| Background:There is a substantial genetic heterogeneity among Helicobacter pylori strains, and certain genotypes have been suggested to be associated with the virulence of this pathogen. Studies on Helicobacter pylori genotype have focused on adults in different countries, and data on genotypes of H.pylori recovered from the children are rare, The aim of this study was to investigate the distribution of H.pylori CagA and VacA genetypes and their association with gastric duodenal diseases in children . Materials and methods:A total of 156 children with upper abdominal discomfort were recruited in this study,endoscopy was carried out on all the subjects. H.pylori infection was determined on serum anti-H.pylori IgG assay, Warthin-Starry silver staining, urease testion and PCR analysis for ureC gene, Eighty biopsy samples from patients with H.pylori infection were studied. PCR analysis for CagA and VacA genotypes was performed using DNA extracted from biopsy specimens. Results:(1)In the 80 cases, With five pairs of primers it was revealed that the positive rates of CagA DNA fragments of 400bp,280bp,349bp,298bp and 191bp were 43.75%,20%,3 55%,32.5%and 61.2%respectively, the general positive rate of CagA gene was 83.7% ,higher than the positive rates of CagA gene with a pairs of primers. The positive rates of CagA gene in mild inflammation and moderate or severe inflammation were 81% and 86.8% respectivedly,there was no significant difference betreen the two groups(P>0.05).(2)The positive amplification products of VacA gene were found in all samples, the 80(100%) had VacA signal sequence s1a strains,s1b and s2 were absent;VacA middle region sequences, m1 and m2, were detected in 3(3.75%) and 53(66.25%),respectivedly. Eleveen (13.75%) cases contained multiple VacA subtypes.There were 13(16.25%) strains carring neither VacAm1 nor VacAm2 genes.Those cases with polyinfections and couldn't be divided with m1 and m2 were rejected,there were two VacA mosaicisms including 3 for s1a/m1(3.75%) and 55 for s1a/m2(66.25%). (3) CagA~+,VacAs1a/m2 subtype of H.pylori are predominant in the PU or DU patients in Nanning.(4)No statistical differences were found in the distribution of CagA gene and VacA genotype of H.pylori strain infection between chronic superficial gastritis and peptic ulcer(P>0.05). Conclusion(1)In GuangXi province, the CagA positive of H.pylori was predominant in children , the positive rate of CagA DNA fragments of 191bp was highest in five pairs of primers.To increase the pairs of primer could raise the detection rate of CagA gene. the positive rates of CagA gene examined by PCR with different primers, which suggests there exists the variavility of CagA gene in children.(2) CagA gene was not associated with the degree of gastric mucosal inflammation. (3) VacAs1a/m2 genotype of H.pylori was predominant in children, Part of patients may be coinfected with different VacA genotypes of H.pylori .(4)Neither CagA gene and VacA genotype can not be considered the markers of H.pylori which was more pathogenic in children in Nanning.
|
PDF Full Text Request