scholarly journals Health risk assessment resulting from the presence of Legionella bacteria in domestic hot water in public buildings – the results of a pilot study

2021 ◽  
Vol 47 (1) ◽  
pp. 41-52
Author(s):  
Ewa Kmiecik ◽  
Katarzyna Wątor ◽  
Aneta Chochorek ◽  
Mateusz Kołodziej ◽  
Anna Mika ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Legionella Pneumophila ◽  
Inhalation Exposure ◽  
Cumulative Risk ◽  
Water System ◽  
Hot Water ◽  
Public Utility ◽  
Quantitative Microbial Risk Assessment ◽  
Matrix Approach ◽  
Risk Matrix

The aim of the study was to assess the risk posed by Legionella bacteria in a public building in Krakow. An old building with internal installation risers of different ages, as well as draw-off points of different types, was selected for testing. Samples were collected during two campaigns. In one sample of the first series of tests, no bacteria were found. During the second series of tests, no Legionella bacilli were found in just one sample and in one sample only 4 colony-forming units were detected. At the remaining draw-off points (water taps), the bacteria count detected were greater than the maximum threshold allowed by legal regulations (admissible threshold for public utility buildings – 100 cfu/100 mL). No morphological differences were observed with respect to the occurrence of specific serogroups. In 14 samples, Legionella pneumophila serogroups 2–14 were found, while the Legionella pneumophila serogroup 1 was only found in one sample. The risk assessment was also carried out based on a semi-quantitative risk matrix approach and as a quantitative microbial risk assessment. The risk matrix approach was successfully implemented for the recognition of the potential risk associated with the Legionella occurrence in a water system. The calculated annual cumulative risk is high. The research shows that even if the weekly inhalation exposure dose (and therefore the calculated risk) is high, the number of Legionella pneumophila illness cases found can be equal to zero. This is probably due to the large uncertainty associated with QMRA determination. The size of the room in which the contaminated water is used also affects the possibility of infection.

Effect of heat flushing on the concentrations of Legionella pneumophila and other heterotrophic microbes in hot water systems of apartment buildings

1996 ◽  
Vol 42 (8) ◽  
pp. 811-818 ◽  
Author(s):  
Outi M. Zacheus ◽  
Pertti J. Martikainen
Keyword(s):  
Water Temperature ◽  
Legionella Pneumophila ◽  
Heterotrophic Bacteria ◽  
Water System ◽  
Water Systems ◽  
Hot Water ◽  
Circulating Water ◽  
Heterotrophic Microbes ◽  
Before And After ◽  
Circulating Water System

The decontamination of Legionella pneumophila and other heterotrophic microbes by heat flushing in four legionellae-positive hot water systems was studied. Before the decontamination procedure, the concentration of legionellae varied from 3.0 × 10−3 to 3.5 × 10−5 cfu/L and the hot water temperature from 43.6 to 51.5 °C. During the contamination the temperature was raised to 60–70 °C. All taps and showers were cleaned from sediments and flushed with hot water twice a day for several minutes. The decontamination lasted for 2–4 weeks. In a few weeks the heat-flushing method reduced the concentration of legionellae below the detection limit (50 cfu/L) in the hot circulating water system just before and after the heat exchanger. The high hot water temperature also decreased the viable counts of heterotrophic bacteria, fungi, and total microbial cells determined by the epifluorescent microscopy. However, the eradication of legionellae failed in a water system where the water temperature remained below 60 °C in some parts of the system. After the decontamination, the temperature of hot water was lowered to 55 °C. Thereafter, all the studied hot water systems were recolonized by legionellae within a few months, showing that the decontamination by heat flushing was temporary. Also, the contamination of other bacteria increased in a few months to the level before decontamination.Key words: legionellae, hot water system, decontamination, water temperature, heterotrophic bacteria.

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

2012 ◽  
Vol 78 (19) ◽  
pp. 6850-6858 ◽  
Author(s):  
Maha Farhat ◽  
Marina Moletta-Denat ◽  
Jacques Frère ◽  
Séverine Onillon ◽  
Marie-Cécile Trouilhé ◽  
...  
Keyword(s):  
Community Structure ◽  
Heat Shock ◽  
Legionella Pneumophila ◽  
Water System ◽  
Single Strand Conformation Polymorphism ◽  
Pilot Scale ◽  
Small Subunit ◽  
Hot Water ◽  
Content Type ◽  
Chemical Treatments

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.

scholarly journals Integrated Real-Time PCR for Detection and Monitoring of Legionella pneumophila in Water Systems

2006 ◽  
Vol 73 (5) ◽  
pp. 1452-1456 ◽  
Author(s):  
Diaraf Farba Yaradou ◽  
Sylvie Hallier-Soulier ◽  
Sophie Moreau ◽  
Florence Poty ◽  
Yves Hillion ◽  
...  
Keyword(s):  
Real Time ◽  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Water System ◽  
Culture Method ◽  
Hot Water ◽  
Pcr Assay ◽  
Standard Culture ◽  
Serial Samples ◽  
Over Time

ABSTRACT We evaluated a ready-to-use real-time quantitative Legionella pneumophila PCR assay system by testing 136 hot-water-system samples collected from 55 sites as well as 49 cooling tower samples collected from 20 different sites, in parallel with the standard culture method. The PCR assay was reproducible and suitable for routine quantification of L. pneumophila. An acceptable correlation between PCR and culture results was obtained for sanitary hot-water samples but not for cooling tower samples. We also monitored the same L. pneumophila-contaminated cooling tower for 13 months by analyzing 104 serial samples. The culture and PCR results were extremely variable over time, but the curves were similar. The differences between the PCR and culture results did not change over time and were not affected by regular biocide treatment. This ready-to-use PCR assay for L. pneumophila quantification could permit more timely disinfection of cooling towers.

Disconnecting central hot water and using electric showers to avoid colonization of the water system by Legionella pneumophila: an 11-year study

2007 ◽  
Vol 66 (4) ◽  
pp. 327-331 ◽  
Author(s):  
M.S. Oliveira ◽  
F.R. Maximino ◽  
R.D. Lobo ◽  
S. Gobara ◽  
S.I. Sinto ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Water System ◽  
Hot Water

scholarly journals Quantitative Real-Time Legionella PCR for Environmental Water Samples: Data Interpretation

2006 ◽  
Vol 72 (4) ◽  
pp. 2801-2808 ◽  
Author(s):  
Philippe Joly ◽  
Pierre-Alain Falconnet ◽  
Janine André ◽  
Nicole Weill ◽  
Monique Reyrolle ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Water System ◽  
Data Interpretation ◽  
Environmental Water ◽  
Hot Water ◽  
Rrna Gene ◽  
Conventional Culture

ABSTRACT Quantitative Legionella PCRs targeting the 16S rRNA gene (specific for the genus Legionella) and the mip gene (specific for the species Legionella pneumophila) were applied to a total of 223 hot water system samples (131 in one laboratory and 92 in another laboratory) and 37 cooling tower samples (all in the same laboratory). The PCR results were compared with those of conventional culture. 16S rRNA gene PCR results were nonquantifiable for 2.8% of cooling tower samples and up to 39.1% of hot water system samples, and this was highly predictive of Legionella CFU counts below 250/liter. PCR cutoff values for identifying hot water system samples containing >103 CFU/liter legionellae were determined separately in each laboratory. The cutoffs differed widely between the laboratories and had sensitivities from 87.7 to 92.9% and specificities from 77.3 to 96.5%. The best specificity was obtained with mip PCR. PCR cutoffs could not be determined for cooling tower samples, as the results were highly variable and often high for culture-negative samples. Thus, quantitative Legionella PCR appears to be applicable to samples from hot water systems, but the positivity cutoff has to be determined in each laboratory.

scholarly journals Multiple Types of Legionella pneumophilaSerogroup 6 in a Hospital Heated-Water System Associated with Sporadic Infections

1999 ◽  
Vol 37 (7) ◽  
pp. 2189-2196 ◽  
Author(s):  
Paolo Visca ◽  
Paola Goldoni ◽  
P. Christian Lück ◽  
Jürgen H. Helbig ◽  
Lorena Cattani ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Water Samples ◽  
Water System ◽  
Hot Water ◽  
Control Measures ◽  
Hospital Environment ◽  
Modes Of Transmission ◽  
Sequence Of Events ◽  
Single Clone ◽  
Arbitrarily Primed Pcr

Five sporadic cases of nosocomial Legionnaires’ disease were documented from 1989 to 1997 in a hospital in northern Italy. Two of them, which occurred in a 75-year-old man suffering from ischemic cardiopathy and in an 8-year-old girl suffering from acute leukemia, had fatal outcomes. Legionella pneumophila serogroup 6 was isolated from both patients and from hot-water samples taken at different sites in the hospital. These facts led us to consider the possibility that a single clone of L. pneumophila serogroup 6 had persisted in the hospital environment for 8 years and had caused sporadic infections. Comparison of clinical and environmental strains by monoclonal subtyping, macrorestriction analysis (MRA), and arbitrarily primed PCR (AP-PCR) showed that the strains were clustered into three different epidemiological types, of which only two types caused infection. An excellent correspondence between the MRA and AP-PCR results was observed, with both techniques having high discriminatory powers. However, it was not possible to differentiate the isolates by means of ribotyping and analysis of rrnoperon polymorphism. Environmental strains that antigenically and chromosomally matched the infecting organism were present at the time of infection in hot-water samples taken from the ward where the patients had stayed. Interpretation of the temporal sequence of events on the basis of the typing results for clinical and environmental isolates enabled the identification of the ward where the patients became infected and the modes of transmission of Legionellainfection. The long-term persistence in the hot-water system of different clones of L. pneumophila serogroup 6 indicates that repeated heat-based control measures were ineffective in eradicating the organism.

scholarly journals Draft Genome Sequences of Seven Legionella pneumophila Isolates from a Hot Water System of a Large Building

2019 ◽  
Vol 8 (18) ◽  
Author(s):  
Vicente Gomez-Alvarez ◽  
Laura Boczek ◽  
Dawn King ◽  
Adin Pemberton ◽  
Stacy Pfaller ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Draft Genome ◽  
Water System ◽  
Disease Outbreaks ◽  
Hot Water ◽  
Genome Sequences ◽  
Content Type ◽  
Public Health Data ◽  
Premise Plumbing ◽  
Large Building

Public health data show that a significant fraction of the nation’s waterborne disease outbreaks are attributable to premise plumbing. We report the draft genome sequences of seven Legionella pneumophila serogroup 1 isolates from hot water lines of a large building.

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