Evaluation of the effectiveness of the Pastormaster method for disinfection of legionella in a hospital water distribution system

Callizo, E.F. Peiró; Sierra, Jordi; Pombo, J.M. Santos; Baquedano, Carmen Ezpeleta; Huerta, B. Pérez

doi:10.1016/j.jhin.2004.11.018

Cited by 14 publications

(11 citation statements)

References 30 publications

(35 reference statements)

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“…Before the beginning of the treatments, Legionella concentrations in water and biofilm were around 10 5 CFU l −1 and 10 3 CFU cm −2 respectively. These concentrations were within the range of values previously reported for hot water systems and cooling towers (Peiro Callizo et al. 2005; Saby et al.…”

Section: Discussionsupporting

confidence: 89%

Development of a pilot‐scale 1 for Legionella elimination in biofilm in hot water network: heat shock treatment evaluation

Farhat

Trouilhé

Briand³

et al. 2010

Journal of Applied Microbiology

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Aims: (i) To develop an analytical tool in order to evaluate the effectiveness of anti‐Legionella treatment in biofilm and (ii) study the fate of Legionella populations in water and biofilm after applying a heat shock treatment. Methods and Results: A pilot‐scale unit simulating a hot water system was built and designed by the Scientific and Technical Building Centre (CSTB, France). At the end of the contamination period, a stable cultivable Legionella spp. concentration of 5 × 105 CFU l−1 was obtained. Two heat shock treatments (70°C for 30 min) were applied. The results showed that the first treatment had a transitional effect on the abatement of Legionella concentrations, while the second treatment had no detectable effect on Legionella populations in water and biofilm. The DAPI (4′,6′‐diamidino‐2‐phenylindole), Legionella PCR and GVPC (glycocolle vancomycin pyrophosphate cycloheximide) counts measured in the dead leg water of the Test Loop were 1, 2 and 2 log units higher than results found in the Test Loop water. Moreover, Legionella spp. count in tap water was about 104 GU l−1. These analyses revealed that they are responsible for the rapid recolonization as well as the uncomplete destroyed biofilm. In addition, a resistance test was conducted and showed that Legionella in the second heat shock treatment was not thermo‐resistant but thermo‐acclimated. Conclusion: Thermal disinfection does not seem to be efficient enough to eliminate Legionella when it is used as a curative treatment. Significance and Impact of the Study: This work could help water managers for a better management of water network and for a better control of Legionella.

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Section: Discussionsupporting

confidence: 89%

Development of a pilot‐scale 1 for Legionella elimination in biofilm in hot water network: heat shock treatment evaluation

Farhat

Trouilhé

Briand³

et al. 2010

Journal of Applied Microbiology

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“…Pasteurization of water distribution systems is often preferentially selected as a disinfection process due to the fact that no special equipment is needed and it can be implemented expeditiously (Chen et al, 2005). Previous studies have demonstrated the success of this process in reducing the number of Legionella present (Best et al, 1983; Zacheus and Martikainen, 1996; Darelid et al, 2002; Peiró Callizo et al, 2005). However, despite the successful decrease in Legionella , either complete elimination was not achieved (Darelid et al, 2002) or the system was quickly recolonized after thermal disinfection (Zacheus and Martikainen, 1996).…”

Section: Thermal Disinfection Of Manufactured Water Systemsmentioning

confidence: 99%

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

2017

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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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“…have been done using culture methods (9,37,38,44). However, it is well known that only a small portion of bacteria can be cultivated in all environments (4,41).…”

mentioning

confidence: 99%

Effects of Disinfection on Legionella spp., Eukarya, and Biofilms in a Hot Water System

Farhat

Moletta-Denat

Frère

et al. 2012

Appl Environ Microbiol

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ABSTRACTLegionellaspecies are frequently detected in hot water systems, attached to the surface as a biofilm. In this work, the dynamics ofLegionellaspp. and diverse bacteria and eukarya associated together in the biofilm, coming from a pilot scale 1 system simulating a real hot water system, were investigated throughout 6 months after two successive heat shock treatments followed by three successive chemical treatments. Community structure was assessed by a fingerprint technique, single-strand conformation polymorphism (SSCP). In addition, the diversity and dynamics ofLegionellaand eukarya were investigated by small-subunit (SSU) ribosomal cloning and sequencing. Our results showed that pathogenicLegionellaspecies remained after the heat shock and chemical treatments (Legionella pneumophilaandLegionella anisa, respectively). The biofilm was not removed, and the bacterial community structure was transitorily affected by the treatments. Moreover, several amoebae had been detected in the biofilm before treatments (Thecamoebaesp.,Vannellasp., andHartmanella vermiformis) and after the first heat shock treatment, but onlyH. vermiformisremained. However, another protozoan affiliated with Alveolata, which is known as a host cell forLegionella, dominated the eukaryal species after the second heat shock and chemical treatment tests. Therefore, effectiveLegionelladisinfection may be dependent on the elimination of these important microbial components. We suggest that eradicatingLegionellain hot water networks requires better study of bacterial and eukaryal species associated withLegionellain biofilms.

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Evaluation of the effectiveness of the Pastormaster method for disinfection of legionella in a hospital water distribution system

Cited by 14 publications

References 30 publications

Development of a pilot‐scale 1 for Legionella elimination in biofilm in hot water network: heat shock treatment evaluation

Development of a pilot‐scale 1 for Legionella elimination in biofilm in hot water network: heat shock treatment evaluation

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

Effects of Disinfection on Legionella spp., Eukarya, and Biofilms in a Hot Water System

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