Журнал «Здоровье ребенка» 8 (59) 2014

Background. Helicobacter pylori affects nearly half of the world’s population and, thus, is one of the most frequent and persistent bacterial infections worldwide. This microorganism is associated with peptic ulcer disease and gastric cancer. Colonization of mucosa always results in chronic gastritis. Helicobacter pylori strains display extensive genetic variability with considerable variation in the presence of virulence factors, which is thought to cause the many different clinical presentations of Helicobacter pylori infections. The formation of chronic gastroduodenal pathology begins in most patients in childhood. The rate of contamination of Helicobacter pylori in adolescence is no different from adults. The aim of the research was to study the frequency of virulent genotypes of Helicobacter pylori in children with chronic pathology of the stomach and duodenum, and their impact on severity of the disease.

Material and methods. The study was conducted on the basis of the City children's clinical hospital № 1 in Donetsk and Medical centre «Gastro-line». The study involved 230 children aged 8-17 years with chronic gastroduodenal pathology against the background of Helicobacter pylori infection (60 children with duodenal ulcer, 120 – with erosive bulbitis, 50 – with chronic superficial gastroduodenitis. In order to confirm the diagnosis, all children underwent gastric and duodenal endoscopy examination with target biopsy of gastric and duodenum mucosa, and the subsequent morphologic estimation. The genotyping of Helicobacter pylori was performed by polymerase chain reaction to detecting cagA, vacA, iceA and babA genes. To establish links between factor characteristics and risks of development of clinical manifestations of the disease were involved methods of mathematical modeling.

Results. The analysis of the genetic peculiarities of Helicobacter pylori showed a wide heterogeneity of microbe genome among examined children. Feature of the research was the presence of a high percentage of occurrence combined vacA and cagA genes in genotype of Helicobacter pylori. It has been established that virulent strains of Helicobacter pylori, which have the genotype cagA+vacAs1m1 or cagA+vacs1s2/m1m2 are specific for children with destructive changes in the mucous membrane of the stomach and duodenum. The presence of cagA+vacAs1s2/m1m2 genotype was related to the presence of duodenal ulcer. It was identified in 30 (50,0±6,5 %) patients of this group.  The cagA+vacAs1/m1 genotype was associated with erosive bulbitis in children. It was identified in 41 (34,2±4,3 %) patients of this group. The absence of virulent strains of Helicobacter pylori was determined in 16 (32,0±6,6 %) children with chronic gastroduodenitis. The vacAs2m2 combination was the most predominant vacA genotype in patients with chronic gastroduodenitis. The significance of such factors as сagA, vacAs1s2, vacA m1 genes and disease duration in determining the severity of chronic gastroduodenal pathology was proved in children by the using of the method of mathematical models construction. Genes iceA and babA was installed in only a small number of patients with destructive inflammatory changes in the mucous membrane of the stomach and duodenum

Conclusion. The cagA+vacAs1m1 and cagA+vacs1s2/m1m2 of Helicobacter pylori were the most common genes in isolates with erosive bulbitis and duodenal ulcer. These genotypes of Helicobacter pylori led to the development of destructive processes in the mucous membrane of the stomach and duodenum in children. In addition, the duration of chronic gastroduodenal pathology in children has a great importance on the severity of the inflammatory process in the mucous membrane. The presence of genes iceA and babA in the structure of Helicobacter pylori genome is not specific to children with chronic gastroduodenal pathology.