Objectives

The aim of this study was to monitor the spread, persistence and antibiotic resistance patterns of Legionella spp. strains found in a hospital water distribution system. These environmental studies are intended to help detect the presence of antibiotic resistant strains before they infect patients. Methods: Antimicrobial surveillance tests were performed at 27 different sampling points of the water network of a large Spanish hospital over two years. Water samples were screened for Legionella according to ISO 11731:2007. Legionella spp. isolates were identified by serotyping and by mass spectrometry (MALDI-ToF). Epidemiological molecular typing was done by Pulse-Field Gel Electrophoresis (PFGE) and by Sequence-Based Typing (SBT). Antibiotic susceptibility tests were performed using disk diffusion and ETEST®.

Results

Legionella spp. were recurrently isolated for 2 years. All isolates belonged the same group, L. pneumophila serogroups 2–14. Isolates were all attributed by SBT to sequence type (ST) ST328, although PFGE revealed 5 different patterns. No significant change in antibiotic susceptibility could be observed for this study period, irrespectively of the method used.

Conclusion

Colonization of water systems by Legionella spp. is still occurring, although all the prevention rules were strictly followed. Antibiotic resistance monitoring may help us to find resistance in bacteria with environmental reservoirs but difficult to isolate from patients. The knowledge of the antibiotic susceptibility in environmental strains may help us to predict changes in clinical strains. This study might also help reconsidering Legionnaires’ disease (LD) diagnostic methods. L. pneumophila serogroups 2–14 present all along the time of the investigation in the water distribution system can cause LD. However, they may not be detected by routine urine tests run on patients, thereby missing an ongoing LD infection.

中文翻译：

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在西班牙一家医院中反复分离出军团杆菌：两年的抗菌素耐药性监测

目标

这项研究的目的是监测军团菌的传播，持久性和抗生素耐药性模式。在医院供水系统中发现的菌株。这些环境研究旨在帮助在感染患者之前检测出抗生素抗性菌株的存在。方法：在两年内，在西班牙一家大型医院的供水网络的27个不同采样点进行了抗菌素监测测试。根据ISO 11731：2007对水样本进行军团菌筛查。军团菌spp。通过血清分型和质谱（MALDI-ToF）鉴定分离株。流行病学分子分型是通过脉冲场凝胶电泳（PFGE）和基于序列的分型（SBT）完成的。使用圆盘扩散仪和ETEST®进行了药敏试验。

结果

军团菌属 被隔离了2年。所有分离株均属于同一组，嗜肺乳杆菌血清群2–14。尽管PFGE揭示了5种不同的模式，但所有分离物都被SBT归因于序列类型（ST）ST328。不论使用哪种方法，在本研究期间均未观察到抗生素敏感性的显着变化。

结论

军团菌属菌种对水系统的定殖。尽管严格遵守所有预防规则，但仍在发生。抗生素耐药性监测可以帮助我们在具有环境储库但难以与患者隔离的细菌中发现耐药性。对环境菌株中抗生素敏感性的了解可能有助于我们预测临床菌株的变化。这项研究也可能有助于重新考虑退伍军人病（LD）的诊断方法。在配水系统中，在调查期间一直存在的嗜肺乳杆菌血清群2-14会导致LD。但是，对患者进行的常规尿液检测可能无法检测到它们，从而错过了正在进行的LD感染。