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Clements E, Crank K, Nerenberg R, Atkinson A, Gerrity D, Hannoun D. Quantitative Microbial Risk Assessment Framework Incorporating Water Ages with Legionella pneumophila Growth Rates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6540-6551. [PMID: 38574283 PMCID: PMC11025131 DOI: 10.1021/acs.est.4c01208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/20/2024] [Accepted: 03/21/2024] [Indexed: 04/06/2024]
Abstract
Water age in drinking water systems is often used as a proxy for water quality but is rarely used as a direct input in assessing microbial risk. This study directly linked water ages in a premise plumbing system to concentrations of Legionella pneumophila via a growth model. In turn, the L. pneumophila concentrations were used for a quantitative microbial risk assessment to calculate the associated probabilities of infection (Pinf) and clinically severe illness (Pcsi) due to showering. Risk reductions achieved by purging devices, which reduce water age, were also quantified. The median annual Pinf exceeded the commonly used 1 in 10,000 (10-4) risk benchmark in all scenarios, but the median annual Pcsi was always 1-3 orders of magnitude below 10-4. The median annual Pcsi was lower in homes with two occupants (4.7 × 10-7) than with one occupant (7.5 × 10-7) due to more frequent use of water fixtures, which reduced water ages. The median annual Pcsi for homes with one occupant was reduced by 39-43% with scheduled purging 1-2 times per day. Smart purging devices, which purge only after a certain period of nonuse, maintained these lower annual Pcsi values while reducing additional water consumption by 45-62%.
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Affiliation(s)
- Emily Clements
- Southern
Nevada Water Authority, P.O. Box 99954, Las Vegas, Nevada 89193, United States
| | - Katherine Crank
- Southern
Nevada Water Authority, P.O. Box 99954, Las Vegas, Nevada 89193, United States
| | - Robert Nerenberg
- Department
of Civil & Environmental Engineering & Earth Science, University of Notre Dame, 156 Fitzpatrick Hall, Notre
Dame, Indiana 46556, United States
| | - Ariel Atkinson
- Southern
Nevada Water Authority, P.O. Box 99954, Las Vegas, Nevada 89193, United States
| | - Daniel Gerrity
- Southern
Nevada Water Authority, P.O. Box 99954, Las Vegas, Nevada 89193, United States
| | - Deena Hannoun
- Southern
Nevada Water Authority, P.O. Box 99954, Las Vegas, Nevada 89193, United States
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Hayatimehr S, Mirkalantari S, Amirmozafari N, Jazi FM, Moghadam MT. Virulence Genes and Biofilm Formation Among Legionella pneumophila Isolates Collected from Hospital Water Sources. Curr Microbiol 2024; 81:141. [PMID: 38625380 DOI: 10.1007/s00284-023-03609-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 12/29/2023] [Indexed: 04/17/2024]
Abstract
Legionella pneumophila can be transmitted to people, especially immunocompromised patients, via hospital water pipe systems and cause severe pneumonia. The aim of our study was to investigate the presence of major virulence factor genes, ability of biofilms formation, and correlation between presence of Legionella isolates and temperature, pH, and residual chlorine of water. Hundred water samples were collected from nine hospitals in Tehran, Iran. Temperature, pH, and residual chlorine were determined during sampling. Different virulence genes and the ability to form biofilms were subsequently analyzed among the L. pneumophila isolates. Results showed that 12 (12%) samples were positive in culture method and all of the isolates were positive as L. pneumophila species (mip). A correlation was found between Legionella culture positivity and temperature and pH of water, but there was no significant correlation between residual chlorine of water samples and the presence of Legionella. The isolation of Legionella rate in summer and spring was higher than winter and autumn. Twelve (100%) isolates were positive for mip genes, 9 (75%) for dot genes, 8 (66.66%) for hsp, 6 (50%) for lvh, and 4 (33.33%) for rtx. All of the isolates displayed strong ability for biofilm production every three days. Two of these isolates (16.6%) displayed weak ability to form biofilm on the first day of incubation. This study revealed that water sources in hospitals were colonized by virulent Legionella and should be continuously monitored to avoid elevated concentrations of Legionella with visible biofilm formation.
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Affiliation(s)
- Sara Hayatimehr
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Shiva Mirkalantari
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran.
| | - Nour Amirmozafari
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Faramarz Masjedian Jazi
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
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Sauget M, Richard M, Chassagne S, Hocquet D, Bertrand X, Jeanvoine A. Validation of quantitative real-time PCR for detection of Legionella pneumophila in hospital water networks. J Hosp Infect 2023:S0195-6701(23)00195-0. [PMID: 37353007 DOI: 10.1016/j.jhin.2023.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/08/2023] [Accepted: 06/10/2023] [Indexed: 06/25/2023]
Abstract
BACKGROUND Rapid monitoring of Legionella pneumophila (Lp) is essential to reduce the risk of Legionnaires' disease in healthcare facilities. However, culture results take at least eight days, delaying the implementation of corrective measures. Here, we assessed the performance of a qPCR method and determined qPCR action thresholds for the detection of Lp in hospital hot water networks (HWNs). METHODS Hot water samples (n=459) were collected from a hospital HWNs. Lp were quantified using iQ-Check® Quanti real-time PCR Quantification kits (Bio-Rad) and the results were compared with those of culture. qPCR thresholds corresponding to the culture action thresholds of 10 and 1,000 CFU/L were determined on a training dataset and validated on an independent dataset. RESULTS Lp concentrations measured by culture and qPCR were correlated for both the training dataset (Spearman's correlation coefficient ρ = 0.687, p-value < 0.0001) and the validation dataset (ρ = 0.661, p-value < 0.0001). Lp qPCR positivity thresholds corresponding to culture action thresholds of 10 CFU/L was 91 genome units (GU) per liter (sensitivity, 86.4%; negative predictive value - NPV, 93.3%) and that corresponding to culture action thresholds of 1,000 CFU/L was 1,048 GU/L (sensitivity, 100%; NPV, 100%). CONCLUSION Detection of Lp by qPCR could be implemented with confidence in hospitals as a complement to culture in the monitoring strategy to speed up the implementation of corrective measures.
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Affiliation(s)
- Marlène Sauget
- Hygiène Hospitalière, Centre Hospitalier Universitaire de Besançon, Besançon, France; Centre de Ressources Biologiques, Centre Hospitalier Universitaire de Besançon, Besançon, France.
| | - Marion Richard
- Hygiène Hospitalière, Centre Hospitalier Universitaire de Besançon, Besançon, France; Centre de Ressources Biologiques, Centre Hospitalier Universitaire de Besançon, Besançon, France
| | - Sophie Chassagne
- Hygiène Hospitalière, Centre Hospitalier Universitaire de Besançon, Besançon, France
| | - Didier Hocquet
- Hygiène Hospitalière, Centre Hospitalier Universitaire de Besançon, Besançon, France; Chrono-environnement, Université de Franche-Comté, CNRS, Besançon, France; Centre de Ressources Biologiques, Centre Hospitalier Universitaire de Besançon, Besançon, France
| | - Xavier Bertrand
- Hygiène Hospitalière, Centre Hospitalier Universitaire de Besançon, Besançon, France; Chrono-environnement, Université de Franche-Comté, CNRS, Besançon, France
| | - Audrey Jeanvoine
- Hygiène Hospitalière, Centre Hospitalier Universitaire de Besançon, Besançon, France
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Ashbolt NJ. Conceptual model to inform Legionella-amoebae control, including the roles of extracellular vesicles in engineered water system infections. Front Cell Infect Microbiol 2023; 13:1200478. [PMID: 37274310 PMCID: PMC10232903 DOI: 10.3389/fcimb.2023.1200478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 05/08/2023] [Indexed: 06/06/2023] Open
Abstract
Extracellular vesicles (EVs or exosomes) are well described for bacterial pathogens associated with our gastrointestinal system, and more recently as a novel mechanism for environmental persistence, dissemination and infection for human enteric viruses. However, the roles played by EVs in the ancient arms race that continues between amoebae and one of their prey, Legionella pneumophila, is poorly understood. At best we know of intracellular vesicles of amoebae containing a mix of bacterial prey species, which also provides an enhanced niche for bacteriophage infection/spread. Free-living amoeba-associated pathogens have recently been recognized to have enhanced resistance to disinfection and environmental stressors, adding to previously understood (but for relatively few species of) bacteria sequestered within amoebal cysts. However, the focus of the current work is to review the likely impacts of large numbers of respiratory-sized EVs containing numerous L. pneumophila cells studied in pure and biofilm systems with mixed prey species. These encapsulated pathogens are orders of magnitude more resistant to disinfection than free cells, and our engineered systems with residual disinfectants could promote evolution of resistance (including AMR), enhanced virulence and EV release. All these are key features for evolution within a dead-end human pathogen post lung infection. Traditional single-hit pathogen infection models used to estimate the probability of infection/disease and critical environmental concentrations via quantitative microbial risk assessments may also need to change. In short, recognizing that EV-packaged cells are highly virulent units for transmission of legionellae, which may also modulate/avoid human host immune responses. Key data gaps are raised and a previous conceptual model expanded upon to clarify where biofilm EVs could play a role promoting risk as well as inform a more wholistic management program to proactively control legionellosis.
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Inaccuracies of the ISO 11731 Method for Environmental Validation of Legionella in Building Water Systems: Opportunities to Improve Sensitivity and Detect Viable but Non-Culturable Legionella. Microorganisms 2022; 11:microorganisms11010094. [PMID: 36677386 PMCID: PMC9865130 DOI: 10.3390/microorganisms11010094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/24/2022] [Accepted: 12/27/2022] [Indexed: 12/31/2022] Open
Abstract
Current environmental diagnostics for the detection of Legionella fail to detect viable but non-culturable Legionella, have sensitivity limitations and are time-consuming (10-14 days to results). The objective of this study was to compare Legionella detection results between the standard ISO 11731 and an innovative Legionella detection method that utilizes a hybrid methodology of traditional microbiology and molecular detection. In this study, four hundred and seventy-six (476) potable building water samples were analyzed with ISO 11731 and the novel method in parallel. Of the 476 total samples that were tested, a discrepancy of 21% was observed when comparing the ISO 11731 method to the novel method. Separating the samples based on hazard control methods yielded a 15.4% discrepancy for chlorinated systems (n = 284) and a 29% discrepancy for monochloraminated systems (n = 192). The data presented here conclusively show inaccuracies in environmental validation for building water systems based on results returned by the standard ISO 11731 method. This is especially evident in systems primarily disinfected with monochloramines. Overall, these data highlight the need for new and innovative methods to overcome the inaccuracies of the traditional ISO 11731 spread plates to prevent disease and injury caused by Legionella.
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Yin X, Chen YZ, Ye QQ, Liao LJ, Cai ZR, Lin M, Li JN, Zhang GB, Peng XL, Shi WF, Guo XG. Detection performance of PCR for Legionella pneumophila in environmental samples: a systematic review and meta-analysis. Ann Clin Microbiol Antimicrob 2022; 21:12. [PMID: 35303873 PMCID: PMC8934000 DOI: 10.1186/s12941-022-00503-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 03/07/2022] [Indexed: 11/25/2022] Open
Abstract
Background Legionellosis remains a public health problem. The most common diagnostic method to detect Legionella pneumophila (L. pneumophila) is culture. Polymerase chain reaction (PCR) is a fast and accurate method for this detection in environmental samples. Methods Four databases were searched for studies that evaluated the detection efficiency of PCR in L. pneumophila. The quality evaluation was conducted using Review Manager 5.3. We used Meta-DiSc 1.4 software and the Stata 15.0 software to create forest plots, a meta-regression, a bivariate boxplot and a Deeks’ funnel plot. Results A total of 18 four-fold tables from 16 studies were analysed. The overall pooled sensitivity and specificity of PCR was 94% and 72%, respectively. The positive likelihood ratio (RLR) and negative likelihood ratio (NLR) was 2.73 and 0.12, respectively. The result of the diagnostic odds ratio (DOR) was 22.85 and the area under the curve (AUC) was 0.7884. Conclusion Establishing a laboratory diagnostic tool for L. pneumophila detection is important for epidemiological studies. In this work, PCR demonstrated a promising diagnostic accuracy for L. pneumophila. Supplementary Information The online version contains supplementary material available at 10.1186/s12941-022-00503-9.
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Affiliation(s)
- Xin Yin
- Department of Clinical Laboratory Medicine, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.,Department of Pediatrics, The Pediatrics School of Guangzhou Medical University, Guangzhou, 510182, China
| | - Ying-Zhou Chen
- Department of Clinical Laboratory Medicine, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.,Department of Clinical Medicine, The First Clinical School of Guangzhou Medical University, Guangzhou, 511436, China
| | - Qi-Qing Ye
- Department of Clinical Laboratory Medicine, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.,Department of Pediatrics, The Pediatrics School of Guangzhou Medical University, Guangzhou, 510182, China
| | - Li-Juan Liao
- Department of Clinical Medicine, The First Clinical School of Guangzhou Medical University, Guangzhou, 511436, China
| | - Zhuo-Rui Cai
- Department of Preventive Medicine, The School of Public Health of Guangzhou Medical University, Guangzhou, 511436, China
| | - Min Lin
- Department of Traditional Chinese and Western Medicine in Clinical Medicine, The Clinical School of Traditional Chinese and Western Medicine of Guangzhou Medical University, Guangzhou, 511436, China
| | - Jia-Na Li
- Department of Medical Imaging, The Second Clinical School of Guangzhou Medical University, Guangzhou, 511436, China
| | - Geng-Biao Zhang
- Department of Medical Imaging, The Second Clinical School of Guangzhou Medical University, Guangzhou, 511436, China
| | - Xiao-Li Peng
- Department of Traditional Chinese and Western Medicine in Clinical Medicine, The Clinical School of Traditional Chinese and Western Medicine of Guangzhou Medical University, Guangzhou, 511436, China
| | - Wen-Fang Shi
- Department of Clinical Medicine, The Third Clinical School of Guangzhou Medical University, Guangzhou, 511436, China
| | - Xu-Guang Guo
- Department of Clinical Laboratory Medicine, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China. .,Department of Clinical Medicine, The Third Clinical School of Guangzhou Medical University, Guangzhou, 511436, China. .,Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China. .,Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.
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7
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Zhang C, Lu J. Legionella: A Promising Supplementary Indicator of Microbial Drinking Water Quality in Municipal Engineered Water Systems. FRONTIERS IN ENVIRONMENTAL SCIENCE 2021; 9:1-22. [PMID: 35004706 PMCID: PMC8740890 DOI: 10.3389/fenvs.2021.684319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Opportunistic pathogens (OPs) are natural inhabitants and the predominant disease causative biotic agents in municipal engineered water systems (EWSs). In EWSs, OPs occur at high frequencies and concentrations, cause drinking-water-related disease outbreaks, and are a major factor threatening public health. Therefore, the prevalence of OPs in EWSs represents microbial drinking water quality. Closely or routinely monitoring the dynamics of OPs in municipal EWSs is thus critical to ensuring drinking water quality and protecting public health. Monitoring the dynamics of conventional (fecal) indicators (e.g., total coliforms, fecal coliforms, and Escherichia coli) is the customary or even exclusive means of assessing microbial drinking water quality. However, those indicators infer only fecal contamination due to treatment (e.g., disinfection within water utilities) failure and EWS infrastructure issues (e.g., water main breaks and infiltration), whereas OPs are not contaminants in drinking water. In addition, those indicators appear in EWSs at low concentrations (often absent in well-maintained EWSs) and are uncorrelated with OPs. For instance, conventional indicators decay, while OPs regrow with increasing hydraulic residence time. As a result, conventional indicators are poor indicators of OPs (the major aspect of microbial drinking water quality) in EWSs. An additional or supplementary indicator that can well infer the prevalence of OPs in EWSs is highly needed. This systematic review argues that Legionella as a dominant OP-containing genus and natural inhabitant in EWSs is a promising candidate for such a supplementary indicator. Through comprehensively comparing the behavior (i.e., occurrence, growth and regrowth, spatiotemporal variations in concentrations, resistance to disinfectant residuals, and responses to physicochemical water quality parameters) of major OPs (e.g., Legionella especially L. pneumophila, Mycobacterium, and Pseudomonas especially P. aeruginosa), this review proves that Legionella is a promising supplementary indicator for the prevalence of OPs in EWSs while other OPs lack this indication feature. Legionella as a dominant natural inhabitant in EWSs occurs frequently, has a high concentration, and correlates with more microbial and physicochemical water quality parameters than other common OPs. Legionella and OPs in EWSs share multiple key features such as high disinfectant resistance, biofilm formation, proliferation within amoebae, and significant spatiotemporal variations in concentrations. Therefore, the presence and concentration of Legionella well indicate the presence and concentrations of OPs (especially L. pneumophila) and microbial drinking water quality in EWSs. In addition, Legionella concentration indicates the efficacies of disinfectant residuals in EWSs. Furthermore, with the development of modern Legionella quantification methods (especially quantitative polymerase chain reactions), monitoring Legionella in ESWs is becoming easier, more affordable, and less labor-intensive. Those features make Legionella a proper supplementary indicator for microbial drinking water quality (especially the prevalence of OPs) in EWSs. Water authorities may use Legionella and conventional indicators in combination to more comprehensively assess microbial drinking water quality in municipal EWSs. Future work should further explore the indication role of Legionella in EWSs and propose drinking water Legionella concentration limits that indicate serious public health effects and require enhanced treatment (e.g., booster disinfection).
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Affiliation(s)
- Chiqian Zhang
- Pegasus Technical Services, Inc., Cincinnati, OH, United States
| | - Jingrang Lu
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH, United States
- Correspondence: Jingrang Lu,
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8
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Zhang C, Struewing I, Mistry JH, Wahman DG, Pressman J, Lu J. Legionella and other opportunistic pathogens in full-scale chloraminated municipal drinking water distribution systems. WATER RESEARCH 2021; 205:117571. [PMID: 34628111 PMCID: PMC8629321 DOI: 10.1016/j.watres.2021.117571] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 08/02/2021] [Accepted: 08/13/2021] [Indexed: 05/06/2023]
Abstract
Water-based opportunistic pathogens (OPs) are a leading cause of drinking-water-related disease outbreaks, especially in developed countries such as the United States (US). Physicochemical water quality parameters, especially disinfectant residuals, control the (re)growth, presence, colonization, and concentrations of OPs in drinking water distribution systems (DWDSs), while the relationship between OPs and those parameters remain unclear. This study aimed to quantify how physicochemical parameters, mainly monochloramine residual concentration, hydraulic residence time (HRT), and seasonality, affected the occurrence and concentrations of four common OPs (Legionella, Mycobacterium, Pseudomonas, and Vermamoeba vermiformis) in four full-scale DWDSs in the US. Legionella as a dominant OP occurred in 93.8% of the 64 sampling events and had a mean density of 4.27 × 105 genome copies per liter. Legionella positively correlated with Mycobacterium, Pseudomonas, and total bacteria. Multiple regression with data from the four DWDSs showed that Legionella had significant correlations with total chlorine residual level, free ammonia concentration, and trihalomethane concentration. Therefore, Legionella is a promising indicator of water-based OPs, reflecting microbial water quality in chloraminated DWDSs. The OP concentrations had strong seasonal variations and peaked in winter and/or spring possibly because of reduced water usage (i.e., increased water stagnation or HRT) during cold seasons. The OP concentrations generally increased with HRT presumably because of disinfectant residual decay, indicating the importance of well-maintaining disinfectant residuals in DWDSs for OP control. The concentrations of Mycobacterium, Pseudomonas, and V. vermiformis were significantly associated with total chlorine residual concentration, free ammonia concentration, and pH and trihalomethane concentration, respectively. Overall, this study demonstrates how the significant spatiotemporal variations of OP concentrations in chloraminated DWDSs correlated with critical physicochemical water quality parameters such as disinfectant residual levels. This work also indicates that Legionella is a promising indicator of OPs and microbial water quality in chloraminated DWDSs.
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Affiliation(s)
- Chiqian Zhang
- Pegasus Technical Services, Inc., Cincinnati, Ohio, USA
| | - Ian Struewing
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio, USA
| | - Jatin H Mistry
- United States Environmental Protection Agency, Region 6, Dallas, Texas, USA
| | - David G Wahman
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio, USA
| | - Jonathan Pressman
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio, USA
| | - Jingrang Lu
- Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio, USA.
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Walker JT, McDermott PJ. Confirming the Presence of Legionella pneumophila in Your Water System: A Review of Current Legionella Testing Methods. J AOAC Int 2021; 104:1135-1147. [PMID: 33484265 PMCID: PMC8378878 DOI: 10.1093/jaoacint/qsab003] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 12/18/2020] [Accepted: 12/18/2020] [Indexed: 12/24/2022]
Abstract
Legionnaires' disease has been recognized since 1976 and Legionella pneumophila still accounts for more than 95% of cases. Approaches in countries, including France, suggest that focusing risk reduction specifically on L. pneumophila is an effective strategy, as detecting L. pneumophila has advantages over targeting multiple species of Legionella. In terms of assays, the historically accepted plate culture method takes 10 days for confirmed Legionella spp. results, has variabilities which affect trending and comparisons, requires highly trained personnel to identify colonies on a plate in specialist laboratories, and does not recover viable-but-non-culturable bacteria. PCR is sensitive, specific, provides results in less than 24 h, and determines the presence/absence of Legionella spp. and/or L. pneumophila DNA. Whilst specialist personnel and laboratories are generally required, there are now on-site PCR options, but there is no agreement on comparing genome units to colony forming units and action limits. Immunomagnetic separation assays are culture-independent, detect multiple Legionella species, and results are available in 24 h, with automated processing options. Field-use lateral flow devices provide presence/absence determination of L. pneumophila serogroup 1 where sufficient cells are present, but testing potable waters is problematic. Liquid culture most probable number (MPN) assays provide confirmed L. pneumophila results in 7 days that are equivalent to or exceed plate culture, are robust and reproducible, and can be performed in a variety of laboratory settings. MPN isolates can be obtained for epidemiological investigations. This accessible, non-technical review will be of particular interest to building owners, operators, risk managers, and water safety groups and will enable them to make informed decisions to reduce the risk of L. pneumophila.
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Martinelli M, Calaresu E, Musumeci R, Giubbi C, Perdoni F, Frugoni S, Castriciano S, Scaturro M, Ricci ML, Cocuzza CE. Evaluation of an Environmental Transport Medium for Legionella pneumophila Recovery. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18168551. [PMID: 34444305 PMCID: PMC8394066 DOI: 10.3390/ijerph18168551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/04/2021] [Accepted: 08/06/2021] [Indexed: 11/16/2022]
Abstract
The collection and storage of water-related matrices such as biofilm from collection to processing are critical for the detection of Legionella pneumophila by cultural and molecular tests. SRK™ is a liquid medium that acts both as an antimicrobial neutralizing agent and a transport medium for bacterial culture enumeration and is useful to maintain the stability of the sample from collection to analysis. The aims of this study were to evaluate Legionella pneumophila viability and bacterial nucleic acids’ stability in SRK™ medium over time at different storage conditions. Artificial bacterial inoculates with an approximate concentration of 104, 103 and 102 CFU/mL were made using Legionella pneumophila certified reference material suspended in SRK™ medium. Bacteria recovery was analyzed by cultural and molecular methods at time 0, 24 and 48 h at room temperature and at 0, 24, 48 and 72 h at 2–8 °C, respectively. SRK™ medium supported Legionella pneumophila culture viability with CFU counts within the expected range. The recovery after 72 h at 2–8 °C was 83–100% and 75–95% after 48 h at room temperature. Real-time PCR appropriately detected Legionella pneumophila DNA at each temperature condition, dilution and time point. Results demonstrated a good performance of SRK™ medium for the reliable recovery of environmental Legionella.
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Affiliation(s)
- Marianna Martinelli
- Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.C.); (R.M.); (C.G.); (F.P.); (S.F.); (C.E.C.)
- Correspondence: ; Tel.: +39-02-6448-8359
| | - Enrico Calaresu
- Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.C.); (R.M.); (C.G.); (F.P.); (S.F.); (C.E.C.)
| | - Rosario Musumeci
- Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.C.); (R.M.); (C.G.); (F.P.); (S.F.); (C.E.C.)
| | - Chiara Giubbi
- Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.C.); (R.M.); (C.G.); (F.P.); (S.F.); (C.E.C.)
| | - Federica Perdoni
- Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.C.); (R.M.); (C.G.); (F.P.); (S.F.); (C.E.C.)
| | - Sergio Frugoni
- Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.C.); (R.M.); (C.G.); (F.P.); (S.F.); (C.E.C.)
| | | | - Maria Scaturro
- Istituto Superiore di Sanità, 00161 Roma, Italy; (M.S.); (M.L.R.)
| | | | - Clementina E. Cocuzza
- Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.C.); (R.M.); (C.G.); (F.P.); (S.F.); (C.E.C.)
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Toplitsch D, Platzer S, Zehner R, Maitz S, Mascher F, Kittinger C. Comparison of Updated Methods for Legionella Detection in Environmental Water Samples. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18105436. [PMID: 34069615 PMCID: PMC8161308 DOI: 10.3390/ijerph18105436] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 05/11/2021] [Accepted: 05/14/2021] [Indexed: 12/04/2022]
Abstract
The difficulty of cultivation of Legionella spp. from water samples remains a strenuous task even for experienced laboratories. The long incubation periods for Legionellae make isolation difficult. In addition, the water samples themselves are often contaminated with accompanying microbial flora, and therefore require complex cultivation methods from diagnostic laboratories. In addition to the recent update of the standard culture method ISO 11731:2017, new strategies such as quantitative PCR (qPCR) are often discussed as alternatives or additions to conventional Legionella culture approaches. In this study, we compared ISO 11731:2017 with qPCR assays targeting Legionella spp., Legionella pneumophila, and Legionella pneumophila serogroup 1. In samples with a high burden of accompanying microbial flora, qPCR shows an excellent negative predictive value for Legionella pneumophila, thus making qPCR an excellent tool for pre-selection of negative samples prior to work-intensive culture methods. This and its low limit of detection make qPCR a diagnostic asset in Legionellosis outbreak investigations, where quick-risk assessments are essential, and are a useful method for monitoring risk sites.
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12
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Mori J, Uprety S, Mao Y, Koloutsou-Vakakis S, Nguyen TH, Smith RL. Quantification and Comparison of Risks Associated with Wastewater Use in Spray Irrigation. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2021; 41:745-760. [PMID: 33084120 DOI: 10.1111/risa.13607] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 09/12/2020] [Accepted: 09/22/2020] [Indexed: 06/11/2023]
Abstract
In the U.S., spray irrigation is the most common method used in agriculture and supplementing with animal wastewater has the potential to reduce water demands. However, this could expose individuals to respiratory pathogens such as Legionella pneumophila and nontuberculosis Mycobacteria (NTM). Disinfection with methods like anaerobic digestion is an option but can increase concentrations of cytotoxic ammonia (personal communication). Our study aimed to model the annual risks of infection from these bacterial pathogens and the air concentrations of ammonia and determine if anaerobically digesting this wastewater is a safe option. Air dispersion modeling, conducted in AERMOD, generated air concentrations of water during the irrigation season (May-September) for the years 2013-2018. These values fed into the quantitative microbial risk assessments for the bacteria and allowed calculation of ammonia air concentrations. The outputs of these models were compared to the safety thresholds of 10-4 infections/year and 0.5 mg/m3 , respectively, to determine their potential for negative health outcomes. It was determined that infection from NTM was not a concern for individuals near active spray irrigators, but that infection with L. pneumophila could be a concern, with a maximum predicted annual risk of infection of 3.5 × 10-3 infections/year and 25.2% of parameter combinations exceeding the established threshold. Ammonia posed a minor risk, with 1.5% of parameter combinations surpassing the risk threshold of 0.5 mg/m3 . These findings suggest that animal wastewater should be anaerobically digested prior to use in irrigation to remove harmful pathogens.
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Affiliation(s)
- Jameson Mori
- Department of Pathobiology, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Sital Uprety
- Department of Civil & Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Yuqing Mao
- Department of Civil & Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Sotiria Koloutsou-Vakakis
- Department of Civil & Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Thanh H Nguyen
- Department of Civil & Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign
| | - Rebecca L Smith
- Department of Pathobiology, University of Illinois Urbana-Champaign, Urbana, IL, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign
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13
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Eble D, Gehrig V, Schubert-Ullrich P, Köppel R, Füchslin HP. Comparison of the culture method with multiplex PCR for the confirmation of Legionella spp. and Legionella pneumophila. J Appl Microbiol 2021; 131:2600-2609. [PMID: 33847421 PMCID: PMC9292777 DOI: 10.1111/jam.15103] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 04/04/2021] [Accepted: 04/09/2021] [Indexed: 11/30/2022]
Abstract
AIMS The detection and enumeration of Legionella spp. in water samples are typically performed via a cultural technique standardized in ISO 11731. This method is time-consuming (up to 15 days), and the specificity of the confirmation step is questionable. This study proposes the use of multiplex polymerase chain reaction (PCR) to confirm presumptive Legionella colonies directly from the culture plate; this shortens the response time by 2-5 days while still reporting results in colony forming units (CFU). METHODS AND RESULTS Two laboratories analysed a total of 290 colonies to compare the confirmation step of Legionella spp. and Legionella pneumophila in accordance with ISO 11731 by culture growth and agglutination vs multiplex PCR. Discordant results were resolved by the swiss national reference laboratory. The data were evaluated following ISO 16140 and showed that the PCR-technique had higher specificity. CONCLUSIONS The confirmation of Legionella spp., L. pneumophila and L. pneumophila serogroup 1 by multiplex PCR allows detection of positive colonies more rapidly and with higher specificity. SIGNIFICANCE AND IMPACT OF THE STUDY The study highlights a possibility to shorten the response time significantly during the enumeration of Legionella spp. and achieving a higher specificity while adhering to the legally recognized reporting in CFU.
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Affiliation(s)
- D Eble
- Industrielle Werke Basel, Basel, Switzerland
| | - V Gehrig
- Kantonales Labor Zürich, Zürich, Switzerland
| | | | - R Köppel
- Kantonales Labor Zürich, Zürich, Switzerland
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14
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Evaluation of Legiolert™ for the Detection of Legionella pneumophila and Comparison with Spread-Plate Culture and qPCR Methods. Curr Microbiol 2021; 78:1792-1797. [PMID: 33758992 DOI: 10.1007/s00284-021-02436-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 02/24/2021] [Indexed: 10/21/2022]
Abstract
Legionella pneumophila, the organism responsible for Legionnaires' disease, a potentially lethal pneumonia, is an opportunistic bacterium spread via inhalation of contaminated, aerosolized water. The detection and control of L. pneumophila is crucial to reduce the risk it poses to human health. L. pneumophila is generally detected and quantified by the plating method, ISO 11731:2017 and by qPCR. ISO 11731 is based on the filtration of the water sample through a membrane, which is placed on selective agar medium, and after colony growth, presumptive Legionella are then confirmed by subculturing, serology, or PCR. Quantitative Polymerase Chain Reaction (qPCR) is based on the amplification of a DNA sequence specific to L. pneumophila, usually within the mip gene. The objective of this study was to compare these methods to a new, liquid culture method based on the Most Probable Number (MPN) technique, Legiolert™/Quanti-Tray® with data obtained with ISO 11731 and a viability quantitative qPCR (v-qPCR), for quantification of L. pneumophila in potable and non-potable waters. Data showed that the Legiolert method revealed concentrations of L. pneumophila greater than ISO 11731 and generally similar results to those of v-qPCR. The Legiolert method was highly specific and easy to use, representing a significant advancement in the quantification of L. pneumophila from potable and non-potable waters.
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15
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Young C, Smith D, Wafer T, Crook B. Rapid Testing and Interventions to Control Legionella Proliferation following a Legionnaires' Disease Outbreak Associated with Cooling Towers. Microorganisms 2021; 9:microorganisms9030615. [PMID: 33802700 PMCID: PMC8002549 DOI: 10.3390/microorganisms9030615] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/04/2021] [Accepted: 03/13/2021] [Indexed: 11/16/2022] Open
Abstract
Most literature to date on the use of rapid Legionella tests have compared different sampling and analytical techniques, with few studies on real-world experiences using such methods. Rapid tests offer a significantly shorter feedback loop on the effectiveness of the controls. This study involved a complex of five factories, three of which had a history of Legionella contamination in their cooling water distribution system. Multiple sampling locations were utilised to take monthly water samples over 39 months to analyse for Legionella by both culture and quantitative polymerase chain reaction (qPCR). Routine monitoring gave no positive Legionella results by culture (n = 330); however, samples were frequently (68%) positive by qPCR for Legionella spp. (n = 1564). Legionella spp. qPCR assay was thus found to be a good indicator of cooling tower system health and suitable as a routine monitoring tool. An in-house qPCR limit of 5000 genomic units (GU)/L Legionella spp. was established to trigger investigation and remedial action. This approach facilitated swift remedial action to prevent Legionella proliferation to levels that may represent a public health risk. Cooling tower operators may have to set their own action levels for their own systems; however, in this study, 5000 GU/L was deemed appropriate and pragmatic.
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Affiliation(s)
| | - Duncan Smith
- Health and Safety Executive, Newcastle NE98 1YX, UK;
| | - Tim Wafer
- Water Solutions Group, Harrogate HG3 1EQ, UK;
| | - Brian Crook
- Health and Safety Executive, Buxton SK17 9JN, UK;
- Correspondence: ; Tel.: +44-203-028-1882
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16
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Pascale MR, Mazzotta M, Salaris S, Girolamini L, Grottola A, Simone ML, Cordovana M, Bisognin F, Dal Monte P, Bucci Sabattini MA, Viggiani M, Cristino S. Evaluation of MALDI-TOF Mass Spectrometry in Diagnostic and Environmental Surveillance of Legionella Species: A Comparison With Culture and Mip-Gene Sequencing Technique. Front Microbiol 2021; 11:589369. [PMID: 33384668 PMCID: PMC7771186 DOI: 10.3389/fmicb.2020.589369] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 11/19/2020] [Indexed: 12/19/2022] Open
Abstract
Legionella spp. are widespread bacteria in aquatic environments with a growing impact on human health. Between the 61 species, Legionella pneumophila is the most prevalent in human diseases; on the contrary, Legionella non-pneumophila species are less detected in clinical diagnosis or during environmental surveillance due to their slow growth in culture and the absence of specific and rapid diagnostic/analytical tools. Reliable and rapid isolate identification is essential to estimate the source of infection, to undertake containment measures, and to determine clinical treatment. Matrix-assisted laser desorption ionization–time-of-flight mass spectrometry (MALDI–TOF MS), since its introduction into the routine diagnostics of laboratories, represents a widely accepted method for the identification of different bacteria species, described in a few studies on the Legionella clinical and environmental surveillance. The focus of this study was the improvement of MALDI–TOF MS on Legionella non-pneumophila species collected during Legionella nosocomial and community surveillance. Comparative analysis with cultural and mip-gene sequencing results was performed. Moreover, a phylogenetic analysis was carried out to estimate the correlations amongst isolates. MALDI–TOF MS achieved correct species-level identification for 45.0% of the isolates belonging to the Legionella anisa, Legionella rubrilucens, Legionella feeleii, and Legionella jordanis species, displaying a high concordance with the mip-gene sequencing results. In contrast, less reliable identification was found for the remaining 55.0% of the isolates, corresponding to the samples belonging to species not yet included in the database. The phylogenetic analysis showed relevant differences inside the species, regruped in three main clades; among the Legionella anisa clade, a subclade with a divergence of 3.3% from the main clade was observed. Moreover, one isolate, identified as Legionella quinlivanii, displayed a divergence of 3.8% from the corresponding reference strain. However, these findings require supplementary investigation. The results encourage the implementation of MALDI–TOF MS in routine diagnostics and environmental Legionella surveillance, as it displays a reliable and faster identification at the species level, as well as the potential to identify species that are not yet included in the database. Moreover, phylogenetic analysis is a relevant approach to correlate the isolates and to track their spread, especially in unconventional reservoirs, where Legionella prevention is still underestimated.
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Affiliation(s)
- Maria Rosaria Pascale
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Bologna, Italy
| | - Marta Mazzotta
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Bologna, Italy
| | - Silvano Salaris
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Bologna, Italy
| | - Luna Girolamini
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Bologna, Italy
| | - Antonella Grottola
- Regional Reference Laboratory for Clinical Diagnosis of Legionellosis, Unit of Microbiology and Virology, Modena University Hospital, Modena, Italy
| | - Maria Luisa Simone
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Miriam Cordovana
- Microbiology Unit-Department of Experimental, Diagnostic and Specialty Medicine, S. Orsola-Malpighi University Hospital, Bologna, Italy
| | - Francesco Bisognin
- Microbiology Unit-Department of Experimental, Diagnostic and Specialty Medicine, S. Orsola-Malpighi University Hospital, Bologna, Italy
| | - Paola Dal Monte
- Microbiology Unit-Department of Experimental, Diagnostic and Specialty Medicine, S. Orsola-Malpighi University Hospital, Bologna, Italy
| | | | | | - Sandra Cristino
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Bologna, Italy
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Hozalski RM, LaPara TM, Zhao X, Kim T, Waak MB, Burch T, McCarty M. Flushing of Stagnant Premise Water Systems after the COVID-19 Shutdown Can Reduce Infection Risk by Legionella and Mycobacterium spp. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:15914-15924. [PMID: 33232602 DOI: 10.1021/acs.est.0c06357] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
There is concern about potential exposure to opportunistic pathogens when reopening buildings closed due to the COVID-19 pandemic. In this study, water samples were collected before, during, and after flushing showers in five unoccupied (i.e., for ∼2 months) university buildings with quantification of opportunists via a cultivation-based assay (Legionella pneumophila only) and quantitative PCR. L. pneumophila were not detected by either method; Legionella spp., nontuberculous mycobacteria (NTM), and Mycobacterium avium complex (MAC), however, were widespread. Using quantitative microbial risk assessment (QMRA), the estimated risks of illness from exposure to L. pneumophila and MAC via showering were generally low (i.e., less than a 10-7 daily risk threshold), with the exception of systemic infection risk from MAC exposure in some buildings. Flushing rapidly restored the total chlorine (as chloramine) residual and decreased bacterial gene targets to building inlet concentrations within 30 min. During the postflush stagnation period, the residual chlorine dissipated within a few days and bacteria rebounded, approaching preflush concentrations after 6-7 days. These results suggest that flushing can quickly improve water quality in unoccupied buildings, but the improvement may only last a few days.
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Affiliation(s)
- Raymond M Hozalski
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis 55455, Minnesota, United States
| | - Timothy M LaPara
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis 55455, Minnesota, United States
| | - Xiaotian Zhao
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis 55455, Minnesota, United States
| | - Taegyu Kim
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis 55455, Minnesota, United States
| | - Michael B Waak
- Norwegian University of Science and Technology, Trondheim 7031, Norway
- Department of Infrastructure, SINTEF Community, Trondheim 7031, Norway
| | - Tucker Burch
- Agricultural Research Service, U.S. Department of Agriculture, Marshfield, Wisconsin 54449, United States
| | - Michael McCarty
- School of Public Health, University of Minnesota, Minneapolis 55455, Minnesota, United States
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18
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Evaluation of GVPC and BCYE Media for Legionella Detection and Enumeration in Water Samples by ISO 11731: Does Plating on BCYE Medium Really Improve Yield? Pathogens 2020; 9:pathogens9090757. [PMID: 32948082 PMCID: PMC7559527 DOI: 10.3390/pathogens9090757] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/14/2020] [Accepted: 09/15/2020] [Indexed: 11/19/2022] Open
Abstract
Legionella spp are the causative agents of Legionnaires’ diseases, which is a pneumonia of important public health concern. Ubiquitous freshwater and soil inhabitants can reach man-made water systems and cause illness. Legionella enumeration and quantification in water systems is crucial for risk assessment and culture examination is the gold standard method. In this study, Legionella recovery from potable water samples, at presumably a low concentration of interfering microorganisms, was compared by plating on buffered charcoal yeast extract (BCYE) and glycine, vancomycin, polymyxin B, cycloheximide (GVPC) Legionella agar media, according to the International Standard Organization (ISO) 11731: 2017. Overall, 556 potable water samples were analyzed and 151 (27.1%) were positive for Legionella. Legionella grew on both BCYE and GVPC agar plates in 85/151 (56.3%) water samples, in 65/151 (43%) on only GVPC agar plates, and in 1/151 (0.7%) on only BCYE agar plates. In addition, GVPC medium identified Legionella species other than pneumophila in six more samples as compared with the culture on BCYE. Although the medians of colony forming units per liter (CFU/L) detected on the BCYE and GVPC agar plates were 2500 and 1350, respectively (p-value < 0.0001), the difference did not exceed one logarithm, and therefore is not relevant for Legionella risk assessment. These results make questionable the need to utilize BCYE agar plates to analyze potable water samples.
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19
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Performance of Legiolert Test vs. ISO 11731 to Confirm Legionella pneumophila Contamination in Potable Water Samples. Pathogens 2020; 9:pathogens9090690. [PMID: 32842454 PMCID: PMC7560050 DOI: 10.3390/pathogens9090690] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/21/2020] [Accepted: 08/21/2020] [Indexed: 12/15/2022] Open
Abstract
Detection and enumeration of Legionella in water samples is of great importance for risk assessment analysis. The plate culture method is the gold standard, but has received several well-known criticisms, which have induced researchers to develop alternative methods. The purpose of this study was to compare Legionella counts obtained by the analysis of potable water samples through the plate culture method and through the IDEXX liquid culture Legiolert method. Legionella plate culture, according to ISO 11731:1998, was performed using 1 L of water. Legiolert was performed using both the 10 mL and 100 mL Legiolert protocols. Overall, 123 potable water samples were analyzed. Thirty-seven (30%) of them, positive for L. pneumophila, serogroups 1 or 2–14 by plate culture, were used for comparison with the Legiolert results. The Legiolert 10 mL test detected 34 positive samples (27.6%) and the Legiolert 100 mL test detected 37 positive samples, 27.6% and 30% respectively, out of the total samples analyzed. No significant difference was found between either the Legiolert 10 mL and Legiolert 100 mL vs. the plate culture (p = 0.9 and p = 0.3, respectively) or between the Legiolert 10 mL and Legiolert 100 mL tests (p = 0.83). This study confirms the reliability of the IDEXX Legiolert test for Legionella pneumophila detection and enumeration, as already shown in similar studies. Like the plate culture method, the Legiolert assay is also suitable for obtaining isolates for typing purposes, relevant for epidemiological investigations.
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20
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Nocker A, Schulte-Illingheim L, Frösler J, Welp L, Sperber O, Hugo A. Microbiological examination of water and aerosols from four industrial evaporative cooling systems in regard to risk of Legionella emissions and methodological suggestions for surveillance. Int J Hyg Environ Health 2020; 229:113591. [DOI: 10.1016/j.ijheh.2020.113591] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 12/22/2022]
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Buse HY, Morris BJ, Gomez-Alvarez V, Szabo JG, Hall JS. Legionella Diversity and Spatiotemporal Variation in The Occurrence of Opportunistic Pathogens within a Large Building Water System. Pathogens 2020; 9:E567. [PMID: 32668779 PMCID: PMC7400177 DOI: 10.3390/pathogens9070567] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 01/22/2023] Open
Abstract
Understanding Legionella survival mechanisms within building water systems (BWSs) is challenging due to varying engineering, operational, and water quality characteristics unique to each system. This study aimed to evaluate Legionella, mycobacteria, and free-living amoebae occurrence within a BWS over 18-28 months at six locations differing in plumbing material and potable water age, quality, and usage. A total of 114 bulk water and 57 biofilm samples were analyzed. Legionella culturability fluctuated seasonally with most culture-positive samples being collected during the winter compared to the spring, summer, and fall months. Positive and negative correlations between Legionella and L. pneumophila occurrence and other physiochemical and microbial water quality parameters varied between location and sample types. Whole genome sequencing of 19 presumptive Legionella isolates, from four locations across three time points, identified nine isolates as L. pneumophila serogroup (sg) 1 sequence-type (ST) 1; three as L. pneumophila sg5 ST1950 and ST2037; six as L. feeleii; and one as Ochrobactrum. Results showed the presence of a diverse Legionella population with consistent and sporadic occurrence at four and two locations, respectively. Viewed collectively with similar studies, this information will enable a better understanding of the engineering, operational, and water quality parameters supporting Legionella growth within BWSs.
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Affiliation(s)
- Helen Y. Buse
- Homeland Security and Materials Management Division, Center for Environmental Solutions & Emergency Response (CESER), Office of Research and Development (ORD), US Environmental Protection Agency (USEPA), Cincinnati, OH 45268, USA; (J.G.S.); (J.S.H.)
| | - Brian J. Morris
- Pegasus Technical Services, Inc c/o US EPA, Cincinnati, OH 45268, USA;
| | - Vicente Gomez-Alvarez
- Water Infrastructure Division, Center for Environmental Solutions & Emergency Response (CESER), US Environmental Protection Agency (USEPA), Office of Research and Development (ORD), Cincinnati, OH 45268, USA;
| | - Jeffrey G. Szabo
- Homeland Security and Materials Management Division, Center for Environmental Solutions & Emergency Response (CESER), Office of Research and Development (ORD), US Environmental Protection Agency (USEPA), Cincinnati, OH 45268, USA; (J.G.S.); (J.S.H.)
| | - John S. Hall
- Homeland Security and Materials Management Division, Center for Environmental Solutions & Emergency Response (CESER), Office of Research and Development (ORD), US Environmental Protection Agency (USEPA), Cincinnati, OH 45268, USA; (J.G.S.); (J.S.H.)
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22
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Reuter C, Slesiona N, Hentschel S, Aehlig O, Breitenstein A, Csáki A, Henkel T, Fritzsche W. Loop-mediated amplification as promising on-site detection approach for Legionella pneumophila and Legionella spp. Appl Microbiol Biotechnol 2019; 104:405-415. [PMID: 31832709 DOI: 10.1007/s00253-019-10286-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 11/08/2019] [Accepted: 11/28/2019] [Indexed: 12/16/2022]
Abstract
Recently Legionella pneumophila is the main causative waterborne organism of severe respiratory infections. Additionally, other Legionella species are documented as human pathogens. In our work, we describe a rapid detection method which combines two advantages for sensitive and specific detection of the genus Legionella: the fast isothermal amplification method "Loop-mediated isothermal AMPlification" (LAMP), and a colorimetric detection method using the metal indicator hydroxynaphtol blue (HBN) which allows to determine an optical signal with a simple readout (with the naked eye). Moreover, we present two approaches for minimizing the assay volume using a stationary microchip LAMP and droplet digital-based LAMP (ddLAMP) as promising highly sensitive setups.
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Affiliation(s)
- Cornelia Reuter
- Leibniz Institute of Photonic Technology (Leibniz IPHT) Jena, Member of the Leibniz Research Alliance-Leibniz Health Technologies, Albert-Einstein-Straße 9, 07745, Jena, Germany.
| | - Nicole Slesiona
- Leibniz Institute of Photonic Technology (Leibniz IPHT) Jena, Member of the Leibniz Research Alliance-Leibniz Health Technologies, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Stefanie Hentschel
- Leibniz Institute of Photonic Technology (Leibniz IPHT) Jena, Member of the Leibniz Research Alliance-Leibniz Health Technologies, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Oliver Aehlig
- Leibniz Institute of Photonic Technology (Leibniz IPHT) Jena, Member of the Leibniz Research Alliance-Leibniz Health Technologies, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | | | - Andrea Csáki
- Leibniz Institute of Photonic Technology (Leibniz IPHT) Jena, Member of the Leibniz Research Alliance-Leibniz Health Technologies, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Thomas Henkel
- Leibniz Institute of Photonic Technology (Leibniz IPHT) Jena, Member of the Leibniz Research Alliance-Leibniz Health Technologies, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Wolfgang Fritzsche
- Leibniz Institute of Photonic Technology (Leibniz IPHT) Jena, Member of the Leibniz Research Alliance-Leibniz Health Technologies, Albert-Einstein-Straße 9, 07745, Jena, Germany
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23
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Hamilton KA, Hamilton MT, Johnson W, Jjemba P, Bukhari Z, LeChevallier M, Haas CN, Gurian PL. Risk-Based Critical Concentrations of Legionella pneumophila for Indoor Residential Water Uses. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:4528-4541. [PMID: 30629886 DOI: 10.1021/acs.est.8b03000] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
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.
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Affiliation(s)
- Kerry A Hamilton
- School for Sustainable Engineering and the Built Environment , Arizona State University , Tempe , Arizona 85281 , United States
- The Biodesign Institute Center for Environmental Health Engineering , Arizona State University , Tempe , Arizona 85281 , United States
| | - Mark T Hamilton
- Microsoft Applied Artificial Intelligence Group , 1 Memorial Drive , Cambridge , Massachusetts 02142 , United States
| | - William Johnson
- American Water Research Laboratory , 213 Carriage Lane , Delran , New Jersey 08075 , United States
| | - Patrick Jjemba
- American Water Research Laboratory , 213 Carriage Lane , Delran , New Jersey 08075 , United States
| | - Zia Bukhari
- American Water Research Laboratory , 213 Carriage Lane , Delran , New Jersey 08075 , United States
| | - Mark LeChevallier
- American Water Research Laboratory , 213 Carriage Lane , Delran , New Jersey 08075 , United States
| | - Charles N Haas
- Drexel University , 3141 Chestnut Street , Philadelphia , Pennsylvania 19104 , United States
| | - P L Gurian
- Drexel University , 3141 Chestnut Street , Philadelphia , Pennsylvania 19104 , United States
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24
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Ahmed S, Liwak-Muir U, Walker D, Zoldowski A, Mears A, Golovan S, Mohr S, Lem P, Harder C. Validation and in-field testing of a new on-site qPCR system for quantification of Legionella pneumophila according to ISO/TS 12869:2012 in HVAC cooling towers. JOURNAL OF WATER AND HEALTH 2019; 17:237-253. [PMID: 30942774 DOI: 10.2166/wh.2019.252] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Legionella pneumophila, found in engineered water systems such as HVAC cooling towers, poses a significant public health risk. Culture, though routinely used to quantify L. pneumophila, has several disadvantages including long turnaround time, low sensitivity, and inter-laboratory variability. In this study, we validated the performance of an on-site quantitative polymerase chain reaction (qPCR) detection system for L. pneumophila in accordance with International Standards Organization Technical Specification 12869:2012. We evaluated specificity, limit of detection and quantification, and calibration curve linearity. Additionally, we evaluated whole system recovery and robustness using samples taken from taps and evaporative cooling towers. We then compared the system's performance against laboratory culture and laboratory qPCR across 53 cooling towers in a 12-week in-field study. We found that concordance between on-site qPCR and culture was both laboratory- and site/sample-dependent. Comparison of laboratory qPCR with on-site qPCR revealed that laboratory results were highly variable and showed little concordance. Some discordance may be explained by time delay between sample collection and testing ('shipping effect') which may lead to inaccurate reporting. Overall, our study highlights the value of on-site qPCR detection of L. pneumophila, demonstrates that laboratories are prone to misreporting results due to shipping effects, and reveals significant discordance between laboratory qPCR and culture.
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Affiliation(s)
- Shaimaa Ahmed
- Spartan Bioscience Inc., 2934 Baseline Road, Suite 500, Ottawa, ON K2H 1B2, Canada E-mail:
| | - Urszula Liwak-Muir
- Spartan Bioscience Inc., 2934 Baseline Road, Suite 500, Ottawa, ON K2H 1B2, Canada E-mail:
| | - Danielle Walker
- Spartan Bioscience Inc., 2934 Baseline Road, Suite 500, Ottawa, ON K2H 1B2, Canada E-mail:
| | - Agnes Zoldowski
- Spartan Bioscience Inc., 2934 Baseline Road, Suite 500, Ottawa, ON K2H 1B2, Canada E-mail:
| | - Alan Mears
- Spartan Bioscience Inc., 2934 Baseline Road, Suite 500, Ottawa, ON K2H 1B2, Canada E-mail:
| | - Sergey Golovan
- Spartan Bioscience Inc., 2934 Baseline Road, Suite 500, Ottawa, ON K2H 1B2, Canada E-mail:
| | - Steve Mohr
- Spartan Bioscience Inc., 2934 Baseline Road, Suite 500, Ottawa, ON K2H 1B2, Canada E-mail:
| | - Paul Lem
- Spartan Bioscience Inc., 2934 Baseline Road, Suite 500, Ottawa, ON K2H 1B2, Canada E-mail:
| | - Chris Harder
- Spartan Bioscience Inc., 2934 Baseline Road, Suite 500, Ottawa, ON K2H 1B2, Canada E-mail:
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25
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Caicedo C, Rosenwinkel KH, Exner M, Verstraete W, Suchenwirth R, Hartemann P, Nogueira R. Legionella occurrence in municipal and industrial wastewater treatment plants and risks of reclaimed wastewater reuse: Review. WATER RESEARCH 2019; 149:21-34. [PMID: 30445393 DOI: 10.1016/j.watres.2018.10.080] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 10/26/2018] [Accepted: 10/27/2018] [Indexed: 05/22/2023]
Abstract
Wastewater treatment plants (WWTPs) have been identified as confirmed but until today underestimated sources of Legionella, playing an important role in local and community cases and outbreaks of Legionnaires' disease. In general, aerobic biological systems provide an optimum environment for the growth of Legionella due to high organic nitrogen and oxygen concentrations, ideal temperatures and the presence of protozoa. However, few studies have investigated the occurrence of Legionella in WWTPs, and many questions in regards to the interacting factors that promote the proliferation and persistence of Legionella in these treatment systems are still unanswered. This critical review summarizes the current knowledge about Legionella in municipal and industrial WWTPs, the conditions that might support their growth, as well as control strategies that have been applied. Furthermore, an overview of current quantification methods, guidelines and health risks associated with Legionella in reclaimed wastewater is also discussed in depth. A better understanding of the conditions promoting the occurrence of Legionella in WWTPs will contribute to the development of improved wastewater treatment technologies and/or innovative mitigation approaches to minimize future Legionella outbreaks.
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Affiliation(s)
- C Caicedo
- Leibniz University Hannover, Institute for Sanitary Engineering and Waste Management, Hannover, 30167, Germany.
| | - K-H Rosenwinkel
- Leibniz University Hannover, Institute for Sanitary Engineering and Waste Management, Hannover, 30167, Germany
| | - M Exner
- University of Bonn, Institute for Hygiene and Public Health, Bonn, Germany
| | - W Verstraete
- Ghent University, CMET, Ghent, and Avecom, Wondelgem, Belgium
| | - R Suchenwirth
- Public Health Office of Lower Saxony, Hannover, Germany
| | - P Hartemann
- Faculty of Medicine, Department of Environment and Public Health, Nancy University-CHU Nancy, Vandoeuvre Les Nancy, France
| | - R Nogueira
- Leibniz University Hannover, Institute for Sanitary Engineering and Waste Management, Hannover, 30167, Germany.
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26
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Ricci ML, Grottola A, Fregni Serpini G, Bella A, Rota MC, Frascaro F, Pegoraro E, Meacci M, Fabio A, Vecchi E, Girolamo A, Rumpianesi F, Pecorari M, Scaturro M. Improvement of Legionnaires' disease diagnosis using real-time PCR assay: a retrospective analysis, Italy, 2010 to 2015. Euro Surveill 2018; 23:1800032. [PMID: 30563592 PMCID: PMC6299505 DOI: 10.2807/1560-7917.es.2018.23.50.1800032] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 08/06/2018] [Indexed: 12/29/2022] Open
Abstract
AimTo evaluate real-time PCR as a diagnostic method for Legionnaires' disease (LD). Detection of Legionella DNA is among the laboratory criteria of a probable LD case, according to the European Centre for Disease Prevention and Control, although the utility and advantages, as compared to culture, are widely recognised.MethodsTwo independent laboratories, one using an in-house and the other a commercial real-time PCR assay, analysed 354 respiratory samples from 311 patients hospitalised with pneumonia between 2010-15. The real-time PCR reliability was compared with that of culture and urinary antigen tests (UAT). Concordance, specificity, sensitivity and positive and negative predictive values (PPV and NPV, respectively) were calculated.ResultsOverall PCR detected eight additional LD cases, six of which were due to Legionella pneumophila (Lp) non-serogroup 1. The two real-time PCR assays were concordant in 99.4% of the samples. Considering in-house real-time PCR as the reference method, specificity of culture and UAT was 100% and 97.9% (95% CI: 96.2-99.6), while the sensitivity was 63.6% (95%CI: 58.6-68.6) and 77.8% (95% CI: 72.9-82.7). PPV and NPV for culture were 100% and 93.7% (95% CI: 91.2-96.3). PPV and NPV for UAT were 87.5% (95% CI: 83.6-91.4) and 95.8% (95% CI: 93.5-98.2).ConclusionRegardless of the real-time PCR assay used, it was possible to diagnose LD cases with higher sensitivity than using culture or UAT. These data encourage the adoption of PCR as routine laboratory testing to diagnose LD and such methods should be eligible to define a confirmed LD case.
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Affiliation(s)
- Maria Luisa Ricci
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Antonella Grottola
- Unit of Microbiology and Virology, Polyclinic University Hospital, Modena, Italy
- Department of Surgery, Medicine, Dentistry and Morphological Scientists with Transplant Surgery, Oncology and Regenerative Medicine Relevance, University of Modena and Reggio Emilia, Modena, Italy
| | | | - Antonino Bella
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Maria Cristina Rota
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Francesca Frascaro
- Unit of Microbiology and Virology, Polyclinic University Hospital, Modena, Italy
| | - Emanuela Pegoraro
- U.O.C. of Microbiology and Virology, Azienda Ospedaliero-Universitaria, Verona, Italy
| | - Marisa Meacci
- Unit of Microbiology and Virology, Polyclinic University Hospital, Modena, Italy
| | - Anna Fabio
- Unit of Microbiology and Virology, Polyclinic University Hospital, Modena, Italy
| | - Elena Vecchi
- Hospital Hygiene, Polyclinic University Hospital, Modena, Italy
| | - Antonietta Girolamo
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Fabio Rumpianesi
- Unit of Microbiology and Virology, Polyclinic University Hospital, Modena, Italy
| | - Monica Pecorari
- Unit of Microbiology and Virology, Polyclinic University Hospital, Modena, Italy
| | - Maria Scaturro
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
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27
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Lecointe D, Beauvais R, Breton N, Cailleret R, Pangon B. Control of legionellae in a new healthcare facility following implementation of a thermal control strategy. Infect Dis (Lond) 2018; 51:102-112. [DOI: 10.1080/23744235.2018.1518582] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Affiliation(s)
- Didier Lecointe
- Unité Fonctionnelle d’Hygiène Hospitalière et de Lutte contre les Infections Nosocomiales, Centre Hospitalier Sud Francilien, Corbeil-Essonnes, France
| | - Raphaëlle Beauvais
- Unité Fonctionnelle d’Hygiène Hospitalière et de Lutte contre les Infections Nosocomiales, Centre Hospitalier Sud Francilien, Corbeil-Essonnes, France
| | - Nelly Breton
- Service de Biologie, Unité de Microbiologie-Hygiène, Le Chesnay, France
| | | | - Béatrice Pangon
- Service de Biologie, Unité de Microbiologie-Hygiène, Le Chesnay, France
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28
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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. Control and prevention measures for legionellosis in hospitals: A cross-sectional survey in Italy. ENVIRONMENTAL RESEARCH 2018; 166:55-60. [PMID: 29864633 DOI: 10.1016/j.envres.2018.05.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/09/2018] [Accepted: 05/27/2018] [Indexed: 06/08/2023]
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.
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Affiliation(s)
- Maria Teresa Montagna
- Department of Biomedical Science and Human Oncology, University of Bari Aldo Moro, Square G. Cesare 11, 70124 Bari, Italy.
| | - Osvalda De Giglio
- Department of Biomedical Science and Human Oncology, University of Bari Aldo Moro, Square G. Cesare 11, 70124 Bari, Italy
| | - Christian Napoli
- Department of Medical and S urgical Sciences and Translational Medicine, Sapienza University of Roma, Square A. Moro 5, 00185 Roma, Italy
| | - Giusy Diella
- Department of Biomedical Science and Human Oncology, University of Bari Aldo Moro, Square G. Cesare 11, 70124 Bari, Italy
| | - Serafina Rutigliano
- Department of Biomedical Science and Human Oncology, University of Bari Aldo Moro, Square G. Cesare 11, 70124 Bari, Italy
| | - Antonella Agodi
- Department of Medical and Surgical Sciences and Advanced Technologies 'GF Ingrassia', University of Catania, Str. S. Sofia, 87, Comparto 10 Edificio C, 95123 Catania, Italy
| | - Francesco Auxilia
- Department of Biomedical Sciences for Health, University of Milano, Str. Pascal 36, 20133 Milano, Italy
| | - Tatjana Baldovin
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padova, Hygiene and Public Health Unit, Str. Loredan, 18.35131 Padova, Italy
| | - Francesco Bisetto
- Presidio Ospedaliero di Camposampiero, AULss6 Euganea Str. P. Cosma 1, 35012 Camposampiero, PD, Italy
| | - Luca Arnoldo
- Department of Medicine, University of Udine, Str. Colugna 50, 33100 Udine, Italy
| | - Silvio Brusaferro
- Department of Medicine, University of Udine, Str. Colugna 50, 33100 Udine, Italy
| | - Marina Busetti
- University Hospital ASUITS, Microbiology Unit, Strada di Fiume, 447, 34149 Trieste, Italy
| | - Gioia Calagreti
- Hospital "Alto Tevere", AUSL Umbria 1, Città di Castello, PG, Italy
| | - Beatrice Casini
- Department of Translational Research, N.T.M.S. - Hygiene and Epidemiology Unit, University of Pisa, Str. S. Zeno 35-39, 56127 Pisa, Italy
| | - Maria Luisa Cristina
- Department of Health Sciences, University of Genova, Str. A. Pastore 1, 16132 Genova, Italy
| | | | | | - Maurizio Formoso
- Hospital "Miulli", Str. 127 km 4.1, Santeramo-Acquaviva delle Fonti, BA, Italy
| | - Giorgio Liguori
- Department of Movement Sciences and Wellbeing, University "Parthenope", Napoli, Italy
| | - Enrica Martini
- AOU "Ospedali Riuniti", Str. Conca, 71, 60126 Ancona, Italy
| | - Andrea Molino
- Hospital "Madonna delle Grazie", Contrada Cattedra Ambulante s.nc. 75100 Matera, Italy
| | | | - Ida Mura
- Department of Biomedical Science, University of Sassari, Sassari, Italy
| | | | - Giovanni Battista Orsi
- Department of Public Health and Infectious Disease, Sapienza University of Roma, Roma, Italy
| | - Andrea Patroni
- ASST Valcamonica, Str. Manzoni 142, 25040 Esine, BS, Italy
| | - Anna Poli
- Hospital "San Giovanni di Dio", Str. Torre Galli 3, 50143 Firenze, Italy
| | - Gaetano Privitera
- Department of Translational Research, N.T.M.S. - Hygiene and Epidemiology Unit, University of Pisa, Str. S. Zeno 35-39, 56127 Pisa, Italy
| | - Giancarlo Ripabelli
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Andrea Rocchetti
- ASO "SS. Antonio, Biagio and C. Arrigo", Str. Venezia 17, 15121 Alessandria, Italy
| | | | - Mario Sarti
- Hospital "OCSAE", Str. Giardini 1355, Baggiovara, MO, Italy
| | - Sandra Savini
- AOU "Ospedali Riuniti", Str. Conca, 71, 60126 Ancona, Italy
| | - Antonio Silvestri
- Hospital "San Camillo Forlanini", Circonvallazione Gianicolense 87, 00152 Roma, Italy
| | - Luisa Sodano
- Hospital "San Camillo Forlanini", Circonvallazione Gianicolense 87, 00152 Roma, Italy
| | - Anna Maria Spagnolo
- Department of Health Sciences, University of Genova, Str. A. Pastore 1, 16132 Genova, Italy
| | - Stefano Tardivo
- Department of Diagnostic and Public Health, University of Verona, Str. Le Grazie 8, 37134 Verona, Italy
| | | | - Maria Valeria Torregrossa
- Department of Sciences for Health Promotion and Mother-Child Care "G. D'Alessandro", University of Palermo, Str. Vespro, 133, 90127 Palermo, Italy
| | - Emanuele Torri
- Department of Health ans Social Policy, Str. Gilli 4, 38123 Trento, Italy
| | - Licia Veronesi
- Department of Medicine and Surgery, University of Parma, Str. Volturno 39, Parma, Italy
| | - Raffaele Zarrilli
- Department of Public Health, University of Napoli "Federico II", Str. S. Pansini, 5, Napoli, Italy
| | - Claudia Pacifico
- Centre of Biostatistics for Clinical Epidemiology, School of Medicine and Surgery, University of Milano-Bicocca, Milano, Italy
| | | | - Matteo Moro
- Hospital "San Raffaele", Str. Olgettina 60, 20132 Milano, Italy
| | - Cesira Pasquarella
- Department of Medicine and Surgery, University of Parma, Str. Volturno 39, Parma, Italy
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29
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Lizana X, López A, Benito S, Agustí G, Ríos M, Piqué N, Marqués A, Codony F. Viability qPCR, a new tool for Legionella risk management. Int J Hyg Environ Health 2017; 220:1318-1324. [DOI: 10.1016/j.ijheh.2017.08.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 08/23/2017] [Accepted: 08/23/2017] [Indexed: 10/18/2022]
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30
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Samhan FA, Stedtfeld TM, Waseem H, Williams MR, Stedtfeld RD, Hashsham SA. On-filter direct amplification of Legionella pneumophila for rapid assessment of its abundance and viability. WATER RESEARCH 2017; 121:162-170. [PMID: 28527390 PMCID: PMC5525548 DOI: 10.1016/j.watres.2017.05.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 05/08/2017] [Accepted: 05/12/2017] [Indexed: 05/14/2023]
Abstract
Guidelines and regulations to control Legionella pneumophila in cooling water systems of large buildings are evolving due to the increasing number of outbreaks. Rapid, on-site, simple, and sensitive quantification methods that are also able to assess viability may be extremely useful in monitoring and control. Culture-based methods for measuring L. pneumophila may take 4-10 days and qPCR-based methods are also slow, requiring at least a day from sample to result, albeit mainly due to the need for sample transport to a centralized laboratory. This study reports a rapid isothermal amplification method for L. pneumophila concentration and detection with live/dead differentiation under field conditions. Using an on-filter direct amplification (i.e., amplification of cells without DNA extraction and purification) approach with propidium monoazide (PMA), and a real time isothermal amplification platform (Gene-Z), L. pneumophila could be detected in 1-2 h at ∼1 cfu/100 ml of tap water. Signature sequences from 16S rRNA and cadA genes were used as genetic markers for L. pneumophila and loop-mediated isothermal amplification (LAMP) primers were designed using Primer Explorer V4. Result were also compared with direct amplification of cells spiked into distilled, tap, and cooling water samples as well as extracted DNA by qPCR. This method may be useful to managers of cooling water systems in large buildings for rapid detection of L. pneumophila. The overall approach of on-site sample concentration, on-filter amplification, and live/dead differentiation may be extended to other organisms where analytical sensitivity and speed are equally important.
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Affiliation(s)
- Farag A Samhan
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA
| | - Tiffany M Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA
| | - Hassan Waseem
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA
| | - Maggie R Williams
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA
| | - Robert D Stedtfeld
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA
| | - Syed A Hashsham
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA; Center for Microbial Ecology, Michigan State University, East Lansing, MI, USA.
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31
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Kober C, Niessner R, Seidel M. Quantification of viable and non-viable Legionella spp. by heterogeneous asymmetric recombinase polymerase amplification (haRPA) on a flow-based chemiluminescence microarray. Biosens Bioelectron 2017; 100:49-55. [PMID: 28863324 DOI: 10.1016/j.bios.2017.08.053] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 08/01/2017] [Accepted: 08/23/2017] [Indexed: 11/19/2022]
Abstract
Increasing numbers of legionellosis outbreaks within the last years have shown that Legionella are a growing challenge for public health. Molecular biological detection methods capable of rapidly identifying viable Legionella are important for the control of engineered water systems. The current gold standard based on culture methods takes up to 10 days to show positive results. For this reason, a flow-based chemiluminescence (CL) DNA microarray was developed that is able to quantify viable and non-viable Legionella spp. as well as Legionella pneumophila in one hour. An isothermal heterogeneous asymmetric recombinase polymerase amplification (haRPA) was carried out on flow-based CL DNA microarrays. Detection limits of 87 genomic units (GU) µL-1 and 26GUµL-1 for Legionella spp. and Legionella pneumophila, respectively, were achieved. In this work, it was shown for the first time that the combination of a propidium monoazide (PMA) treatment with haRPA, the so-called viability haRPA, is able to identify viable Legionella on DNA microarrays. Different proportions of viable and non-viable Legionella, shown with the example of L. pneumophila, ranging in a total concentration between 101 to 105GUµL-1 were analyzed on the microarray analysis platform MCR 3. Recovery values for viable Legionella spp. were found between 81% and 133%. With the combination of these two methods, there is a chance to replace culture-based methods in the future for the monitoring of engineered water systems like condensation recooling plants.
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Affiliation(s)
- Catharina Kober
- Institute of Hydrochemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Marchioninistrasse 17, 81377 München, Germany
| | - Reinhard Niessner
- Institute of Hydrochemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Marchioninistrasse 17, 81377 München, Germany
| | - Michael Seidel
- Institute of Hydrochemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Marchioninistrasse 17, 81377 München, Germany.
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Montagna MT, De Giglio O, Cristina ML, Napoli C, Pacifico C, Agodi A, Baldovin T, Casini B, Coniglio MA, D'Errico MM, Delia SA, Deriu MG, Guida M, Laganà P, Liguori G, Moro M, Mura I, Pennino F, Privitera G, Romano Spica V, Sembeni S, Spagnolo AM, Tardivo S, Torre I, Valeriani F, Albertini R, Pasquarella C. Evaluation of Legionella Air Contamination in Healthcare Facilities by Different Sampling Methods: An Italian Multicenter Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017. [PMID: 28640202 PMCID: PMC5551108 DOI: 10.3390/ijerph14070670] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Healthcare facilities (HF) represent an at-risk environment for legionellosis transmission occurring after inhalation of contaminated aerosols. In general, the control of water is preferred to that of air because, to date, there are no standardized sampling protocols. Legionella air contamination was investigated in the bathrooms of 11 HF by active sampling (Surface Air System and Coriolis®μ) and passive sampling using settling plates. During the 8-hour sampling, hot tap water was sampled three times. All air samples were evaluated using culture-based methods, whereas liquid samples collected using the Coriolis®μ were also analyzed by real-time PCR. Legionella presence in the air and water was then compared by sequence-based typing (SBT) methods. Air contamination was found in four HF (36.4%) by at least one of the culturable methods. The culturable investigation by Coriolis®μ did not yield Legionella in any enrolled HF. However, molecular investigation using Coriolis®μ resulted in eight HF testing positive for Legionella in the air. Comparison of Legionella air and water contamination indicated that Legionella water concentration could be predictive of its presence in the air. Furthermore, a molecular study of 12 L. pneumophila strains confirmed a match between the Legionella strains from air and water samples by SBT for three out of four HF that tested positive for Legionella by at least one of the culturable methods. Overall, our study shows that Legionella air detection cannot replace water sampling because the absence of microorganisms from the air does not necessarily represent their absence from water; nevertheless, air sampling may provide useful information for risk assessment. The liquid impingement technique appears to have the greatest capacity for collecting airborne Legionella if combined with molecular investigations.
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Affiliation(s)
- Maria Teresa Montagna
- Department of Biomedical Science and Human Oncology, University of Bari "Aldo Moro", Piazza G. Cesare 11, 70124 Bari, Italy.
| | - Osvalda De Giglio
- Department of Biomedical Science and Human Oncology, University of Bari "Aldo Moro", Piazza G. Cesare 11, 70124 Bari, Italy.
| | - Maria Luisa Cristina
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genova, Italy.
| | - Christian Napoli
- Department of Medical and Surgical Sciences and Translational Medicine, Sapienza University of Roma, Via di Grottarossa 1035, 00189 Roma, Italy.
| | - Claudia Pacifico
- Department of Biomedical Science and Human Oncology, University of Bari "Aldo Moro", Piazza G. Cesare 11, 70124 Bari, Italy.
| | - Antonella Agodi
- Department of Medical and Surgical Sciences and Advanced Technologies "GF Ingrassia", University of Catania, Via Sofia 87, 95123 Catania, Italy.
| | - Tatjana Baldovin
- Department of Cardiac, Thoracic and Vascular Sciences, Hygiene and Public Health Unit, University of Padova, Via Loredan 18, 35131 Padova, Italy.
| | - Beatrice Casini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno 35/39, 56127 Pisa, Italy.
| | - Maria Anna Coniglio
- Department of Medical and Surgical Sciences and Advanced Technologies "GF Ingrassia", University of Catania, Via Sofia 87, 95123 Catania, Italy.
| | - Marcello Mario D'Errico
- Department of Biomedical Sciences and Public Health, Polytechnic University of Marche, via Tronto, 10/a Torrette di Ancona, 60020 Ancona, Italy.
| | - Santi Antonino Delia
- Department of Biomedical Science and Morphological and Functional Images, University of Messina, Via C.Valeria snc, 98125 Messina, Italy.
| | - Maria Grazia Deriu
- Department of Biomedical Science-Hygiene Section, University of Sassari, Via Padre Manzella 4, 07100 Sassari, Italy.
| | - Marco Guida
- Department of Biology, University of Napoli "Federico II", Via Cinthia 26, 80126 Napoli, Italy.
| | - Pasqualina Laganà
- Department of Biomedical Science and Morphological and Functional Images, University of Messina, Via C.Valeria snc, 98125 Messina, Italy.
| | - Giorgio Liguori
- Department of Movement Sciences and Wellbeing, University "Parthenope", Via Medina 40, 80133 Napoli, Italy.
| | - Matteo Moro
- IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milano, Italy.
| | - Ida Mura
- Department of Biomedical Science-Hygiene Section, University of Sassari, Via Padre Manzella 4, 07100 Sassari, Italy.
| | - Francesca Pennino
- Department of Public Health, University of Napoli "Federico II", Via S.Pansini 5, 80131 Napoli, Italy.
| | - Gaetano Privitera
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno 35/39, 56127 Pisa, Italy.
| | - Vincenzo Romano Spica
- Department of Movement, Human and Health Sciences, Public Health Unit, University of Roma "Foro Italico", P.zza Lauro De Bosis 6, 00135 Roma, Italy.
| | - Silvia Sembeni
- Department of Diagnostic and Public Health, University of Verona, Strada le Grazie 8, 37134 Verona, Italy.
| | - Anna Maria Spagnolo
- Department of Health Sciences, University of Genoa, Via Pastore 1, 16132 Genova, Italy.
| | - Stefano Tardivo
- Department of Diagnostic and Public Health, University of Verona, Strada le Grazie 8, 37134 Verona, Italy.
| | - Ida Torre
- Department of Public Health, University of Napoli "Federico II", Via S.Pansini 5, 80131 Napoli, Italy.
| | - Federica Valeriani
- Department of Movement, Human and Health Sciences, Public Health Unit, University of Roma "Foro Italico", P.zza Lauro De Bosis 6, 00135 Roma, Italy.
| | - Roberto Albertini
- Department of Medicine and Surgery, University of Parma, Medical Immunology Unit, University Hospital of Parma, Via Gramsci 14, 43126 Parma, Italy.
| | - Cesira Pasquarella
- Department of Medicine and Surgery, University of Parma, Via Volturno 39, 43125 Parma, Italy.
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Wang H, Bédard E, Prévost M, Camper AK, Hill VR, Pruden A. Methodological approaches for monitoring opportunistic pathogens in premise plumbing: A review. WATER RESEARCH 2017; 117:68-86. [PMID: 28390237 PMCID: PMC5693313 DOI: 10.1016/j.watres.2017.03.046] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 03/19/2017] [Accepted: 03/22/2017] [Indexed: 05/06/2023]
Abstract
Opportunistic premise (i.e., building) plumbing pathogens (OPPPs, e.g., Legionella pneumophila, Mycobacterium avium complex, Pseudomonas aeruginosa, Acanthamoeba, and Naegleria fowleri) are a significant and growing source of disease. Because OPPPs establish and grow as part of the native drinking water microbiota, they do not correspond to fecal indicators, presenting a major challenge to standard drinking water monitoring practices. Further, different OPPPs present distinct requirements for sampling, preservation, and analysis, creating an impediment to their parallel detection. The aim of this critical review is to evaluate the state of the science of monitoring OPPPs and identify a path forward for their parallel detection and quantification in a manner commensurate with the need for reliable data that is informative to risk assessment and mitigation. Water and biofilm sampling procedures, as well as factors influencing sample representativeness and detection sensitivity, are critically evaluated with respect to the five representative bacterial and amoebal OPPPs noted above. Available culturing and molecular approaches are discussed in terms of their advantages, limitations, and applicability. Knowledge gaps and research needs towards standardized approaches are identified.
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Affiliation(s)
- Hong Wang
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
| | - Emilie Bédard
- Department of Civil Engineering, Polytechnique Montreal, Montreal, QC, Canada
| | - Michèle Prévost
- Department of Civil Engineering, Polytechnique Montreal, Montreal, QC, Canada
| | - Anne K Camper
- Center for Biofilm Engineering and Department of Civil Engineering, Montana State University, Bozeman, MT 59717, USA
| | - Vincent R Hill
- Waterborne Disease Prevention Branch, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30329, USA
| | - Amy Pruden
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA 24061, USA
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Collins S, Stevenson D, Walker J, Bennett A. Evaluation ofLegionellareal-time PCR against traditional culture for routine and public health testing of water samples. J Appl Microbiol 2017; 122:1692-1703. [DOI: 10.1111/jam.13461] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/25/2017] [Accepted: 03/27/2017] [Indexed: 11/29/2022]
Affiliation(s)
- S. Collins
- Biosafety Air and Water Microbiology Group; Public Health England; Porton Down Salisbury UK
| | - D. Stevenson
- Biosafety Air and Water Microbiology Group; Public Health England; Porton Down Salisbury UK
| | - J. Walker
- Biosafety Air and Water Microbiology Group; Public Health England; Porton Down Salisbury UK
| | - A. Bennett
- Biosafety Air and Water Microbiology Group; Public Health England; Porton Down Salisbury UK
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Scaturro M, Fontana S, Dell’eva I, Helfer F, Marchio M, Stefanetti MV, Cavallaro M, Miglietta M, Montagna MT, De Giglio O, Cuna T, Chetti L, Sabattini MAB, Carlotti M, Viggiani M, Stenico A, Romanin E, Bonanni E, Ottaviano C, Franzin L, Avanzini C, Demarie V, Corbella M, Cambieri P, Marone P, Rota MC, Bella A, Ricci ML. A multicenter study of viable PCR using propidium monoazide to detect Legionella in water samples. Diagn Microbiol Infect Dis 2016; 85:283-288. [DOI: 10.1016/j.diagmicrobio.2016.04.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/21/2016] [Accepted: 04/11/2016] [Indexed: 11/26/2022]
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Combination of Heat Shock and Enhanced Thermal Regime to Control the Growth of a Persistent Legionella pneumophila Strain. Pathogens 2016; 5:pathogens5020035. [PMID: 27092528 PMCID: PMC4931386 DOI: 10.3390/pathogens5020035] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 04/04/2016] [Accepted: 04/11/2016] [Indexed: 11/16/2022] Open
Abstract
Following nosocomial cases of Legionella pneumophila, the investigation of a hot water system revealed that 81.5% of sampled taps were positive for L. pneumophila, despite the presence of protective levels of copper in the water. A significant reduction of L. pneumophila counts was observed by culture after heat shock disinfection. The following corrective measures were implemented to control L. pneumophila: increasing the hot water temperature (55 to 60 °C), flushing taps weekly with hot water, removing excess lengths of piping and maintaining a water temperature of 55 °C throughout the system. A gradual reduction in L. pneumophila counts was observed using the culture method and qPCR in the 18 months after implementation of the corrective measures. However, low level contamination was retained in areas with hydraulic deficiencies, highlighting the importance of maintaining a good thermal regime at all points within the system to control the population of L. pneumophila.
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37
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Kirschner AK. Determination of viable legionellae in engineered water systems: Do we find what we are looking for? WATER RESEARCH 2016; 93:276-288. [PMID: 26928563 PMCID: PMC4913838 DOI: 10.1016/j.watres.2016.02.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Revised: 02/06/2016] [Accepted: 02/09/2016] [Indexed: 05/06/2023]
Abstract
In developed countries, legionellae are one of the most important water-based bacterial pathogens caused by management failure of engineered water systems. For routine surveillance of legionellae in engineered water systems and outbreak investigations, cultivation-based standard techniques are currently applied. However, in many cases culture-negative results are obtained despite the presence of viable legionellae, and clinical cases of legionellosis cannot be traced back to their respective contaminated water source. Among the various explanations for these discrepancies, the presence of viable but non-culturable (VBNC) Legionella cells has received increased attention in recent discussions and scientific literature. Alternative culture-independent methods to detect and quantify legionellae have been proposed in order to complement or even substitute the culture method in the future. Such methods should detect VBNC Legionella cells and provide a more comprehensive picture of the presence of legionellae in engineered water systems. However, it is still unclear whether and to what extent these VBNC legionellae are hazardous to human health. Current risk assessment models to predict the risk of legionellosis from Legionella concentrations in the investigated water systems contain many uncertainties and are mainly based on culture-based enumeration. If VBNC legionellae should be considered in future standard analysis, quantitative risk assessment models including VBNC legionellae must be proven to result in better estimates of human health risk than models based on cultivation alone. This review critically evaluates current methods to determine legionellae in the VBNC state, their potential to complement the standard culture-based method in the near future, and summarizes current knowledge on the threat that VBNC legionellae may pose to human health.
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Affiliation(s)
- Alexander K.T. Kirschner
- Medical University Vienna, Institute for Hygiene and Applied Immunology, Water Hygiene, Kinderspitalgasse 15, A-1090 Vienna, Austria
- Interuniversity Cooperation Centre for Water & Health, Austria
- Medical University Vienna, Institute for Hygiene and Applied Immunology, Water Hygiene Kinderspitalgasse 16, A-1090 Vienna, Austria . URL: http://www.waterandhealth.at
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38
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Wunderlich A, Torggler C, Elsässer D, Lück C, Niessner R, Seidel M. Rapid quantification method for Legionella pneumophila in surface water. Anal Bioanal Chem 2016; 408:2203-13. [DOI: 10.1007/s00216-016-9362-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/15/2016] [Accepted: 01/25/2016] [Indexed: 01/08/2023]
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39
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Lu J, Struewing I, Vereen E, Kirby AE, Levy K, Moe C, Ashbolt N. Molecular Detection of Legionella
spp. and their associations with Mycobacterium
spp., Pseudomonas aeruginosa
and amoeba hosts in a drinking water distribution system. J Appl Microbiol 2016; 120:509-21. [DOI: 10.1111/jam.12996] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 10/08/2015] [Accepted: 10/27/2015] [Indexed: 01/12/2023]
Affiliation(s)
- J. Lu
- U.S. EPA National Exposure Research Laboratory; Cincinnati OH USA
| | | | - E. Vereen
- Center for Global Safe Water; Sanitation and Hygiene; Emory University; Atlanta GA USA
| | - A. E. Kirby
- Center for Global Safe Water; Sanitation and Hygiene; Emory University; Atlanta GA USA
| | - K. Levy
- Center for Global Safe Water; Sanitation and Hygiene; Emory University; Atlanta GA USA
| | - C. Moe
- Center for Global Safe Water; Sanitation and Hygiene; Emory University; Atlanta GA USA
| | - N. Ashbolt
- School of Public Health; University of Alberta; Edmonton AB Canada
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40
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A Fatal Case of Nosocomial Legionnaires’ Disease: Implications From an Extensive Environmental Investigation and Isolation of the Bacterium From Blood Culture. Infect Control Hosp Epidemiol 2015; 36:1483-5. [DOI: 10.1017/ice.2015.225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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41
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Collins S, Jorgensen F, Willis C, Walker J. Real-time PCR to supplement gold-standard culture-based detection of Legionella
in environmental samples. J Appl Microbiol 2015. [DOI: 10.1111/jam.12911] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- S. Collins
- Public Health England; Biosafety Investigation Unit; Salisbury UK
- Public Health England; Food, Water and Environmental Microbiology Laboratory; Salisbury UK
| | - F. Jorgensen
- Public Health England; Food, Water and Environmental Microbiology Laboratory; Salisbury UK
| | - C. Willis
- Public Health England; Food, Water and Environmental Microbiology Laboratory; Salisbury UK
| | - J. Walker
- Public Health England; Biosafety Investigation Unit; Salisbury UK
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42
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Shen SM, Chou MY, Hsu BM, Ji WT, Hsu TK, Tsai HF, Huang YL, Chiu YC, Kao ES, Kao PM, Fan CW. Assessment of Legionella pneumophila in recreational spring water with quantitative PCR (Taqman) assay. Pathog Glob Health 2015; 109:236-41. [PMID: 26184706 DOI: 10.1179/2047773215y.0000000023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Legionella spp. are common in various natural and man-made aquatic environments. Recreational hot spring is frequently reported as an infection hotspot because of various factors such as temperature and humidity. Although polymerase chain reaction (PCR) had been used for detecting Legionella, several inhibitors such as humic substances, calcium, and melanin in the recreational spring water may interfere with the reaction thus resulting in risk underestimation. The purpose of this study was to compare the efficiencies of conventional and Taqman quantitative PCR (qPCR) on detecting Legionella pneumophila in spring facilities and in receiving water. In the results, Taqman PCR had much better efficiency on specifying the pathogen in both river and spring samples. L. pneumophila was detected in all of the 27 river water samples and 45 of the 48 hot spring water samples. The estimated L. pneumophela concentrations ranged between 1.0 × 10(2) and 3.3 × 10(5) cells/l in river water and 72.1-5.7 × 10(6) cells/l in hot spring water. Total coliforms and turbidity were significantly correlated with concentrations of L. pneumophila in positive water samples. Significant difference was also found in water temperature between the presence/absence of L. pneumophila. Our results suggest that conventional PCR may be not enough for detecting L. pneumophila particularly in the aquatic environments full of reaction inhibitors.
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43
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Lu J, Struewing I, Yelton S, Ashbolt N. Molecular survey of occurrence and quantity of Legionella
spp., Mycobacterium
spp., Pseudomonas aeruginosa
and amoeba hosts in municipal drinking water storage tank sediments. J Appl Microbiol 2015; 119:278-88. [DOI: 10.1111/jam.12831] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 02/27/2015] [Accepted: 04/10/2015] [Indexed: 01/03/2023]
Affiliation(s)
- J. Lu
- U.S. EPA National Exposure Research Laboratory; Cincinnati OH USA
| | | | | | - N. Ashbolt
- School of Public Health; University of Alberta; Edmonton AB Canada
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44
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Díaz-Flores Á, Montero JC, Castro FJ, Alejandres EM, Bayón C, Solís I, Fernández-Lafuente R, Rodríguez G. Comparing methods of determining Legionella spp. in complex water matrices. BMC Microbiol 2015; 15:91. [PMID: 25925400 PMCID: PMC4436101 DOI: 10.1186/s12866-015-0423-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 04/15/2015] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Legionella testing conducted at environmental laboratories plays an essential role in assessing the risk of disease transmission associated with water systems. However, drawbacks of culture-based methodology used for Legionella enumeration can have great impact on the results and interpretation which together can lead to underestimation of the actual risk. Up to 20% of the samples analysed by these laboratories produced inconclusive results, making effective risk management impossible. Overgrowth of competing microbiota was reported as an important factor for culture failure. For quantitative polymerase chain reaction (qPCR), the interpretation of the results from the environmental samples still remains a challenge. Inhibitors may cause up to 10% of inconclusive results. This study compared a quantitative method based on immunomagnetic separation (IMS method) with culture and qPCR, as a new approach to routine monitoring of Legionella. RESULTS First, pilot studies evaluated the recovery and detectability of Legionella spp using an IMS method, in the presence of microbiota and biocides. The IMS method results were not affected by microbiota while culture counts were significantly reduced (1.4 log) or negative in the same samples. Damage by biocides of viable Legionella was detected by the IMS method. Secondly, a total of 65 water samples were assayed by all three techniques (culture, qPCR and the IMS method). Of these, 27 (41.5%) were recorded as positive by at least one test. Legionella spp was detected by culture in 7 (25.9%) of the 27 samples. Eighteen (66.7%) of the 27 samples were positive by the IMS method, thirteen of them reporting counts below 10(3) colony forming units per liter (CFU l(-1)), six presented interfering microbiota and three presented PCR inhibition. Of the 65 water samples, 24 presented interfering microbiota by culture and 8 presented partial or complete inhibition of the PCR reaction. So the rate of inconclusive results of culture and PCR was 36.9 and 12.3%, respectively, without any inconclusive results reported for the IMS method. CONCLUSION The IMS method generally improved the recovery and detectability of Legionella in environmental matrices, suggesting the possibility to use IMS method as valuable indicator of risk. Thus, this method may significantly improve our knowledge about the exposure risk to these bacteria, allowing us to implement evidence-based monitoring and disinfection strategies.
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Affiliation(s)
- Álvaro Díaz-Flores
- Departamento de Microbiología General III, Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, Campus Moncloa, 28040, Madrid, Spain.
| | - Juan Carlos Montero
- Instituto de Ciencias de la Salud Ctra, de Extremadura Km. 114, 45600, Talavera de la Reina, Spain.
| | - Francisco Javier Castro
- Laboratorio Regional de Salud Pública Consejería de Sanidad y Consumo/Comunidad de Madrid, C/ Sierra del Alquife N 8, 2 Planta, 28053, Madrid, Spain.
| | - Eva María Alejandres
- Laboratorio Regional de Salud Pública Consejería de Sanidad y Consumo/Comunidad de Madrid, C/ Sierra del Alquife N 8, 2 Planta, 28053, Madrid, Spain.
| | - Carmen Bayón
- Laboratorio Regional de Salud Pública Consejería de Sanidad y Consumo/Comunidad de Madrid, C/ Sierra del Alquife N 8, 2 Planta, 28053, Madrid, Spain.
| | | | - Roberto Fernández-Lafuente
- Departamento de Biocatálisis, Instituto de Catálisis y Petroleoquímica, Consejo Superior de Investigaciones Científicas, Campus UAM-CSIC, 28049, Cantoblanco, Madrid, Spain.
| | - Guillermo Rodríguez
- Biótica, Bioquímica Analítica, S.L, Science and Technology Park of Jaume I University, Campus RiuSec - Espaitec 2, planta baja, E12071, Castellón de la Plana, Spain.
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45
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Bédard E, Fey S, Charron D, Lalancette C, Cantin P, Dolcé P, Laferrière C, Déziel E, Prévost M. Temperature diagnostic to identify high risk areas and optimize Legionella pneumophila surveillance in hot water distribution systems. WATER RESEARCH 2015; 71:244-56. [PMID: 25622002 DOI: 10.1016/j.watres.2015.01.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Revised: 12/22/2014] [Accepted: 01/05/2015] [Indexed: 05/08/2023]
Abstract
Legionella pneumophila is frequently detected in hot water distribution systems and thermal control is a common measure implemented by health care facilities. A risk assessment based on water temperature profiling and temperature distribution within the network is proposed, to guide effective monitoring strategies and allow the identification of high risk areas. Temperature and heat loss at control points (water heater, recirculation, representative points-of-use) were monitored in various sections of five health care facilities hot water distribution systems and results used to develop a temperature-based risk assessment tool. Detailed investigations show that defective return valves in faucets can cause widespread temperature losses because of hot and cold water mixing. Systems in which water temperature coming out of the water heaters was kept consistently above 60 °C and maintained above 55 °C across the network were negative for Legionella by culture or qPCR. For systems not meeting these temperature criteria, risk areas for L. pneumophila were identified using temperature profiling and system's characterization; higher risk was confirmed by more frequent microbiological detection by culture and qPCR. Results confirmed that maintaining sufficiently high temperatures within hot water distribution systems suppressed L. pneumophila culturability. However, the risk remains as shown by the persistence of L. pneumophila by qPCR.
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Affiliation(s)
- Emilie Bédard
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada; INRS-Institut Armand-Frappier, Laval, QC, Canada.
| | - Stéphanie Fey
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada
| | - Dominique Charron
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada
| | | | - Philippe Cantin
- Centre d'expertise en analyse environnementale du Québec, Québec, QC, Canada
| | - Patrick Dolcé
- Department of Medical Microbiology and Infectious Diseases, Centre Hospitalier Régional de Rimouski, Rimouski, QC, Canada
| | - Céline Laferrière
- Department of Microbiology and Immunology (Infection Control), CHU Ste-Justine, Université de Montréal, Montréal, QC, Canada
| | - Eric Déziel
- INRS-Institut Armand-Frappier, Laval, QC, Canada
| | - Michèle Prévost
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada
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46
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Mercante JW, Winchell JM. Current and emerging Legionella diagnostics for laboratory and outbreak investigations. Clin Microbiol Rev 2015; 28:95-133. [PMID: 25567224 PMCID: PMC4284297 DOI: 10.1128/cmr.00029-14] [Citation(s) in RCA: 214] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Legionnaires' disease (LD) is an often severe and potentially fatal form of bacterial pneumonia caused by an extensive list of Legionella species. These ubiquitous freshwater and soil inhabitants cause human respiratory disease when amplified in man-made water or cooling systems and their aerosols expose a susceptible population. Treatment of sporadic cases and rapid control of LD outbreaks benefit from swift diagnosis in concert with discriminatory bacterial typing for immediate epidemiological responses. Traditional culture and serology were instrumental in describing disease incidence early in its history; currently, diagnosis of LD relies almost solely on the urinary antigen test, which captures only the dominant species and serogroup, Legionella pneumophila serogroup 1 (Lp1). This has created a diagnostic "blind spot" for LD caused by non-Lp1 strains. This review focuses on historic, current, and emerging technologies that hold promise for increasing LD diagnostic efficiency and detection rates as part of a coherent testing regimen. The importance of cooperation between epidemiologists and laboratorians for a rapid outbreak response is also illustrated in field investigations conducted by the CDC with state and local authorities. Finally, challenges facing health care professionals, building managers, and the public health community in combating LD are highlighted, and potential solutions are discussed.
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Affiliation(s)
- Jeffrey W Mercante
- Pneumonia Response and Surveillance Laboratory, Respiratory Diseases Branch, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Jonas M Winchell
- Pneumonia Response and Surveillance Laboratory, Respiratory Diseases Branch, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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Lu J, Buse HY, Gomez-Alvarez V, Struewing I, Santo Domingo J, Ashbolt NJ. Impact of drinking water conditions and copper materials on downstream biofilm microbial communities and Legionella pneumophila colonization. J Appl Microbiol 2014; 117:905-18. [PMID: 24935752 DOI: 10.1111/jam.12578] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/27/2014] [Accepted: 06/12/2014] [Indexed: 01/08/2023]
Abstract
AIMS This study examined the impact of pipe materials and introduced Legionella pneumophila on downstream Leg. pneumophila colonization and microbial community structures under conditions of low flow and low chlorine residual. METHODS AND RESULTS CDC biofilm(™) reactors containing either unplasticized polyvinylchloride (uPVC) or copper (Cu) coupons were used to develop mature biofilms on Norprene(™) tubing effluent lines to simulate possible in-premise biofilm conditions. The microbial communities were characterized through 16S and 18S rRNA gene clone libraries and Leg. pneumophila colonization was determined via specific qPCR assays. The Cu significantly decreased downstream microbial diversity, approximately halved bacterial and eukaryotic abundance, with some groups only detected in uPVC-reactor tubing biofilms. However, some probable amoeba-resisting bacteria (ARB) like Mycobacterium spp. and Rhodobacteraceae were significantly more abundant in the Cu than uPVC-reactor tubing biofilms. In particular, Leg. pneumophila only persisted (postinoculation) within the Cu-reactor tubing biofilms, and the controlled low chlorine residue and water flow conditions led to a general high abundance of possible free-living protozoa in all tubing biofilms. The higher relative abundance of ARB-like sequences from Cu-coupons vs uPVC may have been promoted by amoebal selection and subsequent ARB protection from Cu inhibitory effects. CONCLUSIONS Copper pipe and low flow conditions had significant impact on downstream biofilm microbial structures (on plastic pipe) and the ability for Leg. pneumophila colonization post an introduction event. SIGNIFICANCE AND IMPACT OF THE STUDY This is the first report that compares the effects of copper and uPVC materials on downstream biofilm communities grown on a third (Norprene(™)) surface material. The downstream biofilms contained a high abundance of free-living amoebae and ARB, which may have been driven by a lack of residual disinfectant and periodic stagnant conditions. Given the prevalence of Cu-piping in buildings, there may be increased risk from drinking water exposures to ARB following growth on pipe/fixture biofilms within premise drinking water systems.
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Affiliation(s)
- J Lu
- Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH, USA
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Hines SA, Chappie DJ, Lordo RA, Miller BD, Janke RJ, Lindquist HA, Fox KR, Ernst HS, Taft SC. Assessment of relative potential for Legionella species or surrogates inhalation exposure from common water uses. WATER RESEARCH 2014; 56:203-13. [PMID: 24681377 DOI: 10.1016/j.watres.2014.02.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 01/07/2014] [Accepted: 02/03/2014] [Indexed: 05/22/2023]
Abstract
The Legionella species have been identified as important waterborne pathogens in terms of disease morbidity and mortality. Microbial exposure assessment is a tool that can be utilized to assess the potential of Legionella species inhalation exposure from common water uses. The screening-level exposure assessment presented in this paper developed emission factors to model aerosolization, quantitatively assessed inhalation exposures of aerosolized Legionella species or Legionella species surrogates while evaluating two generalized levels of assumed water concentrations, and developed a relative ranking of six common in-home uses of water for potential Legionella species inhalation exposure. Considerable variability in the calculated exposure dose was identified between the six identified exposure pathways, with the doses differing by over five orders of magnitude in each of the evaluated exposure scenarios. The assessment of exposure pathways that have been epidemiologically associated with legionellosis transmission (ultrasonic and cool mist humidifiers) produced higher estimated inhalation exposure doses than pathways where epidemiological evidence of transmission has been less strong (faucet and shower) or absent (toilets and therapy pool). With consideration of the large uncertainties inherent in the exposure assessment process used, a relative ranking of exposure pathways from highest to lowest exposure doses was produced using culture-based measurement data and the assumption of constant water concentration across exposure pathways. In this ranking, the ultrasonic and cool mist humidifier exposure pathways were estimated to produce the highest exposure doses, followed by the shower and faucet exposure pathways, and then the toilet and therapy pool exposure pathways.
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Affiliation(s)
| | | | | | | | - Robert J Janke
- U.S. Environmental Protection Agency, National Homeland Security Research Center, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA
| | - H Alan Lindquist
- U.S. Environmental Protection Agency, National Homeland Security Research Center, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA
| | - Kim R Fox
- U.S. Environmental Protection Agency, National Homeland Security Research Center, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA
| | - Hiba S Ernst
- U.S. Environmental Protection Agency, National Homeland Security Research Center, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA
| | - Sarah C Taft
- U.S. Environmental Protection Agency, National Homeland Security Research Center, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA.
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Donohue MJ, O'Connell K, Vesper SJ, Mistry JH, King D, Kostich M, Pfaller S. Widespread molecular detection of Legionella pneumophila Serogroup 1 in cold water taps across the United States. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:3145-3152. [PMID: 24548208 DOI: 10.1021/es4055115] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In the United States, 6,868 cases of legionellosis were reported to the Center for Disease Control and Prevention in 2009-2010. Of these reports, it is estimated that 84% are caused by the microorganism Legionella pneumophila Serogroup (Sg) 1. Legionella spp. have been isolated and recovered from a variety of natural freshwater environments. Human exposure to L. pneumophila Sg1 may occur from aerosolization and subsequent inhalation of household and facility water. In this study, two primer/probe sets (one able to detect L. pneumophila and the other L. pneumophila Sg1) were determined to be highly sensitive and selective for their respective targets. Over 272 water samples, collected in 2009 and 2010 from 68 public and private water taps across the United States, were analyzed using the two qPCR assays to evaluate the incidence of L. pneumophila Sg1. Nearly half of the taps showed the presence of L. pneumophila Sg1 in one sampling event, and 16% of taps were positive in more than one sampling event. This study is the first United States survey to document the occurrence and colonization of L. pneumophila Sg1 in cold water delivered from point of use taps.
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Affiliation(s)
- Maura J Donohue
- Office of Research and Development, National Exposure Research Laboratory, United States Environmental Protection Agency , 26 West Martin Luther King Drive, Mail Stop 593, Cincinnati, Ohio 45268, United States
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Abstract
Legionella spp. are the causative agent of Legionnaire's disease and an opportunistic pathogen of significant public health concern. Identification and quantification from environmental sources is crucial for identifying outbreak origins and providing sufficient information for risk assessment and disease prevention. Currently there are a range of methods for Legionella spp. quantification from environmental sources, but the two most widely used and accepted are culture and real-time polymerase chain reaction (qPCR). This paper provides a review of these two methods and outlines their advantages and limitations. Studies from the last 10 years which have concurrently used culture and qPCR to quantify Legionella spp. from environmental sources have been compiled. 26/28 studies detected Legionella at a higher rate using qPCR compared to culture, whilst only one study detected equivalent levels of Legionella spp. using both qPCR and culture. Aggregating the environmental samples from all 28 studies, 2856/3967 (72%) tested positive for the presence of Legionella spp. using qPCR and 1331/3967 (34%) using culture. The lack of correlation between methods highlights the need to develop an acceptable standardized method for quantification that is sufficient for risk assessment and management of this human pathogen.
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Affiliation(s)
- Harriet Whiley
- a Department of Health and the Environment , Flinders University , Adelaide , Australia
| | - Michael Taylor
- a Department of Health and the Environment , Flinders University , Adelaide , Australia
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