Vigilancia epidemiológica de la legionelosis en España: 2005-2015 / Epidemiological surveillance of legionellosis in Spain: 2005-2015

Introducción: La legionelosis es una enfermedad de declaración obligatoria en España. Uno de sus mecanismos de prevención y control es el sistema de vigilancia epidemiológica y, en particular, la investigación epidemiológica. Entre 2005 y 2010 se reportó en Europa un aumento de la carga de la enfermedad no descrita en España. Objetivo: Determinar la evolución de los casos de legionelosis en España en la serie 2005-2015. Métodos: Estudio descriptivo de series temporales relativo al recuento de casos notificados a través del Centro Nacional de Epidemiología de España. Se incluyeron variables sociodemográficas del paciente, antecedentes personales y clínicos, síntomas y signos, datos de laboratorio y epidemiológicos. Se determinó la tasa de incidencia por 100 000 habitantes (2005-2010) y la tasa ajustada (población europea) por 100 000 habitantes según sexo (2005-2015), así como según grupo de edad y sexo para la serie 2010-2015. Resultados: España mantiene una tendencia estable respecto a la tasa de incidencia por 1100 000 habitantes (3,5 a 2,5), se produce un incremento relevante en la tasa ajustada a partir de los 50 años, con mayor impacto en los hombres. Conclusión: se evidencia la necesidad de la vigilancia epidemiológica de la legionelosis, la mejora en las medidas de prevención y control, y la consideración de nuevos factores de riesgo(AU)

Introduction: Legionellosis is a notifiable disease in Spain. One of its prevention and control mechanisms is epidemiological surveillance, particularly epidemiological research. An increase in legionellosis disease burden was reported in Europe from 2005 to 2010 which was not described in Spain. Objectives: Determine the evolution of legionellosis cases in Spain in the period 2005-2015. Methods: A descriptive time series analysis was performed based on the cases notified to the Spanish National Epidemiology Center. The variables considered were the patients' sociodemographic characteristics, personal and clinical antecedents, signs and symptoms, laboratory results and epidemiological data. Determination was made of the incidence rate per 100 000 inhabitants (2005-2010) and the adjusted rate per 100 000 inhabitants (European population) by sex (2005-2015) and by age group and sex for the series (2010-2015). Results: Incidence per 100 000 inhabitants has remained stable (3.5 to 2.5) in Spain, which has led to a relevant increase in the adjusted rate as of age 50 years, with a higher impact among men. Conclusion: Evidence was found of the need for epidemiological surveillance of legionellosis, improvement of prevention and control measures, and consideration of new risk factors(AU)

Legionelosis en España, 2010-2015 / Legionellosis in Spain, 2010-2015

Resumen | Introducción. La legionelosis es una enfermedad respiratoria bacteriana de origen ambiental que puede ser adquirida en el ámbito comunitario u hospitalario, y suele estar asociada con equipos, instalaciones y edificios. La forma clínica más conocida es la neumónica, conocida como enfermedad del legionario. Objetivo. Determinar la evolución de los casos de legionelosis en España en el periodo de 2010 a 2015. Materiales y métodos. Se hizo un estudio descriptivo de series temporales y se analizaron los casos de legionelosis notificados al Centro Nacional de Epidemiología del Gobierno de España. Se determinó la distribución de los casos según el sexo, la comunidad autónoma, el mes y los grupos de edad. Para el último se diferenció entre hombres y mujeres. Resultados. El recuento de casos en hombres fue superior al doble con respecto a las mujeres. La distribución en las comunidades autónomas presentó un aumento de los casos notificados al final del periodo en nueve de ellas, siendo notable en Castilla y León, Navarra y el País Vasco, y muy relevante en Castilla-La Mancha. Se estableció un patrón estacional con un pico epidémico en julio-septiembre y un mayor número de casos en torno a los 50 años de edad en ambos sexos. Conclusiones. A pesar de mostrar una prevalencia baja con respecto a otras enfermedades respiratorias, la legionelosis tiene gran impacto en la salud pública. Presenta una distribución global y heterogénea en el territorio español, con un aumento de casos en los dos últimos años, por lo que se requiere una mejor prevención y control de la enfermedad.

Abstract | Introduction: Legionellosis is a bacterial respiratory disease with an environmental origin in the community or in hospitals; it is usually associated with devices, facilities, and buildings. The most common clinical form is the pneumonic, known as legionnaires' disease. Objective: To determine the evolution of legionellosis cases in Spain from 2010 to 2015. Materials and methods: This was a descriptive study of time series with an analysis of the legionellosis cases notified to the Centro Nacional de Epidemiología (Government of Spain). Case distribution was determined according to sex, the autonomous community of origin, month, and age groups differentiating in the latter between men and women. Results: Case count in men was more than double compared to that in women. The cases notified by nine of the autonomous communities showed an increase at the end of the period, especially in Castilla y León, Navarra, and the Basque Country but also notable in Castilla-La Mancha. A seasonal pattern was identified with an epidemic peak in July-September and a greater number of cases among 50-years old people from both sexes. Conclusion: Despite its low prevalence compared to other respiratory diseases, legionellosis has a great impact on public health. Its distribution in Spain is global and heterogeneous with cases increasing in the last two years. Therefore, better disease prevention and control measures are recommended.

Mortalidad por neumonía y legionelosis en España: un estudio de series temporales / Pneumonia and legionellosis mortality in Spain: a time series study

Background: Pneumonia is a disease with great relevance in public health, as a leading individual cause of infant mortality worldwide. Legionellosis is a respiratory disease with a bacterial origin and two different clinical forms. Aim: To determine pneumonia and legionellosis mortality in Spain. Material and Methods: Time series study of pneumonia and legionellosis in Spain in two periods, from 1997 to 2001 and from 2011 to 2015. Mortality was calculated according to disease and sex, number of deaths and rates per 100,000 inhabitants. Results: Pneumonia mortality in the first period shows a relatively stable and similar tendency according to sex, preferably affecting males. In the second period, pneumonia mortality increased significantly in recent years. Although pneumonia mortality in Spain decreased in both sexes in some age groups (especially 75 years. Deaths due to legionellosis were relevant in 1997, 1998 and 2000 and increased in the last period. Conclusions: A higher mortality due to pneumonia along the years was identified. Strategies to reduce the incidence and improve the diagnosis of pneumonia, especially in children and older people elderly, are encouraged.

Legionelosis ocupacional en mayores de 18 años: revisión sistemática / Occupational legionella in adults over 18 years pf age: a systematic review

Resumen El objetivo es revisar la literatura científica sobre los problemas de salud derivados de la exposición laboral a Legionella spp. Revisión sistemática de la literatura científica recogida en las bases de datos MEDLINE (Pubmed), ISI-Web of Science (Institute for Scientific Information), Cochrane Library Plus, Literatura Latinoamericana de Información en Ciencias de la Salud (LILACS) y SCOPUS, hasta febrero 2015. Los descriptores utilizados fueron: "Legionnaires' Disease" "Legionellosis" "Occupational Exposure" "Occupational Diseases". Se obtuvieron 222 referencias, que tras aplicar los criterios de inclusión y exclusión, se seleccionaron 13 artículos a texto completo. De ellos 9 artículos describen la aparición de neumonía, 4 Fiebre de Pontiac, 1 legionelosis o presunta legionelosis y 3 muerte. El principal agente causal en los profesionales expuestos fue Legionella pneumophila serogrupo 1. La infección por legionela está ligada a las profesiones donde existe nebulización por agua, principalmente en los trabajadores sometidos a largas exposiciones o incluso a la re-exposición. Los brotes se producen de forma estacional, sobre todo en los meses más cálidos.

Abstract The scope of this paper is to review the available scientific literature about the effects on health of occupational exposure to Legionella spp. A systematic review of the scientific literature retrieved from the MEDLINE (via PubMed), ISI-Web of Science (Institute for Scientific Information), Cochrane Library, LILCAS and SCOPUS databases through February 2015 was conducted. The key words used were ««Legionnaires' Disease¼ «Legionellosis¼ «Occupational Exposure¼ «Occupational Diseases¼. Two hundred and twenty-two references were retrieved of which, after applying inclusion/exclusion criteria, 13 complete articles were selected. Of these, 9 describe pneumonia, 4 list Pontiac Fever, 1 reveals legionellosis and 3 result in death. The main causative agent of disease in workers exposed was Legionella pneumophila serogroup 1. Legionella spp infection is closely related to professions where there is nebulization with water, mainly among workers subjected to long exposure or even re-exposure. Outbreaks occurs seasonally, especially in the hottest months.

Epidemiology of Legionella and Climatic Variables in Seoul, Korea

Legionella species are abundant in the built environment and are increasingly recognized as a cause of Legionnaires' disease (LD). As the number of cases of Legionnaires' disease acquired by local communities in the Seoul metropolitan area in Korea has been increased, there was concern that changes in environmental factors could affect disease outbreaks. We described the association between climatic variables and occurrence of legionellosis in Korea and Legionella detection rate in Seoul area. A total of 418 cases of legionellosis were reported between 2014 and 2017. There was a seasonal peak in summer. LD continuously occurred from early spring to winter every year and rapidly increased in summer. In the regression analysis, the primary variables of interest- PM2.5 (µg/m³), NO₂ (ppb), and a number of the date of issue O₃ warning were not significant except for average temperature (R²=0.8075). The Legionella detection rate in Seoul, Korea showed a trend similar to precipitation (P=0.708, ANOVA). A relatively high proportion of Legionella detection rate was shown, especially cooling tower (17.7%) and public bath (19.3%). This finding is in line with current understanding of the ecological profile of this pathogen and supports the assertion that legionellosis occurs through contamination of water sources.

Presencia de Legionella spp. en depósitos domiciliarios de agua potable en Resistencia, Chaco, Argentina. Informe preliminar / Presence of Legionella spp. in household drinking water reservoirs in Resistencia, Chaco, Argentina. Preliminary report

Legionella spp. es una bacteria ambiental capaz de sobrevivir en un amplio intervalo de condiciones fisicoquímicas y puede colonizar los sistemas de distribución y almacenamiento del agua potable. Legionella pneumophila es el principal patógeno trasmitido por el agua y produce el 90% de los casos de legionelosis. El objetivo del presente trabajo fue detectar por cultivo la presencia de Legionella spp. en depósitos domiciliarios de agua potable de la ciudad de Resistencia, Chaco. La detección de Legionella en las muestras de agua se realizó por cultivo según lo establecido en la norma ISO 11731:1998. Se analizaron 32 muestras de agua y de 12 (37,5%) de ellas se recuperaron cepas de Legionella spp. La vigilancia de este microorganismo en el agua de consumo humano representa el primer paso para controlar su diseminación hacia huéspedes susceptibles.

Legionella spp. is an environmental bacterium that can survive in a wide range of physicochemical conditions and may colonize distribution systems of drinking water and storage tanks. Legionella pneumophila is the major waterborne pathogen that can cause 90% of Legionnaires' disease cases. The aim of this study was to detect the presence of Legionella spp. in household drinking water tanks in the city of Resistencia, Chaco. The detection of Legionella in water samples was performed by culture methods as set out in ISO 11731:1998. Thirty two water samples were analyzed and Legionella spp. was recovered in 12 (37.5%) of them. The monitoring of this microorganism in drinking water is the first step towards addressing the control of its spread to susceptible hosts.

Implementación de técnica de cultivo para la investigación de Legionella pneumophila en depósitos domiciliarios de agua potable en Resistencia, Chaco / Implementation of cultivation technique for the investigation of Legionella pneumophila in household drinking water Resistencia, Chaco

Legionella pneumophila es una bacteria ambiental capaz de sobrevivir en un amplio intervalo de condiciones físico-químicas y de colonizar los sistemas de distribución y almacenamiento del agua potable. Es el principal patógeno trasmitido por el agua que produce el 90% de los casos de legionelosis. El objetivo del trabajo fue realizar la puesta a punto de la técnica por cultivo para la vigilancia de L. pneumophila en depósitos domiciliarios de agua potable acorde con la normativa internacional. En las muestras de agua analizadas no se obtuvo desarrollo de L. pneumophila; la cepa utilizada como control positivo, permitió constatar la aptitud de los medios utilizados para la detección de este patógeno en las muestras de agua. La vigilancia de este microorganismo en el agua de consumo humano representa el primer paso en pos de abordar el control de su diseminación hacia huéspedes susceptibles

Molecular Characterization of Legionellosis Drug Target Candidate Enzyme Phosphoglucosamine Mutase from Legionella pneumophila (strain Paris): An In Silico Approach

The harshness of legionellosis differs from mild Pontiac fever to potentially fatal Legionnaire's disease. The increasing development of drug resistance against legionellosis has led to explore new novel drug targets. It has been found that phosphoglucosamine mutase, phosphomannomutase, and phosphoglyceromutase enzymes can be used as the most probable therapeutic drug targets through extensive data mining. Phosphoglucosamine mutase is involved in amino sugar and nucleotide sugar metabolism. The purpose of this study was to predict the potential target of that specific drug. For this, the 3D structure of phosphoglucosamine mutase of Legionella pneumophila (strain Paris) was determined by means of homology modeling through Phyre2 and refined by ModRefiner. Then, the designed model was evaluated with a structure validation program, for instance, PROCHECK, ERRAT, Verify3D, and QMEAN, for further structural analysis. Secondary structural features were determined through self-optimized prediction method with alignment (SOPMA) and interacting networks by STRING. Consequently, we performed molecular docking studies. The analytical result of PROCHECK showed that 95.0% of the residues are in the most favored region, 4.50% are in the additional allowed region and 0.50% are in the generously allowed region of the Ramachandran plot. Verify3D graph value indicates a score of 0.71 and 89.791, 1.11 for ERRAT and QMEAN respectively. Arg419, Thr414, Ser412, and Thr9 were found to dock the substrate for the most favorable binding of S-mercaptocysteine. However, these findings from this current study will pave the way for further extensive investigation of this enzyme in wet lab experiments and in that way assist drug design against legionellosis.

Enfoque al riesgo de Legionella sp. en centros sanitarios del sur de España / Approach to the risk of Legionella spp. in health centres in the south of Spain

La legionelosis es una enfermedad respiratoria producida por la bacteria legionella sp. Ésta al colonizar medios artificiales presenta un riesgo para la salud, especialmente en ambientes con población expuesta o especialmente sensible. El ámbito sanitario se presenta como vulnerable, en el que es usual identificar fuentes de desarrollo y proliferación del agente biológico. El objetivo del estudio es establecer la relación entre la estacionalidad de equipos de intercambio aire-agua y la presencia de legionella pneumophila, así como investigar la de ciertos métodos preventivos de desinfección del agua sobre las variables anteriores. Durante 2008 se realiza un estudio en cuatro centros sanitarios situados en Andalucía (España) incluyendo siete torres de refrigeración ubicadas en ellos. Mediante un análisis descriptivo y el empleo de medidas de asociación se identificó: un recuento elevado (>10000 UFC/l) en dispositivos de funcionamiento anual, según los métodos de desinfección empleados un riesgo menor en instalaciones estacionales, e independencia entre el recuento de la bacteria y la estacionalidad de los sistemas. A nivel sanitario y con objeto de prevenir la presencia de la bacteria en el sur de España, se considera preceptivo la realización de estudios ambientales y de control del mantenimiento higiénico de las instalaciones con riesgo de desarrollo de legionella sp.

Legionellosis is a respiratory disease caused by the bacterium Legionella spp. When this colonizes artificial mediums it shows a health risk, especially in environments with particularly sensitive or exposed population. The health centre environment is presented as vulnerable, where it is usual to identify sources of development and proliferation of biological agent. The aim of this study is to establish the relationship between seasonal use of water cooling systems and the presence of Legionella pneumophila, and to investigate certain preventive methods of water disinfection on the above variables. In 2008, a study was performed in four health centres situated in Andalusia (Spain) including seven cooling towers located on them. Through a descriptive analysis and the use of measures of association, these findings were identified: a high count (>10,000 CFU/l) in annual operating devices, according to the methods of disinfection a lower risk in seasonal facilities, and independence between the count of the bacterium and seasonal nature of the systems. At health level and in order to prevent the presence of the bacterium in southern Spain, environmental studies and routine monitoring of sanitary maintenance of facilities with risk of development of Legionella spp. are considered mandatory.

Acciones de prevención y control de la legionelosis: un reto para la salud pública española / Actions for legionellosis prevention and control: a challenge for public health in Spain

La legionelosis es una enfermedad respiratoria con origen en sistemas que formen aerosol y que contenga el agente biológico Legionella sp. En las últimas décadas se ha desarrollado en España un marco normativo para su prevención y control. El presente artículo expone la epidemiología de la legionelosis y la importancia del control de la transmisión de la bacteria en la lucha contra la enfermedad. Para ello, se hace patente la revisión de las instalaciones críticas y la inclusión de otras nuevas en la legislación preventiva así como la estimación del riesgo, la mejora en los procesos de diagnóstico y el avance en nuevos protocolos de prevención.

Legionellosis is a respiratory disease originating in systems that produce aerosol and contain Legionella sp. In recent decades, Spain has developed a regulatory framework for prevention and control of legionellosis. This article describes the epidemiology of legionellosis and the importance of controlling the transmission of bacteria in the fight against the disease. In that regard, it becomes clear the role of reviewing critical facilities and the inclusion of new ones in the preventive legislation, the estimation of risk, and the improvement in the diagnostic processes and progress in new prevention protocols.

An unprecedented outbreak investigation for nosocomial and community-acquired legionellosis in Hong Kong / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The environmental sources associated with community-acquired or nosocomial legionellosis were not always detectable in the mainland of China and Hong Kong, China. The objective of this study was to illustrate the control measures implemented for nosocomial and community outbreaks of legionellosis, and to understand the environmental distribution of legionella in the water system in Hong Kong, China.</p><p><b>METHODS</b>We investigated the environmental sources of two cases of legionellosis acquired in the hospital and the community by extensive outbreak investigation and sampling of the potable water system using culture and genetic testing at the respective premises.</p><p><b>RESULTS</b>The diagnosis of nosocomial legionellosis was suspected in a patient presenting with nosocomial pneumonia not responsive to multiple beta-lactam antibiotics with subsequent confirmation by Legionella pneumophila serogroup 1 antigenuria. High counts of Legionella pneumophila were detected in the potable water supply of the 70-year-old hospital building. Another patient on continuous ambulatory peritoneal dialysis presenting with acute community-acquired pneumonia and severe diarrhoea was positive for Legionella pneumophila serogroup 1 by polymerase chain reaction (PCR) testing on both sputum and nasopharyngeal aspirate despite negative antigenuria. Paradoxically the source of the second case was traced to the water system of a newly commissioned office building complex. No further cases were detected after shock hyperchlorination with or without superheating of the water systems. Subsequent legionella counts were drastically reduced. Point-of-care infection control by off-boiled or sterile water for mouth care and installation of water filter for showers in the hospital wards for immunocompromised patients was instituted. Territory wide investigation of the community potable water supply showed that 22.1% of the household water supply was positive at a mean legionella count of 108.56 CFU/ml (range 0.10 to 639.30 CFU/ml).</p><p><b>CONCLUSIONS</b>Potable water systems are open systems which are inevitably colonized by bacterial biofilms containing Legionella species. High bacterial counts related to human cases may occur with stagnation of flow in both old or newly commissioned buildings. Vigilance against legionellosis is important in healthcare settings with dense population of highly susceptible hosts.</p>

Molecular Epidemiology of Legionella pneumophila Isolated from Bath Facilities of Public Establishments in Seoul

The genus Legionella is common in aquatic environments. Some species of Legionella are recognized as potential opportunistic pathogens for human, notably Legionella pneumophila that causes Legionellosis. During the summer season between June and August in 2010, we isolated 61 L. pneumophila from the bath facilities of public establishments of 25 wards in Seoul. The existence of 16S rRNA and mip gene of L. pneumophila was confirmed in the genome of the isolated strains by PCR. Among the 61 strains of L. pneumophila, thirty three isolates belong to serogroup 1 (54.1%), 13 isolates were serogroup 6 (21.3%), 9 isolates were serogroup 5 (14.8%), 3 isolates were serogroup 3 (4.9%), and 3 isolates were identified in serogroup 2 (4.9%). On pulsed-field gel electrophoresis (PFGE) analysis using SfiI, genetic types of L. pneumophila were classified into 8 (A to H) patterns by the band similarity with excess of 65%. Our results suggest the existence of serological and genetic diversity among the L. pneumophila isolates.

Emerging Infectious Diseases in the Republic of Korea

Many infectious diseases have emerged or re-emerged during the past 50 years in the Republic of Korea. Some of these are new infectious diseases delivered by new or newly recognized micro-organisms. Others are already known infectious diseases which have increased in frequency or have developed an expanded region of occurrence. Still others are infectious diseases that are caused by the same micro-organisms which are resistant to antibiotics, and therefore difficult to treat. Newly recognized Emerging Infectious Diseases (EIDs) include legionellosis, leptospirosis, tsutsugamushi diseases, Vibrio vulnificus sepsis, and brucellosis. New EIDs include acquired immunodeficiency syndrome, enterohemorrhagic E. coli infection, Creutzfeldt-Jacob disease. Of the EIDs occurred in the Republic of Korea during the past 50 years, healthcare-related infections, especially by antibiotic-resistant organisms, are the most important EIDs in terms of morbidity and mortality.

Comparing anti Legionella antibody titers between hospital workers and healthy population; a case-control study

To determinate Legionella antibody titers among healthcare workers and healthy population. The blood samples were collected from all 360 subjects [case and control] and the ELISA method was used to assess the anti-Legionella IgG titer. The statistical analyses were performed using the SPSS software version 13. The mean of antibody titer was 5 +/- 0.38 in all participants. There was a 95.6% negative and a 2.2% positive antibody titer in the case group. In the control group, the negativity rate was 91.1% and the positivity rate was 6.7%. The antibody titer difference between two groups was not statistically significant [P value= 0.167]. The total antibody titer in both healthcare workers and healthy population was not high and the difference was not significant

Antimicrobial Susceptibility Patterns of Legionella isolates in the Environment and in Patients / 대한진단검사의학회지

BACKGROUND: Antimicrobial susceptibility of Legionella spp. has rarely been studied in Korea. Therefore, we aimed to determine the susceptibility of Legionella spp. to various antibiotics. METHODS: We assessed the antimicrobial susceptibility of 66 environmental and clinical Legionella isolates collected between January 2001 and December 2008 from Korea and Japan. The minimum inhibitory concentrations (MICs) of 6 antibiotics, namely, azithromycin, ciprofloxacin, clarithromycin, clindamycin, gatifloxacin, and gemifloxacin were determined by the broth microdilution method using buffered starch yeast extract broth. RESULTS: The MIC ranges of the 6 antibiotics used against the Legionella isolates were as follows: 0.004-0.062 microgram/mL (azithromycin), 0.002-0.5 microgram/mL (ciprofloxacin), 0.004-0.5 microgram/mL (clarithromycin), 0.12-4 microgram/mL (clindamycin), 0.002-0.12 microgram/mL (gatifloxacin), and 0.008-1 microgram/mL (gemifloxacin). CONCLUSIONS: Legionella spp. isolates from Korea and Japan were most susceptible to gatifloxacin. Azithromycin, clarithromycin, ciprofloxacin, and gemifloxacin were also effective for treating legionellosis.

Surveillance of Legionella Contamination on Water Supply Systems of Public Utilizing Facilities in Gwangju, Korea

Legionella is a pathogenic bacteria associated to aquatic habit of natural and artificial environments. Clinical cases of legionellosis have been reported in Korea but there is a lack of information about the incidence of this bacterium on environmental sources. Thus, we investigated the contamination of Legionella on water supply systems in Gwangju, Korea, including cooling towers, public baths, hospitals and fountains. Legionella spp. were detected from 81 samples (16.9%) out of 480 samples collected and the major species of Legionella isolates was identified to L. pneumophila serogroup (sg) 1 (n=33). The result of PFGE pattern analysis for L. pneumophila sg 1 isolates was discriminated into 11 pulsotypes. In dendrogram of PFGE, the clusters of isolates from cooling tower were quite different from those derived from hot water system of public bath. Surveillance for 4 sentinel public baths showed that their water supply systems had been contaminated with Legionella spp. and L. pneumophila sg 5 or sg 6 was the major isolate. The similarity of its PFGE patterns was 92.3%, 96.6%, respectively. Thus, PFGE may be a useful tool in molecular epidemiology studies, and the monitor and control for water supply systems of public utilizing facilities will be able to provide a resolution for the reduction of Legionella infection.

Surveillance of Legionella Contamination on Water Supply Systems of Public Utilizing Facilities in Gwangju, Korea

Legionella is a pathogenic bacteria associated to aquatic habit of natural and artificial environments. Clinical cases of legionellosis have been reported in Korea but there is a lack of information about the incidence of this bacterium on environmental sources. Thus, we investigated the contamination of Legionella on water supply systems in Gwangju, Korea, including cooling towers, public baths, hospitals and fountains. Legionella spp. were detected from 81 samples (16.9%) out of 480 samples collected and the major species of Legionella isolates was identified to L. pneumophila serogroup (sg) 1 (n=33). The result of PFGE pattern analysis for L. pneumophila sg 1 isolates was discriminated into 11 pulsotypes. In dendrogram of PFGE, the clusters of isolates from cooling tower were quite different from those derived from hot water system of public bath. Surveillance for 4 sentinel public baths showed that their water supply systems had been contaminated with Legionella spp. and L. pneumophila sg 5 or sg 6 was the major isolate. The similarity of its PFGE patterns was 92.3%, 96.6%, respectively. Thus, PFGE may be a useful tool in molecular epidemiology studies, and the monitor and control for water supply systems of public utilizing facilities will be able to provide a resolution for the reduction of Legionella infection.