Faculty of Health Scicence School of Medicine 0100107g johannes.geyer@wits.ac.za / The 14C and 13C labelled urea breath tests (UBT) for detecting Helico-bacter pylori infection are well established but scope for improvement exists in both to reduce some of their shortcomings. For this study, the 14C UBT investigation focussed on reducing the quantity of radioactive tracer that is administered to the subject un-dergoing this test, with the aim of lowering the radiation dose to the patient, reducing the impact to the environment and exempting the test from radioactive materials licensing. Wider acceptance, availabil-ity, affordability to lower socio-economic groups and third party medi-cal treatment payers and using readily available equipment were fac-tors considered when developing the method. The principle of the method developed is to collect larger volume breath sample, quantitatively absorbing a defined volume of extracted breath CO2 in an efficient CO2 trapping agent using a specifically de-signed apparatus and measuring the activity with a low background β-spectrometer. A reduction in the quantity of 14C labelled urea administered to the pa-tient was achieved. The method also reduced the counting error mar-gin at a lower detection limit, improving discrimination between H. py-lori positive and negative patients. iii The 13C UBT is a non-radioactive test however, it is substantially more expensive. The 13C UBT investigation aimed to determine whether commercially available un-enriched urea could be used thus reducing the cost of the 13C UBT. A simple protocol with Isotope Ratio Mass Spectrometry (IRMS) for the measurement was used as opposed to the well-established 13C UBT protocol. The principle of the 13C UBT investigation was to detect the change of the breath δ13C (13C/12C) ratio after the administration of un-enriched urea with a δ13C different to the exhaled breath. Theoretical calculations showed that an administered dose of 500mg un-enriched urea with at least a 10‰ δ13C difference may be detectable using IRMS. In vitro investigations confirmed that levels of 0.01 to 0.001‰ δ13C were detectable by IRMS. A change in the δ13C of a standard breath CO2 was confirmed for a range between 0.14 to 50% v/v mixed CO2 samples, i.e. the projected range for in-vivo investigation. Results from the in-vivo investigation however were not able to distinguish positive from negative H. pylori patients. The use of the 1000mg dose of urea appears to have caused saturation of the enzyme. It was con-cluded that some enrichment of the 13C is necessary or less urea be used.

Please read the abstract in the section front of this document / Dissertation (MSc)--University of Pretoria, 2007. / Chemical Pathology / unrestricted

Helicobacter pylori-infektion är en av de ledande orsakerna till utvecklingen av maligniteter i ventrikeln. Tillämpning av pålitliga analytiska metoder är därför väsentlig för en korrekt diagnostik och behandling av infektionen. Syftet med studien var att ge en översikt av icke-invasiva metoder som tillämpas för påvisning av H. pylori och utvärdera vilken metod som är bäst lämpad, med avseende på metodens prestandaegenskaper och det kliniska tillståndet hos patienten. En systematisk litteraturöversikt utfördes, genom sökning efter vetenskapliga artiklar med inklusions- och exklusionskriterier i databaserna PubMed och CINAHL. Utvalda artiklar kvalitetsgranskades och 20 studier inkluderades i resultatet. Sammanställt hade fecesantigentester en sensitivitet och specificitet på 92,64% respektive 91,47%, antikroppstester hade 97,20% respektive 81,59%, urea utandningstester hade 91,40% respektive 91,70% och polymeraskedjereaktionen hade 75,45% respektive 98,30%. Därutöver hade kliniska tillstånd såsom atrofisk gastrit, intestinal metaplasi och gastrointestinal blödning en negativ påverkan på metodernas diagnostiska tillförlitlighet. Studien konstaterade att beträffande metodens prestanda är fecesantigentester mest lämpliga för påvisning av H. pylori- infektion. Vid allvarligare kliniska åkommor bör minst två icke-invasiva diagnostiska metoder tillämpas för att säkerställa pålitliga resultat. / Helicobacter pylori infection is one of the leading causes of ventricular pathologies. Reliable analytic methods are therefore crucial for the correct diagnosis and treatment of the infection. The aim of this study was to provide an overview of non-invasive diagnostic methods used for the detection of H. pylori and to evaluate which method is most suitable, considering its performance and the clinical condition of the patient. A systematic literature review was conducted, searching peer-reviewed research articles with inclusion and exclusion criteria on the databases PubMed and CINAHL. An assessment of the selected articles quality resulted in the inclusion of 20 articles. Overall, stool antigen tests had a sensitivity and specificity of 92,64% and 91,47% respectively, antibody tests 97,20% and 81,59% respectively, urea breath tests 91,40% and 91,70% respectively, and the polymerase chain reaction 75,45% and 98,30% respectively. Furthermore, conditions such as atrophic gastritis, intestinal metaplasia and gastrointestinal bleeding had a negative impact on the diagnostic accuracy of the methods. This study concluded that, regarding the methods performance, stool antigen tests are more suitable for detecting a H. pylori infection. With the mentioned clinical conditions, at least two non- invasive diagnostic methods should be used to ensure reliable results.

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