| (l)To evaluate the usefulness of PCR-RFLP typing method in the epidemiological study of Helicobacter pylori infection (2)To explore the possible source and transmission route of Hp within family members. Methods: A total of 198 children aged at 2-14 with upper abdominal discomfort were recruited in this study, Among the 198 children, sixty index children and their first degree relatives were chosen as subjects for family study. Endoscopy was carried out on all the subjects, Hp infection was determined on serum anti-Hp IgG assay, Warthin-Starry silver staining, urease testing and PCR. PCR was performed on an 820~bp portion of the ureC gene in Hp, the PCR products were then digested with restriction enzymes Hha I and Alu I respectively, PCR-RFLP patterns were obtained by combination of the two digest patterns. We applied the PCR-RFLP method to clinical specimens including gastric mucosa and coupling samples of their saliva in 133 subjects belonging to 60 families. Results: (l)The total Hp infection rate in symptomatic children was 55. 1%(109/198), there was no significant difference between male and female (56. 3% vs 52. 3%, . 05). The Hp infection rate in Han and Zhuang ethnic childrenwere 53. 3% (63/118) and 57. 5% (46/80) respectively, there was no significant difference between the two groups (7^0.05), (2) The incidence of lymphoid follicles in children with Hp infection was significantly higher than in adults (53. 9% vs 23. 1%, KO. 05), but the incidence of gastric atrophy was significantly lower in children than in adults (11.5% vs 42.3% , KO. 05) . (3)Analysis of the PCR-RFLP patterns revealed 22 distinct RFLP types from 78 Hp-positive family members, seven of 28 infected children (25.0%, 7/28) and ten of 30 infected relatives (33.3%, 10/30)were detected Hp in their saliva by PCR, all of the RFLP digest patterns in coupling saliva and gastric mucosa were identical. Sixty-seven of 73 specimens (91.8%, 67/73), with 6 exception, yielded identical digest patterns from the specimens both at antrum and corpus, indicating that multiple strains of Hp infection exist uncommonly in this series . (4) Intrafamilial clustering of Hp infection were revealed in this study, Thirty-one of 60 (51.7%, 31/60) family members were in concordance with Hp infection, and eighteen of 60 (30.0%, 18/60) families were in concordance without Hp infection. On the contrast, only seven of 60 families (11.7%, 7/60) and four of 60 (6.7%, 4/60) families were disagreement with or without Hp infection. Furthermore, twenty-six of 31(83.9%, 26/31) infected children with their relatives shared the identical digest patterns of Hp, whereas the remaining 5(16. 1%,5/31) had different digest patterns. Conclusions: This study demonstrated that (l)PCR-RFLP provides a useful and reliable reproducible and highly discriminatory typing scheme for the epidemiological study of Hp infection. (2) The highly concordance of the Hp genotypes among the intrafamilial members indicates that oral-oral transmission within family members may be the most common way for children infected with Hp in Southern China.
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