Abstract
Nosocomial structures pose a high risk of Legionella spp. contamination due to complex water systems with challenging disinfection; moreover, the risk of severe legionellosis as a consequence of nosocomial exposition is very high in settings characterized by vulnerable patient conditions.
In the present work we described the results of 7 years of environmental surveillance in a reference hospital in Liguria, in which a specific water safety plan (WSP) has been implemented in 2017, including data collected during the Covid-19 pandemic.
During the study period, 1190 water samples were collected, of which 277 (23.3%) tested positive for Legionella spp. Positive samples with concentration values above 1,000 CFU/l were 184 (66.4%).
Based on the new structure categorization contained in the new WSP, hospital buildings classified as “at very high risk” resulted the most affected structures over the entire study period; however, the absolute number of positive samples greatly decreased over time, from 61 contaminated water samples in 2017 to only 6 in 2023.
Our findings prompted the reinforcement of control and prevention measures, affirming the appropriateness of risk-category classification. Indeed, the majority of contamination cases were associated with the water networks of buildings classified as "very high" risk.
References
Barbuti S, Fara GM, Giammanco G. Hygiene- Preventive Medicine- Public Health. EdiSES; 2022
Fraser DW. The challenges were legion. The Lancet infectious diseases 2005 Apr 1;5(4):237-41. doi 10.1016/S1473-3099(05)70054-2
Ministry of Health. Line and guide for the prevention and control of legionellosis (2015). Available from: https://www.salute.gov.it/imgs/C_17_pubblicazioni_2362_allegato.pdf. Accessed on 09/09/2023
Diederen BM. Legionella spp. and Legionnaires' disease. Journal of infection 2008 Jan 1;56(1):1-2. doi 10.1016/j.jinf.2007.09.010
Cunha BA, Burillo A, Bouza E. Legionnaires' disease. The Lancet 2016 Jan 23;387(10016):376-85. doi: 10.1016/S0140-6736(15)60078-2
Phin N, Parry-Ford F, Harrison T, Stagg HR, Zhang N, Kumar K, Lortholary O, Zumla A, Abubakar I. Epidemiology and clinical management of Legionnaires' disease. The Lancet infectious diseases 2014 Oct 1;14(10):1011-21. doi: 10.1016/S1473-3099(14)70713-3
Signorelli. Hygiene and Public Health. 3a ed. Universo Publishing Company; 2021
Girolamini L, Brattich E, Marino F, Pascale MR, Mazzotta M, Spiteri S, Derelitto C, Tositti L, Cristino S. Cooling towers influence in an urban environment: A predictive model to control and prevent Legionella risk and Legionellosis events. Building and Environment. 2023 Jan 15;228:109891. doi: 10.1016/j.buildenv.2022.109891
European Society of Clinical Microbiology and Infectious Diseases Study Group for Legionella Infections. European Technical Guidelines for the Prevention, Control and Investigation of Infections Caused by Legionella Species. Basel: ESCMID; 2017. Available from: https://www.escmid.org/fileadmin/src/media/PDFs/3Research_Projects/ESGLI/ESGLI_European_Technical_Guidelines_for_the_Prevention_Control_and_Investigation_of_Infections_Caused_by_Legionella_species_Ju ne_2017.pdf. Accessed on 09/09/2023
Coniglio MA, Ferrante M, Yassin MH. Preventing healthcare-associated legionellosis: Results after 3 years of continuous disinfection of hot water with monochloramine and an effective water safety plan. International Journal of Environmental Research and Public Health. 2018 Aug;15(8):1594. doi: 10.3390/ijerph15081594
Orsi GB, Vitali M, Marinelli L, Ciorba V, Tufi D, Del Cimmuto A, Ursillo P, Fabiani M, De Santis S, Protano C, Marzuillo C. Legionella control in the water system of antiquated hospital buildings by shock and continuous hyperchlorination: 5 years experience. BMC infectious diseases. 2014 Dec;14(1):1-0. doi: 10.1186/1471-2334-14-394
Vincenti S, De Waure C, Raponi M, Teleman AA, Boninti F, Bruno S, Boccia S, Damiani G, Laurenti P. Environmental surveillance of Legionella spp. colonization in the water system of a large academic hospital: Analysis of the four–year results on the effectiveness of the chlorine dioxide disinfection method. Science of The Total Environment. 2019 Mar 20;657:248-53. doi: 10.1016/j.scitotenv.2018.12.036
Gavaldà L, Garcia-Nuñez M, Quero S, Gutierrez-Milla C, Sabrià M. Role of hot water temperature and water system use on Legionella control in a tertiary hospital: An 8-year longitudinal study. Water research. 2019 Feb 1;149:460-6. doi: 10.1016/j.watres.2018.11.032
Wenzel RP. Health care–associated infections: major issues in the early years of the 21st century. Clinical infectious diseases. 2007 Jul 15;45(Supplement_1):S85-8. doi: 10.1086/518136
Lucentini L, Marchiafava C, Mattei D, Nigro Di Gregorio F, De Giglio O, Montagna MT (Ed.). Water and health: elements of risk analysis in new environmental and climate scenarios. Rome: Istituto Superiore di Sanità; 2020. (ISTISAN Reports 20/19). Available from: https://www.iss.it/documents/20126/0/20-19+web.pdf/5b18b48c-a6f4-4bdf-cba4-e1a22877e0bd?t=1602579117495, Accessed on 09/09/2023
Arrigo I, Galia E, Fasciana T, Diquattro O, Tricoli MR, Serra N, Palermo M, Giammanco A. Four-year environmental surveillance program of legionella spp. in one of Palermo’s largest hospitals. Microorganisms. 2022 Apr 1;10(4):764. doi: 10.3390/microorganisms10040764
Felice A, Franchi M, De Martin S, Vitacolonna N, Iacumin L, Civilini M. Environmental surveillance and spatio-temporal analysis of Legionella spp. in a region of northeastern Italy (2002–2017). Plos one. 2019 Jul 9;14(7):e0218687. doi: 10.1371/journal.pone.0218687
Triassi M, Di Popolo A, D'Alcalà GR, Albanese Z, Cuccurullo S, Montegrosso S, Crispino M, Borella P, Zarrilli R. Clinical and environmental distribution of Legionella pneumophila in a university hospital in Italy: efficacy of ultraviolet disinfection. Journal of Hospital Infection. 2006 Apr 1;62(4):494-501. doi: 10.1016/j.jhin.2005.09.029
Borella P, Montagna MT, Stampi S, Stancanelli G, Romano-Spica V, Triassi M, Marchesi I, Bargellini A, Tato D, Napoli C, Zanetti F. Legionella contamination in hot water of Italian hotels. Applied and Environmental Microbiology. 2005 Oct;71(10):5805-13. doi: 10.1128/AEM.71.10.5805-5813.200