ABSTRACT

Background

Pseudomonas aeruginosa possesses an array of virulence genes ensuring successful infection development. A two-partner secretion system Exolysin BA (ExlBA) is expressed in the PA7-like genetic outliers consisting of ExlA, a pore-forming toxin and ExlB transporter protein. Presence of exlBA in multidrug-resistant (MDR) strains has not been investigated, particularly in the strains isolated from wounded soldiers.

Methods

We screened whole genome sequences of 2439 MDR- P. aeruginosa strains for the presence of exlBA. We compiled all exlBA positive strains and compared them with a diversity set for demographics, antimicrobial profiles and phenotypic characteristics: surface motility, biofilm formation, pyocyanin production and hemolysis. We compared the virulence of strains with comparable phenotypic characteristics in Galleria mellonella.

Results

We identified 33 exlBA-positive strains (1.5%). These strains have increased antibiotic resistance, they are more motile, produce more robust biofilms and have comparable pyocianin production with the diversity set despite the phenotypic differences within the group. In in vivo infection models, these strains were less virulent than Type III Secretion System (T3SS) positive counterparts.

Conclusions

exlBA-positive strains are wide spread among the PA7-like outliers. While not as virulent as strains possessing T3SS, these strains exhibit phenotypic features associated with virulence and are still lethal in vivo.

中文翻译：

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铜绿假单胞菌菌株的比较显示外溶素A毒素在毒力中起附加作用。

摘要

背景

铜绿假单胞菌具有确保成功感染发展的一系列毒力基因。两伙伴分泌系统Exolysin BA（ExlBA）在由ExlA，成孔毒素和ExlB转运蛋白组成的PA7样遗传异常值中表达。还没有研究过exlBA在多药耐药（MDR）菌株中的存在，特别是在从受伤士兵身上分离的菌株中。

方法

我们筛选了2439个MDR-铜绿假单胞菌菌株的全基因组序列是否存在exlBA。我们汇编了所有exlBA阳性菌株，并将它们与人口统计学，抗菌谱和表型特征的多样性集进行了比较：表面运动性，生物膜形成，绿脓素生成和溶血。我们在Galleria mellonella中比较了具有可比的表型特征的菌株的毒力。

结果

我们确定了33 exlBA阳性菌株（1.5％）。尽管该菌株在表型上存在差异，但这些菌株具有增强的抗生素抗性，更具运动性，产生更牢固的生物膜并具有可比拟的海藻素生成，且具有多样性。在体内感染模型中，这些菌株的毒性不如III型分泌系统（T3SS）阳性菌株。

结论

exlBA阳性菌株在PA7类异常值中广泛分布。尽管这些毒株不像具有T3SS的毒株那样强，但它们显示出与毒力相关的表型特征，并且在体内仍然具有致死性。