Infectology Laboratory, Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Cuauhtémoc, 06720, Mexico City, Mexico.
Biological Chemistry Sciences Postgraduate, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico.
BMC Microbiol. 2019 Aug 8;19(1):184. doi: 10.1186/s12866-019-1554-z.
Helicobacter pylori recurrence after successful eradication is an important problem. Children are particularly vulnerable to reinfection, by intrafamilial transmission which facilitates the acquisition or recombination of new genetic information by this bacterium. We investigated the evolutionary dynamics of 80 H. pylori strains isolated from two paediatric patients with recurrent infection (recrudescence and reinfection).
We characterized the virulence genes vacA (s1, m1, s2, and m2), cagA, cagE, and babA2 and performed multilocus sequence typing (MLST) on 7 housekeeping genes (atpA, efp, ureI, ppa, mutY, trpC, and yphC) to infer the evolutionary dynamics of the H. pylori strains through phylogenetic and genealogic inference analyses, genetic diversity analysis and the exploration of recombination events during recurrent infections. The virulence genotype vacAs1m1/cagA+/cagE+/babA2 was present at a high frequency, as were the EPIYA motifs EPIYA-A, -B and -C. Furthermore, the housekeeping genes of the H. pylori strains exhibited high genetic variation, comprising 26 new alleles and 17 new Sequence Type (ST). In addition, the hpEurope (76.5%) and hspWAfrica (23.5%) populations predominated among the paediatric strains. All strains, regardless of their ancestral affiliation, harboured western EPIYA motifs.
This study provides evidence of the evolutionary dynamics of the H. pylori strains in two paediatric patients during recrudescence and reinfection events. In particular, our study shows that the strains changed during these events, as evidenced by the presence of different STs that emerged before and after treatment; these changes may be due to the accumulation of mutations and recombination events during the diversification process and recolonization of the patients by different genotypes.
成功根除幽门螺杆菌后复发是一个重要问题。儿童尤其容易受到家庭内传播的再感染，这使得这种细菌更容易获得或重组新的遗传信息。我们研究了 80 株从两名复发性感染（复发和再感染）的儿科患者中分离的幽门螺杆菌菌株的进化动态。
我们对毒力基因 vacA（s1、m1、s2 和 m2）、cagA、cagE 和 babA2 进行了特征描述，并对 7 个看家基因（atpA、efp、ureI、ppa、mutY、trpC 和 yphC）进行了多位点序列分型（MLST），通过系统发生和系统发育推断分析、遗传多样性分析以及在反复感染期间探索重组事件，推断了幽门螺杆菌菌株的进化动态。高毒力基因型 vacAs1m1/cagA+/cagE+/babA2 以及 EPIYA 基序 EPIYA-A、-B 和 -C 很常见。此外，幽门螺杆菌菌株的看家基因表现出高度的遗传变异，包括 26 个新等位基因和 17 个新序列型（ST）。此外，hpEurope（76.5%）和 hspWAfrica（23.5%）人群在儿科菌株中占主导地位。所有菌株，无论其祖先归属如何，都携带西部 EPIYA 基序。
本研究提供了两名儿科患者在复发和再感染期间幽门螺杆菌菌株进化动态的证据。特别是，我们的研究表明，在治疗前后出现了不同的 ST，这表明菌株在这些事件中发生了变化；这些变化可能是由于在多样化过程中积累了突变和重组事件以及不同基因型重新定植患者。
