Objective

Water-bearing systems are known as frequent Pseudomonas aeruginosa (PA) outbreak sources. Still, many older buildings have sanitary facilities in high-risk departments like the ICU. We present two simultaneous prolonged multidrug-resistant (MDR) PA outbreaks detected at the ICU of a pulmonology hospital, which were resolved by whole-genome sequencing (WGS).

Methods

Outbreak management and investigations were initiated in August 2019 after detecting two patients with nosocomial VIM-2 positive MDR PA. The investigations involved weekly patient screenings for four months and extensive environmental sampling for 15 months. All patient and environmental isolates were collected and analysed by WGS.

Results

From April to September 2019, we identified 10 patients with nosocomial MDR PA, including five VIM-2 positive strains. VIM-2-positive strains were also detected in nine sink drains, two toilets, and a cleaning bucket. WGS revealed that of 16 VIM-2-positive isolates, 14 were ST111 that carried qacE, or qacEΔ1 genes, whereas 13 isolates clustered (difference of ≤11 alleles by cgMLST). OXA-2 (two toilets), and OXA-2, OXA-74, PER-1 (two patients, three toilets) qacEΔ1-positive ST235 isolates dominated among VIM-2 negative isolates. The remaining seven PA strains were ST17, ST233, ST273, ST309, and ST446.

Outbreak containment was achieved by replacing U-bends, and cleaning buckets, and switching from quaternary ammonium compounds (QUATs) to oxygen-releasing disinfectant products.

Conclusion

Comprehension and management of two simultaneous MDR PA outbreaks involving the high-risk strains ST111 and ST235 were facilitated by precise control due to identification of different outbreak sources per strain, and by the in silico detection of high-level QUATs resistance in all isolates.

中文翻译：

---

全基因组测序揭示了两起长期同时发生的疫情，涉及对季铵化合物具有抗性的铜绿假单胞菌高危菌株 ST111 和 ST235

客观的

含水系统是铜绿假单胞菌(PA) 频繁爆发的来源。尽管如此，许多老建筑在重症监护室等高风险部门都设有卫生设施。我们介绍了一家肺科医院 ICU 检测到的两起同时发生的长期多重耐药 (MDR) PA 疫情，并通过全基因组测序 (WGS) 解决了这些问题。

方法

在检测到两名院内 VIM-2 阳性 MDR PA 患者后，于 2019 年 8 月启动了疫情管理和调查。调查包括为期四个月的每周患者筛查和为期 15 个月的广泛环境采样。所有患者和环境分离株均通过全基因组测序收集和分析。

结果

2019年4月至2019年9月，我们鉴定了10例院内MDR PA患者，其中5例为VIM-2阳性菌株。在九个水槽排水管、两个厕所和一个清洁桶中也检测到了 VIM-2 阳性菌株。WGS 显示，在 16 个 VIM-2 阳性分离株中，14 个是携带 qacE 或 qacEΔ1 基因的 ST111，而 13 个分离株聚集在一起（cgMLST 的等位基因差异≤11 个）。OXA-2（两个厕所）和 OXA-2、OXA-74、PER-1（两个患者、三个厕所）qacEΔ1 阳性 ST235 分离株在 VIM-2 阴性分离株中占主导地位。其余 7 个 PA 菌株为 ST17、ST233、ST273、ST309 和 ST446。

通过更换 U 型弯管和清洁桶以及从季铵化合物 (QUAT) 改用释放氧气的消毒剂产品，实现了疫情遏制。

结论

由于确定了每种菌株的不同爆发源，并且通过计算机检测所有分离株中的高水平 QUAT 耐药性，因此有助于对涉及高风险菌株 ST111 和 ST235 的两起同时发生的 MDR PA 爆发的理解和管理。