LEGIONELLA PNEUMOPHILA IN HOSPITAL HOT WATER CYLINDERS

Legionella pneumophila are bacteria that when inhaled cause Legionnaires’ Disease (LD) and febrile illness Pontiac Fever. As of 2014, LD is the most frequent cause of waterborne disease outbreaks due...

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Determinants of Legionella pneumophila Contamination of Water Distribution Systems: 15-Hospital Prospective Study

Infection Control ◽

10.1017/s0195941700067412 ◽

1987 ◽

Vol 8 (9) ◽

pp. 357-363 ◽

Cited By ~ 66

Author(s):

Richard M. Vickers ◽

Victor L. Yu ◽

S. Sue Hanna ◽

Paul Muraca ◽

Warren Diven ◽

...

Keyword(s):

Legionella Pneumophila ◽

Distribution System ◽

Distribution Systems ◽

Water Distribution ◽

Cold Water ◽

Physicochemical Characteristics ◽

Hot Water ◽

Environmental Study ◽

Water Tank ◽

One Year

AbstractWe conducted a prospective environmental study for Legionella pneumophila in 15 hospitals in Pennsylvania. Hot water tanks, cold water sites, faucets, and show-erheads were surveyed four times over a one-year period. Sixty percent (9/15) of hospitals surveyed were contaminated with L pneumophila. Although contamination could not be linked to a specific municipal water supplier, most of the contaminated supplies came from rivers. Parameters found to be significantly associated with contamination included elevated hot water temperature, vertical configuration of the hot water tank, older tanks, and elevated calcium and magnesium concentrations of the water (P < 0.05). This study suggests that L pneumophila contamination could be predicted based on design of the distribution system, as well as physicochemical characteristics of the water.

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Molecular typing of the Legionella pneumophila population isolated from several locations in a contaminated water network

Water Science & Technology ◽

10.2166/wst.2004.0068 ◽

2004 ◽

Vol 50 (1) ◽

pp. 281-285 ◽

Cited By ~ 2

Author(s):

A.-S. Lepeuple ◽

M. Jovic ◽

M.-R. de Roubin

Keyword(s):

Legionella Pneumophila ◽

Molecular Typing ◽

Random Amplified Polymorphic Dna ◽

Hot Water ◽

Water Network ◽

Rapd Pattern ◽

Different Populations ◽

Definition Of ◽

Different Strains ◽

Key Steps

The RAPD (random amplified polymorphic DNA) technique has been developed for the molecular typing of Legionella in order to characterise the populations of hot water systems. During this study, 22 primers were tested and the four most informative ones were selected. The optimisation of the PCR conditions allowed the setting up of a powerful discriminative genotyping method. Moreover, the definition of a quality management method allowed definition of the key steps and the number of replicates to ensure reproducibility of the RAPD pattern. The RAPD was used to study the hot water network of a building. Legionella colonies (91) were isolated from seven locations and genotyped. The diversity of the population in one sample could vary from one to seven different strains. The study of the traceability showed that, in most of the cases, different populations could be present at different locations of the same network.

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How Molecular Typing Can Support Legionella Environmental Surveillance in Hot Water Distribution Systems: A Hospital Experience

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17228662 ◽

2020 ◽

Vol 17 (22) ◽

pp. 8662

Author(s):

Luna Girolamini ◽

Silvano Salaris ◽

Jessica Lizzadro ◽

Marta Mazzotta ◽

Maria Rosaria Pascale ◽

...

Keyword(s):

Legionella Pneumophila ◽

Molecular Typing ◽

Distribution Systems ◽

Water Distribution ◽

Water Distribution Systems ◽

Gene Sequencing ◽

Culture Technique ◽

Hot Water ◽

Environmental Surveillance ◽

Risk Map

In this study, we aimed to associate the molecular typing of Legionella isolates with a culture technique during routine Legionella hospital environmental surveillance in hot water distribution systems (HWDSs) to develop a risk map able to be used to prevent nosocomial infections and formulate appropriate preventive measures. Hot water samples were cultured according to ISO 11731:2017. The isolates were serotyped using an agglutination test and genotyped by sequence-based typing (SBT) for Legionella pneumophila or macrophage infectivity potentiator (mip) gene sequencing for non-pneumophila Legionella species. The isolates’ relationship was phylogenetically analyzed. The Legionella distribution and level of contamination were studied in relation to temperature and disinfectant residues. The culture technique detected 62.21% of Legionella positive samples, characterized by L. pneumophila serogroup 1, Legionella non-pneumophila, or both simultaneously. The SBT assigned two sequence types (STs): ST1, the most prevalent in Italy, and ST104, which had never been isolated before. The mip gene sequencing detected L. anisa and L. rubrilucens. The phylogenetic analysis showed distinct clusters for each species. The distribution of Legionella isolates showed significant differences between buildings, with a negative correlation between the measured level of contamination, disinfectant, and temperature. The Legionella molecular approach introduced in HWDSs environmental surveillance permits (i) a risk map to be outlined that can help formulate appropriate disinfection strategies and (ii) rapid epidemiological investigations to quickly identify the source of Legionella infections.

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

Canadian Journal of Microbiology ◽

10.1139/m96-102 ◽

1996 ◽

Vol 42 (8) ◽

pp. 811-818 ◽

Cited By ~ 19

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.

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

Applied and Environmental Microbiology ◽

10.1128/aem.00831-12 ◽

2012 ◽

Vol 78 (19) ◽

pp. 6850-6858 ◽

Cited By ~ 31

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.

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