[Diagnosis of Helicobacter pylori infections using isotope-selective non dispersive infrared spectrometry with 13C-urea breath test].

Objective: The 13C-Urea Breath Test (13C-UBT) is a non-invasive simple and reliable test for the diagnosis of Helicobacter pylori infection. Widespread use of the test is limited by the high cost of isotope-ratio mass-spectrometry that is required for analysis of the breath samples. The aim of our study was: 1) evaluate the accuracy of a simple optical method called isotope-selective non-dispersive infrared spectrometry (NDIRS), which is designed to measure 13CO2/12CO2 ratio; 2) evaluate the possibility to reduce timing of breath samples collection after 13C-urea ingestion.
Methods: 13C-UBT and gastroscopy were performed in one hundred patients (mean age: 51 years; range: 18-81 years; M/F: 48/52) after overnight fasting. None had taken antibiotics, proton pump inhibitor or bismuth-containing preparations for at least four weeks. Two biopsies from the antrum and two from the body of the stomach were obtained from each patient to investigate the Helicobacter pylori status. Breath samples were collected from each patient in aluminised plastic bags with a volume of 1200 ml, before and 10, 20 and 30 minutes after ingestion of 75 mg 13C-urea dissolved in 200 ml of orange juice. A value of "Delta-Over-Baseline" higher than 4@1000 was considered positive. The operators of each device were unaware of Helicobacter pylori status.
Results: 54/55 patients resulted positive on 13C-UBT in respect of immunohistochemistry. 44/45 patients resulted negative on 13C-UBT in respect of immunohistochemistry. The sensibility resulted 98.1%, specificity 97.7%. No significant difference between sample collection at 10, 20 or 30 minutes after ingestion of 13C-urea was found (Chi square: p: n.s.).
Discussion: This study shows that the diagnostic accuracy of infrared spectroscopy is excellent and comparable with data of other authors about conventional isotope-ratio mass spectrometry. No significant difference between sample collection at 10, 20 or 30 minutes after ingestion of 13C-urea was found (Chi square: p: n.s.). Timing of sample collection may be reduced from 30 to 10 minutes with the purpose of cut down more the costs for this test.