Hygiène Hospitalière, Centre Hospitalier Universitaire, Besançon, France.
Hygiène Hospitalière, Centre Hospitalier Universitaire, Besançon, France; Centre de Ressources Biologiques - Filière Microbiologique de Besançon, Centre Hospitalier Universitaire, Besançon, France.
Int J Hyg Environ Health. 2023 May;250:114143. doi: 10.1016/j.ijheh.2023.114143. Epub 2023 Mar 10.
We assessed the contamination with Legionella pneumophila (Lp) of the hot water network (HWN) of a hospital, mapped the risk of contamination, and evaluated the relatedness of isolates. We further validated phenotypically the biological features that could account for the contamination of the network.
We collected 360 water samples from October 2017 to September 2018 in 36 sampling points of a HWN of a building from a hospital in France. Lp were quantified and identified with culture-based methods and serotyping. Lp concentrations were correlated with water temperature, date and location of isolation. Lp isolates were genotyped by pulsed-field gel electrophoresis and compared to a collection of isolates retrieved in the same HWN two years later, or in other HWN from the same hospital.
207/360 (57.5%) samples were positive with Lp. In the hot water production system, Lp concentration was negatively associated with water temperature. In the distribution system, the risk of recovering Lp decreased when temperature was >55 °C (p < 10), the proportion of samples with Lp increased with distance from the production network (p < 10), and the risk of finding high loads of Lp increased 7.96 times in summer (p = 0.001). All Lp isolates (n = 135) were of serotype 3, and 134 (99.3%) shared the same pulsotype which is found two years later (Lp G). In vitro competition experiments showed that a 3-day culture of Lp G on agar inhibited the growth of a different pulsotype of Lp (Lp O) contaminating another HWN of the same hospital (p = 0.050). We also found that only Lp G survived to a 24h-incubation in water at 55 °C (p = 0.014).
We report here a persistent contamination with Lp of a hospital HWN. Lp concentrations were correlated with water temperature, season, and distance from the production system. Such persistent contamination could be due to biotic parameters such as intra-Legionella inhibition and tolerance to high temperature, but also to the non-optimal configuration of the HWN that prevented the maintenance of high temperature and optimal water circulation.
我们评估了一家医院热水管网（HWN）中嗜肺军团菌（Lp）的污染情况，绘制了污染风险图，并评估了分离株的相关性。我们进一步验证了可以解释管网污染的表型生物学特征。
我们于 2017 年 10 月至 2018 年 9 月在法国一家医院的一栋建筑的 HWN 中 36 个采样点采集了 360 份水样。通过基于培养的方法和血清分型对 Lp 进行定量和鉴定。Lp 浓度与水温、分离日期和位置相关。通过脉冲场凝胶电泳对 Lp 分离株进行基因分型，并与两年后在同一 HWN 或同一医院其他 HWN 中收集的分离株进行比较。
207/360（57.5%）份样本呈 Lp 阳性。在热水生产系统中，Lp 浓度与水温呈负相关。在分配系统中，当水温>55°C 时，回收 Lp 的风险降低（p<0.001），与生产网络的距离越远，有 Lp 的样本比例增加（p<0.001），夏季发现高负荷 Lp 的风险增加 7.96 倍（p=0.001）。所有 Lp 分离株（n=135）均为血清型 3，其中 134 株（99.3%）与两年后发现的相同脉冲型（Lp G）相同。体外竞争实验表明，在琼脂上培养 3 天的 Lp G 抑制了另一个来自同一医院的不同 HWN 的 Lp（Lp O）的生长（p=0.050）。我们还发现，只有 Lp G 在 55°C 的水中孵育 24 小时后存活下来（p=0.014）。
我们在此报告了一家医院 HWN 中持续存在的 Lp 污染。Lp 浓度与水温、季节和与生产系统的距离相关。这种持续的污染可能是由于生物参数，如军团菌内抑制和对高温的耐受，以及 HWN 的非最佳配置，无法维持高温和最佳水循环。
