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Zahid MT, Mustafa G, Sajid R, Razzaq A, Waheed M, Khan MA, Hwang JH, Park YK, Chung WJ, Jeon BH. Surviving chlorinated waters: bleaching sensitivity and persistence of free-living amoebae. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:48073-48084. [PMID: 39017868 DOI: 10.1007/s11356-024-34379-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 07/09/2024] [Indexed: 07/18/2024]
Abstract
Recent advancements in membrane technologies and disinfection methods have enhanced drinking water quality significantly. However, microorganisms, including free-living amoebae (FLA), persist and pose potential threats to humans. FLA are linked to severe neuro-ophthalmic infections and serve as hosts of pathogenic bacteria. This study examined FLA presence in chlorinated and ultrafiltration drinking water and evaluated chlorine's disinfectant. Of 115 water samples, 21 tested positive for Acanthamoeba sp., Allovahlkampfia sp., and Vermamoeba vermiformis, originating from chlorinated sources. FLA trophozoites withstand temperatures up to 37 °C, while the cysts tolerate heat shocks of 60-70 °C. Trophozoites are susceptible to 5 mg L-1 chlorine, but cysts remain viable at concentrations up to 10 mg L-1. FLAs' survival in chlorinated waters is attributed to high cyst tolerance and lower residual chlorine concentrations. These findings highlight the need for ultrafiltration or enhanced chlorination protocols to ensure safer drinking water.
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Affiliation(s)
- Muhammad Tariq Zahid
- Department of Zoology, Dr. Nazir Ahmad Institute of Biological Sciences, Government College University, Lahore, Pakistan
- Department of Earth Resources & Environmental Engineering, Hanyang University, 222-Wangsimni-Ro, Seongdong-Gu, Seoul, 04763, Republic of Korea
| | - Ghulam Mustafa
- Department of Zoology, Dr. Nazir Ahmad Institute of Biological Sciences, Government College University, Lahore, Pakistan
- Department of Earth Resources & Environmental Engineering, Hanyang University, 222-Wangsimni-Ro, Seongdong-Gu, Seoul, 04763, Republic of Korea
| | - Romasa Sajid
- Department of Zoology, Dr. Nazir Ahmad Institute of Biological Sciences, Government College University, Lahore, Pakistan
| | - Ayesha Razzaq
- Department of Zoology, Dr. Nazir Ahmad Institute of Biological Sciences, Government College University, Lahore, Pakistan
| | - Muzdalfa Waheed
- Department of Zoology, Dr. Nazir Ahmad Institute of Biological Sciences, Government College University, Lahore, Pakistan
| | - Moonis Ali Khan
- Chemistry Department, College of Science, King Saud University, 11451, Riyadh, Saudi Arabia
| | - Jae-Hoon Hwang
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC, H3G 1M8, Canada
| | - Young Kwon Park
- School of Environmental Engineering, University of Seoul, Seoul, 02504, Republic of Korea
| | - Woo Jin Chung
- Department of Environmental Energy Engineering, Kyonggi University, 154-42 Gwanggyosan-Ro, Yeongtong-Gu, Suwon-Si, Gyeonggi-Do, 16227, Republic of Korea
| | - Byong-Hun Jeon
- Department of Earth Resources & Environmental Engineering, Hanyang University, 222-Wangsimni-Ro, Seongdong-Gu, Seoul, 04763, Republic of Korea.
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Párraga-Niño N, Cortès-Tarragó R, Quero S, Garcia-Núñez M, Arqué E, Sabaté S, Ramirez D, Gavaldà L. Persistence of viable but nonculturable Legionella pneumophila state in hospital water systems: A hidden enemy? THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 927:172410. [PMID: 38608884 DOI: 10.1016/j.scitotenv.2024.172410] [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: 02/09/2024] [Revised: 04/09/2024] [Accepted: 04/09/2024] [Indexed: 04/14/2024]
Abstract
There is little evidence of the long-term consequences of maintaining sanitary hot water at high temperatures on the persistence of Legionella in the plumbing system. The aims of this study were to describe the persistence and genotypic variability of L. pneumophila in a hospital building with two entirely independent hot water distribution systems, and to estimate the thermotolerance of the genotypic variants by studying the quantity of VBNC L. pneumophila. Eighty isolates from 55 water samples obtained between the years 2012-2017 were analyzed. All isolates correspond to L. pneumophila serogroup 6. The isolates were discriminated in four restriction patterns by pulsed-field gel electrophoresis. In one installation, pattern A + Aa predominated, accounting for 75.8 % of samples, while the other installation exhibited pattern B as the most frequent (81.8 % of samples; p < 0.001). The mean temperature of the isolates was: 52.6 °C (pattern A + Aa) and 55.0 °C (pattern B), being significantly different. Nine strains were selected as representative among patterns to study their thermotolerance by flow-cytometry after 24 h of thermic treatment. VBNC bacteria were detected in all samples. After thermic treatment at 50 °C, 52.0 % of bacteria had an intact membrane, and after 55 °C this percentage decreased to 23.1 %. Each pattern exhibited varying levels of thermotolerance. These findings indicate that the same hospital building can be colonized with different predominant types of Legionella if it has independent hot water installations. Maintaining a minimum temperature of 50 °C at distal points of the system would allow the survival of replicative L. pneumophila. However, the presence of Legionella in hospital water networks is underestimated if culture is considered as the standard method for Legionella detection, because VBNC do not grow on culture plates. This phenomenon can carry implications for the Legionella risk management plans in hospitals that adjust their control measures based on the microbiological surveillance of water.
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Affiliation(s)
- Noemí Párraga-Niño
- Clinical and environmental infectious diseases study group, Fundació Institut d'Investigació Germans Trias i Pujol, Carretera de Can Ruti, Camí de les Escoles s/n, 08916 Badalona, Barcelona, Spain; Fundació Lluita contra les Infeccions, Carretera de Can Ruti, 08916 Badalona, Barcelona, Spain.
| | - Roger Cortès-Tarragó
- Clinical and environmental infectious diseases study group, Fundació Institut d'Investigació Germans Trias i Pujol, Carretera de Can Ruti, Camí de les Escoles s/n, 08916 Badalona, Barcelona, Spain
| | - Sara Quero
- Clinical and environmental infectious diseases study group, Fundació Institut d'Investigació Germans Trias i Pujol, Carretera de Can Ruti, Camí de les Escoles s/n, 08916 Badalona, Barcelona, Spain; Fundació Lluita contra les Infeccions, Carretera de Can Ruti, 08916 Badalona, Barcelona, Spain; CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Av. Monforte de Lemos, 3-5. Pabellón 11. Planta 0, 28029 Madrid, Spain; Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT-CERCA), Universitat Autònoma de Barcelona, Plaça Torre de l'Aigua, s/n, 08208 Sabadell, Barcelona, Spain
| | - Marian Garcia-Núñez
- Clinical and environmental infectious diseases study group, Fundació Institut d'Investigació Germans Trias i Pujol, Carretera de Can Ruti, Camí de les Escoles s/n, 08916 Badalona, Barcelona, Spain
| | - Elisenda Arqué
- Clinical and environmental infectious diseases study group, Fundació Institut d'Investigació Germans Trias i Pujol, Carretera de Can Ruti, Camí de les Escoles s/n, 08916 Badalona, Barcelona, Spain
| | - Sara Sabaté
- Agència de Salut Pública de Barcelona (ASPB), Plaza Lesseps 1, 08023 Barcelona, Spain; Institut d'Investigació Biomèdica Sant Pau (IIB SANT PAU), Sant Quintí 77-79, 08041 Barcelona, Spain
| | - Dolors Ramirez
- Department of Preventive Medicine-Hospital Hygiene. Hospital Universitari de Bellvitge-IDIBELL, Barcelona, Spain
| | - Laura Gavaldà
- Department of Preventive Medicine-Hospital Hygiene. Hospital Universitari de Bellvitge-IDIBELL, Barcelona, Spain
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Chaúque BJM, Corção G, Benetti AD, Rott MB. A challenge in washing water with the sun: 24h of SODIS fails to inactivate Acanthamoeba castellanii cysts and internalized Pseudomonas aeruginosa under strong real sun conditions. Photochem Photobiol Sci 2023; 22:2179-2188. [PMID: 37296325 DOI: 10.1007/s43630-023-00440-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Accepted: 05/19/2023] [Indexed: 06/12/2023]
Abstract
Despite access to drinking water being a basic human right, the availability of safe drinking water remains a privilege that many do not have and as a result, many lives are lost each year due to waterborne diseases associated with the consumption of biologically unsafe water. To face this situation, different low-cost household drinking water treatment technologies (HDWT) have been developed, and among them is solar disinfection (SODIS). Despite the effectiveness of SODIS and the epidemiological gains being consistently documented in the literature, there is a lack of evidence of the effectiveness of the batch-SODIS process against protozoan cysts as well as their internalized bacteria under real sun conditions. This work evaluated the effectiveness of the batch-SODIS process on the viability of Acanthamoeba castellanii cysts, and internalized Pseudomonas aeruginosa. Dechlorinated tap water contaminated with 5.6 × 103 cysts/L, contained in PET (polyethylene terephthalate) bottles, was exposed for 8 h a day to strong sunlight (531-1083 W/m2 of maximum insolation) for 3 consecutive days. The maximum water temperature inside the reactors ranged from 37 to 50 °C. Cyst viability was assessed by inducing excystment on non-nutrient agar, or in water with heat-inactivated Escherichia coli. After sun exposure for 0, 8, 16 and 24 h, the cysts remained viable and without any perceptible impairment in their ability to excyst. 3 and 5.5 log CFU/mL of P. aeruginosa were detected in water containing untreated and treated cysts, respectively, after 3 days of incubation at 30 °C. The batch-SODIS process is unable to inactivate A. castellanii cysts as well as its internalized bacteria. Although the use of batch SODIS by communities should continue to be encouraged, SODIS-disinfected water should be consumed within 3 days.
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Affiliation(s)
- Beni Jequicene Mussengue Chaúque
- Laboratory of Protozoology and Microbiological Analyses, Department of Microbiology, Immunology and Parasitology, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos Street, 2600, Porto Alegre/RS, Brazil
- Center of Studies in Science and Technology (NECET), Biology Course, Universidade Rovuma, Niassa Branch, Lichinga, Mozambique
| | - Gertrudes Corção
- Laboratory of Protozoology and Microbiological Analyses, Department of Microbiology, Immunology and Parasitology, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos Street, 2600, Porto Alegre/RS, Brazil
| | | | - Marilise Brittes Rott
- Laboratory of Protozoology and Microbiological Analyses, Department of Microbiology, Immunology and Parasitology, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos Street, 2600, Porto Alegre/RS, Brazil.
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Cazals M, Bédard E, Doberva M, Faucher S, Prévost M. Compromised Effectiveness of Thermal Inactivation of Legionella pneumophila in Water Heater Sediments and Water, and Influence of the Presence of Vermamoeba vermiformis. Microorganisms 2022; 10:microorganisms10020443. [PMID: 35208896 PMCID: PMC8874534 DOI: 10.3390/microorganisms10020443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/04/2022] [Accepted: 02/09/2022] [Indexed: 11/21/2022] Open
Abstract
Intermittent reduction of temperature set-points and periodic shutdowns of water heaters have been proposed to reduce energy consumption in buildings. However, the consequences of such measures on the occurrence and proliferation of Legionella pneumophila (Lp) in hot water systems have not been documented. The impact of single and repeated heat shocks was investigated using an environmental strain of L. pneumophila and a reference strain of V. vermiformis. Heat shocks at temperatures ranging from 50 °C to 70 °C were applied for 1 h and 4 h in water and water heaters loose deposits (sludge). The regrowth potential of heat-treated culturable L. pneumophila in presence of V. vermiformis in water heaters sludges was evaluated. A 2.5-log loss of culturability of L. pneumophila was observed in simulated drinking water at 60 °C while a 4-log reduction was reached in water heaters loose deposits. Persistence of Lp after 4 h at 55 °C was shown and the presence of V. vermiformis in water heater’s loose deposits resulted in a drastic amplification (5-log). Results show that thermal inactivation by heat shock is only efficient at elevated temperatures (50 °C) in both water and loose deposits. The few remaining organisms can rapidly proliferate during storage at lower temperature in the presence of hosts.
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Affiliation(s)
- Margot Cazals
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC H3C 3A7, Canada; (E.B.); (M.D.); (M.P.)
- Correspondence:
| | - Emilie Bédard
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC H3C 3A7, Canada; (E.B.); (M.D.); (M.P.)
| | - Margot Doberva
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC H3C 3A7, Canada; (E.B.); (M.D.); (M.P.)
| | - Sébastien Faucher
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada;
| | - Michèle Prévost
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC H3C 3A7, Canada; (E.B.); (M.D.); (M.P.)
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5
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Management of Microbiological Contamination of the Water Network of a Newly Built Hospital Pavilion. Pathogens 2021; 10:pathogens10010075. [PMID: 33467059 PMCID: PMC7829805 DOI: 10.3390/pathogens10010075] [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: 10/20/2020] [Revised: 01/13/2021] [Accepted: 01/14/2021] [Indexed: 12/28/2022] Open
Abstract
The good installation, as well as commissioning plan, of a water network is a crucial step in reducing the risk of waterborne diseases. The aim of this study was to monitor the microbiological quality of water from a newly built pavilion before it commenced operation. Overall, 91 water samples were tested for coliforms, Escherichia coli, enterococci, Pseudomonas aeruginosa and Legionella at three different times: T0 (without any water treatment), T1 (after treatment with hydrogen peroxide and silver ions at initial concentration of 20 mg/L and after flushing of water for 20 min/day for seven successive days) and T2 (15 days later). Coliforms were detected in 47.3% of samples at T0, 36.3% at T1 and 4.4% at T2. E. coli was isolated in 4.4% of the samples only at T1, while enterococci appeared in 12.1% of the samples at T1 and in 2.2% at T2. P. aeruginosa was isolated in 50.5% of the samples at T0, 29.7% at T1 and 1.1% at T2. Legionella pneumophila serogroup 8 was isolated in 80.2% of the samples at T0, 36.3% at T1 and 2.2% at T2. Our results confirmed the need for a water safety plan in new hospital pavilions to prevent the risk of waterborne diseases.
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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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Gabriel AA, Panaligan DC. Heat and chlorine resistance of a soil Acanthamoeba sp. cysts in water. J Appl Microbiol 2020; 129:453-464. [PMID: 32012390 DOI: 10.1111/jam.14600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/28/2020] [Accepted: 01/28/2020] [Indexed: 12/24/2022]
Abstract
AIMS The study established the inactivation kinetic parameters of an Acanthamoeba cyst isolate subjected to heating and chlorination. METHODS AND RESULTS A strain of Acanthamoeba was isolated and purified from an area surrounding a pilot food plant. Mature cysts (14 days) were subjected to heat inactivation studies at 71, 76, 81, 86 and 91°C; and chlorination at 100, 200, 300, 400 and 500 ppm. The decimal reduction times (D-values) at 71, 76, 81, 86 and 91°C were 18·31, 9·26, 7·35, 4·52 and 1·81 min respectively. The calculated thermal resistance constant (z-value) was 21·32°C (R2 = 0·96-0·97). The D-value in 100, 200, 300, 400 and 500 ppm chlorine-treated water were 47·17, 25·06, 24·51, 23·70 and 18·55 min respectively. The chlorine resistance constant (z-value) was 1179 ppm chlorine (R2 = 0·65-0·74). CONCLUSIONS Results demonstrated high resistance of the isolated Acanthamoeba cysts towards the common methods applied in ensuring food and food processing environment sanitation. SIGNIFICANCE AND IMPACT OF THE STUDY The resistance parameters of the test organisms established in this study may be used in the establishment of Sanitation Standard Operating Procedures (SSOPs), which are often based on inactivation of bacteria. These SSOPs could render better protection to food and food processing environments.
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Affiliation(s)
- A A Gabriel
- Laboratory of Food Microbiology and Hygiene, Department of Food Science and Nutrition, College of Home Economics, University of the Philippines, Quezon City, Philippines
| | - D C Panaligan
- Laboratory of Food Microbiology and Hygiene, Department of Food Science and Nutrition, College of Home Economics, University of the Philippines, Quezon City, Philippines
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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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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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10
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Scheikl U, Tsao HF, Horn M, Indra A, Walochnik J. Free-living amoebae and their associated bacteria in Austrian cooling towers: a 1-year routine screening. Parasitol Res 2016; 115:3365-74. [PMID: 27177720 PMCID: PMC4980419 DOI: 10.1007/s00436-016-5097-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 04/27/2016] [Indexed: 12/15/2022]
Abstract
Free-living amoebae (FLA) are widely spread in the environment and known to cause rare but often serious infections. Besides this, FLA may serve as vehicles for bacterial pathogens. In particular, Legionella pneumophila is known to replicate within FLA thereby also gaining enhanced infectivity. Cooling towers have been the source of outbreaks of Legionnaires' disease in the past and are thus usually screened for legionellae on a routine basis, not considering, however, FLA and their vehicle function. The aim of this study was to incorporate a screening system for host amoebae into a Legionella routine screening. A new real-time PCR-based screening system for various groups of FLA was established. Three cooling towers were screened every 2 weeks over the period of 1 year for FLA and Legionella spp., by culture and molecular methods in parallel. Altogether, 83.3 % of the cooling tower samples were positive for FLA, Acanthamoeba being the dominating genus. Interestingly, 69.7 % of the cooling tower samples were not suitable for the standard Legionella screening due to their high organic burden. In the remaining samples, positivity for Legionella spp. was 25 % by culture, but overall positivity was 50 % by molecular methods. Several amoebal isolates revealed intracellular bacteria.
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Affiliation(s)
- Ute Scheikl
- Institute of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Vienna, Austria
| | - Han-Fei Tsao
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Matthias Horn
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Alexander Indra
- Department of Mycobacteriology and Clinical Molecular Biology, AGES, Vienna, Austria
| | - Julia Walochnik
- Institute of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Vienna, Austria.
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11
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Bédard E, Prévost M, Déziel E. Pseudomonas aeruginosa in premise plumbing of large buildings. Microbiologyopen 2016; 5:937-956. [PMID: 27353357 PMCID: PMC5221438 DOI: 10.1002/mbo3.391] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 06/01/2016] [Accepted: 06/06/2016] [Indexed: 12/27/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic bacterial pathogen that is widely occurring in the environment and is recognized for its capacity to form or join biofilms. The present review consolidates current knowledge on P. aeruginosa ecology and its implication in healthcare facilities premise plumbing. The adaptability of P. aeruginosa and its capacity to integrate the biofilm from the faucet and the drain highlight the role premise plumbing devices can play in promoting growth and persistence. A meta‐analysis of P. aeruginosa prevalence in faucets (manual and electronic) and drains reveals the large variation in device positivity reported and suggest the high variability in the sampling approach and context as the main reason for this variation. The effects of the operating conditions that prevail within water distribution systems (disinfection, temperature, and hydraulic regime) on the persistence of P. aeruginosa are summarized. As a result from the review, recommendations for proactive control measures of water contamination by P. aeruginosa are presented. A better understanding of the ecology of P. aeruginosa and key influencing factors in premise plumbing are essential to identify culprit areas and implement effective control measures.
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Affiliation(s)
- Emilie Bédard
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada.,INRS-Institut Armand-Frappier, Laval, QC, Canada
| | - Michèle Prévost
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, Canada
| | - Eric Déziel
- INRS-Institut Armand-Frappier, Laval, QC, Canada
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12
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Dietersdorfer E, Cervero-Aragó S, Sommer R, Kirschner AK, Walochnik J. Optimized methods for Legionella pneumophila release from its Acanthamoeba hosts. BMC Microbiol 2016; 16:74. [PMID: 27113731 PMCID: PMC4845434 DOI: 10.1186/s12866-016-0691-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 04/14/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Free-living amoebae (FLA) and particularly acanthamoebae serve as vehicles and hosts for Legionella pneumophila, among other pathogenic microorganisms. Within the amoebae, L. pneumophila activates a complex regulatory pathway that enables the bacteria to resist amoebal digestion and to replicate. Moreover, the amoebae provide the bacteria protection against harsh environmental conditions and disinfectants commonly used in engineered water systems. To study this ecological relationship, co-culture and infection models have been used. However, there is a lack of data regarding the effectiveness of the different methods used to release intracellular bacteria from their amoebal hosts. The aim of this study was to evaluate the impact of the methods used to release intracellular L. pneumophila cells on the culturability of the bacteria. Furthermore, the standard method ISO 11731:1998 for the recovery and enumeration of Legionella from water samples was evaluated for its suitability to quantify intracellular bacteria. RESULTS The effectiveness of the eight release treatments applied to L. pneumophila and Acanthamoeba strains in a free-living state varied between bacterial strains. Moreover, the current study provides numerical data on the state of co-culture suspensions at different time points. The release treatments enhanced survival of both microorganisms in co-cultures of L. pneumophila and Acanthamoeba. Passage through a needle (21G, 27G) and centrifugation at 10,000 × g showed the highest bacterial counts when releasing the bacteria from the intracellular state. Regarding the ISO 11731:1998 method, one of the tested strains showed no differences between the recovery rates of associated and free-living L. pneumophila. However, a reduced bacterial recovery rate was observed for the second L. pneumophila strain used, and this difference is likely linked to the survival of the amoebae. CONCLUSIONS Mechanical release treatments were the most effective methods for providing bacterial release without the use of chemicals that could compromise further study of the intracellular bacteria. The current results demonstrated that the recovery of L. pneumophila from water systems may be underestimated if protozoal membranes are not disrupted.
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Affiliation(s)
- Elisabeth Dietersdorfer
- Institute of Specific Prophylaxis and Tropical Medicine, Department of Medical Parasitology, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria
| | - Sílvia Cervero-Aragó
- Institute for Hygiene and Applied Immunology, Water Hygiene, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria. .,Interuniversity Cooperation Centre for Water & Health, Vienna, Austria.
| | - Regina Sommer
- Institute for Hygiene and Applied Immunology, Water Hygiene, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria.,Interuniversity Cooperation Centre for Water & Health, Vienna, Austria
| | - Alexander K Kirschner
- Institute for Hygiene and Applied Immunology, Water Hygiene, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria.,Interuniversity Cooperation Centre for Water & Health, Vienna, Austria
| | - Julia Walochnik
- Institute of Specific Prophylaxis and Tropical Medicine, Department of Medical Parasitology, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria
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13
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Cervero-Aragó S, Rodríguez-Martínez S, Puertas-Bennasar A, Araujo RM. Effect of Common Drinking Water Disinfectants, Chlorine and Heat, on Free Legionella and Amoebae-Associated Legionella. PLoS One 2015; 10:e0134726. [PMID: 26241039 PMCID: PMC4524690 DOI: 10.1371/journal.pone.0134726] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 07/13/2015] [Indexed: 12/12/2022] Open
Abstract
Chlorine and thermal treatments are the most commonly used procedures to control and prevent Legionella proliferation in drinking water systems of large buildings. However, cases of legionellosis still occur in facilities with treated water. The purpose of this work was to model the effect of temperature and free chlorine applied in similar exposure conditions as in drinking water systems on five Legionella spp. strains and two amoebal strains of the genera Acanthamoeba. Inactivation models obtained were used to determine the effectiveness of the treatments applied which resulted more effective against Legionella than Acanthamoeba, especially those in cystic stages. Furthermore, to determine the influence of the relationship between L. pneumophila and Acanthamoeba spp. on the treatment effectiveness, inactivation models of the bacteria-associated amoeba were also constructed and compared to the models obtained for the free living bacteria state. The Legionella-amoeba association did not change the inactivation models, but it reduced the effectiveness of the treatments applied. Remarkably, at the lowest free chlorine concentration, 0.5 mg L-1, as well as at the lowest temperatures, 50°C and 55°C, the influence of the Legionella-amoeba associate state was the strongest in reducing the effectiveness of the treatments compared to the free Legionella state. Therefore, the association established between L. pneumophila and amoebae in the water systems indicate an increased health risk in proximal areas of the system (close to the tap) where lower free chlorine concentrations and lower temperatures are commonly observed.
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Affiliation(s)
- Sílvia Cervero-Aragó
- Departament de Microbiologia, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain
- Water Hygiene, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Kinderspitalgasse 15, A-1090, Vienna, Austria
| | - Sarah Rodríguez-Martínez
- Departament de Microbiologia, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain
- Department of Biology and Environment, Faculty of Natural Sciences, University of Haifa, Oranim, 36006, Tivon, Israel
| | - Antoni Puertas-Bennasar
- Departament de Microbiologia, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain
| | - Rosa M. Araujo
- Departament de Microbiologia, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain
- * E-mail:
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14
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Canals O, Serrano-Suárez A, Salvadó H, Méndez J, Cervero-Aragó S, Ruiz de Porras V, Dellundé J, Araujo R. Effect of chlorine and temperature on free-living protozoa in operational man-made water systems (cooling towers and hot sanitary water systems) in Catalonia. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:6610-8. [PMID: 25410311 DOI: 10.1007/s11356-014-3839-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 11/10/2014] [Indexed: 05/07/2023]
Abstract
In recent decades, free-living protozoa (FLP) have gained prominence as the focus of research studies due to their pathogenicity to humans and their close relationship with the survival and growth of pathogenic amoeba-resisting bacteria. In the present work, we studied the presence of FLP in operational man-made water systems, i.e. cooling towers (CT) and hot sanitary water systems (HSWS), related to a high risk of Legionella spp. outbreaks, as well as the effect of the biocides used, i.e. chlorine in CT and high temperature in HSWS, on FLP. In CT samples, high-chlorine concentrations (7.5 ± 1.5 mg chlorine L(-1)) reduced the presence of FLP by 63.8 % compared to samples with low-chlorine concentrations (0.04 ± 0.08 mg chlorine L(-1)). Flagellates and amoebae were observed in samples collected with a level of 8 mg chlorine L(-1), which would indicate that some FLP, including the free-living amoeba (FLA) Acanthamoeba spp., are resistant to the discontinuous chlorine disinfection method used in the CT studied. Regarding HSWS samples, the amount of FLP detected in high-temperatures samples (53.1 ± 5.7 °C) was 38 % lower than in low-temperature samples (27.8 ± 5.8 °C). The effect of high temperature on FLP was chiefly observed in the results obtained by the culture method, in which there was a clear reduction in the presence of FLP at temperatures higher than 50 °C, but not in those obtained by PCR. The findings presented here show that the presence of FLP in operational man-made water systems should be taken into account in future regulations.
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Affiliation(s)
- Oriol Canals
- Laboratory of Protistology, Departament de Biologia Animal, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain
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Abstract
Nosocomial waterborne pathogens may reach patients through several modes of transmission. Colonization of healthcare facility waterworks can occur in the proximal infrastructure, in the distal water outlets, or both. Infections with waterborne organisms such as Legionella, mycobacteria, Pseudomonas, and others cause significant morbidity and mortality, particularly in immunocompromised patients. Hospitals should have prospective water safety plans that include preventive measures, as prevention is preferable to remediation of contaminated hospital water distribution systems. Whole-genome sequencing may provide more informative epidemiologic data to link patient infections with hospital water isolates.
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Affiliation(s)
- Brooke K Decker
- National Institutes of Health Clinical Center, 10 Center Drive, 12C103A, Bethesda, MD, 20892, USA
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