scholarly journals Presence ofLegionellaspp. in cooling towers: the role of microbial diversity,Pseudomonas, and continuous chlorine application

2019 ◽  
Author(s):  
Kiran Paranjape ◽  
Émilie Bédard ◽  
Lyle G. Whyte ◽  
Jennifer Ronholm ◽  
Michèle Prévost ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Microbial Diversity ◽  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Severe Pneumonia ◽  
Water Source ◽  
Amplicon Sequencing ◽  
Physical Parameters ◽  
Cooling Towers ◽  
Strong Negative Correlation

ABSTRACTLegionnaire’s Disease (LD) is a severe pneumonia caused byLegionella pneumophila. Cooling towers are the main source ofL. pneumophiladuring large outbreaks. Colonization, survival, and proliferation ofL. pneumophilain cooling towers are necessary for outbreaks to occur. These steps are affected by chemical and physical parameters of the cooling tower environment. We hypothesize that the bacterial community residing in the cooling tower could also affect the presence ofL. pneumophila. A16S rRNAtargeted amplicon sequencing approach was used to study the bacterial community of cooling towers and its relationship with theLegionella spp.andL. pneumophilacommunities. The results indicated that the water source shaped the bacterial community of cooling towers. Several taxa were enriched and positively correlated withLegionella spp.andL. pneumophila. In contrast,Pseudomonasshowed a strong negative correlation withLegionella spp.and several other genera. Most importantly, continuous chlorine application reduced microbial diversity and promoted the presence ofPseudomonascreating a non-permissive environment forLegionella spp. This suggests that disinfection strategies as well as the resident microbial population influences the ability ofLegionella spp.to colonize cooling towers.

scholarly journals Impact of temperature on Legionella pneumophila, its protozoan host cells, and the microbial diversity of the biofilm community of a pilot cooling tower

2019 ◽  
Author(s):  
Adriana Torres Paniagua ◽  
Kiran Paranjape ◽  
Mengqi Hu ◽  
Émilie Bédard ◽  
Sébastien Faucher
Keyword(s):  
Spatial Distribution ◽  
Water Temperature ◽  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Abiotic Factors ◽  
Severe Pneumonia ◽  
Amplicon Sequencing ◽  
Host Cells ◽  
Pipe Material ◽  
Cooling Towers

ABSTRACTLegionella pneumophila (Lp) is a waterborne bacterium known for causing Legionnaires’ Disease, a severe pneumonia. Cooling towers are a major source of outbreaks, since they provide ideal conditions for Lp growth and produce aerosols. In such systems, Lp typically grow inside protozoan hosts. Several abiotic factors such as water temperature, pipe material and disinfection regime affect the colonization of cooling towers by Lp. The local physical and biological factors promoting the growth of Lp in water systems and its spatial distribution are not well understood. Therefore, we built a lab-scale cooling tower to study the dynamics of Lp colonization in relationship to the resident microbiota and spatial distribution. The pilot was filled with water from an operating cooling tower harboring low levels of Lp. It was seeded with Vermamoeba vermiformis, a natural host of Lp, and then inoculated with Lp. After 92 days of operation, the pilot was disassembled, the water was collected, and biofilm was extracted from the pipes. The microbiome was studied using 16S rRNA and 18S rRNA genes amplicon sequencing. The communities of the water and of the biofilm were highly dissimilar. The relative abundance of Legionella in water samples reached up to 11% whereas abundance in the biofilm was extremely low (≤0.5 %). In contrast, the host cells were mainly present in the biofilm. This suggest that Lp grows in host cells associated with biofilm and is then released back into the water following host cell lysis. In addition, water temperature shaped the bacterial and eukaryotic community of the biofilm, indicating that different parts of the systems may have different effects on Legionella growth.

scholarly journals Unravelling the importance of the eukaryotic and bacterial communities and their relationship with Legionella spp. ecology in cooling towers: a complex network

Microbiome ◽  
2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Kiran Paranjape ◽  
Émilie Bédard ◽  
Deeksha Shetty ◽  
Mengqi Hu ◽  
Fiona Chan Pak Choon ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Severe Pneumonia ◽  
Amplicon Sequencing ◽  
Host Community ◽  
Cooling Towers ◽  
Eukaryotic Community ◽  
Protozoan Community ◽  
Survival And Growth

Abstract Background Cooling towers are a major source of large community-associated outbreaks of Legionnaires’ disease, a severe pneumonia. This disease is contracted when inhaling aerosols that are contaminated with bacteria from the genus Legionella, most importantly Legionella pneumophila. How cooling towers support the growth of this bacterium is still not well understood. As Legionella species are intracellular parasites of protozoa, it is assumed that protozoan community in cooling towers play an important role in Legionella ecology and outbreaks. However, the exact mechanism of how the eukaryotic community contributes to Legionella ecology is still unclear. Therefore, we used 18S rRNA gene amplicon sequencing to characterize the eukaryotic communities of 18 different cooling towers. The data from the eukaryotic community was then analysed with the bacterial community of the same towers in order to understand how each community could affect Legionella spp. ecology in cooling towers. Results We identified several microbial groups in the cooling tower ecosystem associated with Legionella spp. that suggest the presence of a microbial loop in these systems. Dissolved organic carbon was shown to be a major factor in shaping the eukaryotic community and may be an important factor for Legionella ecology. Network analysis, based on co-occurrence, revealed that Legionella was correlated with a number of different organisms. Out of these, the bacterial genus Brevundimonas and the ciliate class Oligohymenophorea were shown, through in vitro experiments, to stimulate the growth of L. pneumophila through direct and indirect mechanisms. Conclusion Our results suggest that Legionella ecology depends on the host community, including ciliates and on several groups of organisms that contribute to its survival and growth in the cooling tower ecosystem. These findings further support the idea that some cooling tower microbiomes may promote the survival and growth of Legionella better than others.

scholarly journals Toxoflavin secreted by Pseudomonas alcaliphila inhibits growth of Legionella pneumophila and its host Vermamoeba vermiformis

2022 ◽  
Author(s):  
Sebastien P. Faucher ◽  
Sara Matthews ◽  
Arvin Nickzad ◽  
Passoret Vounba ◽  
Deeksha Shetty ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Severe Pneumonia ◽  
Amplicon Sequencing ◽  
Inhibitory Effect ◽  
Water Systems ◽  
Bulk Water ◽  
Cooling Towers ◽  
High Concentration ◽  
16S Rrna Amplicon Sequencing

Legionella pneumophila is a natural inhabitant of water systems. From there, it can be transmitted to humans by aerosolization resulting in severe pneumonia. Most large outbreaks are caused by cooling towers contaminated with L. pneumophila. The resident microbiota of the cooling tower is a key determinant for the colonization and growth of L. pneumophila. The genus Pseudomonas correlates negatively with the presence of L. pneumophila, but it is not clear which species is responsible. Therefore, we identified the Pseudomonas species inhabiting 14 cooling towers using a Pseudomonas-specific 16S rRNA amplicon sequencing strategy. Cooling towers free of L. pneumophila contained a high relative abundance of members from the Pseudomonas alcaliphila/oleovorans phylogenetic cluster. In vitro, P. alcaliphila JCM 10630 inhibited the growth of L. pneumophila on agar plates. Analysis of the P. alcaliphila genome revealed the presence of a genes cluster predicted to produce toxoflavin. L. pneumophila growth was inhibited by pure toxoflavin and by extract from P. alcaliphila culture found to contain toxoflavin by LC-ESI-MS. In addition, toxoflavin inhibits growth of Vermameoba vermiformis, a host cell of L. pneumophila. Our study indicates that P. alcaliphila may be important to restrict growth of L. pneumophila in water systems through the production of toxoflavin. A sufficiently high concentration is likely not achieved in the bulk water but might have a local inhibitory effect such as in biofilm.

scholarly journals A core microbiota dominates a rich microbial diversity in the bovine udder and may indicate presence of dysbiosis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Davide Porcellato ◽  
Roger Meisal ◽  
Alberto Bombelli ◽  
Judith A. Narvhus
Keyword(s):  
Microbial Diversity ◽  
Amplicon Sequencing ◽  
Rrna Gene ◽  
Lactation Period ◽  
Strong Negative Correlation ◽  
Udder Health ◽  
Milk Samples ◽  
Lactating Cows ◽  
Definition Of ◽  
The 16S Rrna Gene

AbstractThe importance of the microbiome for bovine udder health is not well explored and most of the knowledge originates from research on mastitis. Better understanding of the microbial diversity inside the healthy udder of lactating cows might help to reduce mastitis, use of antibiotics and improve animal welfare. In this study, we investigated the microbial diversity of over 400 quarter milk samples from 60 cows sampled from two farms and on two different occasions during the same lactation period. Microbiota analysis was performed using amplicon sequencing of the 16S rRNA gene and over 1000 isolates were identified using MALDI-TOF MS. We detected a high abundance of two bacterial families, Corynebacteriaceae and Staphylococcaceae, which accounted for almost 50% of the udder microbiota of healthy cows and were detected in all the cow udders and in more than 98% of quarter milk samples. A strong negative correlation between these bacterial families was detected indicating a possible competition. The overall composition of the udder microbiota was highly diverse and significantly different between cows and between quarter milk samples from the same cow. Furthermore, we introduced a novel definition of a dysbiotic quarter at individual cow level, by analyzing the milk microbiota, and a high frequency of dysbiotic quarter samples were detected distributed among the farms and the samples. These results emphasize the importance of deepening the studies of the bovine udder microbiome to elucidate its role in udder health.

Comparison of Legiolert and a Conventional Culture Method for Detection of Legionella pneumophila from Cooling Towers in Québec

2019 ◽  
Vol 102 (4) ◽  
pp. 1235-1240 ◽  
Author(s):  
Isabelle Barrette
Keyword(s):  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Test Procedure ◽  
Agar Plate ◽  
Culture Method ◽  
Most Probable Number ◽  
Cooling Towers ◽  
Plate Method ◽  
Probable Number ◽  
Compliance Testing

Abstract Background: Legionnaires’ disease is a potentially lethal pneumonia contracted through inhalation of aerosolized water contaminated with Legionella bacteria. Detection and control of L. pneumophila, the primary species responsible for the disease, is critical to public health. In Québec, cooling towers and evaporative condensers are required to follow a maintenance and testing program to ensure L. pneumophila concentrations remain at acceptable levels. Objective: This study compared a new culture method based on the most probable number approach, Legiolert®, with the formal culture method used at EnvironeX for regulatory compliance testing to quantify L. pneumophila from cooling tower waters in Québec. Methods: A split-sample analysis was performed in which 401 samples from cooling towers in Québec were tested with both methods. Results: Results with 74 positive samples showed that Legiolert provided a significant increase in sensitivity for L. pneumophila compared with the agar plate method. Cooling tower samples often contain non-Legionella flora that necessitate multiple treatment and plating conditions to prevent interference with the test. Legiolert showed little to no impact from non-Legionella organisms in this study. Conclusions: Overall, Legiolert showed several advantages over the agar plate method, including increased sensitivity, reduced interference, a simplified test procedure, and an easy-to-read positive signal.

scholarly journals Legionella species and serogroups in Malaysian water cooling towers: identification by latex agglutination and PCR-DNA sequencing of isolates

2009 ◽  
Vol 8 (1) ◽  
pp. 92-100 ◽  
Author(s):  
Stacey Foong Yee Yong ◽  
Fen-Ning Goh ◽  
Yun Fong Ngeow
Keyword(s):  
Dna Sequencing ◽  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Latex Agglutination ◽  
Cooling Towers ◽  
Water Cooling ◽  
Public Health Policies ◽  
Legionella Species ◽  
Repeat Sampling ◽  
East West

In this study, we investigated the distribution of Legionella species in water cooling towers located in different parts of Malaysia to obtain information that may inform public health policies for the prevention of legionellosis. A total of 20 water samples were collected from 11 cooling towers located in three different states in east, west and south Malaysia. The samples were concentrated by filtration and treated with an acid buffer before plating on to BCYE agar. Legionella viable counts in these samples ranged from 100 to 2,000 CFU ml−1; 28 isolates from the 24 samples were examined by latex agglutination as well as 16S rRNA and rpoB PCR-DNA sequencing. These isolates were identified as Legionella pneumophila serogroup 1 (35.7%), L. pneumophila serogroup 2–14 (39%), L. pneumophila non-groupable (10.7%), L. busanensis, L. gormanii, L. anisa and L. gresilensis.L. pneumophila was clearly the predominant species at all sampling sites. Repeat sampling from the same cooling tower and testing different colonies from the same water sample showed concurrent colonization by different serogroups and different species of Legionella in some of the cooling towers.

scholarly journals Community outbreak of Legionnaires’ disease in Vic-Gurb, Spain in October and November 2005

2007 ◽  
Vol 12 (3) ◽  
pp. 5-6 ◽  
Author(s):  
M R Sala ◽  
C Arias ◽  
J M Oliva ◽  
A Pedrol ◽  
P Roura ◽  
...  
Keyword(s):  
Central Region ◽  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Weather Conditions ◽  
High Humidity ◽  
Cooling Towers ◽  
Large Area ◽  
Environmental Investigation ◽  
Flat Terrain ◽  
Legionnaires Disease

This paper reports the investigation of a community-acquired outbreak of Legionnaires'; disease in the municipalities of Vic and Gurb (Central Region of Catalonia, Spain). There were 55 cases reported in October and November 2005. An epidemiological and environmental investigation was undertaken. Thirty-five case patients (64%) lived in Vic or Gurb, while 36% had visited or worked in Vic or Gurb during the 10 days before onset of symptoms, but no commonly frequented building could be identified. Water probes for culture were obtained from 30 cooling towers. In five cooling towers of two industrial settings in Gurb (plants A and B), Legionella pneumophila (Lp) serogroup 1 was present. Two Lp-1 strains were recovered from cooling towers in plants A and B. The Lp-1 strain from plant A showed a PGFE profile identical with those obtained from three patients. The exposure to Legionella pneumophila apparently occurred in a large area, since 43 of the 55 cases lived, visited or worked within a distance of 1,800 m from plant A, and six cases in a distance between 2,500 and 3,400 m. The inspections of cooling towers in plant A revealed inadequate disinfectant doses of biocide, non-existent maintenance records on weekends and wrong sample points for routine microbial check-ups. Weather conditions in October 2005 template temperature and high humidity (wind conditions are unappreciable) could have been favourable factors in this outbreak together with the flat terrain of Gurb and Vic area, explaining the extensive horizontal airborne dissemination of contaminated aerosols. The outbreak could have been prevented by proper and correct maintenance of the cooling tower at plant A.

scholarly journals Analysis of Genetic Characterization and Clonality of Legionella pneumophila Isolated from Cooling Towers in Japan

2019 ◽  
Vol 16 (9) ◽  
pp. 1664
Author(s):  
Noriko Nakanishi ◽  
Ryohei Nomoto ◽  
Shinobu Tanaka ◽  
Kentaro Arikawa ◽  
Tomotada Iwamoto
Keyword(s):  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Minimum Spanning Tree ◽  
Genetic Characterization ◽  
Major Type ◽  
Cooling Towers ◽  
Genetic Characteristics ◽  
Clonal Population ◽  
Sequence Types ◽  
Major Sequence

We investigated the genetic characteristics of 161 Legionella pneumophila strains isolated over a period of 10 years from cooling towers in Japan. Minimum spanning tree analysis based on the sequence-based typing (SBT) of them identified three clonal complexes (CCs); CC1 (105/161, 65.2%), CC2 (22 /161, 13.7%), and CC3 (20/161, 12.4%). CC1 was formed by serogroup (SG) 1 and SG7, whereas CC2 was mainly formed by SG1. All of the CC3 isolates except two strains were SG13. The major sequence types (STs) in CC1 and CC2 were ST1 (88/105, 83.8%) and ST154 (15/22, 68.2%), respectively. These STs are known as typical types of L. pneumophila SG1 in Japanese cooling tower. Additionally, we identified 15 strains of ST2603 as the major type in CC3. This ST has not been reported in Japanese cooling tower. Whole genome sequencing (WGS) analysis of the representative strains in the three CCs, which were isolated from various cooling towers over the 10 years, elucidated high clonal population of L. pneumophila in Japanese cooling tower. Moreover, it revealed that the strains of CC2 are phylogenetically distant compared to those of CC1 and CC3, and belonged to L. pneumophila subsp. fraseri.

Experimental Investigation on the Effect of Fill Materials in Cooling Towers

2015 ◽  
Vol 766-767 ◽  
pp. 505-510 ◽  
Author(s):  
J. Jayaprabakar
Keyword(s):  
Corrosion Resistance ◽  
High Efficiency ◽  
Cooling Tower ◽  
Water System ◽  
Cooling Water ◽  
Cross Flow ◽  
Water Source ◽  
Coefficient Of Performance ◽  
Advanced Materials ◽  
Cooling Towers

The cooling water system is the industry’s primary way of conserving water. Modern water cooling towers were invented during the industrial age to dissipate heat when natural cooling water sources were available. The origin of cooling towers made the plant site selection independent of the availability of water source. The development of new, high efficiency film fills produced from light weights, flame retarded PVC reduces the size and weight of cross flow cooling towers. Today’s cooling tower combine the latest advanced materials to achieve the optimum balancing of High corrosion resistance, product durability and cost. Based on their specific functions, cooling tower components are designed using the materials with the best combination of corrosion resistance and physical properties. In this work, the coefficient of performance is determined by using Simpson’s rule and the performance of cooling tower at various L/G ratios is evaluated. The optimum approach of the tower is calculated.

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