[Distribution of cagA 3' region, iceA, vacA and HP0519 on Helicobacter pylori isolated from China].

OBJECTIVE: This study was aimed to characterize the Helicobacter pylori strains isolated from different geographic regions in China and different ethnic groups in Yunnan province in terms of cagA, iceA, vacA and HP0519 genes which were proposed to be related to the pathogenesis. METHODS: 150 Helicobacter pylori strains were collected from Yunnan province, Fujian province and Beijing. Chromosome DNA was extracted and polymerase chain reaction (PCR) was carried out to determine the 3' region of cagA, iceA, vacA and HP0519 status with specific primers. PCR results were analyzed statistically according to their isolated original and clinical outcomes. RESULTS: For cagA 3' region, 93% (139/150) of the Chinese Helicobacter pylori strains belonged to East Asian type according to the specific primer of TF/JR. Among the 150 strains, 75% (113/150) belonged to iceA1, and 19% (29/150) to iceA2. The dissemination of iceA was not associated with any of the geographic regions, different ethnic groups or different clinical outcomes. 96% (144/150) of the vacA s region belonged to s1. In the vacA middle region, m2, m1b, m1b-m2 were 57% (85/150), 27% (41/150) and 11% (16/150) respectively. However, m1a was only observed in two strains from Fujian. Neither vacA s1 nor m2 showed significant difference between Yunnan, Fujian and Beijing. However, the distribution of mlb-m2 in Yunnan was higher than that in Fujian and Beijing. In Yunnan province, the distribution of vacA s1 was not associated with different ethnic groups but m2 from Bai group was less than other two ethnic groups. The ratio of m1b in Bai group was higher than that in other groups. Both vacA' s region and m region alleles had no significant relationship with the clinical outcomes. With the 15 bp and 24 bp DNA insertion and deletion primers test, 93% (140/150) of the strains were positive. The distributions of the 15 bp and 24 bp DNA insertion or deletion were different according to the different ethnic groups. CONCLUSION: By JF/TR primer, 93% of the Chinese strains cagA's 3' region belonged to East Asian type. Most of the Chinese strains vacA's allele was s1. The distribution of vacA s1 had no relationship with the clinical outcome of the isolates. From different geographic regions and ethnic groups, the distribution of vacA m region allele was different. 93% of the Chinese strains HP0519 genes had 24 bp or 15 bp insertion or deletion character. The biological meaning of the polymorphism of HP0519 needs advanced investigation.

[Infection of Helicobacter pylori strains with multiple vacA m-region subtypes and/or iceA mixed genotype among the Bai, Naxi, and Han populations in Yunnan province].

OBJECTIVE: To study the epidemiology and pathogenicity of mixed infection of Helicobacter pylori (H. pylori) strains with multiple vacA m-region subtypes and/or iceA mixed genotype among the Bai, Naxi, and Han populations in Yunnan province. METHODS: Gastric mucous membrane were obtained by gastroscopy from 444 patients with digestive ulcer or chronic gastritis, 165 of Han nationality, 117 of Bai nationality, and 162 of Naxi nationality. H. pylori was isolated from 109 patients and cultured. RT-PCR was used to detect the Helicobacter pylori strains vacA gene subtype and iceA genes. RESULTS: The overall rates of vacA gene s1 type and vacA gene s2 type were 98.2% (107/109) and 1.8% (2/109) respectively. The overall rates of vacA gene m2 type, vacA gene m1a type, vacA gene m1b type, and mixed types were 45.9% (50/109), 0.9% (1.109), 23.9% (26/109), and 11% (12/109) respectively; and m region was not identified in 18.3% (20/109) of the strains. The overall rates of iceA1 and iceA2 genes were 67.0% (73/109) and 41.3% (45/109) respectively. In the specimens from the patients of Bai nationality, as regards the s region, only s1 type was identified in all specimens; the rates of vacA gene m2 type, vacA gene m1a type, vacA gene m1b type, and mixed type were 45.2% (14/31), 3.2% (1/31), 12.9% (4/31), and 16.2% (5/31) respectively, and m region was not identified in 22.6% of the strains; and the rates of iceA1 and iceA2 were 87.1% (27/31) and 61.3% (19/31) respectively. In the specimens from the patients of Naxi nationally, The rates of vacA gene s1 type and s2 type were 95.6% (43/45) and 4.4% (2/45), the rates of vacA gene m2 type, vacA gene m1b type, and mixed m-type were 33.3% (15/45), 37.8% (17/45), and 6.7% (3/45) respectively, no m1a type was found, and m region was not identified in 22.2% of the strains; the rates of iceA1 and iceA2 were 48.9% (22/45) and 31.1% (14/45) respectively. In the specimens of the patients of Han nationality, as regards the s region, all specimens were s1 type; the rates of vacA gene m2 type, vacA gene m1b type, and mixed type were 63.6% (21/33), 15.2% (5/33), and 12.1% (4/33) respectively, and m region was not identified in 9.1% (3/33) of the strains; the rates of iceA1 and iceA2 were 72.7% (24/33) and 36.4% (12/33) respectively. 34 of the 109 patients (31.2%) suffered from mixed infection of vacA gene m mixed subtype and/or iceA mixed genotype, 64.7% of which (22/34) suffering iceA1 + iceA2 infection, 23.5% of which (8/34) being iceA + vacA mixed infection, and 11.8% of which (4/34) being vacA subtype mixed infection, with the former incidence of the former group significantly higher than those of the 2 latter groups (both P < 0.001). The mixed infection rate of the Bai nationality (67.7%, 21/31) was significantly higher than those of the Naxi nationality (20.0%, 9/45, P < 0.001) and Han nationality (12.1%, 4/33, P > 0.001) without a significant difference between the Naxi and Han nationalities (P > 0.05). The mixed infection rate of iceA1 + iceA2 of the Bai nationality (61.3%, 19/31) was significantly higher than those of the Naxi nationality (17.8%, 8/45, P < 0.001) and Han nationality (9.1%, 3/33, P < 0.001) without a significant difference between the Naxi and Han nationalities (P > 0.05). The mixed rate of the patients with digestive ulcer was 30.2% (16/53), not significantly different from that of the patients with chronic gastritis (32.1%, 18/56, P > 0.05). 16 of the 34 cases of mixed infection were patients of digestive ulcer; and 8 of the 34 cases were patients with chronic gastritis. 8 of the 34 cases (23.5%) of mixed infection were cases of infection of vacA gene m mixed subtypes and iceA mixed genotype; among which 7 were patients with digestive ulcer and 1 case was patient of chronic gastritis. Thus the rate of vacA gene m mixed subtypes and iceA mixed genotype was 43.8% (7/16) in the patients with digestive ulcer, significantly higher than in the patient with chronic gastritis (5.6%, 1/18, P = 0.014). 22 of the 34 cases of mixed infection (64.7%) suffered from infection of iceA mixed gene subtypes. Among these 22 cases 15 were patients with chronic gastritis and 7 were patients with digestive ulcer. Thus the rate of iceA mixed subtypes infection was 43.8% (7/16) in the patients with digestive ulcer, significantly lower than in the patient with chronic gastritis (83.3%, 15/18, P = 0.016). In the 21 mixed infection patients of Bai nationality, the rate of vacA gene mixed sybtype + iceA gene mixed subtypes infection was 100% in the patients with digestive ulcer (100%, 5/5), significantly higher than that of single vacA gene subtype + iceA gene mixed subtypes (37.5%, 6/16, P = 0.0258). The mixed infection rate of H. pylori strains was 32.1%. CONCLUSION: The mixed infection rate of the Bai nationality is higher than those of the Han and Naxi nationalities. Detection of mixed infection by vacA genotypes is more sensitive in Han populations. Detection of multiple infections by iceA gene mixed subtypes is more sensitive in Bai and Naxi populations.

[Study on metronidazole resistance to Helicobacter pylori from three populations with different ethnics in Yunnan].

OBJECTIVE: To evaluate the prevalence of Helicobacter pylori (H.pylori) resistance to metronidazole among three populations in Yunnan. METHODS: Susceptibilities to metronidazole among 109 H. pylori strains (33 H. pylori strains from Han, 31 H. pylori strains from Bai and 45 H. pylori strains from Naxi ethnic populations) were tested by Epsilometer test (E-test). RESULTS: In 109 H. pylori strains, the overall metronidazole resistance rate was 67.89%. There were no significant difference in the metronidazole resistant rates of H. pylori among Han, Bai, Naxi populations Yunnan in terms of the distribution on age and upper gastroduodenal diseases. In the facet of gender, metronidazole resistant rate of H. pylori was significantly lower in Han males than in females (chi2=5.304, P=0.027), but not seen in the Bai or Naxi peoples. CONCLUSION: Metronidazole resistance rate of H. pyloriin Yunnan was high, but no significant difference was found among Han, Bai, Naxi peoples in the province.