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Background The accuracy and repeatability of breath test in the diagnosis of Helicobacter pylori infection have not been adequately investigated. Although it has been shown that storage for long periods does not affect the analysis results, no data are available on the effect of repetitive testing. In this study, our aim was to evaluate the repeatability of the analyses of breath samples at room temperature. Methods A total of 202 positive breath samples were collected in duplicates, before and after administration of 75 mg 13C- urea dissolved in 100 ml of orange juice. Breath test results were expressed as delta 13CO2. The cut-off value was 3.5 parts per thousand. Each sample was analyzed in a mass spectrometer 7, 14, 21, and 28 days after collection. The accuracy calculation was based on the comparison of the delta 13CO2 obtained in the three consecutive weeks following the first test run to the delta 13CO2 obtained in the first test run. Results Two hundred (99%), 197 (97.52%), and 196 (97%) of the 202 samples tested positive in the second, third, and fourth test runs, respectively. The accuracy of the delta 13CO2 was 98.6%, 99.2%, and 96.7% in the three consecutive runs, respectively. Conclusion Short-term storage of 1 month does not affect sample stability or the results of 13C-urea breath tests in up to three consecutive repeats.

The lactose breath test (LBT) is the standard technique for diagnosis of lactose malabsorption. However, it is time-consuming, strenuous for the patient and has been reported to have low sensitivity. The lactose intolerance quick test (LIQT) measures lactase activity in duodenal biopsies and may be performed as part of upper gastrointestinal endoscopy. The purpose of this study was to assess the role of the LBT and LIQT in the case management of suspected lactose malabsorption. The study group included 69 consecutive patients evaluated by the LBT followed by the LIQT. The test results were compared, and the sensitivity, specificity, and predictive values of the LBT were calculated. Mean age of the patients was 54.4 years, male/female ratio was 1:3, and mean body mass index was 25.2. None had celiac disease on duodenal biopsy. The LIQT was positive for hypolactasia in 55 patients (80 %): mild in 14 (25 %) and severe in 41 (75 %); 10 (18 %) were symptomatic during the LBT. The LBT was positive for lactose malabsorption in 32 patients (46 %). Of the 37 patients with normal findings on the LBT, 24 (65 %) had positive findings on the LIQT: 11 (30 %) mild hypolactasia, 13 (35 %) severe hypolactasia. In one case, the LBT was positive and the LIQT was negative. The LBT had a sensitivity of 56 %, specificity 93 %, positive predictive value 97 %, and negative predictive value 35 %. The LBT may serve as a diagnostic screening tool for lactose malabsorption. Symptomatic patients with negative LBT results should be referred for second-line testing with the LIQT.

Background Rifaximin is a minimally absorbed antibiotic with high luminal activity, used to treat various gastrointestinal diseases. Although rifaximin has been proposed as first line treatment for small intestinal bacterial overgrowth (SIBO), few data are available regarding its efficacy in non-IBS subjects. We aimed to assess the ability of rifaximin to normalize lactulose-H2 breath tests in non-IBS subjects with symptoms suggestive of SIBO. Materials and methods Consecutive non-IBS patients presenting with bloating and flatulence were prospectively recruited and submitted to lactulose-H2 breath testing (LBT). Patients who had a positive result were offered rifaximin 1200 mg daily for 10 days. Breath testing was repeated two weeks after treatment completion in all patients in order to assess for response. Results A total of 19 patients with a positive result received rifaximin and repeated the breath test (7 (36.8%) males, age 56.5 ± 17.6 years). The mean peak hydrogen excretion was 13.7 ± 2.8 and 10.3 ± 7.3 ppm at baseline and following rifaximin treatment, respectively (t = 1.98, p = 0.06). LBT normalized in 8/19 (42.1%) subjects. No patients reported symptom resolution. No adverse events were reported. Discussion Strengths include the study's prospective design. Limitations include the small sample size and open label design. Conclusion Rifaximin was not effective in normalizing LBT in our cohort of non-IBS subjects with symptoms suggestive of SIBO.

Background The lactose breath test (LBT) is the standard technique for diagnosis of lactose malabsorption. However, it is time-consuming, strenuous for the patient and has been reported to have low sensitivity. The lactose intolerance quick test (LIQT) measures lactase activity in duodenal biopsies and may be performed as part of upper gastrointestinal endoscopy.