Comparison of Four Tests for the Diagnosis of Helicobacter pylori Infection.

BACKGROUND: Due to lower operational costs, health maintenance organizations (HMOs) may prioritize Helicobacter pylori stool antigen testing (HpStAg) for the non-invasive diagnosis of H. pylori infection over 13C-urea breath tests (13C-UBTs). The aim of our study was to compare the accuracy of the diagnostic tests for H. pylori. METHODS: We performed histology, rapid urease test (RUT), 13C-UBT and HpStAg on consecutive patients referred for gastroscopy. Monoclonal stool antigen test was performed using the LIAISON Meridian chemiluminescent immunoassay. Histology was examined with hematoxylin and eosin, and additional stains were performed at the pathologist's discretion. For the assessment of 13C-UBT, we compared concordant histology and RUT. HpStAg was compared to the concordant results of two of the three remaining tests. RESULTS: 103 patients were included (36 males (35.0%), age 50.1 ± 18.4 years). The indication for gastroscopy was dyspepsia in 63 (61.2%). Agreement between RUT and histology was 95.9%. For 13C-UBT and HpStAg, respectively, H. pylori positivity was 30% (30/100) and 27.16% (22/81); sensitivity was 97% and 70%; specificity was 100% and 94.4%; accuracy was 98% and 86%; positive predictive value (PPV) was 100% and 86.4%; negative predictive value (NPV) was 93% and 86%. No demographic, clinical, or endoscopic predictors of HpStAg accuracy were identified using logistic regression. CONCLUSIONS: 13C-UBT performs better than HpStAg at our institution. When interpreting results, clinicians should consider test limitations.

Comparing a New Flow Immune-Chromatography Fast Assay with a Random Access Semi-Automatic Chemiluminescent Immunoassay to Measure Fecal Calprotectin.

OBJECTIVE: The biomarker fecal calprotectin is an efficacious tool for evaluating the level of disease activity in Crohn's and Ulcerative colitis, as well as for discriminating between inflammatory bowel disease and irritable bowel syndrome. The aim of this investigation was to appraise the analytical proficiency of a novel flow immune-chromatography assay through comparison with the established gold standard system in our laboratory. METHODS: A cohort comprising of 125 stool samples, submitted for the purpose of routine calprotectin levels analysis, underwent assessment using two distinct approaches: the Liaison XL system and the SmarTest assay, while adhering to identical cut-off criteria. The present study assessed the performance of the SmarTest assay by calculating its sensitivity, specificity, and accuracy measures. RESULTS: The sensitivity, specificity, and accuracy of the SmarTest assay were found to be 97.75%, 80.56%, and 92.80%, respectively, upon comparison with the gold standard. Moreover, the Pearson correlation coefficient analysis ascertained that the linear correlation pertaining to the calprotectin levels, as identified between both assays, was statistically significant (R=0.8158, P values <0.0001). CONCLUSIONS: Upon comparison with the Liaison XL system, it was found that the SmarTest assay demonstrated satisfactory results in both qualitative and quantitative aspects. This novel and expedient diagnostic assay is commended for evaluating fecal calprotectin in situations where access to laboratory services may be insufficient or nonexistent, rendering it an ideal option for point-of-care or at-home testing purposes.

Gluten Immunogenic Peptides Are Not Correlated With Reported Adherence to Gluten-Free Diet in Children With Celiac Disease.

OBJECTIVE: There is no gold standard to assess adherence to gluten-free diet (GFD) among patients with celiac disease (CeD). Gluten immunogenic peptides (GIPs) in urine and stool were suggested as novel markers for evaluating adherence to GFD. Our aim was to assess the presence of GIP in pediatric patients with CeD, and to compare the results with alternative methods for evaluating GFD adherence. METHODS: Pediatric patients diagnosed with CeD, who were on GFD for at least 1 year, were enrolled and followed prospectively between November 2018 and January 2021. Study visits included clinical assessment, a dietitian interview, Biagi score, food questionnaires, anthropometric and laboratory measurements, and urine and stool samples obtained for laboratory GIP analysis. RESULTS: The study included 74 patients (63.5% females), with median (interquartile range, IQR) age of 9.9 (7.8-11.7) years, and median (IQR) duration on GFD of 2.5 (2-5.5) years. Good GFD adherence, assessed by Biagi score, was reported in 93.1% of cases. GIP was evaluated during 134 visits, with GIP detected in 27 of 134 (20.1%) of the visits (16.3% of stool samples and 5.3% of urine samples). Positive GIP results were significantly more common in males compared to females (30.6% vs 14.1%, respectively, P < 0.05). Detection of positive GIP was not associated with dietary assessment of GFD adherence, celiac serology results, or reported symptoms. CONCLUSIONS: Stool and urine GIP can be detected in children with CeD, even when dietary assessment indicate good adherence to GFD. The role of GIP testing in clinical practice should be further explored.

Lasting Effects of Helicobacter pylori Infection on the Microbial Communities of Patients with and without Small Intestinal Bacterial Overgrowth.

Gastrointestinal (GI) microbial populations are important in maintaining normal functioning of the GI by preventing disorders. Dysbiotic microbiota may increase the likelihood of small intestinal bacterial overgrowth (SIBO), a syndrome associated with significant morbidity. We aimed to inves- tigate the microbiota populations of patients with SIBO. Patients with symptoms of SIBO were consecutively enrolled; they underwent a SIBO hydrogen breath test and stool was collected for microbiome analysis by sequencing of the 16S rRNA. Of the 55 patients recruited, 42 (76.4%) were positive for SIBO. When visualizing the bacterial ß-di- versity, a sub-cluster of patients was identified. Further examination of these patients' records re- vealed previous treatment for Helicobacter pylori (HP). Microbiome analysis of these patients demonstrated a significant decrease in ß-diversity (p-value<0.001) compared to patients without previous HP therapy. Furthermore, ß-diversity was significantly different in this subgroup, and sev- eral bacterial taxa were differentially expressed, including one from the genus Methanobrevibacter, which was reduced in patients that previously underwent HP treatment. Our findings suggest that while symptoms associated with SIBO may cause dysbiosis, there was no differentiation in fecal microbiome composition based on SIBO diagnosis. Furthermore, our results support previous observations regarding antibiotic-altered microbiota with effects extending two and three years post-treatment.

A Novel Fecal Elastase Assay for the Detection of Pancreatic Exocrine Insufficiency.

BACKGROUND: Fecal pancreatic elastase 1 (FPE1) is an established screening test for pancreatic exocrine insufficiency (PEI), a condition that is underdiagnosed and if not treated may cause significant morbidity. The aim of this study was to compare a new FPE1 machine based CLIA kit to an ELISA assay which is considered the de facto gold standard in our laboratory for FPE1 measurement. METHODS: Levels of FPE1 from the 227 stool samples were analyzed by the ScheBo ELISA kit and the CLIA Liaison XL system simultaneously with the same cutoff values for both assays. Performance of the Liaison XL system was assessed by calculating sensitivity, specificity, and accuracy. RESULTS: The comparison between the Liaison XL system performance and the ScheBo ELISA kit as reference revealed a sensitivity, specificity, and accuracy of 86.8%, 94.3%, and 92.1%, respectively, using a cutoff of 100 µg FPE1/g stool. When the cutoff is 200 µg FPE1/g stool the sensitivity, specificity, and accuracy were 86.6%, 97.1%, and 90.7%, respectively. Furthermore, linear correlation of FPE1 levels between the two assays were found to be significant by Pearson's correlation coefficient test (R = 0.85, p-values < 0.0001). CONCLUSIONS: The Liaison XL system showed good laboratory performance with our pre-determined cutoff values when compared to our previous assay. An important advantage of this system is its semi-automated mechanism that enables large scale analysis of FPE1. In addition to that, the Liaison XL system is ideal for both qualitative and quantitative analysis of FPE1 allowing for its application to the clinical setting.

Clinical Accuracy of a New Rapid Assay for Fecal Calprotectin Measurement.

BACKGROUND: Fecal calprotectin is an excellent biomarker for distinguishing inflammatory bowel disease from irritable bowel syndrome and for evaluation of disease activity in Crohn's disease and ulcerative colitis. The aim of this work was to evaluate the analytical performance of a new flow immune chromatography assay by comparing it to our standardized laboratory gold standard system. METHODS: A total of 100 stool samples sent for routine calprotectin level measurements were analyzed by the Liaison XL system and the QuantOn Cal assay simultaneously using the same cutoff values for both assays. Performance of the QuantOn Cal assay was assessed by calculating sensitivity, specificity, and accuracy. RESULTS: Compared with the gold standard, the sensitivity, specificity, and accuracy of the QuantOn Cal assay were 98.7%, 76.2%, and 94.0%, respectively. Furthermore, linear correlation of calprotectin levels between the two assays were found to be significant by Pearson's correlation coefficient test (r = 0.82, p-values < 0.0001). CONCLUSIONS: The QuantOn Cal assay demonstrated good performance, both qualitative and quantitative when compared to the Liaison XL system. This novel and rapid assay is well suited for measuring fecal calprotectin as a point of care or home-based assay when laboratory services are limited or not available.

Novel high resolution melt curve assay for the analysis of predominance of Helicobacter pylori clarithromycin resistance.

Clarithromycin resistance is the most common cause of Helicobacter pylori treatment failure and it is attributed to three point mutations, A2142G, A2142C and A2143G, within the 23S rRNA gene. We aimed to determine the prevalence of H. pylori clarithromycin resistance using a novel high resolution melt assay. A total of 151 stool samples were collected from treatment-naïve patients with general gastric discomfort who also performed 13CO2 breath tests. Stool antigen tests were also performed on 126 of the 151 stool samples collected. Bacterial DNA was extracted from the stool and analyzed by comparing it with four reference plasmids incorporating the three mutations and the wild type (WT) sequences. The melt assay detected 106 H. pylori positive samples, of which 54 had a WT sequence, and 52 had a point mutation associated with clarithromycin resistance, including A2142G in 10, A2142C in 13, A2143G in 18 and heterozygosity (multiple peaks) in 11. Compared with the gold standards (13CO2 breath and stool antigen tests), the melt assay had a sensitivity of 100% and 99% and a specificity of 82% and 78%, respectively. Therefore, our stool-based molecular assay is able to identify H. pylori infection and clarithromycin resistance. It could be used for screening prior to administration of clarithromycin eradication therapy.

Small Intestinal Bacterial Overgrowth May Increase the Likelihood of Lactose and Sorbitol but not Fructose Intolerance False Positive Diagnosis.

BACKGROUND: Small intestinal bacterial overgrowth (SIBO) is defined as a bacterial count of more than 105 colony-forming units per milliliter in duodenal aspirate. It shares many symptoms with carbohydrate intolerance, which makes the clinical distinction of the disorders difficult. The aim of the study was to examine the relationship between a positive carbohydrate breath test and the presence of SIBO suggested by a positive lactulose hydrogen breath test. METHODS: The electronic database of the gastroenterology laboratory of a tertiary medical center was searched for all patients clinically tested for SIBO in 2012-2013 for whom previous results for lactose, fructose, and/or sorbitol breath test were available. The correlation between positive findings for carbohydrate intolerance and for SIBO was statistically analyzed. RESULTS: The study group included 349 patients, 231 female and 118 male, of mean age 53±19 years. All had symptoms of abdominal bloating and gas. There was a statistically significant difference in rates of a positive breath test for lactose and sorbitol at ≤90 minutes between patients who were positive and negative for SIBO [χ2(1)=12.8, p<0.01 and χ2(1)=9.5, p<0.01 respectively]. Findings for fructose were not significant. There was no effect of age or gender. CONCLUSIONS: SIBO may represent an important reversible cause of carbohydrate intolerance. It may be especially prudent to exclude SIBO patients with an early peak (≤90 minutes) in H2 excretion.