20 COMPARISON OF HELICOBACTER PYLORI INFECTION IN CHILDREN BY POLYMERASE CHAIN REACTION (PCR) OF SALIVA AND GASTRIC BIOPSY TO CONVENTIONAL METHODS OF DETECTION.

Introduction: The majority of H. pylori infections are acquired in childhood, with the gastroduodenal sequelae often occurring years later. Oraloral or fecal-oral routes of H. pylori transmission have been postulated. However, the exact route or transmission and the natural history of H. pylori infection after childhood acquisition remain unclear. A sensitive and specific non-invasive assay would be critical for prospective studies to evaluate these questions. Objectives: We used a newly developed, highly sensitive PCR assay to detect H. pylori infection in the saliva and gastric biopsies of symptomatic children undergoing upper endoscopy in comparison to conventional detection methods and serology. Methods:H. pylori infection was defined by standard invasive methods using rapid urease test of gastric biopsy (CLO®) in conjunction with histopathologic staining. A sensitive and specific ELISA was used to determine H. pylori IgG antibodies in subjects' sera. In comparison, saliva and gastric biopsy specimens were analyzed by PCR assay using a novel DNA probe designed from a 417-base-pair fragment of H. pylori DNA from the conserved region of the ureC gene. Results: 47 children (mean age 12.1 yr; range 5-20 yr; 20 (42.5%) were African-American (AA), 27 (57.5%) non-AA, and 57 (27%) female) underwent upper endoscopy and were included in our study. Six out of 47 children (12.7%) were H. pylori (+) by histology, CLO and ELISA. All 6 had (+) PCR of gastric biopsies and 4/6 had (+) H. pylori DNA detected in their saliva by PCR. Of the remaining 40 children who lacked evidence of H. pylori infection by our study standards (i.e., (-) CLO, ELISA, and histological staining), 6 (12.7%) had (+) PCR of gastric biopsies, and 2 (4.2%) had (+) PCR of saliva alone.. One patient had a (+) CLO of the gastric biopsy and was (+) by PCR of both biopsy and saliva. This patient had marked acute gastric inflammation but was negative by ELISA and histology, quite possibly evidence of early infection. Conclusions: Our results may confirm previous adult studies that identified evidence of endoscopic H. pylori transmission. Alternatively, our results may reflect different stages of the evolution of H. pylori infection in children, from mouth to gastric mucosa, the final stage for colonization, with the subsequent development of cellular inflammation and systemic antibodies.