The increasing prevalence of chronic and hospital-acquired infections produced by multidrug-resistant (MDR) or extensively drug-resistant (XDR) Pseudomonas aeruginosa strains is associated with significant morbidity and mortality. This growing threat results from the extraordinary capacity of this pathogen for developing resistance through chromosomal mutations and from the increasing prevalence of transferable resistance determinants, particularly those encoding carbapenemases or extended-spectrum β-lactamases (ESBLs). P. aeruginosa has a nonclonal epidemic population structure, composed of a limited number of widespread clones which are selected from a background of a large quantity of rare and unrelated genotypes that are recombining at high frequency. Indeed, recent concerning reports have provided evidence of the existence of MDR/XDR global clones, denominated high-risk clones, disseminated in hospitals worldwide; ST235, ST111, and ST175 are likely those more widespread. Noteworthy, the vast majority of infections by MDR, and specially XDR, strains are produced by these and few other clones worldwide. Moreover, the association of high-risk clones, particularly ST235, with transferable resistance is overwhelming; nearly 100 different horizontally-acquired resistance elements and up to 39 different acquired β-lactamases have been reported so far among ST235 isolates. Likewise, MDR internationally-disseminated epidemic strains, such as the Liverpool Epidemic Strain (LES, ST146), have been noted as well among cystic fibrosis patients. Here we review the population structure, epidemiology, antimicrobial resistance mechanisms and virulence of the P. aeruginosa high-risk clones. The phenotypic and genetic factors potentially driving the success of high-risk clones, the aspects related to their detection in the clinical microbiology laboratory and the implications for infection control and public health are also discussed.

中文翻译：

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铜绿假单胞菌高风险克隆的威胁日益增加。

由多药耐药性（MDR）或广泛耐药性（XDR）的铜绿假单胞菌菌株产生的慢性和医院获得性感染的患病率和死亡率都很高。这种病原体通过染色体突变产生抗药性的超强能力以及可转移抗药性决定簇（尤其是编码碳青霉烯酶或超广谱β-内酰胺酶（ESBLs）的抗性决定簇）的患病率正在上升，这种威胁越来越大。铜绿假单胞菌具有非克隆的流行种群结构，其由有限数量的广泛克隆组成，所述克隆选自以高频率重组的大量稀有和无关基因型的背景。的确，最近的有关报道提供了证据，证明存在全球各地医院散布的称为高风险克隆的MDR / XDR全球克隆；ST235，ST111和ST175可能更普及。值得注意的是，MDR（尤其是XDR）菌株的绝大多数感染是由这些克隆以及全世界其他少数克隆产生的。此外，高风险克隆，特别是ST235，与可转移抗性的联系是压倒性的。迄今为止，在ST235分离物中已报道了近100种不同的水平获得性抗性元件和多达39种不同的获得性β-内酰胺酶。同样，在囊性纤维化患者中也注意到国际上广泛传播的MDR流行株，例如利物浦流行株（LES，ST146）。在这里，我们回顾了人口结构，流行病学，铜绿假单胞菌高风险克隆的抗药性机制和毒力。还讨论了可能驱动高风险克隆成功的表型和遗传因素，与它们在临床微生物实验室中的检测有关的方面以及对感染控制和公共卫生的影响。