Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México, DF, Mexico.
Arch Med Res. 2012 Jul;43(5):339-46. doi: 10.1016/j.arcmed.2012.07.009. Epub 2012 Aug 8.
Helicobacter pylori iceA1 and iceA2 gene amplification is usually performed to identify mixed populations as both genes are apparently reportedly exclusive. However, some strains isolated from Mexico show both iceA genes. The aim of this study was to establish the frequency of these genes in Mexican isolates and genomic diversity of the H. pylori strains.
One hundred thirty six biopsies were obtained from 68 patients (39 children and 29 adults). The presence of H. pylori was confirmed in 3/18 children and 6/19 adults by culture. There were 93 clinical strains isolated from nine patients. Additionally, we studied 37 strains from a strain collection isolated from 10 patients. The strains were genotyped and dual iceA genes were identified by polymerase chain reaction (PCR) and amplicons were sequenced. In addition, an enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) assay was performed as fingerprinting method.
The genotypification of the H. pylori isolates indicated that all strains were vacA+; 86% babA2+, 86% cagA+, 82% vacA s1m1+, 19% iceA1+, 9% iceA2+, and 72% of them carried both iceA1 and iceA2 genes. The ERIC-PCR profiling revealed that the strains clustered in eight genetic groups depending on the presence of iceA1, iceA2 or both. A basic local multiple alignment analysis of the nucleotide sequences revealed that the iceA1 and iceA2 genes exhibited no relevant similarity.
The results here showed the presence of triple-positive strains (babA, cagA, vacA) of H. pylori and strains carrying simultaneously both iceA1 and iceA2 genes.
通常通过扩增幽门螺杆菌 iceA1 和 iceA2 基因来识别混合种群，因为这两个基因显然是互斥的。然而，一些从墨西哥分离的菌株显示出两个 iceA 基因。本研究的目的是确定这些基因在墨西哥分离株中的频率以及幽门螺杆菌菌株的基因组多样性。
从 68 名患者（39 名儿童和 29 名成人）中获得了 136 个活检样本。通过培养，在 3 名儿童和 6 名成人中证实了 18 名儿童和 19 名成人中有 H. pylori 的存在。从 9 名患者中分离出 93 株临床分离株。此外，我们研究了从 10 名患者中分离出的 37 株菌株。通过聚合酶链反应（PCR）鉴定菌株基因型，并鉴定双 iceA 基因，并对扩增子进行测序。此外，还进行了肠杆菌重复基因间一致 PCR（ERIC-PCR）试验作为指纹图谱方法。
H. pylori 分离株的基因分型表明，所有菌株均为 vacA+；86%的 babA2+，86%的 cagA+，82%的 vacA s1m1+，19%的 iceA1+，9%的 iceA2+，其中 72%携带 iceA1 和 iceA2 基因。ERIC-PCR 分析显示，根据 iceA1、iceA2 或两者的存在，菌株聚类为 8 个遗传群。核苷酸序列的基本局部多重比对分析显示，iceA1 和 iceA2 基因没有明显的相似性。
本研究结果表明存在 H. pylori 的三重阳性菌株（babA、cagA、vacA）和同时携带 iceA1 和 iceA2 基因的菌株。
