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 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 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.

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.

scholarly journals The Impact of Storms on Legionella pneumophila in Cooling Tower Water, Implications for Human Health

2020 ◽  
Vol 11 ◽  
Author(s):  
Robin L. Brigmon ◽  
Charles E. Turick ◽  
Anna S. Knox ◽  
Courtney E. Burckhalter
Keyword(s):  
Human Health ◽  
Legionella Pneumophila ◽  
Count Data ◽  
Distribution Systems ◽  
Cooling Tower ◽  
Water Systems ◽  
The Other ◽  
Cooling Towers ◽  
Legionnaires Disease ◽  
The Impact

At the U.S. Department of Energy’s Savannah River Site (SRS) in Aiken, SC, cooling tower water is routinely monitored for Legionella pneumophila concentrations using a direct fluorescent antibody (DFA) technique. Historically, 25–30 operating SRS cooling towers have varying concentrations of Legionella in all seasons of the year, with patterns that are unpredictable. Legionellosis, or Legionnaires’ disease (LD), is a pneumonia caused by Legionella bacteria that thrive both in man-made water distribution systems and natural surface waters including lakes, streams, and wet soil. Legionnaires’ disease is typically contracted by inhaling L. pneumophila, most often in aerosolized mists that contain the bacteria. At the SRS, L. pneumophila is typically found in cooling towers ranging from non-detectable up to 108 cells/L in cooling tower water systems. Extreme weather conditions contributed to elevations in L. pneumophila to 107–108 cells/L in SRS cooling tower water systems in July–August 2017. L. pneumophila concentrations in Cooling Tower 785-A/2A located in SRS A-Area, stayed in the 108 cells/L range despite biocide addition. During this time, other SRS cooling towers did not demonstrate this L. pneumophila increase. No significant difference was observed in the mean L. pneumophila mean concentrations for the towers (p < 0.05). There was a significant variance observed in the 285-2A/A Tower L. pneumophila results (p < 0.05). Looking to see if we could find “effects” led to model development by analyzing 13 months of water chemistry and microbial data for the main factors influencing the L. pneumophila concentrations in five cooling towers for this year. It indicated chlorine and dissolved oxygen had a significant impact (p < 0.0002) on cooling tower 785A/2A. Thus, while the variation in the log count data for the A-area tower is statistically greater than that of the other four towers, the average of the log count data for the A-Area tower was in line with that of the other towers. It was also observed that the location of 785A/2A and basin resulted in more debris entering the system during storm events. Our results suggest that future analyses should evaluate the impact of environmental conditions and cooling tower design on L. pneumophila water concentrations and human health.

scholarly journals Distribution of Sequence-Based Types of Legionella pneumophila Serogroup 1 Strains Isolated from Cooling Towers, Hot Springs, and Potable Water Systems in China

2014 ◽  
Vol 80 (7) ◽  
pp. 2150-2157 ◽  
Author(s):  
Tian Qin ◽  
Haijian Zhou ◽  
Hongyu Ren ◽  
Hong Guan ◽  
Machao Li ◽  
...  
Keyword(s):  
South Korea ◽  
Legionella Pneumophila ◽  
Potable Water ◽  
Hot Springs ◽  
Cooling Tower ◽  
Hot Spring ◽  
Water Systems ◽  
Cooling Towers ◽  
Content Type ◽  
Legionnaires Disease

ABSTRACTLegionella pneumophilaserogroup 1 causes Legionnaires' disease. Water systems contaminated withLegionellaare the implicated sources of Legionnaires' disease. This study analyzedL. pneumophilaserogroup 1 strains in China using sequence-based typing. Strains were isolated from cooling towers (n= 96), hot springs (n= 42), and potable water systems (n= 26). Isolates from cooling towers, hot springs, and potable water systems were divided into 25 sequence types (STs; index of discrimination [IOD], 0.711), 19 STs (IOD, 0.934), and 3 STs (IOD, 0.151), respectively. The genetic variation among the potable water isolates was lower than that among cooling tower and hot spring isolates. ST1 was the predominant type, accounting for 49.4% of analyzed strains (n= 81), followed by ST154. With the exception of two strains, all potable water isolates (92.3%) belonged to ST1. In contrast, 53.1% (51/96) and only 14.3% (6/42) of cooling tower and hot spring, respectively, isolates belonged to ST1. There were differences in the distributions of clone groups among the water sources. The comparisons amongL. pneumophilastrains isolated in China, Japan, and South Korea revealed that similar clones (ST1 complex and ST154 complex) exist in these countries. In conclusion, in China, STs had several unique allelic profiles, and ST1 was the most prevalent sequence type of environmentalL. pneumophilaserogroup 1 isolates, similar to its prevalence in Japan and South Korea.

scholarly journals Legionella longbeachaedetected in an industrial cooling tower linked to a legionellosis outbreak, New Zealand, 2015; possible waterborne transmission?

2017 ◽  
Vol 145 (11) ◽  
pp. 2382-2389 ◽  
Author(s):  
C. N. THORNLEY ◽  
D. J. HARTE ◽  
R. P. WEIR ◽  
L. J. ALLEN ◽  
K. J. KNIGHTBRIDGE ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Cooling Tower ◽  
Industrial Site ◽  
Cooling Towers ◽  
Environmental Isolates ◽  
Routine Monitoring ◽  
Waterborne Transmission ◽  
Pontiac Fever ◽  
Legionnaires Disease ◽  
And Control

SUMMARYA legionellosis outbreak at an industrial site was investigated to identify and control the source. Cases were identified from disease notifications, workplace illness records, and from clinicians. Cases were interviewed for symptoms and risk factors and tested for legionellosis. Implicated environmental sources were sampled and tested for legionella. We identified six cases with Legionnaires’ disease and seven with Pontiac fever; all had been exposed to aerosols from the cooling towers on the site. Nine cases had evidence of infection with eitherLegionella pneumophilaserogroup (sg) 1 orLegionella longbeachaesg1; these organisms were also isolated from the cooling towers. There was 100% DNA sequence homology between cooling tower and clinical isolates ofL. pneumophilasg1 using sequence-based typing analysis; no clinicalL. longbeachaeisolates were available to compare with environmental isolates. Routine monitoring of the towers prior to the outbreak failed to detect any legionella. Data from this outbreak indicate thatL. pneumophilasg1 transmission occurred from the cooling towers; in addition,L. longbeachaetransmission was suggested but remains unproven.L. longbeachaedetection in cooling towers has not been previously reported in association with legionellosis outbreaks. Waterborne transmission should not be discounted in investigations for the source ofL. longbeachaeinfection.

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