urease activity of H. pylori to detect the presence of active infection. 14 C UBT has proved to be one of the most accurate methods for assessing H. pylori status. The ionizing radiation dose involved in this test is extremely low, much lower than the radiation dose due to natural sources. 209 samples collected from both symptomatic and non-symptomatic persons of Dakhina Kannada District, Karnataka were analysed and the results with discussion are presented in this paper.
Keywords: 14 C Urea Breath Test, Helicobacter pylori, Mucosa
|How to cite this article:|
Swaroop K, Jayachandran, Patil SL, Somashekarappa H M. A study of Helicobacter pylori infection using the 14 C UBT method. Radiat Prot Environ 2011;34:206-9
|How to cite this URL:|
Swaroop K, Jayachandran, Patil SL, Somashekarappa H M. A study of Helicobacter pylori infection using the 14 C UBT method. Radiat Prot Environ [serial online] 2011 [cited 2020 Sep 21];34:206-9. Available from: http://www.rpe.org.in/text.asp?2011/34/3/206/101726
| 1. Introduction|| |
Helicobacter pylori (H. pylori) bacteria are known to cause gastritis, duodenitis, and peptic ulcer in humans. They are also among the most important bacterial pathogens shown recently to be associated with the occurrence of gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphomas. ,,,,, Because H. pylori accounts for two-thirds of gastric cancer globally, it would seem logical to prevent gastric cancer by eradicating this bacterium from the community.  Age, ethnicity, gender, geography, and socioeconomic status are all factors that influence the incidence and prevalence of H. pylori infection. Public health-care measures such as improvements in sanitation and water supply and better housing have resulted in the reduction of H. pylori infection in many countries.
The accurate diagnosis of the H. pylori status of a subject is important for correct therapy and this also helps in designing and executing eradication programs. For a broader application and acceptance, testing for H. pylori should be effective, rapid, safe, cheap, and widely available. As carbon-14 urea breath test ( 14 C UBT) is a simple, innocuous, easy-to-repeat, and one of the most accurate methods available for assessing H. pylori status, it is recommended as the gold standard, a noninvasive method for documenting H. pylori infection.  In this test, a patient with suspected infection ingests 14 C-labelled or 13 C-labelled urea. Although both isotopes seem to offer similar diagnostic accuracy, 13 C-labelled urea has the added advantage of being nonradioactive. However, it has the potential inconvenience of requiring a more complex equipment, and is comparatively more expensive than 14 C urea. , Doctors could use 14 C UBT to diagnose patients with low-resource investment in a less expensive manner. However, both 13 C and 14 C UBT have the advantage of assessing the total presence of H. pylori throughout the stomach, whereas endoscopy-based tests are limited to focal assessments (at the site of biopsy) with the consequent risk of false-negative results due to sampling errors.
14 C is a naturally occurring radionuclide that emits low-energy β radiations (49 keV mean and 156 keV max ). The biological half-life of 14 C is 10-12 days, whereas its physical half-life is 5,730 years. Patients have to swallow 1 μCi (37 kBq) of encapsulated 14 C urea. The available 14 C isotope, in the form of 14 CO 2 will be captured during sampling. By adding a scintillation cocktail, the collected breath sample can be quantified for 14 C radioactivity using a liquid scintillation counter. A positive sample is a conclusive evidence of H. pylori infection. In
H. pylori-negative subjects, up to 30% of the radioactivity is excreted in the breath as 14 CO 2 . The respiratory excretion of 14 CO 2 increases to 60% in H. pylori-positive patients. The biological half-life of 14 CO 2 is 15 minutes. The remaining radioactivity is excreted by the kidneys, with an elimination half-life of 12 hours. ,
| 2. Principles of 14C Urea Breath Test|| |
As pointed out earlier, the 14 C UBT is a noninvasive and sensitive test which can be used to determine the presence of H. pylori prior to initial treatment and to follow up after the treatment. The test is based on the detection of 14 C in the breath sample due to splitting of the 14 C urea by enzyme urease. In the presence of urease, the 14 C urea is converted into 14 C bicarbonate and ammonium ions. The 14 C bicarbonate anion is absorbed into the blood stream, transported to the lungs, and subsequently exhaled as [ 14 C]CO 2 . Detection of radioactive [ 14 C]CO 2 in the breath samples indicates an H. pylori infection, as other urease-producing bacteria do not colonize the stomach. 14 C can be readily detected using a liquid scintillation counter. The pictorial representation of the 14 C UBT method is given in [Figure 1].
| 3. Methodology|| |
3.1 Patient preparation
Prior to 14 C UBT, subjects were advised not to use antibiotics and acid-suppressive treatment during the four weeks before testing. The exclusion criterion included the use of proton pump inhibitors and sucralfate within 14 days. Information such as family history, education, history of peptic ulcer, duodenal ulcer or dyspepsia, socioeconomic background and lifestyle related items, and food habits and alcohol consumption was collected. The 14 C UBT method of diagnosing and its radiopharmaceutical details were explained to the subjects and consent was obtained before subjecting them to testing.
Blank samples were collected prior to the administration of the 14 C urea capsule by asking the subjects to breathe into a precisely titrated solution of hyamine hydroxide (1 mL benzethonium hydroxide in 1 mL methanol) containing a thymolphthalein blue indicator. This is used as a solution to 'trap' the exhaled CO 2 . When sufficient CO 2 is exhaled, the solution becomes acidic and the indicator changes its color to become a clear colorless solution. A capsule containing the 14 C urea is then administered to the subject and a breath sample is obtained after 10±0.5 minutes. The amount of radioactivity present in the sample represents the amount of [ 14 C]CO 2 exhaled, which is proportional to the amount of 14 C urea metabolized by the bacteria. After adding the scintillation fluid to the collected breath sample, the 14 C concentration is quantified using a liquid scintillation counter.
| 4. Results and Discussion|| |
The 14 C UBT was performed on 209 individuals and the results are shown in [Table 1]. From a total of 209 samples collected, 133 were from men and 76 from women. It can be seen that 39.8% of the men and 34.2% of the women subjects were found to be H. pylori positive. Of the 133 male subjects, 77 were symptomatic, and among them 44.1% were found to be positive. Thirty-four percent of the 56 asymptomatic cases were found to be positive. Of the 76 female subjects, 49 were symptomatic and among them, 36.7% were found to be H. pylori positive. Fourteen percent of the 27 asymptomatic cases were found to be positive. It can also be seen from the overall results that of a total of 209 subjects, 126 were found to be symptomatic and of this, 41.2% were found to be H. pylori positive. Of the 83 asymptomatic subjects, 32.5% were found to be positive. If we combine the symptomatic and asymptomatic male and female subjects, the overall prevalence of H. pylori infection in the Dakshina Kannada district would be 37.7%.
|Table 1: H. pylori infection prevalence in Dakhina Kannada District, Karnataka|
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According to the reports of the World Gastroenterology Organization (WGO),  the prevalence of H. pylori is more in the adult population of the Asian and African countries (70 to >90%) when compared to the developed countries of Europe and North America (30 to 50%). It was also reported that the global prevalence of H. pylori infection is more than 50% and the prevalence may vary significantly within and between countries. Singh et al.  reported that the prevalence of H. pylori infection is around 56.7% in asymptomatic and 61.3% in symptomatic individuals with an overall figure of 59.2% in the Indian population. In the same report they pointed out that the colonization of H. pylori bacteria increases with age. Berry et al.  conducted several H. pylori infection studies employing rapid urease test and reported 10.93% H. pylori-positive cases in the communities of Ludhiana, India. Singh et al.  described the Asian enigma of the causal role of H. pylori infection in gastric cancer and cited the seroprevalence of H. pylori in adult populations of India, Bangladesh, Pakistan, and Thailand in the range of 55-92%. In contrast, the seroprevalence of H. pylori in Chinese and Japanese adults is 44 and 55%, respectively.
| 4. Conclusion|| |
This study employed the 14 C UBT method for measuring the urease activity directly and indicating the colonization of H. pylori in the upper gastrointestinal (GI) tract indirectly. The study conducted shows that H. pylori infection in this part of the country is much lower (37.7%) than the reported range for Asian and African countries (70 to >90%) by the WGO.  The results obtained compare well with the reported range for Europe and North American countries (30-50%). The results of this study also indicate that H. pylori infection is relatively higher among male (39.8%) than female subjects (34.2%). It is interesting to note that the difference in H. pylori infection among the asymptomatic subjects (32.5%) is very narrow (7%) when compared with the symptomatic subjects (41.2%). The difference in the proportion of infection is not significant which shows that symptomatic history and H. pylori infection need not go together.
| 5. Acknowledgements|| |
Authors are grateful to Prof. T C Shivashankara Murthy, Vice Chancellor, Mangalore University for his keen interest in this study and encouragement. Authors are thankful to Dr. N Sivaprasad, BRIT, Mumbai for his guidance, help and cooperation in carrying out this study. Authors are also thankful to Dr. Khamar Jaha Banu, KSHEMA, Nitte University, Mangalore, Dr.Patrik D'Souza, Medical Officer, Mangalore University and Dr.Jeevan Lesrado, Medical Officer, Primary Health Centre, Surathkal, Mangalore for their help and cooperation in the study. Authors are grateful to Board of Research in Nuclear Science for funding this research work.
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