Category Archives: Cooling Towers

Research – Heterotrophic Plate Count Can Predict the Presence of Legionella spp. in Cooling Towers

Posted on March 18, 2023 | Leave a comment

MDPI

Abstract

Legionella pneumophila (Lp) colonizes aquatic environments and is a potential pathogen to humans, causing outbreaks of Legionnaire’s disease. It is mainly associated with contaminated cooling towers (CTs). Several regulations, including Spanish legislation (Sl), have introduced the analysis of heterotrophic plate count (HPC) bacteria and Legionella spp. (Lsp) in management plans to prevent and control Legionella outbreaks from CTs. The 2003 Sl for CTs (RD 865/2003) considered that concentrations of HPC bacteria ≤10,000 cfu/mL and of Lsp ≤100 cfu/L are safe; therefore, no action is required, whereas management actions should be implemented above these standards. We have investigated to what extent the proposed standard for HPC bacteria is useful to predict the presence of Lsp in cooling waters. For this, we analyzed Lsp and HPC concentrations, water temperature, and the levels of chlorine in 1376 water samples from 17 CTs. The results showed that in the 1138 water samples negative for Legionella spp. (LN), the HPC geometric mean was significantly lower (83 cfu/mL, p < 0.05) than in the positive Lsp. samples (135 cfu/mL). Of the 238 (17.3%) LP samples, 88.4% (210/238) were associated with values of HPC ≤10,000 cfu/mL and most of them showed HPC concentrations ≤100 (53.7%). In addition, a relatively low percentage of LP (28/238, 11.6%) samples were associated with HPC bacteria concentrations >10,000 cfu/mL, indicating that this standard does not predict the colonization risk for Legionella in the CTs studied. The present study has demonstrated that a threshold concentration ≤100 cfu/mL of HPC bacteria could better predict the higher concentration of Legionella in CTs, which will aid in preventing possible outbreaks.

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Posted in Cooling Towers, Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Legionella, Legionnaires’ disease, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Water, water microbiology, Water Safety

Research – Legionella pneumophila Risk from Air–Water Cooling Units Regarding Pipe Material and Type of Water

Posted on March 2, 2023 | Leave a comment

MDPI

Legionella A

Abstract

Legionellosis is a respiratory disease related to environmental health. There have been manifold studies of pipe materials, risk installations and legionellosis without considering the type of transferred water. The objective of this study was to determine the potential development of the causative agent Legionella pneumophila regarding air–water cooling units, legislative compliance, pipe material and type of water. Forty-four hotel units in Andalusia (Spain) were analysed with respect to compliance with Spanish health legislation for the prevention of legionellosis. The chi-square test was used to explain the relationship between material–water and legislative compliance, and a biplot of the first two factors was generated. Multiple correspondence analysis (MCA) was performed on the type of equipment, legislative compliance, pipe material and type of water, and graphs of cases were constructed by adding confidence ellipses by categories of the variables. Pipe material–type of water (p value = 0.29; p < 0.05) and legislative compliance were not associated (p value = 0.15; p < 0.05). Iron, stainless steel, and recycled and well water contributed the most to the biplot. MCA showed a global pattern in which lead, iron and polyethylene were well represented. Confidence ellipses around categories indicated significant differences among categories. Compliance with Spanish health legislation regarding the prevention and control of legionellosis linked to pipe material and type of water was not observed.

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Posted in Contaminated water, Cooling Towers, Decontamination Microbial, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Legionella, Legionnaires’ disease, microbial contamination, Microbial growth, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Microbiology Risk, Water, water microbiology, Water Safety

ECDC – Legionnaires’ disease – Annual Epidemiological Report for 2020

Posted on May 10, 2022 | Leave a comment

ECDC

ECDC’s annual surveillance reports provide a wealth of epidemiological data to support decision-making at the national level. They are mainly intended for public health professionals and policymakers involved in disease prevention and control programmes.

Executive summary

  • Legionnaires’ disease remains an uncommon and mainly sporadic respiratory infection with an overall notification rate of 1.9 cases per 100 000 population for the EU/EEA in 2020.
  • A small decrease in the annual notification rate was observed, down from the 2.2 cases per 100 000 population reported in 2019.
  • Notification rates remained heterogenous across the EU/EEA, varying from fewer than 0.5 cases per 100 000 population to 5.7 cases per 100 000 population, with the highest rate reported by Slovenia.
  • Four countries (France, Germany, Italy and Spain) accounted for 72% of all notified cases.
  • Males aged 65 years and older were most affected (7.1 cases per 100 000 population).
  • The number of reported cases to the travel-associated surveillance scheme decreased by 67% in 2020 compared with 2019.
  • Only 10% of cases were culture confirmed (10%), likely leading to underestimation of disease caused by Legionella species other than Legionella pneumophila.

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Legionnaires’ disease – Annual Epidemiological Report for 2020 – EN – [PDF-2.45 MB]

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Posted in Contaminated water, Cooling Towers, Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Legionella, Legionnaires’ disease, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Water, water microbiology, Water Safety

Research – Innovative Antibiofilm Smart Surface against Legionella for Water Systems

Posted on April 24, 2022 | Leave a comment

MDPI

Legionella pneumophila contamination of water systems is a crucial issue for public health. The pathogen is able to persist in water as free-living planktonic bacteria or to grow within biofilms that adhere to and clog filters and pipes in a water system, reducing its lifespan and, in the case of hospital buildings, increasing the risk of nosocomial infections. The implementation of water management is considered to be the main prevention measure and can be achieved from the optimization of water system architecture, notably introducing new materials and strategies to contrast Legionella biofilm proliferation and so prolong the water system functionality. In this research, we propose a new smart surface against L. pneumophila biofilm formation. This is based on an innovative type of coating consisting of a sulfonated pentablock copolymer (s-PBC, commercially named Nexar™) deposited on top of a polypropylene (PP) coupon in a sandwich filter model. The covering of PP with s-PBC results in a more hydrophilic, acid, and negatively charged surface that induces microbial physiological inhibition thereby preventing adhesion and/or proliferation attempts of L. pneumophila prior to the biofilm formation. The antibiofilm property has been investigated by a Zone of Inhibition test and an in vitro biofilm formation analysis. Filtration tests have been performed as representative of possible applications for s-PBC coating. Results are reported and discussed.

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Posted in Contaminated water, Cooling Towers, Decontamination Microbial, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Legionella, Legionnaires’ disease, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Water, water microbiology, Water Safety

Research – Rising Incidence of Legionnaires’ Disease and Associated Epidemiologic Patterns, United States, 1992–2018

Posted on March 6, 2022 | Leave a comment

CDC

Abstract

Reported Legionnaires’ disease (LD) cases began increasing in the United States in 2003 after relatively stable numbers for >10 years; reasons for the rise are unclear. We compared epidemiologic patterns associated with cases reported to the Centers for Disease Control and Prevention before and during the rise. The age-standardized average incidence was 0.48 cases/100,000 population during 1992–2002 compared with 2.71 cases/100,000 in 2018. Reported LD incidence increased in nearly every demographic, but increases tended to be larger in demographic groups with higher incidence. During both periods, the largest number of cases occurred among White persons, but the highest incidence was in Black or African American persons. Incidence and increases in incidence were generally largest in the East North Central, Middle Atlantic, and New England divisions. Seasonality was more pronounced during 2003–2018, especially in the Northeast and Midwest. Rising incidence was most notably associated with increasing racial disparities, geographic focus, and seasonality.

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Posted in Contaminated water, Cooling Towers, Food Microbiology Research, Legionella, Legionnaires’ disease, Research, Water, water microbiology, Water Safety

Research – Legionellosis: A novel mechanism by which the bacterium Legionella pneumophila regulates the immune response of its host cells

Posted on February 27, 2022 | Leave a comment

Science Daily

Legionellosis or Legionnaires’ disease affected more than 1 800 people in France in 2019 and caused 160 deaths. This emerging disease is caused by Legionella pneumophila, an environmental bacterium that thrives in hot water systems. Researchers have discovered a mechanism that allows Legionella pneumophila to target the immune response of the cells it infects by secreting a small regulatory RNA. This mechanism, not described before, facilitates the survival and proliferation of Legionella pneumophila during infection. The work provides precious information on the strategies used by bacteria to manipulate their host cells.

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Posted in Contaminated water, Cooling Towers, Decontamination Microbial, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Legionella, Legionnaires’ disease, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Water, water microbiology, Water Safety

Research – Emerging Legionella species data

Posted on February 13, 2022 | Leave a comment

HPS

Legionella_Plate_01

08 February 2022

Article: 56/502

In July 2021, the Legionella Control Association (LCA), in conjunction with the Health and Safety Executive (HSE), Public Health England (PHE) and local authorities, held a webinar aimed at raising awareness of increasing Legionella positivity rates post lockdown.  The data demonstrated that the average positive rate in the UK had increased by around 2% following the lockdowns in response to COVID-19.

To investigate if there were particular species that could have led to this increase, LCA approached the three commercial laboratories in the UK that use MALDI-ToF to confirm down to species level, and asked if they would share their data. This information has now been returned by some laboratories, with findings from over 70,000 positive result samples in a two-year period revealing:

  • over 53% of the results were L.anisa
  • over 32% of the positives were L. pneumophilia, both SeroGroup 1 and SeroGroup 2-15
  • nearly 1% of positives were for L. rubilucens
  • over 6.5% of the results did not confirm a species type
  • there were over a dozen other species identified in results that accounted for less than 1% of the data set

The first line clinical diagnostic tool used to confirm Legionnaire’s disease in the UK is commonly a urinary antigen test (UAT), and this method looks predominantly for L. pneumophilia SeroGroup 1. Given the data LCA has provided so far, this could potentially mean missing over 70% of Legionella infections in patients. It should be highlighted that this data is in its infancy, and LCA state that further research needs to take place before any significant changes are considered or undertaken.

Source: LCA, January 2022

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Posted in Contaminated water, Cooling Towers, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, L. pneumophilia, Legionella, Legionella anisa, Legionella rubilucens, Legionnaires’ disease, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Water, water microbiology, Water Safety

Germany – Legionnaires’ disease sickens five, kills 2 in Heilbronn

Posted on July 19, 2021 | Leave a comment

Outbreak News Today

CDC legionella

In Heilbronn District, in northern Baden-Württemberg, Germany, it is reported that five men and women have contracted Legionnaires’ disease and two have died.

The patients came from Obersulm, Ellhofen, Weinsberg and Löwenstein, health officials announced. Most of them are middle-aged and older men. The two deceased men had a previous illness and were 49 and 81 years old.

Health authorities are feverishly looking for the source of the contamination.

Experts from the Heilbronn health department are not assuming that contaminated drinking water is the cause of the infections. The sick lived in different places, there are several water suppliers. “The surrounding sewage treatment plants were also sampled,” said a spokeswoman for the dpa office. “We assume that the cause can be found in an evaporative cooling system.” The health department fears that there may be more cases.

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Posted in Contaminated water, Cooling Towers, Food Micro Blog, Food Microbiology Blog, Food Microbiology Testing, Legionella, Legionnaires’ disease, microbial contamination, Microbiological Risk Assessment, Microbiology, Water, water microbiology, Water Safety

Research – Legionella and Biofilms—Integrated Surveillance to Bridge Science and Real-Field Demands

Posted on June 5, 2021 | Leave a comment

MDPI

Legionella_Plate_01

Legionella is responsible for the life-threatening pneumonia commonly known as Legionnaires’ disease or legionellosis. Legionellosis is known to be preventable if proper measures are put into practice. Despite the efforts to improve preventive approaches, Legionella control remains one of the most challenging issues in the water treatment industry. Legionellosis incidence is on the rise and is expected to keep increasing as global challenges become a reality. This puts great emphasis on prevention, which must be grounded in strengthened Legionella management practices. Herein, an overview of field-based studies (the system as a test rig) is provided to unravel the common roots of research and the main contributions to Legionella’s understanding. The perpetuation of a water-focused monitoring approach and the importance of protozoa and biofilms will then be discussed as bottom-line questions for reliable Legionella real-field surveillance. Finally, an integrated monitoring model is proposed to study and control Legionella in water systems by combining discrete and continuous information about water and biofilm. Although the successful implementation of such a model requires a broader discussion across the scientific community and practitioners, this might be a starting point to build more consistent Legionella management strategies that can effectively mitigate legionellosis risks by reinforcing a pro-active Legionella prevention philosophy. View Full-Text

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Posted in Contaminated water, Cooling Towers, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Legionella, Legionnaires’ disease, microbial contamination, Microbiological Risk Assessment, Microbiology, Research, Water, water microbiology, Water Safety

EU – Legionnaires’ disease – Annual Epidemiological Report for 2019

Posted on May 25, 2021 | Leave a comment

ECDC

Legionella_Plate_01

ECDC’s annual surveillance reports provide a wealth of epidemiological data to support decision-making at the national level. They are mainly intended for public health professionals and policymakers involved in disease prevention and control programmes.

Executive summary

  • Legionnaires’ disease remains an uncommon and mainly sporadic respiratory infection with an overall notification rate in 2019 for the EU/EEA of 2.2 cases per 100 000 population.
  • There is heterogeneity in notification rates between EU/EEA countries, with the highest rate reported by Slovenia (9.4 cases per 100 000 population).
  • The annual notification rate increased in recent years, from 1.4 in 2015 to 2.2 cases per 100 000 population in 2019.
  • There was a marginal decrease of less than 1% in the number of reported cases in 2019, compared with 2018.
  • Four countries (France, Germany, Italy, and Spain) accounted for 71% of all notified cases in 2019.
  • Males aged 65 years and above were most affected (8.4 cases per 100 000 population).
  • Only 10% of cases were culture-confirmed (10%) probably meaning that disease caused by Legionella species other than Legionella pneumophila is under-estimated.

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Legionnaires’ disease – Annual Epidemiological Report for 2019 – EN – [PDF-2.1 MB]

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Posted in Contaminated water, Cooling Towers, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Legionella, Legionnaires’ disease, microbial contamination, Microbiological Risk Assessment, Microbiology, Research, Water, water microbiology, Water Safety