Seng Rathanin, Phunpang Rungnapa, Saiprom Natnaree, Dulsuk Adul, Chewapreecha Claire, Thaipadungpanit Janjira, Batty Elizabeth M, Chantratita Wasun, West T Eoin, Chantratita Narisara
Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
Front Microbiol. 2023 Feb 6;14:1103297. doi: 10.3389/fmicb.2023.1103297. eCollection 2023.
The bacterium is the causative agent of melioidosis, a severe tropical disease associated with high mortality and relapse and persistent infections. Treatment of melioidosis requires prolonged antibiotic therapy; however, little is known about relapse and persistent infections, particularly the phenotypic and genetic alterations of in patients. In this study, we performed pulsed-field gel electrophoresis (PFGE) to compare the bacterial genotype between the initial isolate and the subsequent isolate from each of 23 suspected recurrent and persistent melioidosis patients in Northeast Thailand. We used whole-genome sequencing (WGS) to investigate multilocus sequence types and genetic alterations of within-host strain pairs. We also investigated the bacterial phenotypes associated with relapse and persistent infections, including multinucleated giant cell (MNGC) formation efficiency and intracellular multiplication. We first identified 13 (1.2%) relapse, 7 (0.7%) persistent, and 3 (0.3%) reinfection patients from 1,046 survivors. Each of the 20 within-host strain pairs from patients with relapse and persistent infections shared the same genotype, suggesting that the subsequent isolates arise from the infecting isolate. Logistic regression analysis of clinical data revealed regimen and duration of oral antibiotic therapies as risk factors associated with relapse and persistent infections. WGS analysis demonstrated 17 within-host genetic alteration events in 6 of 20 paired isolates, including a relatively large deletion and 16 single-nucleotide polymorphism (stocktickerSNP) mutations distributed across 12 genes. In 1 of 20 paired isolates, we observed significantly increased cell-to-cell fusion and intracellular replication in the second isolate compared with the initial isolate from a patient with persistent infection. WGS analysis suggested that a non-synonymous mutation in the gene, which encoded an essential component of the type VI secretion system, may be associated with the increased intracellular replication and MNGC formation efficiency of the second isolate of the patient. This information provides insights into genetic and phenotypic alterations in in human melioidosis, which may represent a bacterial strategy for persistent and relapse infections.
该细菌是类鼻疽病的病原体，类鼻疽病是一种严重的热带疾病，与高死亡率、复发及持续性感染相关。类鼻疽病的治疗需要长期抗生素治疗；然而，对于复发和持续性感染，尤其是患者体内该细菌的表型和基因改变，人们了解甚少。在本研究中，我们进行了脉冲场凝胶电泳（PFGE），以比较泰国东北部23例疑似复发性和持续性类鼻疽病患者各自的初始分离株与后续分离株之间的细菌基因型。我们使用全基因组测序（WGS）来研究宿主内菌株对的多位点序列类型和基因改变。我们还研究了与复发和持续性感染相关的细菌表型，包括多核巨细胞（MNGC）形成效率和细胞内增殖。我们首先从1046名幸存者中确定了13例（1.2%）复发患者、7例（0.7%）持续性感染患者和3例（0.3%）再次感染患者。20对复发和持续性感染患者的宿主内菌株对中的每一对都具有相同的基因型，这表明后续分离株源自感染性分离株。对临床数据的逻辑回归分析显示，口服抗生素治疗的方案和持续时间是与复发和持续性感染相关的风险因素。WGS分析在20对配对分离株中的6对中显示出17次宿主内基因改变事件，包括一个相对较大的缺失和分布在12个基因中的16个单核苷酸多态性（SNP）突变。在20对配对分离株中的1对中，我们观察到与一名持续性感染患者的初始分离株相比，该患者的第二个分离株中细胞间融合和细胞内复制显著增加。WGS分析表明，编码VI型分泌系统必需成分的基因中的一个非同义突变可能与该患者第二个分离株细胞内复制增加和MNGC形成效率增加有关。这些信息为人类类鼻疽病中该细菌的基因和表型改变提供了见解，这可能代表了细菌持续性和复发性感染的一种策略。
