Persistence of Legionella pneumophila in a hospital's water system: a 13-year survey.

OBJECTIVE: To describe the molecular epidemiology of Legionella pneumophila infections in the University of Iowa Hospitals and Clinics (UIHC). DESIGN: Molecular epidemiological study using pulsed-field gel electrophoresis (PFGE). SETTING: A large university teaching hospital. ISOLATES: All surviving isolates obtained from culture-proven nosocomial L. pneumophila infections and all surviving isolates obtained from the University of Iowa Hospital and Clinics' water supply between 1981 and 1993. RESULTS: Thirty-three isolates from culture-proven nosocomial cases of L. pneumophila pneumonia were available for typing. PFGE of genomic DNA from the clinical isolates identified six different strains. However, only strain C (16 cases) and strain D (13 cases) caused more than 1 case. Strain C caused clusters of nosocomial infection in 1981, 1986, and 1993 and also caused 4 sporadic cases. Strain D caused a cluster in 1987 and 1988 plus 4 sporadic cases. Of the six strains causing clinical infections, only strains C and D were identified in water samples. PFGE identified three strains in the water supply, of which strains C and D caused clinical disease and also persisted in the water supply during most of the study period. CONCLUSION: Specific strains of L. pneumophila can colonize hospital water supplies and cause nosocomial infections over long periods of time.     

常州市公共浴池水中嗜肺军团菌的调查

目的了解常州市公共浴池水中嗜肺军团菌的污染状况。方法于2016年,选择常州市2家温泉场所和12家热水浴室进行浴池水样采集,采用实时荧光PCR方法检测水样中的嗜肺军团菌,并对分离菌株进行血清学鉴定。结果共采集公共浴池水样72件,嗜肺军团菌的阳性率为20.8%(15/72),其中,温泉浴池水中嗜肺军团菌的阳性率为30.0%(12/40),高于热水浴池水[9.4%(3/32)],差异有统计学意义(P=0.032)。共分离出11株嗜肺军团菌,血清型以LP1型为主,占比54.5%(6/11)。水样中嗜肺军团菌浓度范围为3.19×10^5-2.18×10^7,copies/ml。结论常州市公共浴池水中存在不同程度的嗜肺军团菌污染,尤其温泉浴池可能是公共场所军团菌污染的一个重要来源。     

集中空调系统中嗜肺军团菌污染状况调查

随着人们生活水平的不断提高,被称为“城市文明病”的军团菌病发病率有上升趋势。近年来研究表明,军团菌长期存活于空调冷却水或冷凝水中,是引起军团菌病散发和流行的重要来源,因而人们对空调系统的卫生状况越来越关注。为了解湖州市区公共场所集中空调系统中嗜肺军团菌的污染状况,我们于2008年8月对部分大型公共场所的空调冷却水、冷凝水进行了检测,现将结果报告如下。     

Legionella pneumophila contamination in a steam towel warmer in a hospital setting

For prevention of nosocomial legionellosis, environmental investigation to identify possible infectious sources is essential. An environmental study in a ward of our hospital revealed that a steam towel warmer was contaminated with legionella whereas no legionella was detected in tap water supplies and shower heads. Water in the apparatus may be a reservoir of legionella. We abandoned the use of all steam towel warmers in our hospital. Based on this finding, we recommend that steam towel warmers in hospital settings be avoided. Otherwise, the apparatus should be drained, cleaned and dried every?day.     

深圳公共场所水系统嗜肺军团菌污染研究

目的了解深圳公共场所水系统嗜肺军团菌污染现状,为卫生监督管理提供依据。方法依照《公共场所集中空调通风系统卫生规范》附录A方法,随机采集本市177家公共场所冷却水、冷凝水、淋浴水、泳池水、生活饮用水共500份水样,检测嗜肺军团菌及其菌型。结果冷却水、冷凝水、淋浴水嗜肺军团菌检出率分别为11.0%(28/255)、1.1%(2/176)、30.0%(12/40),泳池水、生活饮用水未检出嗜肺军团菌;酒店、公共浴室、候诊室、地铁站冷却水嗜肺军团菌检出率分别为18.1%(19/105)、4.0%(1/25)、31.8%(7/22)、0.1%(1/103),差异有统计学意义(χ2=11.74,P<0.05);分离出44株嗜肺军团菌,菌型以LP1型为主,占70.5%(31/44),LP3型、LP6型分别占2.3%(1/44)、27.2(12/44)。结论本市公共场所空调冷却水和冷凝水、淋浴水受嗜肺军团菌污染,存在健康隐患,应加强空调系统和淋浴-热水系统的清洗消毒。     

Each water outlet is a unique ecological niche for Legionella pneumophila.

We determined the natural history of the colonization of our hospital's potable water by culturing water approximately biweekly from 20 sites throughout the hospital for 4 years. Overall, 545 (24.7%) of the 2200 samples grew Legionella pneumophila. During hyperchlorination, 11.7% of the samples were positive while 41.6% were positive in the absence of chlorination. There was no seasonal trend towards positivity, but there was marked inter-site variation in the semi-quantitative culture results. However, a single strain of legionella (as defined by plasmid profiling) tended to persist at a site. Such a site was a unique ecological niche in that different sites in the same wing were populated by distinct strains. The two wings of our hospital had a significantly different distribution of strains of legionella-plasmid profile type III predominated in the Victoria Wing while types II and VI predominated in Centennial Wing. Twenty-four of our 28 cases of nosocomial Legionnaires' disease occurred in the Centennial Wing. Three of the four cases in the Victoria Wing were caused by plasmid profile type III while 18 of the 24 isolates from patients who acquired their infection in the Centennial Wing were type II. We conclude that each water outlet serves as its own ecological niche of L. pneumophila.     

Endemicity of Legionella pneumophila serogroup 3 in a hospital water supply

A microbiological and epidemiological investigation at the Infectious Diseases Hospital in Turin, Italy, demonstrated Legionella pneumophila serogroup 3 at 10(2) to greater than 4 X 10(3) cfu l-1 from 24 of 32 hot water samples collected from hand-basins in six separate buildings. A sample taken from the public water supply, and a hot water sample (80 degrees C) collected from hot water tanks, did not yield legionellas. Legionella pneumophila serogroup 3 was found in samples taken at the first point of mixed hot and cold water (50 degrees C) at 3 X 10(2) cfu l-1. 12 of 26 samples from the shower-heads yielded 10(3) to 2.5 X 10(5) cfu l-1 and one of 12 water samples from oxygen bubble humidifiers tested yielded 1.6 X 10(4) cfu l-1. No other legionellas species or serogroups of Legionella pneumophila were isolated during the study. No cases of nosocomial pneumonia were detected among 3653 patients' records, nor was there serological evidence of Legionella infection in the 180 patients tested.     

Legionella pneumophila in coal miners.

Legionnaires' disease was diagnosed in three mineworkers at a colliery. Investigation of water samples from various sites at the colliery did not discover a source of the infection. Results of serological surveys undertaken on the workmates of the patients and other miners showed only one additional positive Legionella indirect fluorescent antibody test. There was, therefore, no justification for any alteration in the water supply or the ventilation at the colliery.     

Genetic diversity of Legionella pneumophila in hospital water systems

It has been shown that different patients who had acquired legionellosis in a hospital setting were infected with the same strain even years apart. However, there are no longitudinal data describing the molecular epidemiology of Legionella pneumophila strains that contaminate a water system. This raised the question if there are any shifts of L. pneumophila strains over time, or after carrying out control measures. Using genotyping on a large collection of isolates, we investigated in a retrospective study the distribution of L. pneumophila serogroups and PFGE types in six different hospitals of the University of Heidelberg between 1991 and 2001. A total of 2012 water samples were drawn for routine testing and for evaluation of control measures, 747 samples were positive for L. pneumophila. Serogroups were determined by latex agglutination or by direct fluorescence assay; and 515 L. pneumophila isolates from water systems and six from patients underwent PFGE typing after SfiI-restriction. We identified seven serogroups and 19 genotypes among the water isolates. Each hospital had one to four predominating PFGE types that were stable over the investigation period. The oldest buildings in hospitals 4 and 5 (built 1876 and 1907) had more types than the newest one (built 1986). In all hospitals PFGE types were identified that could be found only sporadically. Although each hospital had its own warm water supply, we identified types that could be found in more than one hospital. However, there was no overlap of types in buildings that were fed from different wells. Infrequently occurring nosocomial legionellosis (n=3) were only caused by predominant strains. Contamination of water supplies seemed to be dominated by stable genotypes, even after various control measures. Additional genotypes could be isolated sporadically, however, their pathogenetic relevance seemed to be questionable.     

酒店浴室花洒头上检出嗜肺军团菌的报告

目的 了解上海市奉贤区部分公共场所环境中军团菌的污染状况,为军团菌病的预防控制提供依据.方法 采集该区使用集中式空调系统的大型酒店及超市的环境样品共80份进行军团菌检测,将聚合酶链反应(PCR)技术和常规方法结合,样品先进行PCR检测,阳性样品再进行常规分离和鉴定.结果 从某酒店的浴室花洒环节标本中检出2株嗜肺军团菌.结论 环境中有嗜肺军团菌存在,易受到感染,存在隐患.     

Different growth rates in amoeba of genotypically related environmental and clinical Legionella pneumophila strains isolated from a thermal spa

Two cases of legionellosis occurring 3 years apart were acquired in the same French thermal spa and were apparently due to the same strain of Legionella pneumophila serogroup 1, as shown by genomic macrorestriction analysis. Minor differences between the two isolates were found by random amplification PCR profiling which showed an additional band with one of the isolates. Analysis of 107 L. pneumophila strains isolated from the spa waters by genome macrorestriction failed to identify the infective strain, but a closely related L. pneumophila serogroup 3 strain differing from the clinical isolates by only one band was found. To determine if the clinical L. pneumophila serogroup 1 isolates was better adapted for intracellular multiplication than related serogroup 3 environmental isolates, the growth kinetics of six isolates were determined in co-culture with Acanthamoeba lenticulata. One clinical isolate failed to grow within amoeba, while the other clinical isolate yielded the highest increase in bacterial cell count per amoeba (1,200%) and the environmental isolates gave intermediate values. Genetic analysis of L. pneumophila isolates by DNA macrorestriction does not therefore appear to reflect their growth kinetics within amoeba, and is not sufficiently discriminatory to identify potentially virulent strains.     

多重PCR快速检测空调冷却塔水中军团菌

目的 传统的方法分离培养军团菌，时间长，价格贵，培养较困难，本文建立多重PCR方法，快速检测空调冷却塔水中军团菌属和嗜肺军团菌种。方法 利用军团菌属保守基因片段16SrRNA和嗜肺军团型菌巨噬细胞感染增强因子（mip）基因序列的特异性引物，对空调冷却塔水样中分离的疑似军团菌株进行特异性扩增，并且为了增强敏感性，运用递减温度PCR扩增。结果：PCR扩增的阳性结果与生化培养和血清学鉴定为军团菌的菌株结果—致。结论：与传统的分离培养方法相比，多重PCR方法检测军团菌，快速敏感，成本低，具有较好的特异性。     

Correlation between Legionella contamination in water and surrounding air.

We evaluated Legionella pneumophila contamination of water and surrounding air in a burn care department equipped with bathtubs. In water, the bacterium always aerosolized, but in surrounding air, it diluted itself to such a point that it became undetectable at 1 m or more from the source of emission, which indicated that patients were at low risk of inhaling a dangerous quantity of the microbe.     

Widespread Legionella pneumophila contamination of dental stations in a dental school without apparent human infection

Following isolation of Legionella pneumophila from a special dental station water circuit, used primarily to cool high-speed dental drills which produce fine aerosols, a case finding and environmental survey was undertaken. Widespread colonization of the dental stations was found and the results suggested that amplification of the background levels of L. pneumophila was taking place within the stations. However there was no evidence for transmission causing human infection.     

Evaluation of a Legionella urinary antigen enzyme immunoassay for rapid detection of Legionella pneumophila in water samples

Despite advances in medium formulations and pretreatment techniques, recovery of Legionella from water samples can still be quite low, difficult and time consuming. The aim of this study was to evaluate the utility of a Legionella urinary antigen enzyme immunoassay (Bartels ELISA, Trinity Biotech, Ireland) for the detection of Legionella in water samples. Reference ATCC Legionella strains were used to spike water samples to a final concentration of 10⁴–10⁵ cfu/ml. The lower detection limit of the test for all Legionella pneumophila serogroups was assessed by serial dilutions of spiked water samples. Legionella antigen was detected in all filtered samples except for those spiked with L. bozemanii and L. longbeachae. The lower detection limit for soluble L. pneumophila serogroup 1 antigen was 780 cfu/ml. Bartels ELISA could be a useful method for antigen detection in water samples when a high recovery of L. pneumophila is suspected. The test could be used as a rapid screening method for the detection of Legionella in a large number of samples. However, the low sensitivity of the test requires to keep on performing conventional culture for isolation and for further studies on isolated bacteria.     

广州市部分中央空调冷却塔水中军团菌污染状况

目的了解广州市中央空调冷却塔水中军团菌污染状况。方法于2004年1月至2005年10月在广州市随机抽检22家单位的空调冷却水,进行军团菌培养和鉴定,检测和评价方法参照《公共场所集中空调通风系统卫生规范》。结果共抽水样80份,军团菌检出率为58.75%。对空调冷却塔水进行消毒前后对比,消毒前军团菌检出率为62.9%(44/70),消毒后检出率为23.7%(9/38),差异有统计学意义(P<0.01)。结论广州市部分空调冷却塔水中存在军团菌的污染,需加强监测,以防引起军团菌病的流行。     

公共场所室内空气质量与嗜肺军团菌气溶胶污染水平关系

目的 探讨公共场所室内空气质量与嗜肺军团菌气溶胶浓度关系。方法 2011-2014年,选取北京市丰台区、江苏省南京市和常州市、广东省深圳市的公共场所,检测室内空气温度、湿度、风速、PM₁₀和PM_2.5。采集公共场所气溶胶样本,荧光定量聚合酶链反应（PCR）法检测嗜肺军团菌污染水平。结果 公共场所室内空气温度、湿度、风速、PM₁₀和PM_2.5的合格率分别为79.4%、88.2%、75.0%、76.9%和62.1%。嗜肺军团菌气溶胶浓度均值为2.15×10⁵ copies/mL,浓度范围8.75×10²~1.79×10⁶ copies/mL。嗜肺军团菌气溶胶浓度与室内空气温度（P=0.002）、湿度（P=0.038）、PM₁₀（P=0.002）和PM_2.5（P=0.000）相关性有统计学意义。结论 公共场所室内空气质量与嗜肺军团菌气溶胶浓度间存在相关性。     

福建省公共场所集中空调冷却塔水及冷凝水军团菌污染调查

目的 调查福建省公共场所集中空调冷却塔水及冷凝水嗜肺军团菌的污染状况及主要血清型.方法 2009年采集全省106家集中空调冷却塔水113份及52家冷凝水79份,进行嗜肺军团菌分离鉴定及血清分型,用PCR验证.结果 106家公共场所污染率27.4％(29/106);冷却塔水嗜肺军团菌检出率25.7％(29/113),以血清1型为优势(62.1％).52家冷凝水污染率为19.2％(10/52);冷凝水嗜肺军团菌检出率13.9％(11/79).受污染的7个设区市的冷却塔水检出率有差异;受污染的4个设区市的冷凝水检出率类似.结论 福建省公共场所集中空调冷却塔水及冷凝水受到嗜肺军团菌不同程度污染,冷却塔水检出率高于冷凝水;应加强集中空调系统监测,预防军团菌病的发生.     

Survival of virulent Legionella pneumophila in aerosols.

Aqueous suspensions of virulent Legionella pneumophila grown on solid medium retained virulence and aerosol survival characteristics for several months. Significant numbers of viable organisms were recovered from aerosols held at various relative humidities (r.h.) for up to 2 h. The organisms survived best at 65% r.h. and were least stable at 55% r.h. Exponential phase broth-grown organisms survived poorly in aerosols in comparison with stationary phase broth cultures or organisms grown on solid medium, suggesting that the metabolic status of Legionella pneumophila organisms may be an important factor affecting their ability to survive in aerosols and cause respiratory disease.     

Factors predisposing to Legionella pneumophila colonization in residential water systems

Fifty-five homes in the Pittsburgh area were surveyed for the presence of Legionella pneumophila colonization. Hot water tanks, faucets, and showerheads were sampled. Six homes yielded Legionella pneumophila within the water distribution system. Lower water temperatures (less than 48.8 degrees C) within the hot water system were significantly associated with the presence of L. pneumophila colonization. A similar association was found for electric heaters; however, this association may be an indirect one. Water temperatures in electrically heated tanks were significantly lower than in gas-heated tanks. City residences were also more likely to be colonized than suburban residences. Because acquisition of Legionnaires' disease in the community has been linked to colonization of the water supplies in the homes of affected patients, these findings may have clinical implications for susceptible individuals residing in homes with water supplies colonized by L. pneumophila.