[Genotypic study on the Helicobacter pylori vacA, cagA and iceA genes in the infected children in Guangzhou area].

OBJECTIVE

To investigative vacA, cagA and iceA genes dominant genotypes of Helicobacter pylori (Hp) isolated from children suffering from gastric and duodenal diseases in Guangzhou area.

METHODS

Totally 105 children who underwent gastroscopy in Guangzhou Children's Hospital were enrolled into this study. From each patient, 3 biopsy specimens from the gastric antrum were taken, one was used for rapid urease test, one for histological examination, and one for polymerase chain reaction (PCR) for detecting ureA, vacA, cagA, and iceA genes. DNA was prepared directly from the biopsy specimens from the gastric antrum using a QIAamp DNA mini kit (Qiagen, Germany) according to the manufacturer's instructions. Then 11 primers were used for detecting the genotypes including ureas, (s1, s1a, s1b, s1c, s2) and m (m1, m1T, m2) region of vacA, cagA and iceA (iceA1 and iceA2) genotypes in the 105 children. The distribution of the genotypes of Hp was analyzed.

RESULT

Among the 105 children, only 52 children were positive by the three methods, among these 52 children, 26 were boys and 26 girls. Hp vacA s1as1c/m2 was detected in 43 out of 52 children (82.7%), s1as1c/m1T in 9.6% (5/52), m region that could not betyped was 7.7% (4/52). No strains presented genotypes vacA s1b, s2, m1. The comparison of the positive ratio of vacA s1as1 c/m2 detected in the children infected with Hp and that of the other combination of signal region and middle region was statistically significantly different (P < 0.01). With regard to cagA gene, cagA(+) gene and cagA(-) gene were found in 90.4% (47/52) and 9.6% (5/52) of the children, respectively. The cagA(+) gene was more frequent in the children infected with Hp. Single iceA1 was detected in 78.8% (41/52) children, and single iceA2 was detected to be 1.9% (1/52), multiple strains infection of iceA1 and iceA2 were detected in 3.8% (2/52) children, iceA1 and iceA2 were not detected in 15.4% (8/52), the comparison of the positive ratio of iceA1 detected in the children infected with Hp and that of the other genotypes was statistically significantly different (P < 0.01).

CONCLUSION

The s1as1c/m2, cagA and iceA1 were the dominant genotypes of Hp in the children in Guangzhou area and s1as1c/m2, cagA and iceA1 were the dominant genotypes combination of Hp in the children in this area.