Helicobacter pylori infection in pediatrics

Validation of a monoclonal stool antigen test for diagnosing Helicobacter pylori infection in young children

BACKGROUND AND OBJECTIVE

The monoclonal stool antigen test for diagnosing Helicobacter pylori infection in children has been tested in developed countries, showing sensitivity and specificity higher than 90%. However, its accuracy in young children from developing countries is not well established. The aim of the study was to determine the accuracy of the monoclonal stool antigen test for diagnosing H pylori infection in children up to 7 years old.

PATIENTS AND METHODS

Two hundred seventy-six patients (53.6% female; ages 0.35-6.99 years) were evaluated. Gold standard positive culture or positive histology and rapid urease tests were performed. The test (Amplified IDEIATM Hp StAR) was done according to the manufacturer's instructions. Results were expressed as optical density (OD) and an OD more than or equal to 0.190 was considered positive. Additionally, a receiver operating characteristic curve was used to find the best cutoff.

RESULTS

The monoclonal stool antigen test for diagnosing H pylori infection showed 100% sensitivity (95% confidence interval [CI] 92.7%-100%) and 76.2% specificity (95% CI 70.1%-81.4%), considering the manufacturer's cutoff. After setting a new cutoff with the receiver operating characteristic curve (OD = 0.400), sensitivity remained 100% (95% CI 92.7%-100%), but the specificity improved to 97.7% (95% CI 94.7%-99%). At ages up to 2 years, sensitivity was 100% (95% CI 43.8%-100%) and specificity was 100% (95% CI 92.4%-100%); at ages 2 to 4 years, 100% (95% CI 80.6%-100%) and 97.6% (95% CI 96%-99.2%); at ages older than 4 years, 100% (95% CI 88.6%-100%) and 96.6% (95% CI 94.7%-98%), respectively.

CONCLUSIONS

The monoclonal stool antigen test is accurate for diagnosing H pylori in children younger than 7 years old, but it must be locally validated in order to find the best cutoff for each population.

Helicobacter pylori: prevalence and relationship with abdominal pain in school children in Makkah City, western Saudi Arabia

BACKGROUND/AIM

The published data on Helicobacter pylori (H. pylori) prevalence and its relationship with abdominal pain in Saudi Arabia is scarce. This study was carried out to determine the prevalence of H. pylori and its relationship with chronic recurrent abdominal pain (RAP) among school students in Makkah City, Saudi Arabia.

MATERIALS AND METHODS

Three hundred and fourteen school students, 103 at the intermediate level (grades 7-9) aged 12-15 years and 211 at the secondary level (grades 10-12) aged 15-18 years were tested for H. pylori. Urea breath test (UBT) was used for this purpose. Children with chronic RAP were identified as per the Apley criteria.

RESULTS

Overall, the UBT was positive in 86/314 (27.4%) students. It was positive in 45/103 (43.7%) intermediate school students and 41/211 (19.4%) secondary students. Out of the 55 students with chronic RAP, 40 (73%) were positive for H. pylori. Further, 62.9% and 82.1% were positive among the intermediate and secondary school students with RAP, respectively. The overall and specific odds ratios of RAP were 12.35 [95% confidence interval (C.I.) 6.30-24.22] and 10.40 (95% C.I. 1.75-11.73) for the intermediate school students and 22.69 (95% C.I. 7.99-64.44) for the secondary school students.

CONCLUSION

The prevalence of H. pylori among the school children in Makkah, Saudi Arabia, is relatively low compared with developing countries. The prevalence was found to be higher among the younger age group. Further, there was a significant relation between H. pylori infection and RAP among the school students.

Evaluation of the stool antigen test for Helicobacter pylori in children and adolescents

The stool antigen test for Helicobacter pylori is a noninvasive immunoassay to diagnose active infection with Helicobacter pylori in human fecal samples. Its performance in children and teenagers has been tested in some developed countries, showing a sensitivity and specificity above 90%, however, its accuracy in developing countries and in children under 6 years is not well established. To determine the accuracy of the test for diagnosing Helicobacter pylori infection in children and teenagers, we evaluated 133 patients (4 months to 17 years old). The gold standard was a positive culture or positive histology and rapid urease test. The test was done according to the manufacturer's instructions. However, modifications were introduced for better reproducibility. Samples were analyzed twice and results are expressed as optical density (OD) determined spectrophotometrically at 450 nm. HpSA was considered positive at OD > or =0.160 and negative at OD <0.140. One hundred twenty-seven of the 133 (95.5%) patients were included. There were no infected infants. The test showed a 94.6% sensitivity (95% CI: 90.6-98.5) and a 96.5% specificity (95% CI: 93.3-99.7). At ages 2 to 6 years the specificity was 96.4% (95% CI: 85.1-99.2) and the sensitivity was 80.0% (95% CI: 64.8-89.7), at ages 6 to 10 years the sensitivity was 100.0% and the specificity 95.7%, and above 10 years the sensitivity and specificity were 100.0%. We conclude that the test is efficient in adolescents and children, however there is a need for further studies with a greater number of patients for evaluation of its accuracy in infants.

Evaluation of stool antigen test, PCR on ORAL samples and serology for the noninvasive detection of Helicobacter pylori infection in children

BACKGROUND

Endoscopy represents the gold standard for the diagnosis of Helicobacter pylori infection. We evaluated three noninvasive tests in a group of children: the immunoassay for detection of H. pylori stool antigen, the polimerase chain reaction for identification of bacterial DNA on the oral cavity and the serum specific antibodies.

MATERIALS AND METHODS

One hundred and ninety children underwent endoscopy for various gastrointestinal symptoms. H. pylori stool antigen and anti-H. pylori antibodies were assayed by commercial kits. The bacterial DNA on saliva and oral plaque was detected by a seminested PCR.

RESULTS

Based on the positivity of culture or urease rapid test and histology, infection was detected in 47 patients. The statistical analysis showed that, for the detection of the infection, stool antigen assay is more effective in sensitivity and negative predictive value (91.5% and 96.5%), whereas specificity and positive predictive values appear slightly better in serology (89.6% and 76.0%). Correlations between serum IgG both with patients' age (r = 0.21, p < .05) and H. pylori stool antigen (r = 0.47, p < .01) were found. The search for bacterial DNA on oral samples proved to be very specific (99.1% on saliva and 98.2% on plaque), but insensitive (22.2% and 25.7%). CONCLUSIONS. In children H. pylori stool antigen represents a sensitive test, suitable for detecting H. pylori infection. Serum IgG proved to be more specific; the PCR on the oral cavity resulted as being a very specific, but insensitive test.