Five different PCR methods for the detection of Helicobacter pylori were evaluated. The results of this study indicate that of the five PCR methods examined, the ureC (glmM) gene PCR is the most sensitive and specific for the detection ofH. pylori in gastric biopsy specimens.

The H. pylori seropositivity rate of GI referral children with symptoms of abdominal pain was significantly higher. H. pylori infection in early childhood was found to be associated primarily with the child's household size and socioeconomic status.

The PCR primer set Hp1-Hp2, which amplifies a 109-bp fragment of the 16S rRNA gene of Helicobacter pylori, has been widely used for the detection of H. pylori in clinical specimens. We have examined 34 stool samples and 50 human tissue samples from H. pylori-infected and uninfected patients, five human leukocyte samples, and one human cell line by this PCR method. All of these specimens produced a 109-bp PCR product. When Escherichia coli DNA was used as the template, several nonspecific bands, but not the 109-bp band, were observed. No PCR products were generated when DNA samples from five different fungi were used as templates. These results indicate that this 109-bp PCR product was amplified from the human genome. The 109-bp PCR product generated from various clinical specimens also hybridized with the probe pHp, corresponding to a region internal to the PCR product of Hp1-Hp2. We conclude that the 16S rRNA gene PCR with the primer set Hp1-Hp2 is not specific and cannot be used to detect H. pylori in clinical specimens.

Objective. To determine the role of Helicobacter pylori infection in children with recurrent abdominal pain and the usefulness of serologic tests in screening H pylori infection and monitoring treatment of H pylori-associated gastritis. Methods. During a 3 year period, we investigated the presence of serum immunoglobulin G (IgG) antibody to H pylori in 456 children using the high-molecular-weight cell-associated protein H pylori enzyme immunoassay kit. Among the 456 children studied, 218 (age range, 3 to 18 years; mean age, 9.5 years) had symptoms of recurrent abdominal pain (RAP syndrome) with or without vomiting, and the remaining 238 (age range, 3 to 18 years; mean age, 9.8 years) had no RAP (non-RAP syndrome). We performed upper gastrointestinal endoscopy on 111 consecutive children of the 218 with RAP syndrome and obtained mucosal biopsies for culture, histologic analysis, CLO test (Delta West, Perth, Australia), and H pylori detection by polymerase chain reaction. Results. Thirty-eight (17.4%) of 218 children in the RAP group and 25 (10.5%) of 238 children in the non-RAP group were seropositive for H pylori. Of the 111 children endoscoped, 95 were found to be negative, and 12 were positive by all five assays. Specimens from 2 children were negative by culture and the CLO test but positive by the other three assays. Specimens from 1 child were negative by histologic analysis but positive by all other tests. The remaining child was positive for anti-H pylori IgG but negative by all of the other four assays. Upper gastrointestinal endoscopy detected 14 children with peptic ulcer disease (9 duodenal ulcer and 5 gastric ulcer) and 12 with antral nodular gastritis. Only 4 of the 14 diagnosed with peptic ulcer were H pylori positive by all five assays, whereas all 12 children with antral nodular gastritis were H pylori positive. Nine of the 12 H pylori-positive children were treated with a combination of bismuth subsalicylate, amoxicillin, and metronidazole for 2 weeks. Sera obtained at 2, 4, and 6 months after treatment from all 9 children showed a decrease in anti-H pylori IgG titer. Three H pylori-infected children who did not receive any treatment served as control children, and their IgG levels remained elevated or increased over time. Conclusion. The results from our study indicate that screening for the serum IgG antibody to H pylori is a practical method for diagnosing H pylori infection in children, and that serial measurements of the H pylori IgG antibody are useful for monitoring treatment of H pylori because of its high sensitivity and ease of performance. Only 4 of the 14 children diagnosed with peptic ulcer disease were confirmed to be infected with H pylori, whereas all 12 children with antral nodular gastritis were found to be infected by H pylori. These observations suggest that H pylori infection is more frequently associated with gastritis than with peptic ulcer disease in children, and that H pylori gastritis is a cause of RAP syndrome in children.

We have developed a novel method for the preparation of fecal specimens for PCR assays. Approximately 100 mg of solid stool or 200 l of liquid fecal sample was thoroughly suspended in 1 ml of water. Fecal debris was removed by low-speed centrifugation (2,800 ؋ g for 2 min). The supernatant was then boiled for 10 min in a water bath and further clarified by high-speed centrifugation (12,000 ؋ g for 5 min). Fifty microliters of the clarified supernatant was then purified by Sepharose CL-6B spin column chromatography, and a portion of the purified supernatant was used for PCR. By this method, stools containing enterotoxigenic Escherichia coli H10407 were amplified by colonization factor antigen I fimbrial gene PCR, with a sensitivity of 100 organisms per reaction. The method was also effective for processing stool specimens for Clostridium difficile toxin A and B gene PCRs. This method is rapid, effective, and simple to perform and will improve the applications of PCR to stool specimens for diagnostic purposes.