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Furst KE, Graham KE, Weisman RJ, Adusei KB. It's getting hot in here: Effects of heat on temperature, disinfection, and opportunistic pathogens in drinking water distribution systems. WATER RESEARCH 2024; 260:121913. [PMID: 38901309 DOI: 10.1016/j.watres.2024.121913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 06/06/2024] [Accepted: 06/07/2024] [Indexed: 06/22/2024]
Abstract
As global temperatures rise with climate change, the negative effects of heat on drinking water distribution systems (DWDS) are of increasing concern. High DWDS temperatures are associated with degradation of water quality through physical, chemical and microbial mechanisms. Perhaps the most pressing concern is proliferation of thermotolerant opportunistic pathogens (OPs) like Legionella pneumophila and Naegleria Fowleri. Many OPs can be controlled in DWDS by residual disinfectants such as chlorine or chloramine, but maintaining protective residuals can be challenging at high temperatures. This critical review evaluates the literature on DWDS temperature, residual disinfectant decay, and OP survival and growth with respect to high temperatures. The findings are synthesized to determine the state of knowledge and future research priorities regarding OP proliferation and control at high DWDS temperatures. Temperatures above 40 °C were reported from multiple DWDS, with a maximum of 52 °C. Substantial diurnal temperature swings from ∼30-50 °C occurred in one DWDS. Many OPs can survive or even replicate at these temperatures. However, most studies focused on just a few OP species, and substantial knowledge gaps remain regarding persistence, infectivity, and shifts in microbial community structure at high temperatures relative to lower water temperatures. Chlorine decay rates substantially increase with temperature in some waters but not in others, for reasons that are not well understood. Decay rates within real DWDS are difficult to accurately characterize, presenting practical limitations for application of temperature-dependent decay models at full scale. Chloramine decay is slower than chlorine except in the presence of nitrifiers, which are especially known to grow in DWDS in warmer seasons and climates, though the high temperature range for nitrification is unknown. Lack of knowledge about DWDS nitrifier communities may hinder development of solutions. Fundamental knowledge gaps remain which prevent understanding even the occurrence of high temperatures in DWDS, much less the overall effect on exposure risk. Potential solutions to minimize DWDS temperatures or mitigate the impacts of heat were identified, many which could be aided by proven models for predicting DWDS temperature. Industry leadership and collaboration is needed to generate practical knowledge for protecting DWDS water quality as temperatures rise.
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Affiliation(s)
- Kirin E Furst
- Department of Civil, Environmental, & Infrastructure Engineering, George Mason University, 4400 University Drive, Fairfax, VA 22030, United States.
| | - Katherine E Graham
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Richard J Weisman
- Department of Civil, Environmental, & Infrastructure Engineering, George Mason University, 4400 University Drive, Fairfax, VA 22030, United States
| | - Kadmiel B Adusei
- Department of Civil, Environmental, & Infrastructure Engineering, George Mason University, 4400 University Drive, Fairfax, VA 22030, United States
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2
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Song Y, Mena-Aguilar D, Brown CL, Rhoads WJ, Helm RF, Pruden A, Edwards MA. Effects of Copper on Legionella pneumophila Revealed via Viability Assays and Proteomics. Pathogens 2024; 13:563. [PMID: 39057790 PMCID: PMC11279431 DOI: 10.3390/pathogens13070563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 06/22/2024] [Accepted: 06/27/2024] [Indexed: 07/28/2024] Open
Abstract
Cu is an antimicrobial that is commonly applied to premise (i.e., building) plumbing systems for Legionella control, but the precise mechanisms of inactivation are not well defined. Here, we applied a suite of viability assays and mass spectrometry-based proteomics to assess the mechanistic effects of Cu on L. pneumophila. Although a five- to six-log reduction in culturability was observed with 5 mg/L Cu2+ exposure, cell membrane integrity only indicated a <50% reduction. Whole-cell proteomic analysis revealed that AhpD, a protein related to oxidative stress, was elevated in Cu-exposed Legionella relative to culturable cells. Other proteins related to cell membrane synthesis and motility were also higher for the Cu-exposed cells relative to controls without Cu. While the proteins related to primary metabolism decreased for the Cu-exposed cells, no significant differences in the abundance of proteins related to virulence or infectivity were found, which was consistent with the ability of VBNC cells to cause infections. Whereas the cell-membrane integrity assay provided an upper-bound measurement of viability, an amoebae co-culture assay provided a lower-bound limit. The findings have important implications for assessing Legionella risk following its exposure to copper in engineered water systems.
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Affiliation(s)
- Yang Song
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA (M.A.E.)
- Utilities Department, 316 N. Academy St., Town of Cary, Cary, NC 27513, USA
| | - Didier Mena-Aguilar
- Biochemistry, Virginia Tech, 340 W Campus Dr, Blacksburg, VA 24060, USA
- Department of Biochemistry, University of Nebraska-Lincoln, N106, The Beadle Center, Lincoln, NE 68588, USA
| | - Connor L. Brown
- Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Steger Hall, Blacksburg, VA 24061, USA
| | - William J. Rhoads
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA (M.A.E.)
- Black & Veatch, 8400 Ward Pkwy, Kansas City, MO 64114, USA
| | - Richard F. Helm
- Department of Biochemistry, Virginia Tech, 1015 Life Science Circle, 211B Steger Hall, Blacksburg, VA 24061, USA;
| | - Amy Pruden
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA (M.A.E.)
| | - Marc A. Edwards
- Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA (M.A.E.)
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Schwaiger G, Matt M, Streich P, Bromann S, Clauß M, Elsner M, Seidel M. Standard addition method for rapid, cultivation-independent quantification of Legionella pneumophila cells by qPCR in biotrickling filters. Analyst 2024; 149:2978-2987. [PMID: 38602145 DOI: 10.1039/d3an02207b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Cultivation-independent molecular biological methods are essential to rapidly quantify pathogens like Legionella pneumophila (L. pneumophila) which is important to control aerosol-generating engineered water systems. A standard addition method was established to quantify L. pneumophila in the very complex matrix of process water and air of exhaust air purification systems in animal husbandry. Therefore, cryopreserved standards of viable L. pneumophila were spiked in air and water samples to calibrate the total bioanalytical process which includes cell lysis, DNA extraction, and qPCR. A standard addition algorithm was employed for qPCR to determine the initial concentration of L. pneumophila. In mineral water, the recovery rate of this approach (73%-134% within the concentration range of 100-5000 Legionella per mL) was in good agreement with numbers obtained from conventional genomic unit (GU) calibration with DNA standards. In air samples of biotrickling filters, in contrast, the conventional DNA standard approach resulted in a significant overestimation of up to 729%, whereas our standard addition gave a more realistic recovery of 131%. With this proof-of-principle study, we were able to show that the molecular biology-based standard addition approach is a suitable method to determine realistic concentrations of L. pneumophila in air and process water samples of biotrickling filter systems. Moreover, this quantification strategy is generally a promising method to quantify pathogens in challenging samples containing a complex microbiota and the classical GU approach used for qPCR leads to unreliable results.
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Affiliation(s)
- Gerhard Schwaiger
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany.
| | - Marco Matt
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany.
| | - Philipp Streich
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany.
| | - Sarah Bromann
- Thuenen-Institute for Agricultural Technology, Bundesallee 47, D-38116 Braunschweig, Germany
| | - Marcus Clauß
- Thuenen-Institute for Agricultural Technology, Bundesallee 47, D-38116 Braunschweig, Germany
| | - Martin Elsner
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany.
| | - Michael Seidel
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany.
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Hu Z, Bai X. Self-repair and resuscitation of viable injured bacteria in chlorinated drinking water: Achromobacter as an example. WATER RESEARCH 2023; 245:120585. [PMID: 37690414 DOI: 10.1016/j.watres.2023.120585] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/24/2023] [Accepted: 09/04/2023] [Indexed: 09/12/2023]
Abstract
Chlorine disinfection for the treatment of drinking water can cause injury to the membrane and DNA of bacterial cells and may induce the surviving injured bacteria into a viable but non-culturable (VBNC) state. It is difficult to monitor viable injured bacteria by heterotrophic plate counting (HPC), and their presence is also easily miscalculated in flow cytometry intact cell counting (FCM-ICC). Viable injured bacteria have a potential risk of resuscitation in drinking water distribution systems (DWDSs) and pose a threat to public health when drinking from faucets. In this study, bacteria with injured membranes were isolated from chlorinated drinking water by FCM cell sorting. The culture rate of injured bacteria varied from 0.08% to 2.6% on agar plates and 0.39% to 6.5% in 96-well plates. As the dominant genus among the five identified genera, as well as an opportunistic pathogen with multiple antibiotic resistance, Achromobacter was selected and further studied. After treatment with chlorine at a concentration of 1.2 mg/L, Achromobacter entered into the intermediate injured state on the FCM plot, and the injury on the bacterial surface was observed by electron microscopy. However, the CTC respiratory activity assay showed that 75.0% of the bacteria were still physiologically active, and they entered into a VBNC state. The injured VBNC Achromobacter in sterile drinking water were resuscitated after approximately 25 h. The cellular repair behavior of injured bacteria was studied by Fourier transform infrared attenuated total reflectance (FTIR-ATR) and comet assays. It was found that DNA injury rather than membrane injury was repaired first. The expression of Ku and ligD increased significantly during the DNA repair period, indicating that non-homologous end-joining (NHEJ) played an important role in repairing DNA double-strand breaks. This study deepened the understanding of the effect of chlorine disinfection on bacterial viability in drinking water and will provide support for the improvement of the chlorine disinfection process for the treatment of drinking water.
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Affiliation(s)
- Zengyi Hu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xiaohui Bai
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
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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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Nisar MA, Ros KE, Brown MH, Bentham R, Best G, Xi J, Hinds J, Whiley H. Stagnation arising through intermittent usage is associated with increased viable but non culturable Legionella and amoeba hosts in a hospital water system. Front Cell Infect Microbiol 2023; 13:1190631. [PMID: 37351181 PMCID: PMC10282743 DOI: 10.3389/fcimb.2023.1190631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 05/18/2023] [Indexed: 06/24/2023] Open
Abstract
Hospital water systems are a significant source of Legionella, resulting in the potentially fatal Legionnaires' disease. One of the biggest challenges for Legionella management within these systems is that under unfavorable conditions Legionella transforms itself into a viable but non culturable (VBNC) state that cannot be detected using the standard methods. This study used a novel method (flow cytometry-cell sorting and qPCR [VFC+qPCR] assay) concurrently with the standard detection methods to examine the effect of temporary water stagnation, on Legionella spp. and microbial communities present in a hospital water system. Water samples were also analyzed for amoebae using culture and Vermamoeba vermiformis and Acanthamoeba specific qPCR. The water temperature, number and duration of water flow events for the hand basins and showers sampled was measured using the Enware Smart Flow® monitoring system. qPCR analysis demonstrated that 21.8% samples were positive for Legionella spp., 21% for L. pneumophila, 40.9% for V. vermiformis and 4.2% for Acanthamoeba. All samples that were Legionella spp. positive using qPCR (22%) were also positive for VBNC Legionella spp.; however, only 2.5% of samples were positive for culturable Legionella spp. 18.1% of the samples were positive for free-living amoebae (FLA) using culture. All samples positive for Legionella spp. were also positive for FLA. Samples with a high heterotrophic plate count (HPC ≥ 5 × 103 CFU/L) were also significantly associated with high concentrations of Legionella spp. DNA, VBNC Legionella spp./L. pneumophila (p < 0.01) and V. vermiformis (p < 0.05). Temporary water stagnation arising through intermittent usage (< 2 hours of usage per month) significantly (p < 0.01) increased the amount of Legionella spp. DNA, VBNC Legionella spp./L. pneumophila, and V. vermiformis; however, it did not significantly impact the HPC load. In contrast to stagnation, no relationship was observed between the microbes and water temperature. In conclusion, Legionella spp. (DNA and VBNC) was associated with V. vermiformis, heterotrophic bacteria, and stagnation occurring through intermittent usage. This is the first study to monitor VBNC Legionella spp. within a hospital water system. The high percentage of false negative Legionella spp. results provided by the culture method supports the use of either qPCR or VFC+qPCR to monitor Legionella spp. contamination within hospital water systems.
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Affiliation(s)
- Muhammad Atif Nisar
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Kirstin E. Ros
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Melissa H. Brown
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
- Australian Research Council Training Centre for Biofilm Research and Innovation, Flinders University, Bedford Park, SA, Australia
| | - Richard Bentham
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
| | - Giles Best
- College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
- Flow Cytometry Facility, Flinders University, Bedford Park, SA, Australia
| | - James Xi
- Enware Australia Pty Ltd., Caringbah, NSW, Australia
| | - Jason Hinds
- Enware Australia Pty Ltd., Caringbah, NSW, Australia
| | - Harriet Whiley
- College of Science and Engineering, Flinders University, Bedford Park, SA, Australia
- Australian Research Council Training Centre for Biofilm Research and Innovation, Flinders University, Bedford Park, SA, Australia
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Heining L, Welp L, Hugo A, Elsner M, Seidel M. Immunomagnetic separation coupled with flow cytometry for the analysis of Legionella pneumophila in aerosols. Anal Bioanal Chem 2023:10.1007/s00216-023-04738-z. [PMID: 37204446 PMCID: PMC10404198 DOI: 10.1007/s00216-023-04738-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 05/04/2023] [Accepted: 05/08/2023] [Indexed: 05/20/2023]
Abstract
Legionella pneumophila are pathogenic bacteria that can be found in high concentrations in artificial water systems like evaporative cooling towers, which have been the source of frequent outbreaks in recent years. Since inhaled L. pneumophila can lead to Legionnaires' disease, the development of suitable sampling and rapid analysis strategies for these bacteria in aerosols is therefore of great relevance. In this work, different concentrations of viable L. pneumophila Sg 1 were nebulized and sampled by the cyclone sampler Coriolis® µ under defined conditions in a bioaerosol chamber. To quantify intact Legionella cells, the collected bioaerosols were subsequently analyzed by immunomagnetic separation coupled with flow cytometry (IMS-FCM) on the platform rqmicro.COUNT. For analytical comparison, measurements with qPCR and cultivation were performed. Limits of detection (LOD) of 2.9 × 103 intact cells m-3 for IMS-FCM and 7.8 × 102 intact cells m-3 for qPCR indicating a comparable sensitivity as in culture (LOD = 1.5 × 103 culturable cells m-3). Over a working range of 103 - 106 cells mL-1, the analysis of nebulized and collected aerosol samples with IMS-FCM and qPCR provides higher recovery rates and more consistent results than by cultivation. Overall, IMS-FCM is a suitable culture-independent method for quantification of L. pneumophila in bioaerosols and is promising for field application due to its simplicity in sample preparation.
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Affiliation(s)
- Lena Heining
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, School of Natural Sciences, Technical University of Munich, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Laura Welp
- Institut für Energie- und Umwelttechnik e.V., Bliersheimer Straße 58-60, 47229, Duisburg, Germany
| | - Achim Hugo
- Institut für Energie- und Umwelttechnik e.V., Bliersheimer Straße 58-60, 47229, Duisburg, Germany
| | - Martin Elsner
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, School of Natural Sciences, Technical University of Munich, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Michael Seidel
- Institute of Water Chemistry, Chair of Analytical Chemistry and Water Chemistry, School of Natural Sciences, Technical University of Munich, Lichtenbergstraße 4, 85748, Garching, Germany.
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Crespi S, Drašar V, Salvà-Serra F, Jaén-Luchoro D, Piñeiro-Iglesias B, Lindemann PC, Aliaga-Lozano F, Fernández-Juárez V, Coll-García G, Moore ERB, Bennasar-Figueras A. Legionella maioricensis sp. nov., a new species isolated from the hot water distribution systems of a hospital and a shopping center during routine sampling. Int J Syst Evol Microbiol 2023; 73. [PMID: 36748493 DOI: 10.1099/ijsem.0.005686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Two Legionella-like strains isolated from hot water distribution systems in 2012 have been characterized phenotypically, biochemically and genomically in terms of DNA relatedness. Both strains, HCPI-6T and EUR-108, exhibited biochemical phenotypic profiles typical of Legionella species. Cells were Gram-negative motile rods which grew on BCYEα agar but not on blood agar and displayed phenotypic characteristics typical of the family Legionellaceae, including a requirement for l-cysteine and testing catalase positive. Both strains were negative for oxidase, urease, nitrate reduction and hippurate negative, and non-fermentative. The major ubiquinone was Q12 (59.4 % HCPI-6T) and the dominant fatty acids were C16 : 1 ω7c (28.4 % HCPI-6T, ≈16 % EUR-108), C16 : 0 iso (≈22.5 % and ≈13 %) and C15 : 0 anteiso (19.5 % and ≈23.5 %, respectively). The percent G+C content of genomic DNA was determined to be 39.3 mol %. The 16S rRNA gene, mip sequence and comparative genome sequence-based analyses (average nucleotide identity, ANI; digital DNA-DNA hybridization, dDDH; and phylogenomic treeing) demonstrated that the strains represent a new species of the genus Legionella. The analysis based on the 16S rRNA gene sequences showed that the sequence similarities for both strains ranged from 98.8-90.1 % to other members of the genus. The core genome-based phylogenomic tree (protein-concatemer tree based on concatenation of 418 proteins present in single copy) revealed that these two strains clearly form a separate cluster within the genus Legionella. ANI and dDDH values confirmed the distinctiveness of the strains. Based on the genomic, genotypic and phenotypic findings from a polyphasic study, the isolates are considered to represent a single novel species, for which the name Legionella maioricensis sp. nov. is proposed. The type strain is HCPI-6T (=CCUG 75071T=CECT 30569T).
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Affiliation(s)
- Sebastian Crespi
- Biolinea Int.; Calle Sócrates, 4; ES-07007 Palma de Mallorca, Spain
| | - Vladimír Drašar
- Public Health Institute Ostrava - National Legionella Reference Laboratory; Masarykovo nam., 16; 682 01 Vyškov, Czech Republic
| | - Francisco Salvà-Serra
- Culture Collection University of Gothenburg (CCUG), Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Clinical Microbiology, Sahlgrenska University Hospital; Region Västra Götaland, Gothenburg, Sweden.,Microbiologia - Departament de Biologia, Universitat de les Illes Balears; Campus UIB - Ctra. Valldemossa, Km 7.5; ES-07122 Palma de Mallorca, Spain
| | - Daniel Jaén-Luchoro
- Culture Collection University of Gothenburg (CCUG), Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Beatriz Piñeiro-Iglesias
- Culture Collection University of Gothenburg (CCUG), Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | | | - Francisco Aliaga-Lozano
- Laboratorio Microbiología. Clínica Rotger, Grupo Quirónsalud - Vía Roma, 3, Carrer de Santiago Rusiñol, 9: ES-07012 Palma de Mallorca, Spain
| | - Victor Fernández-Juárez
- Marine Biology Section, Department of Biology, University of Copenhagen, 3000 Helsingør, Denmark
| | - Guillem Coll-García
- Microbiologia - Departament de Biologia, Universitat de les Illes Balears; Campus UIB - Ctra. Valldemossa, Km 7.5; ES-07122 Palma de Mallorca, Spain
| | - Edward R B Moore
- Culture Collection University of Gothenburg (CCUG), Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Clinical Microbiology, Sahlgrenska University Hospital; Region Västra Götaland, Gothenburg, Sweden
| | - Antoni Bennasar-Figueras
- Microbiologia - Departament de Biologia, Universitat de les Illes Balears; Campus UIB - Ctra. Valldemossa, Km 7.5; ES-07122 Palma de Mallorca, Spain
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Consonni M, Grassi A, Scuri S, Gori M, Tanzi E, Tesauro M. Assessing the viability of Legionella pneumophila in environmental samples: regarding the filter application of Ethidium Monoazide Bromide. ANN MICROBIOL 2021. [DOI: 10.1186/s13213-021-01653-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Purpose
Analyses of 34 water samples from 13 healthcare structures revealed how culture method and quantitative PCR (qPCR) often differ in the detection of Legionella pneumophila (Lp). With these considerations in hand, culture method, PCR and Ethidium Monoazide Bromide (EMA) qPCR have all been compared in order to detect Lp in water samples, identify a method able to speed up the procedures, detect the “viable but not cultivable” bacteria (VBNC) and exclude non-viable bacteria using a commercial kit for extraction and amplification as well as modification of the protocol.
Methods
Pure water samples artificially spiked with viable, non-viable and VBNC Lp ATCC 33152 were analyzed using a commercial kit for both qPCR and EMA-qPCR, while ISO 11731-2-2004 was used for culture method.
Results
Only 35% (12/34) of the environmental samples were positive in both culture and qPCR methods. With regard to EMA-qPCR, results showed the absence of dye toxicity on viable and VBNC strains and an incomplete effectiveness on the non-viable ones. In both viable and VBNC strains, a decrease of bacterial DNA amplification was recorded as a function of sample dilution but not of EMA concentration.
Conclusions
Discrepancies between culture method and EMA-qPCR were observed and may be due to different causes such as membrane-dye interactions, presence of interfering compounds and the sensitivity of the kit used.
Study significance and impact
In the presence of one or more suspected cases of nosocomial legionellosis, the application of a rapid molecular method able to identify only the viable and VBNC Lp would be useful in order to quickly identify the source of infection and to intervene with sanitation treatments. However, seeing that in our experience EMA pretreatment on the filter membrane did not come up with the expected results, it would be necessary to proceed with other experiments and/or different dyes.
Graphical Abstract
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10
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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
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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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Keserue HA, Cornillie N, Ehlert AK, Mills DC, Morger D, Piffaretti A, Schaffhauser DF, Schwyzer II. Validation of the Legionella pneumophila SG1 DETECT Kit for Quantification of Legionella pneumophila Serogroup 1 Bacteria in Potable Waters, Process Waters, and Surface Waters: AOAC Performance Tested MethodSM 052002. J AOAC Int 2021; 104:776-789. [PMID: 33609035 DOI: 10.1093/jaoacint/qsaa126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 08/26/2020] [Indexed: 11/12/2022]
Abstract
The L.p.SG1 DETECT Kit is a rapid, quantitative method for the detection and enumeration of Legionella pneumophila serogroup 1 (L.p. SG1) bacteria from different water matrixes. The method is based on a combination of immunomagnetic separation (IMS) and flow cytometric (FCM) quantification. To this end, the method employs magnetic particles conjugated to anti-L.p. SG1 antibodies for the IMS of the target bacteria from environmental matrices and fluorescently labeled anti-L.p. SG1 antibodies for subsequent quantification by FCM. The IMS can be performed either manually with a magnetic rack (rqmicro.MIMS) or automated with the rqmicro.STREAM sample preparation instrument. Compared to the reference method ISO 11731:2017, which is based on culturing and enumeration of colony forming units (CFU) on agar plates, and can take up to 10 days until results are available, analysis with the L.p. SG1 DETECT Kit is culture-independent and delivers results within 2 h. This Performance Tested Method validation study demonstrates a robust method with recoveries exceeding 69%, inclusivity of 100%, exclusivity of 97.2%, and a shelf life of at least 6 months at 4°C or 40 days at 25°C. The Limit of Detection (LOD) was determined at 21 CFU/L and the Limit of Quantification (LOQ) at 80 CFU/L for potable water using the rqmicro.STREAM. The matrix study across three different types of water matrixes (potable, surface, and industrial process water), demonstrates superior repeatability and reproducibility, as well as equivalent or even superior detection of L.p. SG1 bacteria compared to the standard ISO 11731 method.
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Affiliation(s)
| | | | | | | | - Damien Morger
- rqmicro AG, Brandstrasse 24, 8952 Schlieren, Switzerland
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Pereira A, Silva AR, Melo LF. Legionella and Biofilms-Integrated Surveillance to Bridge Science and Real-Field Demands. Microorganisms 2021; 9:microorganisms9061212. [PMID: 34205095 PMCID: PMC8228026 DOI: 10.3390/microorganisms9061212] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/28/2021] [Accepted: 05/31/2021] [Indexed: 11/16/2022] Open
Abstract
Legionella is responsible for the life-threatening pneumonia commonly known as Legionnaires’ disease or legionellosis. Legionellosis is known to be preventable if proper measures are put into practice. Despite the efforts to improve preventive approaches, Legionella control remains one of the most challenging issues in the water treatment industry. Legionellosis incidence is on the rise and is expected to keep increasing as global challenges become a reality. This puts great emphasis on prevention, which must be grounded in strengthened Legionella management practices. Herein, an overview of field-based studies (the system as a test rig) is provided to unravel the common roots of research and the main contributions to Legionella’s understanding. The perpetuation of a water-focused monitoring approach and the importance of protozoa and biofilms will then be discussed as bottom-line questions for reliable Legionella real-field surveillance. Finally, an integrated monitoring model is proposed to study and control Legionella in water systems by combining discrete and continuous information about water and biofilm. Although the successful implementation of such a model requires a broader discussion across the scientific community and practitioners, this might be a starting point to build more consistent Legionella management strategies that can effectively mitigate legionellosis risks by reinforcing a pro-active Legionella prevention philosophy.
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Boczek LA, Tang M, Formal C, Lytle D, Ryu H. Comparison of two culture methods for the enumeration of Legionella pneumophila from potable water samples. JOURNAL OF WATER AND HEALTH 2021; 19:468-477. [PMID: 34152299 PMCID: PMC8358784 DOI: 10.2166/wh.2021.051] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Legionella infections have steadily increased in the United States over the last 20 years, and most of these infections have been attributed to contaminated water. The gold standard for confirmation of Legionella presence in water is culturing with Buffered Charcoal Yeast Extract (BCYE) agar. Following many modifications, this method is still time-consuming, expensive, and can take longer than 10 days for full confirmation. The Legiolert is a newer and simpler culture product that is claimed to be able to quantify Legionella pneumophila in 7 days with high sensitivity and specificity and does not need further confirmation for the presence of L. pneumophila. This study compared the culturability of L. pneumophila occurring in a simulated home plumbing system using both Legiolert and BCYE agar methods. Out of 185 water samples, Legiolert and BCYE method detected L. pneumophila in 83 and 85% of the samples, respectively. The two methods were determined to be statistically equivalent for culturability of L. pneumophila, though the detected levels by Legiolert were slightly higher than the BCYE method. The molecular confirmation of positive (n = 254) and negative wells (n = 82) with Legiolert also showed a high specificity of 96.5% (i.e., 3.5% false positives (9/254) and 0% false negatives (0/82)).
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Affiliation(s)
- Laura A Boczek
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Solutions and Emergency Response, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA E-mail:
| | - Min Tang
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Solutions and Emergency Response, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA E-mail:
| | - Casey Formal
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Solutions and Emergency Response, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA E-mail:
| | - Darren Lytle
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Solutions and Emergency Response, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA E-mail:
| | - Hodon Ryu
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Solutions and Emergency Response, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA E-mail:
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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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Mazzotta M, Salaris S, Pascale MR, Girolamini L, Cristino S. Occurrence of Legionella spp. in Man-Made Water Sources: Isolates Distribution and Phylogenetic Characterization in the Emilia-Romagna Region. Pathogens 2021; 10:552. [PMID: 34063633 PMCID: PMC8147600 DOI: 10.3390/pathogens10050552] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 04/29/2021] [Accepted: 05/01/2021] [Indexed: 11/16/2022] Open
Abstract
Legionella species distribution in the Emilia-Romagna region, involving hospital (H) and community (C) environments, was conducted. Legionella culture, agglutination test, and mip-gene sequencing were applied on 240 isolates. The analysis showed a higher prevalence of non-Legionellapneumophila (n-Lp) species (84.1%) compared with L. pneumophila (Lp) (15.9%), with a higher frequency of n-Lp with respect to Lp species in both environments (77.6% and 96.4%, in H and C, respectively). The Shannon index showed a significant difference in Legionella distribution (p = 0.00017), with a significant abundance of Lp in the H compared with C environment (p = 0.00028). The continuous disinfection treatment in H could contribute to adaptive survival of the Lp species. Phylogenetic analysis revealed a conservative clade distribution between H and C: L. feeleii clade with three subclades in C and the Lp clade with five subclades in H and two in C, respectively. Our findings suggest the importance of Legionella surveillance both in H and C, with a focus on n-Lp species less connected to human disease. The Legionella prevalence and diversity found here indicate that geographical and temporal isolate evolution should be considered during surveillance, particularly in the light of global warming and changes in population risk factors.
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Affiliation(s)
| | | | | | | | - Sandra Cristino
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, via San Giacomo 12, 40126 Bologna, Italy; (M.M.); (S.S.); (M.R.P.); (L.G.)
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SCHIAVANO GIUDITTAFIORELLA, BALDELLI GIULIA, CEPPETELLI VERONICA, BRANDI GIORGIO, AMAGLIANI GIULIA. Assessment of hygienic conditions of recreational facility restrooms: an integrated approach. JOURNAL OF PREVENTIVE MEDICINE AND HYGIENE 2021; 62:E48-E53. [PMID: 34322616 PMCID: PMC8283657 DOI: 10.15167/2421-4248/jpmh2021.62.1.1455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 01/15/2021] [Indexed: 11/20/2022]
Abstract
Introduction Microbiological quality of recreational environments included restrooms, is generally assessed by water and surface monitoring. In this study, an environmental monitoring, conducted in spring, of swimming pool restrooms of a recreation center located in the Marche region has been carried out. Seven water samples and seven surface swabs were collected. Moreover, six air samples have been included. The aim of this study was to evaluate if air microbiological monitoring, along with molecular detection in real-time PCR, could give additional useful information about the hygienic conditions of the facility. Methods Heterotrophic Plate Count (HPC) both at 22°C (psychrophilic) and 37°C (mesophilic) was determined by separate cultures in all samples. The presence of Legionella pneumophila and Pseudomonas aeruginosa was evaluated by both culture and real-time PCR. Results The analysis of shower water recorded a HPC load of mesophilic bacteria (37°C) more than 10-fold higher in men restroom, respect to women’s one (> 100 vs < 10 CFU/ml), while in air samples was between < 100 and > 500. Concerning pathogen presence, both species Legionella pneumophila and Pseudomonas aeruginosa were detected only in men restroom, but in different sample types by using different methods (culture and real-time PCR). Conclusions Air sampling may offer the advantage of giving more representative data about microbial presence in restrooms, including bacterial species transmitted through aerosol, like Legionella. Moreover, the concurrent use of molecular and microbiological detection in an integrated approach could offer the advantage of greater sensitivity.
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Affiliation(s)
- GIUDITTA FIORELLA SCHIAVANO
- Department of Humanities, University of Urbino Carlo Bo, Urbino (PU), Italy
- Correspondence: Giuditta Fiorella Schiavano, University of Urbino Carlo Bo, Department of Humanities, via Bramante 17, 61029 Urbino (PU), Italy - Tel. +39 0722 303546 - E-mail:
| | - GIULIA BALDELLI
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino (PU), Italy
| | | | - GIORGIO BRANDI
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino (PU), Italy
| | - GIULIA AMAGLIANI
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino (PU), Italy
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Sciuto EL, Laganà P, Filice S, Scalese S, Libertino S, Corso D, Faro G, Coniglio MA. Environmental Management of Legionella in Domestic Water Systems: Consolidated and Innovative Approaches for Disinfection Methods and Risk Assessment. Microorganisms 2021; 9:577. [PMID: 33799845 PMCID: PMC8001549 DOI: 10.3390/microorganisms9030577] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 12/31/2022] Open
Abstract
Legionella is able to remain in water as free-living planktonic bacteria or to grow within biofilms that adhere to the pipes. It is also able to enter amoebas or to switch into a viable but not culturable (VBNC) state, which contributes to its resistance to harsh conditions and hinders its detection in water. Factors regulating Legionella growth, such as environmental conditions, type and concentration of available organic and inorganic nutrients, presence of protozoa, spatial location of microorganisms, metal plumbing components, and associated corrosion products are important for Legionella survival and growth. Finally, water treatment and distribution conditions may affect each of these factors. A deeper comprehension of Legionella interactions in water distribution systems with the environmental conditions is needed for better control of the colonization. To this purpose, the implementation of water management plans is the main prevention measure against Legionella. A water management program requires coordination among building managers, health care providers, and Public Health professionals. The review reports a comprehensive view of the state of the art and the promising perspectives of both monitoring and disinfection methods against Legionella in water, focusing on the main current challenges concerning the Public Health sector.
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Affiliation(s)
- Emanuele Luigi Sciuto
- Azienda Ospedaliero Universitaria Policlinico “G. Rodolico-San Marco”, Via Sofia 78, 95123 Catania, Italy;
| | - Pasqualina Laganà
- Regional Reference Laboratory of Clinical and Environmental Surveillance of Legionellosis, Messina, Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Torre Biologica 3p, AOU ‘G. Martino, Via C. Valeria, s.n.c., 98125 Messina, Italy;
| | - Simona Filice
- Istituto per la Microelettronica e Microsistemi–Consiglio Nazionale delle Ricerche (CNR-IMM), Ottava Strada 5, 95121 Catania, Italy; (S.F.); (S.S.); (S.L.); (D.C.)
| | - Silvia Scalese
- Istituto per la Microelettronica e Microsistemi–Consiglio Nazionale delle Ricerche (CNR-IMM), Ottava Strada 5, 95121 Catania, Italy; (S.F.); (S.S.); (S.L.); (D.C.)
| | - Sebania Libertino
- Istituto per la Microelettronica e Microsistemi–Consiglio Nazionale delle Ricerche (CNR-IMM), Ottava Strada 5, 95121 Catania, Italy; (S.F.); (S.S.); (S.L.); (D.C.)
| | - Domenico Corso
- Istituto per la Microelettronica e Microsistemi–Consiglio Nazionale delle Ricerche (CNR-IMM), Ottava Strada 5, 95121 Catania, Italy; (S.F.); (S.S.); (S.L.); (D.C.)
| | - Giuseppina Faro
- Azienda Sanitaria Provinciale di Catania, Via S. Maria La Grande 5, 95124 Catania, Italy;
| | - Maria Anna Coniglio
- Azienda Ospedaliero Universitaria Policlinico “G. Rodolico-San Marco”, Via Sofia 78, 95123 Catania, Italy;
- Regional Reference Laboratory of Clinical and Environmental Surveillance of Legionellosis, Catania, Department of Medical and Surgical Sciences and Advanced Technologies “G.F. Ingrassia”, University of Catania, Via Sofia 87, 95123 Catania, Italy
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Quero S, Párraga-Niño N, Garcia-Núñez M, Pedro-Botet ML, Gavaldà L, Mateu L, Sabrià M, Mòdol JM. The impact of pipeline changes and temperature increase in a hospital historically colonised with Legionella. Sci Rep 2021; 11:1916. [PMID: 33479467 PMCID: PMC7820426 DOI: 10.1038/s41598-021-81625-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/01/2021] [Indexed: 01/25/2023] Open
Abstract
Healthcare-related Legionnaires’ disease has a devastating impact on high risk patients, with a case fatality rate of 30–50%. Legionella prevention and control in hospitals is therefore crucial. To control Legionella water colonisation in a hospital setting we evaluated the effect of pipeline improvements and temperature increase, analysing 237 samples over a 2-year period (first year: 129, second year: 108). In the first year, 25.58% of samples were positive for Legionella and 16.67% for amoeba. Assessing the distance of the points analysed from the hot water tank, the most distal points presented higher proportion of Legionella colonisation and lower temperatures (nearest points: 6.4% colonised, and temperature 61.4 °C; most distal points: 50% and temperature 59.1 °C). After the first year, the hot water system was repaired and the temperature stabilised. This led to a dramatic reduction in Legionella colonisation, which was negative in all the samples analysed; however, amoeba colonisation remained stable. This study shows the importance of keeping the temperature stable throughout the circuit, at around 60 °C. Special attention should be paid to the most distal points of the circuit; a fall in temperature at these weak points would favour the colonisation and spread of Legionella, because amoeba (the main Legionella reservoir) are not affected by temperature.
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Affiliation(s)
- S Quero
- Infectious Diseases Unit, Fundació Institut d'Investigació Germans Trias I Pujol, Carretera de Can Ruti, Camí de les Escoles s/n, 08916, Badalona, Barcelona, Spain. .,CIBER de Enfermedades Respiratorias, CIBERES, Av. de Monforte de Lemos, 3-5, 28029, Madrid, Spain. .,Institut d'Investigació i Innovació Parc Taulí, I3PT, Parc Taulí, 1, 08208, Sabadell, Barcelona, Spain.
| | - N Párraga-Niño
- Infectious Diseases Unit, Fundació Institut d'Investigació Germans Trias I Pujol, Carretera de Can Ruti, Camí de les Escoles s/n, 08916, Badalona, Barcelona, Spain
| | - M Garcia-Núñez
- Infectious Diseases Unit, Fundació Institut d'Investigació Germans Trias I Pujol, Carretera de Can Ruti, Camí de les Escoles s/n, 08916, Badalona, Barcelona, Spain.,CIBER de Enfermedades Respiratorias, CIBERES, Av. de Monforte de Lemos, 3-5, 28029, Madrid, Spain.,Institut d'Investigació i Innovació Parc Taulí, I3PT, Parc Taulí, 1, 08208, Sabadell, Barcelona, Spain
| | - M L Pedro-Botet
- CIBER de Enfermedades Respiratorias, CIBERES, Av. de Monforte de Lemos, 3-5, 28029, Madrid, Spain.,Hospital Universitari Germans Trias i Pujol, Carretera de Canyet, s/n, 08916, Badalona, Barcelona, Spain
| | - L Gavaldà
- Hospital Universitari de Bellvitge-IDIBELL, Feixa Llarga, s/n., 08907, L'Hospitalet de Llobregat, Barcelona, Spain
| | - L Mateu
- Hospital Universitari Germans Trias i Pujol, Carretera de Canyet, s/n, 08916, Badalona, Barcelona, Spain
| | - M Sabrià
- CIBER de Enfermedades Respiratorias, CIBERES, Av. de Monforte de Lemos, 3-5, 28029, Madrid, Spain.,Hospital Universitari Germans Trias i Pujol, Carretera de Canyet, s/n, 08916, Badalona, Barcelona, Spain
| | - J M Mòdol
- Hospital Universitari Germans Trias i Pujol, Carretera de Canyet, s/n, 08916, Badalona, Barcelona, Spain
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An Approach to Ring Resonator Biosensing Assisted by Dielectrophoresis: Design, Simulation and Fabrication. MICROMACHINES 2020; 11:mi11110954. [PMID: 33105846 PMCID: PMC7690605 DOI: 10.3390/mi11110954] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 12/12/2022]
Abstract
The combination of extreme miniaturization with a high sensitivity and the potential to be integrated in an array form on a chip has made silicon-based photonic microring resonators a very attractive research topic. As biosensors are approaching the nanoscale, analyte mass transfer and bonding kinetics have been ascribed as crucial factors that limit their performance. One solution may be a system that applies dielectrophoretic forces, in addition to microfluidics, to overcome the diffusion limits of conventional biosensors. Dielectrophoresis, which involves the migration of polarized dielectric particles in a non-uniform alternating electric field, has previously been successfully applied to achieve a 1000-fold improved detection efficiency in nanopore sensing and may significantly increase the sensitivity in microring resonator biosensing. In the current work, we designed microring resonators with integrated electrodes next to the sensor surface that may be used to explore the effect of dielectrophoresis. The chip design, including two different electrode configurations, electric field gradient simulations, and the fabrication process flow of a dielectrohoresis-enhanced microring resonator-based sensor, is presented in this paper. Finite element method (FEM) simulations calculated for both electrode configurations revealed ∇E2 values above 1017 V2m−3 around the sensing areas. This is comparable to electric field gradients previously reported for successful interactions with larger molecules, such as proteins and antibodies.
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Rasheduzzaman M, Singh R, Haas CN, Gurian PL. Required water temperature in hotel plumbing to control Legionella growth. WATER RESEARCH 2020; 182:115943. [PMID: 32590203 DOI: 10.1016/j.watres.2020.115943] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 05/12/2020] [Accepted: 05/13/2020] [Indexed: 05/07/2023]
Abstract
Legionella spp. occurring in hotel hot water systems, in particular Legionella pneumophila, are causing serious pneumonic infections, and water temperature is a key factor to control their occurrence in plumbing systems. We performed a systematic review and meta-analyses of the available evidence on the association between water temperature and Legionella colonization to identify the water temperature in hotel hot water systems required for control of Legionella. Qualitative synthesis and quantitative analysis were performed on 13 studies that met our inclusion criteria to identify the effect of temperature. The Receiver Operating Characteristic (ROC) curve identified 55 °C as a cutoff point for hotel hot water temperature with an Area Under the Curve (AUC) value of 0.914. The odds ratios (OR) for detecting Legionella at temperatures >55 °C compared to lower temperatures from a meta-analysis of three studies was 0.17 [95% CI: 0.11, 0.25], which indicates a strong negative association between temperature and Legionella colonization. A logistic regression on results from multiple studies using both molecular and culture methods found a temperature of 59 °C associated with an 8% probability of detectable Legionella. Only two studies reported sufficiently detailed data to allow a model of concentration vs. temperature to be fit, and this model was not statistically significant. Additional research or more detailed reporting of existing datasets is required to assess if Legionella growth can be limited below particular concentration targets at different temperatures.
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Affiliation(s)
- Md Rasheduzzaman
- Department of Civil, Architectural and Environmental Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA, 19104, USA.
| | - Rajveer Singh
- Department of Civil, Architectural and Environmental Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA, 19104, USA
| | - Charles N Haas
- Department of Civil, Architectural and Environmental Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA, 19104, USA
| | - Patrick L Gurian
- Department of Civil, Architectural and Environmental Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA, 19104, USA
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Laribi A, Allegra S, Souiri M, Mzoughi R, Othmane A, Girardot F. Legionella pneumophila sg1-sensing signal enhancement using a novel electrochemical immunosensor in dynamic detection mode. Talanta 2020; 215:120904. [PMID: 32312449 DOI: 10.1016/j.talanta.2020.120904] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 03/03/2020] [Accepted: 03/05/2020] [Indexed: 01/20/2023]
Abstract
This work presents a comparison between static and dynamic modes of biosensing using a novel microfluidic assay for continuous and quantitative detection of Legionella pneumophila sg1 in artificial water samples. A self-assembled monolayer of 16-amino-1-hexadecanethiol (16-AHT) was covalently linked to a gold substrate, and the resulting modified surface was used to immobilize an anti-Legionella pneumophila monoclonal antibody (mAb). The modified surfaces formed during the biosensor functionalization steps were characterized using electrochemical measurements and microscopic imaging techniques. Under static conditions, the biosensor exhibited a wide linear response range from 10 to 108 CFU/mL and a detection limit of 10 CFU/mL. Using a microfluidic system, the biosensor responses exhibited a linear relationship for low bacterial concentrations ranging from 10 to 103 CFU/mL under dynamic conditions and an enhancement of sensing signals by a factor of 4.5 compared to the sensing signals obtained under static conditions with the same biosensor for the detection of Legionella cells in artificially contaminated samples.
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Affiliation(s)
- Ahlem Laribi
- Environments, Territories, Societies (EVS) Lab, Mixed Research Unit (Jean Monnet University - French National Centre for Scientific Research) 5600, University of Lyon, F42023, France; Laboratory of Advanced Materials and Interfaces, Faculty of Medicine, University of Monastir, 5019, Monastir, Tunisia.
| | - Séverine Allegra
- Environments, Territories, Societies (EVS) Lab, Mixed Research Unit (Jean Monnet University - French National Centre for Scientific Research) 5600, University of Lyon, F42023, France
| | - Mina Souiri
- Laboratory of Advanced Materials and Interfaces, Faculty of Medicine, University of Monastir, 5019, Monastir, Tunisia
| | - Ridha Mzoughi
- Regional Laboratory of Hygiene, University Hospital Farhat Hached, 4000 Sousse, Tunisia and Laboratory of Analysis Treatment and Valorization of Pollutants and Products, Faculty of Pharmacy, 5000, Monastir, Tunisia
| | - Ali Othmane
- Laboratory of Advanced Materials and Interfaces, Faculty of Medicine, University of Monastir, 5019, Monastir, Tunisia
| | - Françoise Girardot
- Environments, Territories, Societies (EVS) Lab, Mixed Research Unit (Jean Monnet University - French National Centre for Scientific Research) 5600, University of Lyon, F42023, France
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Cervero-Aragó S. MUW researcher of the month. Wien Klin Wochenschr 2020; 132:412-413. [DOI: 10.1007/s00508-020-01716-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Lampl BMJ, Lang M, Wodnick S. Can mandatory monitoring in rental apartments effectively prevent legionellosis? A retrospective analysis of data from Regensburg with a review of the literature. GMS HYGIENE AND INFECTION CONTROL 2020; 15:Doc14. [PMID: 32685358 PMCID: PMC7336046 DOI: 10.3205/dgkh000349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background:Legionella pneumophila can cause severe, often fatal, pneumonia in humans. Mandatory water sampling in commercially used buildings (mainly rental apartments) as regulated in the Drinking Water Ordinance (Trinkwasserverordnung) aim to protect the population against infection with Legionella. However, no data exist to date that could prove the effectiveness of the measures. At the same time, having the Public Health Department’s Infection Control Division deal with Legionalla is very time consuming. Methods: A retrospective analysis of data from the city and district of Regensburg, a selective literature search, a prospective survey of workload using an anonymous questionnaire were performed. Results: The evaluated data from the city/district of Regensburg suggest underreporting to a similar extent as shown by the RKI’s data in the compared period. Neither is the actual incidence known, nor can exposures be clearly determined in most cases. The exposure categories “travel” and “private/occupational” seem to be the most pertinent. The potential public hazard of Legionella posed by domestic plumbing systems is unclear. A connection between exceeding the technical measurement limit (Technischer Maßnahmenwert, TMW) in routine tests in rental apartments and disease cases cannot be shown. A survey among non-medical personnel in the field of infection control and hygiene on the time spent on the topic of Legionella yielded a mean number of 39% of daily working hours for the observed 2-month period. Conclusion: The data on incidence, exposure, and causality are incomplete. Evidence of effective protection by the current practice of sampling in apartment buildings could not be found. For many aspects, there are no unambiguous data in the literature. Restricting mandatory monitoring to certain public/commercial institutions should be discussed, given the high workload for the Public Health Department and the unproven protective effect. Further research on this topic is necessary.
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Affiliation(s)
| | - Markus Lang
- Public Health Department, Regensburg, Germany
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Yakunin E, Kostyal E, Agmon V, Grotto I, Valinsky L, Moran-Gilad J. A Snapshot of the Prevalence and Molecular Diversity of Legionella pneumophila in the Water Systems of Israeli Hotels. Pathogens 2020; 9:pathogens9060414. [PMID: 32471136 PMCID: PMC7350324 DOI: 10.3390/pathogens9060414] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/19/2020] [Accepted: 05/23/2020] [Indexed: 11/16/2022] Open
Abstract
Exposure to Legionella spp. contaminated aerosols in hotel settings confers risk for travel-associated Legionnaire’s disease (TALD). In this study, we investigated the prevalence of Legionella contamination and its molecular diversity in hotels and resorts across Israel. The study was comprised of a convenience sample of water systems from 168 hotels and resorts countrywide, routinely inspected between March 2015 and February 2017. Isolation and quantitation of Legionella were performed in a water laboratory using the ISO 11731 method. The distribution of Legionella isolates was analyzed according to geography and source. The genetic diversity of a subset of isolates was analyzed by sequence-based typing (SBT) at the National Reference Laboratory for Legionella and compared to the national database. Out of 2830 samples tested, 470 (17%) obtained from 102 different premises (60% of hotels) were positive for Legionella spp. In 230 samples (49% of all positive, 8% of total samples), accounting for 37% of hotels, Legionella spp. counts exceeded the regulatory threshold of 1000 CFU/L. The most frequently contaminated water sources were cooling towers (38%), followed by faucets, hot tubs, water lines, and storage tanks (14–17% each). Furthermore, 32% and 17% of samples obtained from cooling towers and hot tubs, respectively, exceeded the regulatory thresholds. SBT was performed on 78 strains and revealed 27 different sequence types (STs), including two novel STs. The most prevalent STs found were ST1 (26%), ST87 (10%), ST93 (6%), and ST461 and ST1516 (5% each). Several L. pneumophila STs were found to be limited to certain geographical regions. This is the first study to investigate the prevalence and diversity of Legionella in hotels and resorts in Israel during non-outbreak environmental inspections. These findings will inform risk assessment, surveillance, and control measures of TALD.
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Affiliation(s)
- Eugenia Yakunin
- Central Laboratories and Public Health Services, Ministry of Health, Jerusalem 9134302, Israel; (E.Y.); (V.A.); (I.G.); (L.V.)
| | - Eszter Kostyal
- Department of Water Microbiology, Biolab Ltd., Jerusalem 9134001, Israel;
| | - Vered Agmon
- Central Laboratories and Public Health Services, Ministry of Health, Jerusalem 9134302, Israel; (E.Y.); (V.A.); (I.G.); (L.V.)
| | - Itamar Grotto
- Central Laboratories and Public Health Services, Ministry of Health, Jerusalem 9134302, Israel; (E.Y.); (V.A.); (I.G.); (L.V.)
- Department of Health Systems Management, School of Public Health, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Lea Valinsky
- Central Laboratories and Public Health Services, Ministry of Health, Jerusalem 9134302, Israel; (E.Y.); (V.A.); (I.G.); (L.V.)
| | - Jacob Moran-Gilad
- Central Laboratories and Public Health Services, Ministry of Health, Jerusalem 9134302, Israel; (E.Y.); (V.A.); (I.G.); (L.V.)
- Department of Health Systems Management, School of Public Health, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
- Correspondence:
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Nisar MA, Ross KE, Brown MH, Bentham R, Whiley H. Legionella pneumophila and Protozoan Hosts: Implications for the Control of Hospital and Potable Water Systems. Pathogens 2020; 9:pathogens9040286. [PMID: 32326561 PMCID: PMC7238060 DOI: 10.3390/pathogens9040286] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 04/10/2020] [Accepted: 04/14/2020] [Indexed: 12/12/2022] Open
Abstract
Legionella pneumophila is an opportunistic waterborne pathogen of public health concern. It is the causative agent of Legionnaires’ disease (LD) and Pontiac fever and is ubiquitous in manufactured water systems, where protozoan hosts and complex microbial communities provide protection from disinfection procedures. This review collates the literature describing interactions between L. pneumophila and protozoan hosts in hospital and municipal potable water distribution systems. The effectiveness of currently available water disinfection protocols to control L. pneumophila and its protozoan hosts is explored. The studies identified in this systematic literature review demonstrated the failure of common disinfection procedures to achieve long term elimination of L. pneumophila and protozoan hosts from potable water. It has been demonstrated that protozoan hosts facilitate the intracellular replication and packaging of viable L. pneumophila in infectious vesicles; whereas, cyst-forming protozoans provide protection from prolonged environmental stress. Disinfection procedures and protozoan hosts also facilitate biogenesis of viable but non-culturable (VBNC) L. pneumophila which have been shown to be highly resistant to many water disinfection protocols. In conclusion, a better understanding of L. pneumophila-protozoan interactions and the structure of complex microbial biofilms is required for the improved management of L. pneumophila and the prevention of LD.
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Lampl BMJ, Strigl W, Winner D, Pawlik MT. Case report: 38-year-old female patient with severe legionellosis but no source of infection. GMS HYGIENE AND INFECTION CONTROL 2019; 14:Doc13. [PMID: 31728267 PMCID: PMC6838731 DOI: 10.3205/dgkh000329] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We report about a 38-year-old female patient with an extremely severe case of legionellosis. The patient had to be treated in the intensive care unit for more than a month. Extracorporeal membrane oxygenation (ECMO) had to be established in order to save the patient's life. The patient did not belong to any risk group (i.e., age >50, smoker, immunosuppression, chronic disease, male sex). Infection control investigations carried out by the Public Health Department could not reveal concrete exposures likely to cause the infection. The serotypes in the patient material (Legionella pneumophila serotype 2-14) and in the samples taken from the showerhead in the patient's apartment (Legionella pneumophila serotype 1) were not identical. Results of the examination performed according to the German Drinking Water Ordinance (Trinkwasserverordnung, TrinkwV) carried out in 2017 in the patient's apartment, showed that the technical measures limit (Technischer Maßnahmenwert, TMW) was not exceeded. The patient has survived through the extensive use and efforts of intensive care measures. In general, a concrete exposure to Legionella is often not ascertainable, as in the case presented. This raises the question of how and whether such cases of legionellosis are preventable.
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Affiliation(s)
| | | | - Dieter Winner
- Caritas-Krankenhaus St. Josef, Department of Anesthesiology, Regensburg, Germany
| | - Michael T. Pawlik
- Caritas-Krankenhaus St. Josef, Department of Anesthesiology, Regensburg, Germany
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28
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Moreno Y, Moreno-Mesonero L, García-Hernández J. DVC-FISH to identify potentially pathogenic Legionella inside free-living amoebae from water sources. ENVIRONMENTAL RESEARCH 2019; 176:108521. [PMID: 31195295 DOI: 10.1016/j.envres.2019.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 04/11/2019] [Accepted: 06/01/2019] [Indexed: 06/09/2023]
Abstract
Despite all safety efforts, drinking and wastewater can still be contaminated by Legionella and free-living amoebae (FLA) since these microorganisms are capable of resisting disinfection treatments. An amoebae cyst harboring pathogenic Legionella spp. can be a transporter of this organism, protecting it and enhancing its infection abilities. Therefore, the aim of this work is to identify by DVC-FISH viable Legionella spp and Legionella pneumophila cells inside FLA from water sources in a specific and rapid way with the aim of assessing the real risk of these waters. A total of 55 water samples were processed, 30 reclaimed wastewater and 25 drinking water. FLA presence was detected in 52.7% of the total processed water samples. When DVC-FISH technique was applied, the presence of viable internalized Legionella spp. cells was identified in 69.0% of the total FLA-positive samples, concretely in 70.0% and 66.7% of wastewater and drinking water samples, respectively. L. pneumophila was simultaneously identified in 48.3% of the total FLA-positive samples, specifically in 50.0% and 44.4% of wastewater and drinking water samples, respectively. By culture, potentially pathogenic Legionella cells were recovered in 27.6% of the total FLA-positive bacteria, particularly in 35.0% and 11.1% of wastewater and drinking water samples, respectively. These findings demonstrate that FLA may promote resistance of bacteria to the performed disinfection treatments for drinking as well as for wastewater. So, in addition to the risk for the presence of pathogenic FLA in water it is necessary to take into account that these can be transporters of the pathogenic bacteria Legionella, which are able to survive inside them. The DVC-FISH method described here has been proved to be a rapid and specific tool to identify pathogenic Legionella spp. and L. penumophila viable cells harboured by FLA in these water sources, posing particular public health concern.
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Affiliation(s)
- Y Moreno
- Research Institute of Water and Environmental Ingeneering (IIAMA), Universitat Politècnica de València, 46022 Valencia, Spain.
| | - L Moreno-Mesonero
- Research Institute of Water and Environmental Ingeneering (IIAMA), Universitat Politècnica de València, 46022 Valencia, Spain
| | - J García-Hernández
- Biotechnology Department, Universitat Politècnica de València, 46022 Valencia, Spain
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Environmental surveillance and spatio-temporal analysis of Legionella spp. in a region of northeastern Italy (2002-2017). PLoS One 2019; 14:e0218687. [PMID: 31287819 PMCID: PMC6615612 DOI: 10.1371/journal.pone.0218687] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 06/06/2019] [Indexed: 01/01/2023] Open
Abstract
Legionella spp. are considered an important cause of potentially preventable morbidity and mortality, making environmental surveillance a crucial component of risk assessment plans. In this work, 20,319 water samples were collected in 3,983 environmental surveys during a 16-year period by ARPA, the Regional Agency for Environmental Protection, Friuli Venezia Giulia, and the results were studied to better understand the diffusion mechanisms of Legionella. The data showed a strong seasonal signal, a prevalence of L. pneumophila serogroup 2–15 in most environments (63% of positive samples), a prevalence of L. pneumophila serogroup 1 in swimming pool-associated environments (82% of positive samples), a persistent presence of Legionella in hospitals and a recurrent presence of Legionella in other facilities such as hotels, possibly years after interventions, highlighting the difficulty of eradicating the bacteria. Retrospective spatio-temporal analyses on geocoded historical data were carried out with SaTScan using an ordinal model with risk as a covariate to identify potential clusters with an excess of cases in the higher-risk categories. Although no outbreaks occurred during the period of study, such analyses identified spatially restricted zones with unusual contamination, which sometimes were also areas in which several surveys triggered by notifications of clinical cases were performed. Simulations of periodic prospective analyses permitted the assessment of the efficacy of the method in early detection of such clusters. The proposed method may be a useful tool in environmental surveillance, prevention and control of Legionella.
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30
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Cervero-Aragó S, Schrammel B, Dietersdorfer E, Sommer R, Lück C, Walochnik J, Kirschner A. Viability and infectivity of viable but nonculturable Legionella pneumophila strains induced at high temperatures. WATER RESEARCH 2019; 158:268-279. [PMID: 31048196 PMCID: PMC6520252 DOI: 10.1016/j.watres.2019.04.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 04/05/2019] [Accepted: 04/06/2019] [Indexed: 06/09/2023]
Abstract
Thermal disinfection is commonly used to prevent the proliferation of culturable Legionella in engineered water systems (EWS). In response to such stress, culturable Legionella populations can switch into a viable but nonculturable (VBNC) state. The importance of such VBNC Legionella cells is currently hotly debated. Here, we investigated the stress response patterns and transitions of the bacteria to the VBNC state at 55 °C, 60 °C and 70 °C on two L. pneumophila strains for >80 days using a combination of cell-based viability indicators. Complete loss of culturability at 55 °C, 60 °C and 70 °C occurred after 3-8 h, 60 min and <2 min, respectively. In contrast, L. pneumophila strains required 9 days at 55 °C, 8 h at 60 °C and 20 min at 70 °C to achieve a 2 log reduction in cells with intact membranes and high esterase activity; a 4 log reduction was achieved only after 150, 8-15 and 1-4 days, respectively. In parallel, the presence of diagnostic outer-membrane epitopes (OMEs) and changes in the infectivity patterns of the two strains towards amoebae and THP-1 cells were assessed. OMEs were more persistent than viability indicators, showing their potential as targets for VBNC Legionella detection. L. pneumophila strains infected amoebae and THP-1 cells for at least 85 days at 55 °C and 60 °C and for up to 8 days at 70 °C. However, they did so with reduced efficiency, requiring prolonged co-incubation times with the hosts and higher Legionella cell numbers in comparison to culturable cells. Consequently, infection of amoebae by thermally induced VBNC L. pneumophila with lowered virulence can be expected in EWS. Although the gold standard method cannot detect VBNC Legionella, it provides important information about the most virulent bacterial subpopulations. Our results indicate that a prolonged thermal regime ≥60 °C at the central parts of warm water systems is not only effective against culturable L. pneumophila but in the long run even against VBNC cells.
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Affiliation(s)
- Sílvia Cervero-Aragó
- Medical University of Vienna, Institute for Hygiene and Applied Immunology, Water Hygiene, Kinderspitalgasse 15, A-1090, Vienna, Austria; Interuniversity Cooperation Centre for Water & Health, Vienna, Austria.
| | - Barbara Schrammel
- Medical University of Vienna, Institute for Hygiene and Applied Immunology, Water Hygiene, Kinderspitalgasse 15, A-1090, Vienna, Austria
| | - Elisabeth Dietersdorfer
- Medical University of Vienna, Institute of Specific Prophylaxis and Tropical Medicine, Kinderspitalgasse 15, A-1090, Vienna, Austria
| | - Regina Sommer
- Medical University of Vienna, Institute for Hygiene and Applied Immunology, Water Hygiene, Kinderspitalgasse 15, A-1090, Vienna, Austria; Interuniversity Cooperation Centre for Water & Health, Vienna, Austria
| | - Christian Lück
- Technical University Dresden, Institute for Medical Microbiology and Hygiene, Medical Faculty "Carl Gustav Carus", Helmholtzstr. 10, D 01069, Dresden, Germany
| | - Julia Walochnik
- Medical University of Vienna, Institute of Specific Prophylaxis and Tropical Medicine, Kinderspitalgasse 15, A-1090, Vienna, Austria
| | - Alexander Kirschner
- Medical University of Vienna, Institute for Hygiene and Applied Immunology, Water Hygiene, Kinderspitalgasse 15, A-1090, Vienna, Austria; Interuniversity Cooperation Centre for Water & Health, Vienna, Austria; Karl Landsteiner University of Health Sciences, Division Water Quality and Health, Dr. Karl Dorrekstraße 30, A-3400, Krems, Austria
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Abstract
PURPOSE OF REVIEW The present review summarizes new knowledge about Legionella epidemiology, clinical characteristics, community-associated and hospital-based outbreaks, molecular typing and molecular epidemiology, prevention, and detection in environmental and clinical specimens. RECENT FINDINGS The incidence of Legionnaire's disease is rising and the mortality rate remains high, particularly for immunocompromised patients. Extracorporeal membrane oxygenation may help support patients with severe respiratory failure. Fluoroquinolones and macrolides appear to be equally efficacious for treating Legionnaires' disease. Whole genome sequencing is an important tool for determining the source for Legionella infections and for understanding routes of transmission and mechanisms by which new pathogenic clones emerge. Real-time quantitative polymerase chain reaction testing of respiratory specimens may improve our ability to diagnose Legionnaire's disease. The frequency of viable but nonculturable organisms is quite high in some water systems but their role in causing clinical disease has not been defined. SUMMARY Legionellosis remains an important public health threat. To prevent these infections, staff of municipalities and large buildings must implement effective water system management programs that reduce Legionella growth and transmission and all Medicare-certified healthcare facilities must have water management policies. In addition, we need better methods for detecting Legionella in water systems and in clinical specimens to improve prevention strategies and clinical diagnosis.
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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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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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Zamfir M, Gerstner DG, Walser SM, Bünger J, Eikmann T, Heinze S, Kolk A, Nowak D, Raulf M, Sagunski H, Sedlmaier N, Suchenwirth R, Wiesmüller GA, Wollin KM, Tesseraux I, Herr CE. A systematic review of experimental animal studies on microbial bioaerosols: Dose-response data for the derivation of exposure limits. Int J Hyg Environ Health 2019; 222:249-259. [DOI: 10.1016/j.ijheh.2018.11.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 11/09/2018] [Accepted: 11/18/2018] [Indexed: 12/23/2022]
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Cebrián F, Montero JC, Fernández PJ. New approach to environmental investigation of an explosive legionnaires´ disease outbreak in Spain: early identification of potential risk sources by rapid Legionella spp immunosensing technique. BMC Infect Dis 2018; 18:696. [PMID: 30587144 PMCID: PMC6307211 DOI: 10.1186/s12879-018-3605-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 12/10/2018] [Indexed: 02/05/2023] Open
Abstract
Background An explosive outbreak of Legionnaires’ disease (LD) was identified on 11 December 2015 in Manzanares, Ciudad Real, Spain, and was declared closed by 03 February 2016. The number of declared cases was 593 with 277 confirmed cases so that it can be considered as one of the outbreaks with highest attack rate. This rate could be attributed to the ageing of the population, among others, in addition to various risk factors and habits, and the meteorological conditions (thermal inversion) maintained in this municipality at the time. The Public Health Services succeeded in breaking the bacterial transmission. Several facilities were early identified by microbiological analysis, including a cooling tower and a decorative fountain, as possible infectious sources. Rapid analytical techniques for rapid Legionella detection and the shutdown and preventative closure of positive installations have been considered key elements in the control of this outbreak. Results Rapid microbiological analysis helped to the early identification of potential risk sources in a Legionnaires´ disease outbreak, reducing decision-making processes according to the actual needs of the intervention in public health and shortening the exposure of the population. Conclusions Protocolized and immediate intervention in an outbreak is a crucial issue to reduce their effects on public health. For this, identification and control of the suspicious sources able to disseminate the bacteria and cause the illness is required. Rapid analytical techniques like immunomagnetic separation (IMS) method based on the whole bacterial cell detection are shown as excellent tools to investigate all the potential sources of risk.
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Affiliation(s)
- Fernando Cebrián
- Ministry of Health of the Council of Communities of Castilla - La Mancha, Av. de Madrid s/n, 45600 Talavera de la Reina, Toledo, Spain
| | - Juan C Montero
- Ministry of Health of the Council of Communities of Castilla - La Mancha, Av. de Madrid s/n, 45600 Talavera de la Reina, Toledo, Spain.
| | - Pedro J Fernández
- Ministry of Health of the Council of Communities of Castilla - La Mancha, Av. de Madrid s/n, 45600 Talavera de la Reina, Toledo, Spain
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De Filippis P, Mozzetti C, Messina A, D'Alò GL. Prevalence of Legionella in retirement homes and group homes water distribution systems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 643:715-724. [PMID: 29957436 DOI: 10.1016/j.scitotenv.2018.06.216] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/25/2018] [Accepted: 06/17/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Although historically the focus has been placed above all on hospital infections and travel-associated outbreaks, most of the cases of Legionella infection are sporadic and occur in community-dwellers. OBJECTIVES To evaluate the presence and load of Legionella in hot water systems of non-healthcare facilities that host closed communities. Furthermore, we tried to verify the association between Heterotrophic Plate Counts (HPCs) and presence of Legionella. METHODS We collected hot water and biofilm samples from the showerheads of retirement homes and group homes. Samples were tested by culture method for the presence of Legionella. Confirmation and identification were carried out through Latex test and PCR. We determined the HPCs at 22 and 37 °C by the pour plate method. Statistics performed through STATA. RESULTS We collected 140 hot water and biofilm samples, 95 from 26 retirement homes and 35 from 9 group homes. Legionella was found in 36.8% samples collected from retirement homes and only in 10.3% group homes' samples (p = 0.01). Legionella was identified more frequently in water than in biofilm (29.8% vs 16.9%); just in one case the pathogen was found in the biofilm only. L. pneumophila sg 1 was the pathogen more frequently isolated (65.8%), with an average load of 2720 CFU/L (SD = 8393 CFU/L). We have often noticed a high microbial contamination (67% of HPCs >200 CFU/mL) and identified a higher prevalence of Legionella for intermediate values of HPC 22 °C (p = 0.011). 32% of people hosted in retirement homes were exposed to Legionella. CONCLUSIONS Colonization of water-systems of retirement homes and group homes is anything but occasional, and in our survey it mainly affects the former, moreover often due to L. pneumophila sg 1. The search for the pathogen in the biofilm has proved to be of little use. The relationship between HPC and Legionella deserves further studies.
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Affiliation(s)
- Patrizia De Filippis
- Section of Hygiene, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Via Montpellier 1, 00133 Rome, Italy.
| | - Cinzia Mozzetti
- Section of Hygiene, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Via Montpellier 1, 00133 Rome, Italy.
| | - Alessandra Messina
- Section of Hygiene, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Via Montpellier 1, 00133 Rome, Italy.
| | - Gian Loreto D'Alò
- Section of Hygiene, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Via Montpellier 1, 00133 Rome, Italy.
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Schrammel B, Cervero-Aragó S, Dietersdorfer E, Walochnik J, Lück C, Sommer R, Kirschner A. Differential development of Legionella sub-populations during short- and long-term starvation. WATER RESEARCH 2018; 141:417-427. [PMID: 29685632 DOI: 10.1016/j.watres.2018.04.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 04/10/2018] [Accepted: 04/10/2018] [Indexed: 06/08/2023]
Abstract
Legionellae are among the most important waterborne pathogens in industrialized countries. Monitoring and surveillance of Legionella in engineered water systems is usually performed with culture-based methods. Since the advent of culture-independent techniques, it has become clear that Legionella concentrations are often several orders of magnitude higher than those measured by culture-based techniques and that a variable proportion of these non-culturable cells are viable. In engineered water systems, the formation of these viable but non-culturable (VBNC) cells can be caused by different kinds of stress, such as, and most importantly, nutrient starvation, oxidative stress and heat. In this study, the formation of VBNC cells of six Legionella strains under conditions of starvation was monitored in mono-species microcosms for up to one year using a combination of different viability indicators. Depending on the strain, complete loss of culturability was observed from 11 days to 8 weeks. During the starvation process, three distinct phases and different sub-populations of VBNC cells were identified. Until complete loss of culturability, the number of membrane-intact cells decreased rapidly to 5.5-69% of the initial cell concentration. The concentration of the sub-population with low esterase activity dropped to 0.03-55%, and the concentration of the highly esterase-active sub-population dropped to 0.01-1.2% of the initial concentration; these sub-populations remained stable for several weeks to months. Only after approximately 200 days of starvation, the number of VBNC cells started to decrease below detection limits. The most abundant VBNC sub-populations were characterized by partially damaged membranes and low esterase-activity. With this study, we showed that upon starvation, a stable VBNC Legionella community may be present over several months in a strain-dependent manner even under harsh conditions. Even after one year of starvation, a small proportion of L. pneumophila cells with high esterase-activity was detected. We speculate that this highly active VBNC subpopulation is able to infect amoebae and human macrophages.
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Affiliation(s)
- Barbara Schrammel
- Institute for Hygiene and Applied Immunology, Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Austria
| | - Sílvia Cervero-Aragó
- Institute for Hygiene and Applied Immunology, Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Austria; Interuniversity Cooperation Centre for Water and Health, Austria
| | - Elisabeth Dietersdorfer
- Institute for Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Austria
| | - Julia Walochnik
- Institute for Specific Prophylaxis and Tropical Medicine, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Austria
| | - Christian Lück
- Institute for Medical Microbiology and Hygiene, Medical Faculty "Carl Gustav Carus", Technical University Dresden, Germany
| | - Regina Sommer
- Institute for Hygiene and Applied Immunology, Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Austria; Interuniversity Cooperation Centre for Water and Health, Austria
| | - Alexander Kirschner
- Institute for Hygiene and Applied Immunology, Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Austria; Interuniversity Cooperation Centre for Water and Health, Austria.
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Dietersdorfer E, Kirschner A, Schrammel B, Ohradanova-Repic A, Stockinger H, Sommer R, Walochnik J, Cervero-Aragó S. Starved viable but non-culturable (VBNC) Legionella strains can infect and replicate in amoebae and human macrophages. WATER RESEARCH 2018; 141:428-438. [PMID: 29409685 DOI: 10.1016/j.watres.2018.01.058] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/24/2018] [Accepted: 01/24/2018] [Indexed: 05/22/2023]
Abstract
Legionella infections are among the most important waterborne infections with constantly increasing numbers of cases in industrialized countries, as a result of aging populations, rising numbers of immunocompromised individuals and increased need for conditioned water due to climate change. Surveillance of water systems is based on microbiological culture-based techniques; however, it has been shown that high percentages of the Legionella populations in water systems are not culturable. In the past two decades, the relevance of such viable but non-culturable (VBNC) legionellae has been controversially discussed, and whether VBNC legionellae can directly infect human macrophages, the primary targets of Legionella infections, remains unclear. In this study, it was demonstrated for the first time that several starved VBNC Legionella strains (four L. pneumophila serogroup 1 strains, a serogroup 6 strain and a L. micdadei strain) can directly infect different types of human macrophages and amoebae even after one year of starvation in ultrapure water. However, under these conditions, the strains caused infection with reduced efficacy, as represented by the lower percentages of infected cells, prolonged time in co-culture and higher multiplicities of infection required. Interestingly, the VBNC cells remained mostly non-culturable even after multiplication within the host cells. Amoebal infection by starved VBNC Legionella, which likely occurs in oligotrophic biofilms, would result in an increase in the bacterial concentration in drinking-water systems. If cells remain in the VBNC state, the real number of active legionellae will be underestimated by the use of culture-based standard techniques. Thus, further quantitative research is needed in order to determine, whether and how many starved VBNC Legionella cells are able to cause disease in humans.
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Affiliation(s)
- Elisabeth Dietersdorfer
- Medical University of Vienna, Institute of Specific Prophylaxis and Tropical Medicine, Department of Medical Parasitology, Kinderspitalgasse 15, A-1090, Vienna, Austria
| | - Alexander Kirschner
- Medical University of Vienna, Institute for Hygiene and Applied Immunology, Water Hygiene, Kinderspitalgasse 15, A-1090, Vienna, Austria; Interuniversity Cooperation Centre for Water & Health, Vienna, Austria.
| | - Barbara Schrammel
- Medical University of Vienna, Institute for Hygiene and Applied Immunology, Water Hygiene, Kinderspitalgasse 15, A-1090, Vienna, Austria
| | - Anna Ohradanova-Repic
- Medical University of Vienna, Institute for Hygiene and Applied Immunology, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Hannes Stockinger
- Medical University of Vienna, Institute for Hygiene and Applied Immunology, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Regina Sommer
- Medical University of Vienna, Institute for Hygiene and Applied Immunology, Water Hygiene, Kinderspitalgasse 15, A-1090, Vienna, Austria; Interuniversity Cooperation Centre for Water & Health, Vienna, Austria
| | - Julia Walochnik
- Medical University of Vienna, Institute of Specific Prophylaxis and Tropical Medicine, Department of Medical Parasitology, Kinderspitalgasse 15, A-1090, Vienna, Austria.
| | - Sílvia Cervero-Aragó
- Medical University of Vienna, Institute for Hygiene and Applied Immunology, Water Hygiene, Kinderspitalgasse 15, A-1090, Vienna, Austria; Interuniversity Cooperation Centre for Water & Health, Vienna, Austria
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Farhat M, Shaheed RA, Al-Ali HH, Al-Ghamdi AS, Al-Hamaqi GM, Maan HS, Al-Mahfoodh ZA, Al-Seba HZ. Legionella confirmation in cooling tower water. Comparison of culture, real-time PCR and next generation sequencing. Saudi Med J 2018; 39:137-141. [PMID: 29436561 PMCID: PMC5885089 DOI: 10.15537/smj.2018.2.21587] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Objectives: To investigate the presence of Legionella spp in cooling tower water. Legionella proliferation in cooling tower water has serious public health implications as it can be transmitted to humans via aerosols and cause Legionnaires’ disease. Methods: Samples of cooling tower water were collected from King Fahd Hospital of the University (KFHU) (Imam Abdulrahman Bin Faisal University, 2015/2016). The water samples were analyzed by a standard Legionella culture method, real-time polymerase chain reaction (RT-PCR), and 16S rRNA next-generation sequencing. In addition, the bacterial community composition was evaluated. Results: All samples were negative by conventional Legionella culture. In contrast, all water samples yielded positive results by real-time PCR (105 to 106 GU/L). The results of 16S rRNA next generation sequencing showed high similarity and reproducibility among the water samples. The majority of sequences were Alpha-, Beta-, and Gamma-proteobacteria, and Legionella was the predominant genus. The hydrogen-oxidizing gram-negative bacterium Hydrogenophaga was present at high abundance, indicating high metabolic activity. Sphingopyxis, which is known for its resistance to antimicrobials and as a pioneer in biofilm formation, was also detected. Conclusion: Our findings indicate that monitoring of Legionella in cooling tower water would be enhanced by use of both conventional culturing and molecular methods.
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Affiliation(s)
- Maha Farhat
- Department of Biochemistry, Imam Abdulrahman Bin Faisal University, Dammam, Kindgdom of Saudi Arabia. E-mail.
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Legionella Detection in Environmental Samples as an Example for Successful Implementation of qPCR. WATER 2018. [DOI: 10.3390/w10081012] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Waterborne diseases are a serious threat because of their ability to infect a high number of individuals in a short time span, such as during outbreaks of Legionellosis. This significantly highlights the need for the rapid detection and quantification of bacteria in environmental water samples. The aim of this study was to investigate the feasibility of quantitative Polymerase Chain Reaction (qPCR) for the detection of Legionellapneumophila (L. pneumophila) in environmental water samples and comparison of standard culture methods for Legionella detection with qPCR. Our study reached a negative predictive value (NPV) for L. pneumophila of 80.7% and for L. pneumophila serogroup 1 (sg1) the calculated NPV was 87.0%. The positive predictive value (PPV) for L. pneumophila was 53.9% and for L. pneumophila sg1 PPV was 21.4%. Results showed a correlation between qPCR and culture with an R2 value of 0.8973 for L. pneumophila, whereas no correlation was observed for the detection of L. pneumophila sg1. In our study, qPCR proved useful for the identification of L. pneumophila negative samples. However, despite the obvious benefits (sample handling, rapid generation of results), qPCR needs to be improved regarding the PPV before it can replace culture in water quality assessment.
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Boss R, Baumgartner A, Kroos S, Blattner M, Fretz R, Moor D. Rapid detection of viableLegionella pneumophilain tap water by a qPCR and RT-PCR-based method. J Appl Microbiol 2018; 125:1216-1225. [DOI: 10.1111/jam.13932] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 05/04/2018] [Accepted: 05/23/2018] [Indexed: 12/22/2022]
Affiliation(s)
- R. Boss
- Federal Food Safety and Veterinary Office; Berne Switzerland
| | - A. Baumgartner
- Federal Food Safety and Veterinary Office; Berne Switzerland
| | - S. Kroos
- Food Safety and Veterinary Office; Canton of Basel-Landschaft; Liestal Switzerland
| | - M. Blattner
- Food Safety and Veterinary Office; Canton of Basel-Landschaft; Liestal Switzerland
| | - R. Fretz
- Food Safety and Veterinary Office; Canton of Basel-Landschaft; Liestal Switzerland
| | - D. Moor
- Federal Food Safety and Veterinary Office; Berne Switzerland
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Schrammel B, Petzold M, Cervero-Aragó S, Sommer R, Lück C, Kirschner A. Persistent presence of outer membrane epitopes during short- and long-term starvation of five Legionella pneumophila strains. BMC Microbiol 2018; 18:75. [PMID: 30016940 PMCID: PMC6050704 DOI: 10.1186/s12866-018-1220-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 06/29/2018] [Indexed: 11/25/2022] Open
Abstract
Background Legionella pneumophila, the causative agent of Legionnaire’s disease, may enter a viable but non-culturable (VBNC) state triggered by environmental stress conditions. Specific outer-membrane epitopes of L. pneumophila are used in many diagnostic applications and some of them are linked to important virulence-related factors or endotoxins. However, it is not clear how the presence and status of these epitopes are influenced by environmental stress conditions. In this study, changes of outer membrane epitopes for monoclonal antibodies (mAb) from the Dresden panel and the major outer membrane protein MOMP were analysed for five L. pneumophila strains during short- and long-term starvation in ultrapure water. Results With ELISA and single cell immuno-fluorescence analysis, we could show that for most of the investigated mAb-strain combinations the total number of mAb-stained Legionella cells stayed constant for up to 400 days. Especially the epitopes of mAb 3/1, 8/5, 26/1 and 20/1, which are specific for L. pneumophila serogroup 1 subtypes, and the mAb 9/1, specific for serogroup 6, showed long-term persistence. For most mAb- stained cells, a high percentage of viable cells was observed at least until 118 days of starvation. At the same time, we observed a reduction of the fluorescence intensity of the stained cells during starvation indicating a loss of epitopes from the cell surface. However, most of the epitopes, including the virulence-associated mAb 3/1 epitope were still present with high fluorescence intensity after 400 days of starvation in up to 50% of the starved L. pneumophila population. Conclusions The results demonstrate the continuous presence of outer membrane epitopes of L. pneumophila during short-term and long-term starvation. Thus, culture-independent mAb-based diagnostic and detection tools, such as immuno-magnetic separation and microarray techniques are applicable for both L. pneumophila in the culturable and the VBNC state even after long-term starvation but nevertheless require careful testing before application. However, the mere presence of those epitopes is not necessarily an indication of viability or infectivity. Electronic supplementary material The online version of this article (10.1186/s12866-018-1220-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Barbara Schrammel
- Institute for Hygiene and Applied Immunology - Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria
| | - Markus Petzold
- Institute for Medical Microbiology and Hygiene, Medical Faculty "Carl Gustav Carus", University of Technology Dresden, Dresden, Germany
| | - Sílvia Cervero-Aragó
- Institute for Hygiene and Applied Immunology - Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria.,Interuniversity Cooperation Centre for Water and Health, Vienna, Austria
| | - Regina Sommer
- Institute for Hygiene and Applied Immunology - Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria.,Interuniversity Cooperation Centre for Water and Health, Vienna, Austria
| | - Christian Lück
- Institute for Medical Microbiology and Hygiene, Medical Faculty "Carl Gustav Carus", University of Technology Dresden, Dresden, Germany
| | - Alexander Kirschner
- Institute for Hygiene and Applied Immunology - Water Hygiene, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria. .,Interuniversity Cooperation Centre for Water and Health, Vienna, Austria.
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Stüken A, Haverkamp THA, Dirven HAAM, Gilfillan GD, Leithaug M, Lund V. Microbial Community Composition of Tap Water and Biofilms Treated with or without Copper-Silver Ionization. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:3354-3364. [PMID: 29461810 DOI: 10.1021/acs.est.7b05963] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Copper-silver ionization (CSI) is an in-house water disinfection method primarily installed to eradicate Legionella bacteria from drinking water distribution systems (DWDS). Its effect on the abundance of culturable Legionella and Legionella infections has been documented in several studies. However, the effect of CSI on other bacteria in DWDS is largely unknown. To investigate these effects, we characterized drinking water and biofilm communities in a hospital using CSI, in a neighboring building without CSI, and in treated drinking water at the local water treatment plant. We used 16S rDNA amplicon sequencing and Legionella culturing. The sequencing results revealed three distinct water groups: (1) cold-water samples (no CSI), (2) warm-water samples at the research institute (no CSI), and (3) warm-water samples at the hospital (after CSI; ANOSIM, p < 0.001). Differences between the biofilm communities exposed and not exposed to CSI were less clear (ANOSIM, p = 0.022). No Legionella were cultured, but limited numbers of Legionella sequences were recovered from all 25 water samples (0.2-1.4% relative abundance). The clustering pattern indicated local selection of Legionella types (Kruskal-Wallis, p < 0.001). Furthermore, one unclassified Betaproteobacteria OTU was highly enriched in CSI-treated warm water samples at the hospital (Kruskal-Wallis, p < 0.001).
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Affiliation(s)
- Anke Stüken
- Dept. Zoonotic, Food and Waterborne Infections , Norwegian Institute of Public Health , Oslo , Norway
| | - Thomas H A Haverkamp
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences , University of Oslo , Blindern, Oslo , Norway
| | - Hubert A A M Dirven
- Dept. Toxicology and Risk Assessment , Norwegian Institute of Public Health , Oslo , Norway
| | - Gregor D Gilfillan
- Dept. Medical Genetics , Oslo University Hospital and University of Oslo , Oslo , Norway
| | - Magnus Leithaug
- Dept. Medical Genetics , Oslo University Hospital and University of Oslo , Oslo , Norway
| | - Vidar Lund
- Dept. Zoonotic, Food and Waterborne Infections , Norwegian Institute of Public Health , Oslo , Norway
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Casini B, Baggiani A, Totaro M, Mansi A, Costa AL, Aquino F, Miccoli M, Valentini P, Bruschi F, Lopalco PL, Privitera G. Detection of viable but non-culturable legionella in hospital water network following monochloramine disinfection. J Hosp Infect 2017; 98:46-52. [PMID: 28917570 DOI: 10.1016/j.jhin.2017.09.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 09/04/2017] [Accepted: 09/07/2017] [Indexed: 10/18/2022]
Abstract
BACKGROUND Prevention of legionellosis remains a critical issue in healthcare settings where monochloramine (MC) disinfection was recently introduced as an alternative to chlorine dioxide in controlling Legionella spp. contamination of the hospital water network. Continuous treatments with low MC doses in some instances have induced a viable but non-culturable state (VBNC) of Legionella spp. AIM To investigate the occurrence of such dormant cells during a long period of continuous MC treatment. METHODS Between November 2010 and April 2015, 162 water and biofilm samples were collected and Legionella spp. isolated in accordance with standard procedures. In sampling sites where MC was <1.5mg/L, VBNC cells were investigated by ethidium monoazide bromide (EMA)-real-time polymerase chain reaction (qPCR) and 'resuscitation' test into Acanthamoeba polyphaga CCAP 1501/18. According to the Health Protection Agency protocol, free-living protozoa were researched in 60 five-litre water samples. FINDINGS In all, 136 out of 156 (87.2%) of the samples taken from sites previously positive for L. pneumophila ST269 were negative by culture, but only 47 (34.5%) negative by qPCR. Although no positive results were obtained by EMA-qPCR, four out of 22 samples associated with MC concentration of 1.3 ± 0.5mg/L showed VBNC legionella resuscitation. The presence of the amoeba A. polyphaga in the hospital water network was demonstrated. CONCLUSION Our study is the first report evidencing the emergence of VNBC legionella during a long period of continuous MC treatment of a hospital water network, highlighting the importance of keeping an appropriate and uninterrupted MC dosage to ensure the control of legionella colonization in hospital water supplies.
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Affiliation(s)
- B Casini
- Department of Translational Research, N.T.M.S., University of Pisa, Pisa, Italy.
| | - A Baggiani
- Department of Translational Research, N.T.M.S., University of Pisa, Pisa, Italy
| | - M Totaro
- Department of Translational Research, N.T.M.S., University of Pisa, Pisa, Italy
| | - A Mansi
- INAIL, Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, Monte Porzio Catone (Roma), Roma, Italy
| | - A L Costa
- Department of Translational Research, N.T.M.S., University of Pisa, Pisa, Italy
| | - F Aquino
- Department of Translational Research, N.T.M.S., University of Pisa, Pisa, Italy
| | - M Miccoli
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - P Valentini
- Department of Translational Research, N.T.M.S., University of Pisa, Pisa, Italy
| | - F Bruschi
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - P L Lopalco
- Department of Translational Research, N.T.M.S., University of Pisa, Pisa, Italy
| | - G Privitera
- Department of Translational Research, N.T.M.S., University of Pisa, Pisa, Italy
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45
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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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46
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Whiley H, Bentham R, Brown MH. Legionella Persistence in Manufactured Water Systems: Pasteurization Potentially Selecting for Thermal Tolerance. Front Microbiol 2017; 8:1330. [PMID: 28769899 PMCID: PMC5515819 DOI: 10.3389/fmicb.2017.01330] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 06/30/2017] [Indexed: 01/13/2023] Open
Abstract
Legionella is an opportunistic waterborne pathogen of increasing public health significance. Pasteurization, otherwise known as super-heat and flush (increasing water temperature to above 70°C and flushing all outlets), has been identified as an important mechanism for the disinfection of Legionella in manufactured water systems. However, several studies have reported that this procedure was ineffective at remediating water distribution systems as Legionella was able to maintain long term persistent contamination. Up to 25% of L. pneumophila cells survived heat treatment of 70°C, but all of these were in a viable but non-culturable state. This demonstrates the limitations of the culture method of Legionella detection currently used to evaluate disinfection protocols. In addition, it has been demonstrated that pasteurization and nutrient starvation can select for thermal tolerant strains, where L. pneumophila was consistently identified as having greater thermal tolerance compared to other Legionella species. This review demonstrates that further research is needed to investigate the effectiveness of pasteurization as a disinfection method. In particular, it focuses on the potential for pasteurization to select for thermal tolerant L. pneumophila strains which, as the primary causative agent of Legionnaires disease, have greater public health significance compared to other Legionella species.
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Affiliation(s)
- Harriet Whiley
- College of Science and Engineering, Flinders University, Bedford ParkSA, Australia
| | - Richard Bentham
- College of Science and Engineering, Flinders University, Bedford ParkSA, Australia
| | - Melissa H Brown
- College of Science and Engineering, Flinders University, Bedford ParkSA, Australia
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47
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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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48
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Temperature-Dependent Growth Modeling of Environmental and Clinical Legionella pneumophila Multilocus Variable-Number Tandem-Repeat Analysis (MLVA) Genotypes. Appl Environ Microbiol 2017; 83:AEM.03295-16. [PMID: 28159784 DOI: 10.1128/aem.03295-16] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 01/25/2017] [Indexed: 01/02/2023] Open
Abstract
Legionella pneumophila causes waterborne infections resulting in severe pneumonia. High-resolution genotyping of L. pneumophila isolates can be achieved by multiple-locus variable-number tandem-repeat analysis (MLVA). Recently, we found that different MLVA genotypes of L. pneumophila dominated different sites in a small drinking-water network, with a genotype-related temperature and abundance regime. The present study focuses on understanding the temperature-dependent growth kinetics of the genotypes that dominated the water network. Our aim was to model mathematically the influence of temperature on the growth kinetics of different environmental and clinical L. pneumophila genotypes and to compare it with the influence of their ecological niches. Environmental strains showed a distinct temperature preference, with significant differences among the growth kinetics of the three studied genotypes (Gt4, Gt6, and Gt15). Gt4 strains exhibited superior growth at lower temperatures (25 and 30°C), while Gt15 strains appeared to be best adapted to relatively higher temperatures (42 and 45°C). The temperature-dependent growth traits of the environmental genotypes were consistent with their distribution and temperature preferences in the water network. Clinical isolates exhibited significantly higher growth rates and reached higher maximal cell densities at 37°C and 42°C than the environmental strains. Further research on the growth preferences of L. pneumophila clinical and environmental genotypes will result in a better understanding of their ecological niches in drinking-water systems as well as in the human body.IMPORTANCELegionella pneumophila is a waterborne pathogen that threatens humans in developed countries. The bacteria inhabit natural and man-made freshwater environments. Here we demonstrate that different environmental L. pneumophila genotypes have different temperature-dependent growth kinetics. Moreover, Legionella strains that belong to the same species but were isolated from environmental and clinical sources possess adaptations for growth at different temperatures. These growth preferences may influence the bacterial colonization at specific ecological niches within the drinking-water network. Adaptations for growth at human body temperatures may facilitate the abilities of some L. pneumophila strains to infect and cause illness in humans. Our findings may be used as a tool to improve Legionella monitoring in drinking-water networks. Risk assessment models for predicting the risk of legionellosis should take into account not only Legionella concentrations but also the temperature-dependent growth kinetics of the isolates.
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Miranda-Castro R, Sánchez-Salcedo R, Suárez-Álvarez B, de-Los-Santos-Álvarez N, Miranda-Ordieres AJ, Jesús Lobo-Castañón M. Thioaromatic DNA monolayers for target-amplification-free electrochemical sensing of environmental pathogenic bacteria. Biosens Bioelectron 2017; 92:162-170. [PMID: 28213329 DOI: 10.1016/j.bios.2017.02.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/26/2017] [Accepted: 02/10/2017] [Indexed: 10/20/2022]
Abstract
Genosensing technology has mostly based on mixed self-assembled monolayers (SAMs) of thiol-modified oligonucleotides and alkanethiols on gold surfaces. However, the typical backfilling approach, which incorporates the alkanethiol in a second step, gives rise to a heterogeneous distribution of oligonucleotide probes on the surface, negatively affecting to both hybridization efficiency and surface stability. Despite aromatic thiols present a remarkably different behavior from alkanethiols, with higher rigidity and stronger intermolecular interactions, they have been scarcely explored for the fabrication of DNA sensing platforms. We have investigated different approaches involving SAMs of aromatic thiols, namely p-mercaptobenzoic acid (p-MBA) and p-aminothiophenol (p-ATP), to yield DNA sensing layers for sequence-specific detection of target oligonucleotides. The studied monolayers were evaluated by DNA surface coverage and further information was obtained by determining their functionality in a sandwich hybridization assay with enzymatic amplification of the electrochemical read-out. The insertion of thiol-oligonucleotides into p-ATP monolayers previously oxidized, and the covalent binding of amino-oligonucleotides to pure p-MBA monolayers give rise to increased storage stability and better analytical performance. The quantification of RNA from Legionella pneumophila cellular lysates was successfully performed, illustrating the usefulness of these sensing architectures for detecting pathogenic bacteria.
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Affiliation(s)
- Rebeca Miranda-Castro
- Departamento de Química Física y Analítica, Universidad de Oviedo, 33006 Oviedo, Spain
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50
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Collins S, Walker J. Comments on Whiley Legionella Risk Management and Control in Potable Water Systems: Argument for the Abolishment of Routine Testing. Int. J. Environ. Res. Public Health 2017, 14, 12. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017; 14:E102. [PMID: 28117715 PMCID: PMC5295352 DOI: 10.3390/ijerph14010102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 01/08/2017] [Accepted: 01/11/2017] [Indexed: 11/16/2022]
Abstract
In their recent article, Whiley makes an interesting case for the abolishment of routine testing in Legionella risk management and control plans. Here, we present our views regarding this suggestion, drawing upon our own experiences in the UK. We urge caution against the removal of routine monitoring from guidelines due to the impending public health risks that would result.
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Affiliation(s)
- Samuel Collins
- Biosafety, Air and Water Microbiology Group, National Infection Service, Public Health England, Salisbury SP4 0JG, UK.
| | - Jimmy Walker
- Biosafety, Air and Water Microbiology Group, National Infection Service, Public Health England, Salisbury SP4 0JG, UK.
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