D'Alessandro D, Fabiani M, Cerquetani F, Orsi G B
Department of Architecture and Planning, Sapienza University of Rome, Italy.
Department of Public Health and Infectious Diseases, Sapienza University of Rome, Italy.
Ann Ig. 2015 Mar-Apr;27(2):460-6. doi: 10.7416/ai.2015.2032.
In many nosocomial Legionella outbreaks water distribution systems are the most frequent source of infection.
Considering the hospital waterline old age, an investigation on colonization by Legionella spp was carried out in order to evaluate the pipeline system weaknesses and to implement environmental preventive measures.
From 2004 to 2010, overall 97 samples from the water line were collected. The samples were analyzed according to the italian Legionella spp standard methods; water temperature, pH and residual free chlorine were determined at the time of collection. X2 test, exact-test and t-test were used to compare proportions and means.
Overall 28 samples (23.7%) were positive for Legionella spp, and five of them (17.9%) exceeded the threshold level >104 cfu/L. The number of positive samples varied along the years, showing a significant increasing trend (X2 for trend = 11.5; p<0.01), but most occurred in 2008 (53,6%), when the hospital underwent major building reconstruction. Samples positive for Legionella spp by comparison to negative ones showed a lower free chlorine concentration (0.08 mg/L vs 0.15 mg/L) and a higher water temperature (46.1° vs 42.7°). Actually the percentage of positive samples decreased significantly with the increasing in free chlorine in the water (X2 for trend = 8.53; p<0.01). The samples collected at the connection between public water line with the hospital supply network were always free from Legionella. All hospital buildings were colonized by Legionella spp, although 80% of samples >104 cfu/L occurred in the C-building. No cases of nosocomial legionellosis were reported during the study period.
Hospital water system showed a diffuse colonization by Legionella spp, although the degree of contamination reached the threshold level (>104 cfu/L) only in a small percentage of samples, showing a substantial effectiveness of the control measures applied.
在许多医院军团菌暴发事件中，水分配系统是最常见的感染源。
鉴于医院水管年代久远，对军团菌属的定植情况进行调查，以评估管道系统的薄弱环节并实施环境预防措施。
2004年至2010年，共采集了97份来自水管的样本。样本按照意大利军团菌属标准方法进行分析；采集样本时测定水温、pH值和游离余氯。采用卡方检验、确切概率检验和t检验比较比例和均值。
总体上，28份样本（23.7%）军团菌属呈阳性，其中5份（17.9%）超过阈值水平>104 cfu/L。阳性样本数量随年份变化，呈现显著上升趋势（趋势卡方值=11.5；p<0.01），但大多数发生在2008年（53.6%），当时医院进行了大规模建筑重建。与阴性样本相比，军团菌属阳性样本的游离氯浓度较低（0.08 mg/L对0.15 mg/L），水温较高（46.1°对42.7°）。实际上，随着水中游离氯的增加，阳性样本百分比显著下降（趋势卡方值=8.53；p<0.01）。在公共水管与医院供水网络连接处采集的样本始终未检测到军团菌。所有医院建筑均有军团菌属定植，尽管超过104 cfu/L的样本80%出现在C楼。研究期间未报告医院内军团菌病病例。
医院水系统显示出军团菌属的广泛定植，尽管污染程度仅在一小部分样本中达到阈值水平（>104 cfu/L），表明所采取的控制措施具有显著效果。
