Legionella Persistence in Manufactured Water Systems: Pasteurization Potentially Selecting for Thermal Tolerance

Whiley, Harriet; Bentham, Richard; Brown, Melissa H.

doi:10.3389/fmicb.2017.01330

Cited by 35 publications

(36 citation statements)

References 60 publications

(78 reference statements)

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“…counts and the decrease and increase of temperature in hot and cold water samples, respectively. A strong correlation between Legionella pneumophila strains and high temperature values have also been observed in further studies [ 22 ], which highlights how pasteurization methods may disinfect the waters, but it may influence the persistence of thermo-tolerant Legionella pneumophila bacteria in viable, but non cultivable (VBNC) forms.…”

Section: Discussionmentioning

confidence: 57%

Evaluation of Legionella spp. Colonization in Residential Buildings Having Solar Thermal System for Hot Water Production

Totaro

Costa

Frendo

et al. 2020

IJERPH

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Despite an increase of literature data on Legionella spp. presence in private water systems, epidemiological reports assert a continuing high incidence of Legionnaires’ disease infection in Italy. In this study, we report a survey on Legionella spp. colonization in 58 buildings with solar thermal systems for hot water production (TB). In all buildings, Legionella spp. presence was enumerated in hot and cold water samples. Microbiological potability standards of cold water were also evaluated. Legionella spp. was detected in 40% of the buildings. Moreover, we detected correlations between the count of Legionella spp. and the presence of the optimal temperature for the microorganism growth (less than 40 °C). Our results showed that cold water was free from microbiological hazards, but Legionella spp., was detected when the mean cold water temperature was 19.1 ± 2.2 °C. This may considered close to the suboptimal value for the Legionella growth (more then 20 °C). In conclusion, we observed the presence of a Legionnaires’ disease risk and the need of some strategies aimed to reduce it, such as the application of training programs for all the workers involved in water systems maintenance.

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Section: Discussionmentioning

confidence: 57%

Evaluation of Legionella spp. Colonization in Residential Buildings Having Solar Thermal System for Hot Water Production

Totaro

Costa

Frendo

et al. 2020

IJERPH

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“…For such conditions to take place, a series of variables must co-occur, such as the increased temperature of cold water or decreased temperature of hot water (optimally 35–46 °C), absence of water disinfectants or under-treated water, out of range pH values (5.5–9.2), presence of substances like iron salts and l -cysteine, as well as, co-existing and supporting microbial flora. Furthermore, other factors such as the complexity of the architecture of the pipe system (high surface to volume ratio), presence of blunt-end pipes, infrequently used pipe terminals, pipelines exposed to the sun heat, close proximity of hot and cold-water pipelines, insufficient maintenance and end-points creating aerosols, have all been evaluated to significantly affect the rate and extent of Legionella colonization in water systems [ 27 ]. All these factors may well be associated with the formation of biofilms, which can provide a means for the survival and dissemination of the pathogen and undermine the efforts to eradicate bacteria from water systems [ 28 ].…”

Section: Discussionmentioning

confidence: 99%

Legionella spp. Risk Assessment in Recreational and Garden Areas of Hotels

Papadakis

Chochlakis

Sandalakis

et al. 2018

IJERPH

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Several Travel-associated Legionnaires’ disease (TALD) cases occur annually in Europe. Except from the most obvious sites (cooling towers and hot water systems), infections can also be associated with recreational, water feature, and garden areas of hotels. This argument is of great interest to better comprehend the colonization and to calculate the risk to human health of these sites. From July 2000–November 2017, the public health authorities of the Island of Crete (Greece) inspected 119 hotels associated with TALD, as reported through the European Legionnaires’ Disease Surveillance Network. Five hundred and eighteen samples were collected from decorative fountain ponds, showers near pools and spas, swimming pools, spa pools, garden sprinklers, drip irrigation systems (reclaimed water) and soil. Of those, 67 (12.93%), originating from 43 (35.83%) hotels, tested positive for Legionella (Legionella pneumophila serogroups 1, 2, 3, 6, 7, 8, 13, 14, 15 and non-pneumophila species (L. anisa, L. erythra, L. taurinensis, L. birminghamensis, L. rubrilucens). A Relative Risk (R.R.) > 1 (p < 0.0001) was calculated for chlorine concentrations of less than 0.2 mg/L (R.R.: 54.78), star classification (<4) (R.R.: 4.75) and absence of Water Safety Plan implementation (R.R.: 3.96). High risk (≥104 CFU/L) was estimated for pool showers (16.42%), garden sprinklers (7.46%) and pool water (5.97%).

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“…Numerous studies have demonstrated the presence of L. pneumophila in disinfected water supplies [60,61]. An important factor enabling L. pneumophila survival in the built environment is its interaction with a protozoan host [62][63][64] (as mentioned in Table 3).…”

Section: Implications For the Control Of L Pneumophilamentioning

confidence: 99%

Legionella pneumophila and Protozoan Hosts: Implications for the Control of Hospital and Potable Water Systems

et al. 2020

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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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Legionella Persistence in Manufactured Water Systems: Pasteurization Potentially Selecting for Thermal Tolerance

Cited by 35 publications

References 60 publications

Evaluation of Legionella spp. Colonization in Residential Buildings Having Solar Thermal System for Hot Water Production

Evaluation of Legionella spp. Colonization in Residential Buildings Having Solar Thermal System for Hot Water Production

Legionella spp. Risk Assessment in Recreational and Garden Areas of Hotels

Legionella pneumophila and Protozoan Hosts: Implications for the Control of Hospital and Potable Water Systems

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