Division of Gastroenterology, Dept. of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
Helicobacter. 2012 Apr;17(2):96-106. doi: 10.1111/j.1523-5378.2011.00919.x.
Helicobacter pylori infection is usually acquired in childhood, but little is known about its natural history in asymptomatic children, primarily due to the paucity of non-invasive diagnostic methods. H. pylori strains harboring cagA and specific alleles of hopQ and vacA are associated with increased risk for gastric cancer. Many studies of H. pylori virulence markers in children have the bias that symptomatic subjects are selected for endoscopy, and these children may harbor the most virulent strains. Our aim is to genotype cagA, hopQ, and vacA alleles in stool DNA samples of healthy Colombian children residing in an area with high incidence of gastric cancer, to avoid selection bias resulting from endoscopy.
H. pylori status of 86 asymptomatic children was assessed by (13) C-urea breath test (UBT) and PCR. H. pylori 16S rRNA, cagA, hopQ, and vacA genes were amplified from stool DNA samples and sequenced.
UBT was positive in 69 (80.2%) of 86 children; in stool DNA analysis, 78.3% were positive by 16S rRNA PCR. cagA, vacA, and hopQ were detected in 66.1%, 84.6%, and 72.3% of stool DNA samples from 16S rRNA-positive children. Of the children's DNA samples, which revealed vacA and hopQ alleles, 91.7% showed vacA s1 and 73.7% showed type I hopQ. Type I hopQ alleles were associated with cagA positivity and vacA s1 genotypes (p < 0.0001).
Using stool DNA samples, virulence markers of H. pylori were successfully genotyped in a high percentage of the asymptomatic infected children, revealing a high prevalence of genotypes associated with virulence. Type I hopQ alleles were associated with the presence of cagA and the vacA s1 genotype.
幽门螺杆菌感染通常在儿童时期获得，但由于缺乏非侵入性诊断方法，人们对无症状儿童的自然史知之甚少。携带 cagA 以及 hopQ 和 vacA 特定等位基因的幽门螺杆菌菌株与胃癌风险增加相关。许多针对儿童幽门螺杆菌毒力标志物的研究存在偏倚，即选择有症状的受试者进行内镜检查，而这些儿童可能携带最具毒力的菌株。我们的目的是在居住在胃癌高发地区的健康哥伦比亚儿童的粪便 DNA 样本中对 cagA、hopQ 和 vacA 等位基因进行基因分型，以避免因内镜检查而导致的选择偏倚。
通过（13）C-尿素呼气试验（UBT）和 PCR 评估 86 名无症状儿童的幽门螺杆菌状态。从粪便 DNA 样本中扩增幽门螺杆菌 16S rRNA、cagA、hopQ 和 vacA 基因并进行测序。
UBT 在 86 名儿童中的 69 名（80.2%）中呈阳性；在粪便 DNA 分析中，16S rRNA PCR 阳性率为 78.3%。在 16S rRNA 阳性儿童的粪便 DNA 样本中，分别有 66.1%、84.6%和 72.3%检测到 cagA、vacA 和 hopQ。在显示 vacA 和 hopQ 等位基因的儿童 DNA 样本中，91.7%显示 vacA s1，73.7%显示 I 型 hopQ。I 型 hopQ 等位基因与 cagA 阳性和 vacA s1 基因型相关（p<0.0001）。
使用粪便 DNA 样本，成功对无症状感染儿童的幽门螺杆菌毒力标志物进行了高比例的基因分型，显示出与毒力相关的基因型的高流行率。I 型 hopQ 等位基因与 cagA 的存在和 vacA s1 基因型相关。
