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Can mandatory monitoring in rental apartments effectively prevent legionellosis? A retrospective analysis of data from Regensburg with a review of the literature

Lampl BMJ, Lang M, Wodnick S.

Public Health Department, Regensburg, Germany.

GMS Hyg Infect Control 2020 Jun 30;15:Doc14.

Abstract: Background: Legionella pneumophila can cause severe, often fatal, pneumonia in humans. Mandatory water sampling in commercially used buildings (mainly rental apartments) as regulated in the Drinking Water Ordinance (Trinkwasserverordnung) aim to protect the population against infection with Legionella. However, no data exist to date that could prove the effectiveness of the measures. At the same time, having the Public Health Department's Infection Control Division deal with Legionella is very time consuming. Methods: A retrospective analysis of data from the city and district of Regensburg, a selective literature search, a prospective survey of workload using an anonymous questionnaire were performed. Results: The evaluated data from the city/district of Regensburg suggest underreporting to a similar extent as shown by the RKI's data in the compared period. Neither is the actual incidence known, nor can exposures be clearly determined in most cases. The exposure categories "travel" and "private/occupational" seem to be the most pertinent. The potential public hazard of Legionella posed by domestic plumbing systems is unclear. A connection between exceeding the technical measurement limit (TMW) in routine tests in rental apartments and disease cases cannot be shown. A survey among non-medical personnel in the field of infection control and hygiene on the time spent on the topic of Legionella yielded a mean number of 39% of daily working hours for the observed 2-month period. Conclusion: The data on incidence, exposure, and causality are incomplete. Evidence of effective protection by the current practice of sampling in apartment buildings could not be found. For many aspects, there are no unambiguous data in the literature. Restricting mandatory monitoring to certain public/commercial institutions should be discussed, given the high workload for the Public Health Department and the unproven protective effect. Further research on this topic is necessary.


Prevention and Control of Legionella and Pseudomonas spp. Colonization in Dental Units

Tuvo B, Totaro M, Cristina ML, Spagnolo AM, Di Cave D, Profeti S, Baggiani A, Privitera G, Casini B.

Department of Translational Research, N.T.M.S., University of Pisa, Pisa, Italy.

Pathogens 2020 Apr 21;9(4):305.

Abstract: Introduction: Dental Unit Waterlines (DUWLs) have shown to be a source of Legionella infection. We report the experience of different dental healthcare settings where a risk management plan was implemented. Materials and methods: In a Hospital Odontostomatology Clinic (HOC) and three Private Dental Clinics (PDCs) housing 13 and six dental units (DUs), respectively, an assessment checklist was applied to evaluate staff compliance with guideline recommendations. DUWLs microbial parameters were investigated before and after the application of corrective actions. Results: In the HOC a poor adherence to good practices was demonstrated, whereas protocols were carefully applied in PDCs. L. pneumophila sg 2-15 was isolated in 31% (4/13) and 33% (2/6) of DUs in HOC and PDCs, respectively, mainly from handpieces (32%, 6/19) with counts >102 colony-forming units per milliliter (CFU/L), often associated with P. aeruginosa (68%, 13/19). The shock disinfection with 3% v/v hydrogen peroxide (HP) showed a limited effect, with a recolonization period of about 4 weeks. Legionella was eradicated only after 6% v/v HP shock disinfection and filters-installation, whilst P. aeruginosa after the third shock disinfection with a solution of 4% v/v HP and biodegradable surfactants. Conclusions: Our data demonstrate the presence and persistence of microbial contamination within the DUWLs, which required strict adherence to control measures and the choice of effective disinfectants.


Implementation of Legionella Prevention Policy in Health Care Facilities: The United States Veterans Health Administration Experience

Ambrose M, Kralovic SM, Roselle GA, Kowalskyj O, Rizzo V Jr, Wainwright DL, Gamage SD.

National Infectious Diseases Service, Specialty Care Services, Veterans Health Administration, Department of Veterans Affairs, Washington, District of Columbia.

J Public Health Manag Pract 2020 Mar/Apr;26(2):E1-E11.

Abstract: Context: The Veterans Health Administration requires implementation of Legionella prevention policy in potable water systems at Department of Veterans Affairs (VA) medical facilities across the United States and territories. Program: The Veterans Health Administration Central Office program offices with expertise in engineering and clinical aspects of Legionella prevention policy have provided joint, structured on-site assistance to VA medical facilities for consultation on policy implementation. Site visits included review of facility documentation and data, discussions with staff, touring of buildings, and development of recommendations. Implementation: Information obtained from on-site consultative assistance provided to VA medical facilities from December 2012 through January 2018 was reviewed to identify engineering and clinical challenges and lessons from implementation of Legionella prevention policy in VA health care buildings. Fifteen consultative site visits were conducted during this period regarding implementation of Legionella prevention and validation of effectiveness. Evaluation: It was found that implementation of Legionella prevention policy in potable water systems was complex and practices varied for each building. Common implementation challenges included capability of applying engineering controls, water stagnation, and assessment of health care association of Legionella cases. Process challenges included routine verification of actions, methods for assessing environmental validation data, and documentation of requirements. It was found that consistent and data-driven implementation of policy is crucial for an effective program. Discussion: Guidance and standards documents in the community for Legionella prevention in building water systems are often general in nature, but implementation requires specific decisions and routine assessments and modifications to optimize outcomes. This real-world review of challenges and lessons from a large health care system with a detailed primary Legionella prevention policy informs future development of guidance and policy, both within and external to VA, and can provide insight to other health care facilities planning to implement practices for water safety.


Water Quality as a Predictor of Legionella Positivity of Building Water Systems

Pierre D, Baron JL, Ma X, Sidari FP 3rd, Wagener MM, Stout JE.

Special Pathogens Laboratory, Pittsburgh, PA 15219, USA.

Pathogens 2019 Dec;8(4):295.

Abstract: Testing drinking water systems for the presence of Legionella colonization is a proactive approach to assess and reduce the risk of Legionnaires' disease. Previous studies suggest that there may be a link between Legionella positivity in the hot water return line or certain water quality parameters (temperature, free chlorine residual, etc.) with distal site Legionella positivity. It has been suggested that these measurements could be used as a surrogate for testing for Legionella in building water systems. We evaluated the relationship between hot water return line Legionella positivity and other water quality parameters and Legionella colonization in premise plumbing systems by testing 269 samples from domestic cold and hot water samples in 28 buildings. The hot water return line Legionella positivity and distal site positivity only demonstrated a 77.8% concordance rate. Hot water return line Legionella positivity compared to distal site positivity had a sensitivity of 55% and a specificity of 96%. There was poor correlation and a low positive predictive value between the hot water return line and distal outlet positivity. There was no correlation between Legionella distal site positivity and total bacteria (heterotrophic plate count), pH, free chlorine, calcium, magnesium, zinc, manganese, copper, temperature, total organic carbon, or incoming cold-water chlorine concentration. These findings suggest that hot water return line Legionella positivity and other water quality parameters are not predictive of distal site positivity and should not be used alone to determine the building's Legionella colonization rate and effectiveness of water management programs


Legionellosis in Health Care Facilities: State of the Art in Control and Prevention in Italy

Napoli C, De Giglio O, Bertamino E, Montagna MT.

Department of Medical Surgical Sciences and Translational Medicine, Sapienza University of Rome, Rome, Italy.

Ann Ig 2019 Sep-Oct;31(5):474-481.  

Abstract: Background: Nosocomial water systems may be contaminated by Legionella spp; therefore, health care facilities represent a potential health risk for patients and health care staff. Active, well-planned clinical and environmental surveillance in hospitals is the most important instrument of prevention. Aims and methods: The aim of the present article was to outline the state of the art in legionellosis control and prevention among Italian health care facilities by reporting some experiences in the field. Results: Our results showed that Legionella spp. are largely reported as both hospital water system contaminants and etiological agents in water-related health care-associated infections (HCAI) in Italy. Among the numerous sources of HCAI, water is the most investigated, although it has been demonstrated that air sampling may provide additional information for risk assessment. Conclusions: More appropriate risk assessment is needed, especially in large facilities. In addition, more sensitive diagnostic tests should be used and dedicated training courses should be implemented in health care facilities.


Overview and Comparison of Legionella Regulations Worldwide

Van Kenhove EDinne KJanssens ALaverge J.

Research Group Building Physics, Construction and Climate Control, Department of Architecture and Urban Planning, Ghent University, Ghent, Belgium.

Am J Infect Control 2019 Aug;47(8):968-978.

Abstract: Background: Legionnaires disease occurs worldwide. Many authorities have guidelines and regulations to prevent and control Legionella in water systems. These regulations are based on often very limited field and laboratory observations and measurements. They are, therefore, very different from country to country. This article aims to map the existing regulatory framework of worldwide Legionella control to assess the feasibility of regulatory unification. Methods: This article gives an overview of the different standards, guidelines, and recommendations as well as how various authorities and/or countries deal with Legionella infection. A 3-step process is followed to identify current regulations. Results: Although Legionella is a global concern with a common scientific base, the regulatory framework is different from country to country. The current guidelines and standards are not the best possible. Despite different regulatory frameworks, there is still broad unification of underlying principles. Common principles across regulations are avoiding and monitoring critical spots, avoiding water stagnation, and maintaining sufficiently high temperature (above 60°C, below 25°C). Differences between regulations are target group and dangerous Legionella concentration levels. Conclusions: The comparative analysis of the framework is a good starting point for reaching future regulatory unification based on common ground.


Risk-Based Critical Concentrations of Legionella pneumophila for Indoor Residential Water Uses

Hamilton KA, Hamilton MT, Johnson W, Jjemba P, Bukhari Z, LeChevallier M, Haas CN, Gurian PL.

School for Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona, USA.

Environ Sci Technol 2019 Apr;53(8):4528-4541.

Abstract: Legionella spp. is a key contributor to the United States waterborne disease burden. Despite potentially widespread exposure, human disease is relatively uncommon, except under circumstances where pathogen concentrations are high, host immunity is low, or exposure to small-diameter aerosols occurs. Water quality guidance values for Legionella are available for building managers but are generally not based on technical criteria. To address this gap, a quantitative microbial risk assessment (QMRA) was conducted using target risk values in order to calculate corresponding critical concentrations on a per-fixture and aggregate (multiple fixture exposure) basis. Showers were the driving indoor exposure risk compared to sinks and toilets. Critical concentrations depended on the dose response model (infection vs clinical severity infection, CSI), risk target used (infection risk vs disability adjusted life years [DALY] on a per-exposure or annual basis), and fixture type (conventional vs water efficient or "green"). Median critical concentrations based on exposure to a combination of toilet, faucet, and shower aerosols ranged from 10-2 to 100 CFU per L and 101 to 103 CFU per L for infection and CSI dose response models, respectively. As infection model results for critical L. pneumophila concentrations were often below a feasible detection limit for culture-based assays, the use of CSI model results for nonhealthcare water systems with a 10-6 DALY pppy target (the more conservative target) would result in an estimate of 12.3 CFU per L (arithmetic mean of samples across multiple fixtures and/or over time). Single sample critical concentrations with a per-exposure-corrected DALY target at each conventional fixture would be 1.06×103 CFU per L (faucets), 8.84×103 CFU per L (toilets), and 14.4 CFU per L (showers). Using a 10-4 annual infection risk target would give a 1.20×103 CFU per L mean for multiple fixtures and single sample critical concentrations of 1.02×105, 8.59×105, and 1.40×103 CFU per L for faucets, toilets, and showers, respectively. Annual infection risk-based target estimates are in line with most current guidance documents of less than 1000 CFU per L, while DALY-based guidance suggests lower critical concentrations might be warranted in some cases. Furthermore, approximately <10 CFU per mL L. pneumophila may be appropriate for healthcare or susceptible population settings. This analysis underscores the importance of the choice of risk target as well as sampling program considerations when choosing the most appropriate critical concentration for use in public health guidance.


Environmental Surveillance of Legionellosis Within an Italian University Hospital-Results of 15 Years of Analysis

Laganà PFacciolà APalermo RDelia S.

Regional Reference Laboratory of Clinical and Environmental Surveillance of Legionellosis, Branch of Messina, Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy.

Int J Environ Res Public Health 2019 Mar;16(7):1103. 

Abstract: Legionnaires' disease is normally acquired by inhalation of legionellae from a contaminated environmental source. Water systems of large and old buildings, such as hospitals, can be contaminated with legionellae and therefore represent a potential risk for the hospital population. In this study, we demonstrated the constant presence of Legionella in water samples from the water system of a large university hospital in Messina (Sicily, Italy) consisting of 11 separate pavilions during a period of 15 years (2004-2018). In total, 1346 hot water samples were collected between January 2004 and December 2018. During this period, to recover Legionella spp. from water samples, the standard procedures reported by the 2000 Italian Guidelines were adopted; from May 2015 to 2018 Italian Guidelines revised in 2015 (ISS, 2015) were used. Most water samples (72%) were positive to L. pneumophila serogroups 2-14, whereas L. pneumophila serogroup 1 accounted for 18% and non-Legionella pneumophila spp. accounted for 15%. Most of the positive samples were found in the buildings where the following critical wards are situated: (Intensive Care Unit) ICU, Neurosurgery, Surgeries, Pneumology, and Neonatal Intensive Unit Care. This study highlights the importance of the continuous monitoring of hospital water samples to prevent the potential risk of nosocomial legionellosis.


A Proactive Environmental Approach for Preventing Legionellosis in Infants: Water Sampling and Antibiotic Resistance Monitoring, a 3-Years Survey Program

Alexandropoulou IParasidis T, Konstantinidis TPanopoulou MConstantinidis TC.

Laboratory of Hygiene and Environmental Protection, Medical School, Democritus University of Thrace, Alexandroupolis, Greece.

Healthcare (Basel) 2019 Mar;7(1):39. 

Abstract: A proactive environmental monitoring program was conducted to determine the risk and prevent nosocomial waterborne infections of Legionella spp. in infants. Sink taps in a neonatal intensive care unit (NICU) and two obstetric clinics were monitored for Legionella spp. A total of 59 water samples were collected during a 3-year period and 20 of them were found colonized with Legionella pneumophila. Standard culture, molecular, and latex agglutination methods were used for the detection and identification of Legionella bacteria. Hospital personnel also proceeded with remedial actions (hyperchlorination and thermal shock treatment) in the event of colonization. The minimal inhibitory concentration (MIC) values of erythromycin, ciprofloxacin was determined for Legionella isolates using the e-test method. Our data indicate that the majority of neonatal sink-taps were colonized at least once during the study with Legionella spp. Among 20 isolates, 5 were considered as low-level resistant, 3 in erythromycin and 2 in ciprofloxacin, while no resistant strains were detected. Environmental surveillance in neonatal and obstetric units is suggested to prevent waterborne infections, and thus to reduce the risk of neonatal nosocomial infections.


Control of Legionellae in a New Healthcare Facility Following Implementation of a Thermal Control Strategy

Lecointe D, Beauvais RBreton NCailleret RPangon B.

Unité Fonctionnelle d'Hygiène Hospitalière et de Lutte contre les Infections Nosocomiales, Centre Hospitalier Sud Francilien, Corbeil-Essonnes, France.

Infect Dis (Lond) 2019 Feb;51(2):102-112.

Abstract: Introduction: The management of the Legionella risk in hospitals is essentially related to preventive measures of the hot-water supplies. Aim: To monitor the control of legionellae before and after moving to a new hospital facility. Methods: We implemented a survey program based on the surveillance of the temperature of the hot-water supply and detection and counting of Legionella pneumophila and Legionella spp. by quantitative polymerase chain reaction and culture methods. Results: Our survey program revealed that the hot-water system was colonized by L. pneumophila and Legionella spp. before the arrival of the first patients, despite the implementation of preventive measures. Thus, maintenance on the hot-water production system and subsequent cleaning and superheat disinfection of the hot-water supplies were performed, leading to the eradication of L. pneumophila reservoirs and the decrease of Legionella spp. reservoirs. No reservoirs of L. pneumophila and only rare persistent reservoirs of Legionella spp. were detected after the transfer of hospitalized patients to the new healthcare facility and during the following four years, demonstrating the effectiveness of our corrective measures, without using biocides. L. anisa was identified as the only strain of viable and cultivable Legionella spp. and was undetected during the last year. Conclusions: The strict application of our survey program before and after moving to the new hospital associated with strict implementation of corrective measures allowed us to efficiently manage the Legionella-linked risk during this period.


Preventing Hospital-Acquired Legionnaires' Disease: A Snapshot of Clinical Practices and Water Management Approaches in US Acute-Care Hospitals

Ehret KM, Chamberlain AT, Berkelman RL, Fridkin SK.

Rollins School of Public Health, Emory University, Atlanta, Georgia.

Infect Control Hosp Epidemiol 2018 Dec;39(12):1470-1472

Abstract: In 2017, we surveyed 101 SHEA Research Network hospitals regarding Legionnaires' disease (LD). Of 29 respondents, 94% have or are developing a water management plan with varying characteristics and personnel engaged. Most LD diagnostic testing is limited to urine antigen testing. Many opportunities to improve LD prevention and diagnosis exist.


Control and Prevention Measures for Legionellosis in Hospitals: A Cross-Sectional Survey in Italy

Montagna MT, De Giglio O, Napoli C, Diella G, Rutigliano S, Agodi A, Auxilia F, Baldovin T, Bisetto F, Arnoldo L, Brusaferro S, Busetti M, Calagreti G, Casini B, Cristina ML, Di Luzio R, Fiorio M, Formoso M, Liguori G, Martini E, Molino A, Mondello P, Mura I, Novati R, Orsi GB, Patroni A, Poli A, Privitera G, Ripabelli G, Rocchetti A, Rose F, Sarti M, Savini S, Silvestri A, Sodano L, Spagnolo AM, Tardivo S, Teti V, Torregrossa MV, Torri E, Veronesi L, Zarrilli R, Pacifico C, Goglio A, Moro M, Pasquarella C.

Department of Biomedical Science and Human Oncology, University of Bari Aldo Moro, Bari, Italy.

Environ Res 2018 Oct;166:55-60.

Abstract: Risk assessment, environmental monitoring, and the disinfection of water systems are the key elements in preventing legionellosis risk. The Italian Study Group of Hospital Hygiene of the Italian Society of Hygiene, Preventive Medicine, and Public Health and the Italian Multidisciplinary Society for the Prevention of Health Care-Associated Infections carried out a national cross-sectional survey to investigate the measures taken to prevent and control legionellosis in Italian hospitals. A multiple-choice questionnaire was developed, comprising 71 questions regarding hospital location, general characteristics, clinical and environmental surveillance, and control and preventive measures for legionellosis in 2015. Overall, 739 hospitals were enrolled from February to June 2017, and 178 anonymous questionnaires were correctly completed and evaluated (response rate: 24.1%). The survey was conducted using the SurveyMonkey® platform, and the data were analyzed using Stata 12 software. Of the participating hospitals, 63.2% reported at least one case of legionellosis, of which 28.2% were of proven nosocomial origin. The highest case numbers were reported in the Northern Italy, in hospitals with a pavilion structure or cooling towers, and in hospitals with higher numbers of beds, wards and operating theaters. Laboratory diagnosis was performed using urinary antigen testing alone (31.9%), both urinary antigen testing and single antibody titer (17.8%), or with seroconversion also added (21.5%). Culture-based or molecular investigations were performed in 28.8% and 22.1% of the clinical specimens, respectively. The water systems were routinely tested for Legionella in 97.4% of the hospitals, 62% of which detected a positive result (>1000 cfu/L). Legionella pneumophila serogroup 2-15 was the most frequently isolated species (58.4%). The most common control measures were the disinfection of the water system (73.7%), mostly through thermal shock (37.4%) and chlorine dioxide (34.4%), and the replacement (69.7%) or cleaning (70.4%) of faucets and showerheads. A dedicated multidisciplinary team was present in 52.8% of the hospitals, and 73% of the hospitals performed risk assessment. Targeted training courses were organized in 36.5% of the hospitals, involving nurses (30.7%), physicians (28.8%), biologists (21.5%), technicians (26.4%), and cleaners (11%). Control and prevention measures for legionellosis are present in Italian hospitals, but some critical aspects should be improved. More appropriate risk assessment is necessary, especially in large facilities with a high number of hospitalizations. Moreover, more sensitive diagnostic tests should be used, and dedicated training courses should be implemented.


Environmental Surveillance of Legionella pneumophila in Distal Water Supplies of a Hospital for Early Identification & Prevention of Hospital-Acquired Legionellosis

Jinna SGaikwad UN.

Department of Microbiology, All India Institute of Medical Sciences, Raipur, India.

Indian J Med Res 2018 Jun;147(6):611-614.

Abstract: Background & objectives: Legionella pneumophila, a ubiquitous aquatic organism is found to be associated with the development of the community as well as hospital-acquired pneumonia. Diagnosing Legionella infection is difficult unless supplemented with, diagnostic laboratory testing and established evidence for its presence in the hospital environment. Hence, the present study was undertaken to screen the hospital water supplies for the presence of L. pneumophila to show its presence in the hospital environment further facilitating early diagnosis and prevention of hospital-acquired legionellosis. Methods: Water samples and swabs from the inner side of the same water taps were collected from 30 distal water outlets present in patient care areas of a tertiary care hospital. The filtrate obtained from water samples as well as swabs were inoculated directly and after acid buffer treatment on plain and selective (with polymyxin B, cycloheximide and vancomycin) buffered charcoal yeast extract medium. The colonies grown were identified using standard methods and confirmed for L. pneumophila by latex agglutination test. Results: About 6.66 per cent (2/30) distal water outlets sampled were found to be contaminated with L. pneumophila serotype 2-15. Isolation was better with swabs compared to water samples. Interpretation & conclusions: The study showed the presence of L. pneumophila colonization of hospital water outlets at low levels. Periodic water sampling and active clinical surveillance in positive areas may be done to substantiate the evidence, to confirm or reject its role as a potential nosocomial pathogen in hospital environment.


Hospital Water Management Programs for Legionella Prevention, Minnesota, 2017

Danila RNKoranteng N, Como-Sabetti KJ, Robinson TJ, Laine ES.

Minnesota Department of Health, St Paul, Minnesota, USA.

Infect Control Hosp Epidemiol 2018 Mar;39(3):336-338.

Abstract: Infection preventionists at Minnesota hospitals were surveyed to determine whether they had Legionella water management plans. Of 137 hospitals, 84 (61%) responded. Among them, 27% hospitals had a water management plan, 21% regularly sampled for Legionella, and 51% had knowledge of ASHRAE Legionella prevention standards. Significant changes are needed to protect patients from nosocomial infection.


Surveillance for Waterborne Disease Outbreaks Associated with Drinking Water - United States, 2013-2014

Benedict KM, Reses H, Vigar M, Roth DM, Roberts VA, Mattioli M, Cooley LA, Hilborn ED, Wade TJ, Fullerton KE, Yoder JS, Hill VR.

Epidemic Intelligence Service, CDC;

MMWR Morb Mortal Wkly Rep 2017 Nov;66(44):1216-1221.

Abstract: Provision of safe water in the United States is vital to protecting public health (1). Public health agencies in the U.S. states and territories report information on waterborne disease outbreaks to CDC through the National Outbreak Reporting System (NORS) ( During 2013-2014, 42 drinking water-associated outbreaks were reported, accounting for at least 1,006 cases of illness, 124 hospitalizations, and 13 deaths. Legionella was associated with 57% of these outbreaks and all of the deaths. Sixty-nine percent of the reported illnesses occurred in four outbreaks in which the etiology was determined to be either a chemical or toxin or the parasite Cryptosporidium. Drinking water contamination events can cause disruptions in water service, large impacts on public health, and persistent community concern about drinking water quality. Effective water treatment and regulations can protect public drinking water supplies in the United States, and rapid detection, identification of the cause, and response to illness reports can reduce the transmission of infectious pathogens and harmful chemicals and toxins.