BACKGROUND Pseudomonas aeruginosa is a major bacterial pathogen responsible for hospital-acquired infections. Although its epidemiology is considered as non-clonal, certain international high-risk multidrug-resistant clones have been recognized. AIM From the first report of an intra-hospital outbreak due to an SHV2a-producing P. aeruginosa strain, to describe the emergence of a new ST235-specific lineage harbouring this rare extended-spectrum β-lactamase (ESBL). METHODS Between May and October 2018, four patients hospitalized in the cardiovascular intensive care unit of a French teaching hospital were infected by a multidrug-resistant P. aeruginosa isolate. Serotype and antimicrobial susceptibility were tested; multi-locus sequence type (MLST), core genome MLST, and resistome were determined through whole genome sequencing. A phylogenetic analysis based on single nucleotide polymorphism was performed using available ST235 genomes. FINDINGS The four strains were susceptible to colistin, ciprofloxacin, ceftazidime-avibactam, and ceftolozane-tazobactam. blaSHV2a was identified in each genome of this ST235-O11 serotype cluster that showed an identical cgMLST profile (0-2 out of 4162 different alleles). The phylogenic analysis of 162 ST235 genomes showed that only four other strains harboured a blaSHV2a, originating from France and USA, clustering together although being different from the outbreak strains. CONCLUSIONS Among the ST235 P. aeruginosa strains, a sub-lineage sharing a common genetic background and harbouring the blaSHV2a ESBL seems to emerge from different locations, yielding secondary local outbreaks.

中文翻译：

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产广谱β-内酰胺酶SHV2a的铜绿假单胞菌的局部暴发揭示了国际ST235高风险克隆的一个新的特定亚谱系的出现。

背景技术铜绿假单胞菌是负责医院获得性感染的主要细菌病原体。尽管其流行病学被认为是非克隆性的，但已经认识到某些国际高风险的多药耐药性克隆。目的从第一例因产生SHV2a的铜绿假单胞菌菌株引起的医院内暴发的报道，描述了一种新的ST235特异性谱系的出现，该谱系带有这种罕见的广谱β-内酰胺酶（ESBL）。方法在2018年5月至2018年10月之间，法国一家教学医院的心血管重症监护病房住院的四名患者被多药耐药铜绿假单胞菌分离株感染。检测血清型和抗菌素敏感性；通过全基因组测序确定了多基因座序列类型（MLST），核心基因组MLST和抵抗基因组。使用可获得的ST235基因组进行了基于单核苷酸多态性的系统发育分析。结果这四个菌株对粘菌素，环丙沙星，头孢他啶-阿维巴坦和头孢洛赞-他唑巴坦敏感。在此ST235-O11血清型簇的每个基因组中鉴定出blaSHV2a，它们显示出相同的cgMLST谱（4162个不同等位基因中的0-2）。对162个ST235基因组的系统发育分析表明，只有四个其他菌株带有blaSHV2a，它们起源于法国和美国，虽然与暴发菌株不同，但它们聚集在一起。结论在ST235铜绿假单胞菌菌株中，具有相同遗传背景并带有blaSHV2a ESBL的亚谱系似乎来自不同位置，从而产生了继发性局部暴发。