Modified Helicobacter test using a new test meal and a 13C-urea breath test in Helicobacter pylori positive and negative dyspepsia patients on proton pump inhibitors

Helicobacter pylori Infection, Its Laboratory Diagnosis, and Antimicrobial Resistance: a Perspective of Clinical Relevance

Despite the recent decrease in overall prevalence of Helicobacter pylori infection, morbidity and mortality rates associated with gastric cancer remain high. The antimicrobial resistance developments and treatment failure are fueling the global burden of H. pylori-associated gastric complications. Accurate diagnosis remains the opening move for treatment and eradication of infections caused by microorganisms. Although several reports have been published on diagnostic approaches for H. pylori infection, most lack the data regarding diagnosis from a clinical perspective. Therefore, we provide an intensive, comprehensive, and updated description of the currently available diagnostic methods that can help clinicians, infection diagnosis professionals, and H. pylori researchers working on infection epidemiology to broaden their understanding and to select appropriate diagnostic methods. We also emphasize appropriate diagnostic approaches based on clinical settings (either clinical diagnosis or mass screening), patient factors (either age or other predisposing factors), and clinical factors (either upper gastrointestinal bleeding or partial gastrectomy) and appropriate methods to be considered for evaluating eradication efficacy. Furthermore, to cope with the increasing trend of antimicrobial resistance, a better understanding of its emergence and current diagnostic approaches for resistance detection remain inevitable.

PROSPECTIVE STUDY FOR VALIDATION OF A SINGLE PROTOCOL FOR THE 13C-UREA BREATH TEST USING TWO DIFFERENT DEVICES IN THE DIAGNOSIS OF H. PYLORI INFECTION

BACKGROUND

13C-urea breath test (UBT) is the gold-standard, noninvasive method for H. pylori diagnosis. However, there is no uniform standardization of the test. This situation can be unpractical for laboratories running with two or more devices.

OBJECTIVE

To perform a prospective comparison validation study of UBT employing one validated protocol for two different devices: BreathID Hp Lab System® (Exalenz Bioscience Ltd, Israel), here called device A and IRIS-Doc2® (Wagner Analysen-Technik, Germany, now Mayoly Spindler Group, France), here called device B, in the diagnosis of H. pylori infection.

METHODS

A total of 518 consecutive patients (365 females, 153 males, mean age 53 years) referred for UBT were included. All patients received device A protocol as follow: after at least one hour fasting, patients filled two bags prior to the test, then ingested an aqueous solution containing 75 mg of 13C-urea with a 4.0 g citric acid powder and filled another two bags 15 min after ingesting the test solution. One pair of breath sample bags (before and after ingestion) was analyzed by the two different devices. A delta over baseline (DOB) ≥5‰ indicated H. pylori infection. Statistics: Wilcoxon test, kappa coefficient with 95% CI, Wilson's method.

RESULTS

Considering the device A protocol as the gold standard, its comparison with device B showed a sensitivity of 99.3% (95% CI: 96.3-99.9) and a specificity of 98.9% (95% CI: 97.3-99.6). Kappa coefficient was 0.976 (95% IC: 0.956-0.997).

CONCLUSION

Correlation between the two devices was excellent and supports a uniform standardization of UBT.

Optimization of 13 C-urea breath test threshold levels for the detection of Helicobacter pylori infection in a national referral laboratory

BACKGROUND

Threshold values for ¹³ C-urea breath test (13C-UBT) positivity may be affected by various sociodemographic, host, bacterial, and laboratory factors. Manufacturer recommended cutoffs for 13C-UBT assays may not be applicable in all settings. Optimizing 13C-UBT cutoffs may have profound public health ramifications. We aimed to determine the optimal threshold for 13C-UBT positivity in our population.

METHODS

Consecutive test samples collected at our central laboratory from patients undergoing a first-time 13C-UBT between 1 January 2010 and 31 December 2015 were included. The difference between values at 30 minutes and at baseline (T30-T0) was expressed as delta over baseline (DOB). Cluster analysis was performed on the 13C-UBT test results to determine the optimal cutoff point with minimal interclass variance.

RESULTS

Two lakhs thirty four thousand eight hundred thirty one patients (87 291 (37.2%) male, age 39.9 ± 19.9) underwent a first-time 13C-UBT, including 124 701 (53.1%) negative and 110 130 (46.9%) positive tests, using the manufacturer-recommended cutoff of 3.5 DOB. Cluster analysis determined an optimized cutoff of 2.74 DOB, representing an additional 2180 (0.93%) positive subjects who had been previously categorized as negative according to the manufacturer-specified cutoff of 3.5 DOB. Mean positive and negative DOB values were 19.54 ± 14.95 and 0.66 ± 0.51, respectively. The cutoffs for male and female subjects were 2.23 and 3.05 DOB, respectively. Threshold values for <45-year-olds, 45-60-year-olds and >60-year-olds were 2.67, 2.55, and 2.93 DOB, respectively. Of the 2180 (0.93%) patients with DOB 2.73-3.49, 289 (13.3%) performed a subsequent 13C-UBT and 140 (48.4%) remained positive when tested at 20.3 ± 14.4 months.

CONCLUSIONS

Major referral laboratories should optimize threshold values for 13C-UBT positivity for their geographical location. Different cutoff values should be applied for male and female subjects.

Diagnosis of Helicobacter pylori infection

The progress this year in Helicobacter pylori diagnosis concerned essentially endoscopy and molecular techniques. New endoscopy techniques such as blue laser imaging and magnifying narrow band imaging allow the visualization of mucosal aspects representing H. pylori infection, intestinal metaplasia, and even ambiguous early gastric cancer. Several real-time PCRs have also been used either to quantify H. pylori or to detect mutations associated with clarithromycin resistance in gastric biopsies or applied on gastric juice, stool specimens, or the oral cavity. The presence of H. pylori in free-living amebae purified from wastewater and drinking water was also determined by PCR and sequencing, as well as culture from a few wastewater samples. Among the noninvasive methods, the urea breath test was used in different conditions, including with a new test meal, which is claimed to avoid the proton-pump inhibitor washout period before testing. Several articles concerning antibody detection and stool antigen test were also published.