Longitudinal Evaluation of the Efficacy of Heat Treatment Procedures against Legionella spp. in Hospital Water Systems by Using a Flow Cytometric Assay
Longitudinal Evaluation of the Efficacy of Heat Treatment Procedures against Legionella spp. in Hospital Water Systems by Using a Flow Cytometric Assay
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DOI：
10.1128/aem.02225-10
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发表时间：
2011-02-01
影响因子：
4.4
通讯作者：
Berthelot, Philippe
中科院分区：
文献类型：
--
作者：
Allegra, Severine;Grattard, Florence;Berthelot, Philippe
军团菌属在医院的供水系统中经常被隔离。世界卫生组织推荐热休克（70 ℃下30分钟）来控制其繁殖。该研究的目的是通过使用能够识别存活但不可培养（VBNC）细胞的流式细胞术测定（FCA）回顾性评价热处理的有效性。该研究包括军团菌菌株（L。pneumophila [3簇]和L. anisa [1簇]），分离自法国圣艾蒂安不同医院建筑的四个热水回路，在20年的前瞻性监测。从不同回路中回收的菌株在流行病学上不相关，但随着时间的推移，在同一回路中分离的菌株表现出相同的基因型特征。在70 ℃下体外处理30分钟后，活细胞和VBNC细胞的平均百分比从4.6%变化到71.7%。体外热敏性差异与用于控制水污染的预防性和纠正性加热措施的观察效果一致。这些结果表明，军团菌菌株可以成为热处理后，长时间和流式细胞仪可以帮助检查热处理对军团菌属的效力。并优化应用于水系统的净化过程，以控制军团菌的增殖。
Legionella spp. are frequently isolated in hospital water systems. Heat shock (30 min at 70 degrees C) is recommended by the World Health Organization to control its multiplication. The aim of the study was to evaluate retrospectively the efficacy of heat treatments by using a flow cytometry assay (FCA) able to identify viable but nonculturable (VBNC) cells. The study included Legionella strains (L. pneumophila [3 clusters] and L. anisa [1 cluster]) isolated from four hot water circuits of different hospital buildings in Saint-Etienne, France, during a 20-year prospective surveillance. The strains recovered from the different circuits were not epidemiologically related, but the strains isolated within a same circuit over time exhibited an identical genotypic profile. After an in vitro treatment of 30 min at 70 degrees C, the mean percentage of viable cells and VBNC cells varied from 4.6% to 71.7%. The in vitro differences in heat sensitivity were in agreement with the observed efficacy of preventive and corrective heating measures used to control water contamination. These results suggest that Legionella strains can become heat resistant after heating treatments for a long time and that flow cytometry could be helpful to check the efficacy of heat treatments on Legionella spp. and to optimize the decontamination processes applied to water systems for the control of Legionella proliferation.