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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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Oder M, Piletić K, Fink R, Marijanović Z, Krištof R, Bićanić L, Tomić Linšak D, Gobin I. A synergistic anti-bacterial and anti-adhesion activity of tea tree ( Melaleuca alternifolia) and lemon eucalyptus tree ( Eucalyptus citriodora Hook) essential oils on Legionella pneumophila. BIOFOULING 2024; 40:54-63. [PMID: 38353250 DOI: 10.1080/08927014.2024.2310482] [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: 07/11/2023] [Accepted: 01/22/2024] [Indexed: 03/09/2024]
Abstract
Legionella pneumophila is a Gram-negative bacterial pathogen that colonizes natural and artificial water systems and has the ability to form a biofilm. The biofilm protects L. pneumophila from various environmental factors and makes it more resistant to chlorine-based disinfectants. This study investigated the anti-bacterial properties of tea tree (Melaleuca alternifolia (Maiden and Betche) Cheel) oil and lemon eucalyptus tree (Eucalyptus citriodora Hook) essential oils (EOs) and their synergistic, additive inhibitory and anti-adhesive effects against L. pneumophila biofilm formation on polystyrene. The minimum effective concentration (MEC) for tea tree is 12.8 mg ml-1 and for lemon eucalyptus tree EO 6.4 mg ml-1. In the checkerboard assay, different combinations of these two EO show synergistic and additive anti-microbial activity. The minimum anti-adhesive concentration (MAC) for tea tree is 12.8 mg ml-1 and for lemon eucalyptus tree EO 6.4 mg ml-1. A combination of 3.2 mg ml-1 tea tree EO and 0.8 mg ml-1 lemon eucalyptus tree EO showed the strongest anti-adhesive effect against L. pneumophila on polystyrene. The tested oils and their combination showed intriguing potential to inhibit L. pneumophila biofilm formation.
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Affiliation(s)
- Martina Oder
- Department of Sanitary Engineering, Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - Kaća Piletić
- Department of Microbiology and Parasitology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Rok Fink
- Department of Sanitary Engineering, Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - Zvonimir Marijanović
- Department of Food Technology and Biotechnology, Faculty of Chemistry and Technology, University of Split, Split, Croatia
| | - Romana Krištof
- Department of Sanitary Engineering, Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - Lucija Bićanić
- Department of Microbiology and Parasitology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Dijana Tomić Linšak
- Department for Health Ecology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Ivana Gobin
- Department of Microbiology and Parasitology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
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Chochlakis D, Sandalakis V, Ntoukakis A, Daskalaki MO, Loppinet T, Thalassinaki N, Makridaki R, Panoulis C, Psaroulaki A. Multi-criterion analysis of the effect of physico-chemical microbiological agents on Legionella detection in hotel water distribution systems in Crete. Front Cell Infect Microbiol 2023; 13:1214717. [PMID: 38188625 PMCID: PMC10770838 DOI: 10.3389/fcimb.2023.1214717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 10/17/2023] [Indexed: 01/09/2024] Open
Abstract
Introduction Water distribution systems in hotels have been related to outbreaks caused by Legionella spp. Certain measures, including disinfection by chlorination, maintaining increased temperatures are usually undertaken to prevent Legionella outbreaks. However, these preventive strategies are not always effective, since there are several factors (e.g., synergistic interactions with other microbes, physico-chemical factors, biofilm formation, availability of nutrients) that promote survival and proliferation of the pathogen in water pipes., Accordingly, there is a need of a holistic approach in development of preventive models for Legionella outbreaks associated with water distribution systems. Methods Water samples were collected from hotel water systems and were tested for the presence of Legionella, E. coli, total coliforms, total mesophilic count and Pseudomonas. In each sample, temperature and chlorine were also tested. Other epidemiological factors were additionally recorded including number of rooms, stars, proximity of sampling point to the boiler, etc. Data were processed by generalized linear analysis, and modeling based on logistic regression analysis to identify independent predictive factors associated with the presence of Legionella in hotel water systems. Results According to the generalized linear model, temperature affected (p<0.05) the presence of Legionella regardless of the species or the water supply (hot or cold). Additionally, opportunistic (P. aeruginosa) or non-opportunistic (E. coli, coliforms) pathogens were significantly associated (p<0.05) with the presence of all Legionella species. Temperature also exhibited a positive effect to all pathogens tested except for Pseudomonas according to the linear model. Multivariate analysis showed that Pseudomonas, total coliforms, HPC and temperature had a statistically significant effect on the presence of Legionella. Based on a binomial model, cold water had a positive effect on Legionella. Type of sampling and proximity of the sample to the boiler seemed to pose different effect on Legionella depending on the cfu/L. The number of hotel stars and rooms did not appear to have any effect in all tested models. Discussion Collectively, these results indicate the need for development of individualized water safety plans tailored by the presence of other microbiological agents, and unique physico-chemical factors, which could facilitate the survival of Legionella.in hotel water systems.
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Affiliation(s)
- Dimosthenis Chochlakis
- Regional Laboratory of Public Health of Crete, School of Medicine, University of Crete, Heraklion, Greece
- Laboratory of Clinical Microbiology and Microbial Pathogenesis, School of Medicine, University of Crete, Heraklion, Greece
| | - Vassilios Sandalakis
- Laboratory of Clinical Microbiology and Microbial Pathogenesis, School of Medicine, University of Crete, Heraklion, Greece
| | - Apostolos Ntoukakis
- Laboratory of Clinical Microbiology and Microbial Pathogenesis, School of Medicine, University of Crete, Heraklion, Greece
| | - Maria-Olga Daskalaki
- Laboratory of Clinical Microbiology and Microbial Pathogenesis, School of Medicine, University of Crete, Heraklion, Greece
| | - Thomas Loppinet
- Laboratory of Clinical Microbiology and Microbial Pathogenesis, School of Medicine, University of Crete, Heraklion, Greece
| | - Niki Thalassinaki
- Laboratory of Clinical Microbiology and Microbial Pathogenesis, School of Medicine, University of Crete, Heraklion, Greece
| | - Rena Makridaki
- Laboratory of Clinical Microbiology and Microbial Pathogenesis, School of Medicine, University of Crete, Heraklion, Greece
| | - Christos Panoulis
- Laboratory of Clinical Microbiology and Microbial Pathogenesis, School of Medicine, University of Crete, Heraklion, Greece
| | - Anna Psaroulaki
- Regional Laboratory of Public Health of Crete, School of Medicine, University of Crete, Heraklion, Greece
- Laboratory of Clinical Microbiology and Microbial Pathogenesis, School of Medicine, University of Crete, Heraklion, Greece
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Lombardi A, Borriello T, De Rosa E, Di Duca F, Sorrentino M, Torre I, Montuori P, Trama U, Pennino F. Environmental Monitoring of Legionella in Hospitals in the Campania Region: A 5-Year Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:ijerph20085526. [PMID: 37107807 PMCID: PMC10138562 DOI: 10.3390/ijerph20085526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/06/2023] [Accepted: 04/13/2023] [Indexed: 05/11/2023]
Abstract
Legionella is a pathogen that colonizes soils, freshwater, and building water systems. People who are most affected are those with immunodeficiencies, so it is necessary to monitor its presence in hospitals. The purpose of this study was to evaluate the presence of Legionella in water samples collected from hospitals in the Campania region, Southern Italy. A total of 3365 water samples were collected from January 2018 to December 2022 twice a year in hospital wards from taps and showers, tank bottoms, and air-treatment units. Microbiological analysis was conducted in accordance with the UNI EN ISO 11731:2017, and the correlations between the presence of Legionella and water temperature and residual chlorine were investigated. In total, 708 samples (21.0%) tested positive. The most represented species was L. pneumophila 2-14 (70.9%). The serogroups isolated were 1 (27.7%), 6 (24.5%), 8 (23.3%), 3 (18.9%), 5 (3.1%), and 10 (1.1%). Non-pneumophila Legionella spp. represented 1.4% of the total. Regarding temperature, the majority of Legionella positive samples were found in the temperature range of 26.0-40.9 °C. An influence of residual chlorine on the presence of the bacterium was observed, confirming that chlorine disinfection is effective for controlling contamination. The positivity for serogroups other than serogroup 1 suggested the need to continue environmental monitoring of Legionella and to focus on the clinical diagnosis of other serogroups.
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Affiliation(s)
- Annalisa Lombardi
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Tonia Borriello
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Elvira De Rosa
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Fabiana Di Duca
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Michele Sorrentino
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Ida Torre
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Paolo Montuori
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
| | - Ugo Trama
- General Directorate of Health, Campania Region, Centro Direzionale C3, 80143 Naples, Italy
| | - Francesca Pennino
- Department of Public Health, University “Federico II”, Via Sergio Pansini N° 5, 80131 Naples, Italy
- Correspondence:
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