Molecular Typing of Legionella pneumophila Isolates in the Province of Quebec from 2005 to 2015

Lévesque, Simon; Lalancette, Cindy; Bernard, Kathryn; Pacheco, Ana Luisa; Dion, Réjean; Longtin, Jean; Tremblay, Cécile

doi:10.1371/journal.pone.0163818

Cited by 19 publications

(16 citation statements)

References 50 publications

(44 reference statements)

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“…ST1 has been described by numerous studies, amongst a few other STs, as a main causative agent of LD globally, supporting its high pathogenicity [37,38]. Moreover, in contrast to other highly pathogenic clinical strains rarely isolated from the environment, ST1 has been shown to be among the predominant environmental Lp sg1 strains [22,[39][40][41][42][43].…”

Section: Discussionmentioning

confidence: 99%

A Snapshot of the Prevalence and Molecular Diversity of Legionella pneumophila in the Water Systems of Israeli Hotels

Yakunin

Kostyál²,

Agmon

et al. 2020

Pathogens

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Exposure to Legionella spp. contaminated aerosols in hotel settings confers risk for travel-associated Legionnaire’s disease (TALD). In this study, we investigated the prevalence of Legionella contamination and its molecular diversity in hotels and resorts across Israel. The study was comprised of a convenience sample of water systems from 168 hotels and resorts countrywide, routinely inspected between March 2015 and February 2017. Isolation and quantitation of Legionella were performed in a water laboratory using the ISO 11731 method. The distribution of Legionella isolates was analyzed according to geography and source. The genetic diversity of a subset of isolates was analyzed by sequence-based typing (SBT) at the National Reference Laboratory for Legionella and compared to the national database. Out of 2830 samples tested, 470 (17%) obtained from 102 different premises (60% of hotels) were positive for Legionella spp. In 230 samples (49% of all positive, 8% of total samples), accounting for 37% of hotels, Legionella spp. counts exceeded the regulatory threshold of 1000 CFU/L. The most frequently contaminated water sources were cooling towers (38%), followed by faucets, hot tubs, water lines, and storage tanks (14–17% each). Furthermore, 32% and 17% of samples obtained from cooling towers and hot tubs, respectively, exceeded the regulatory thresholds. SBT was performed on 78 strains and revealed 27 different sequence types (STs), including two novel STs. The most prevalent STs found were ST1 (26%), ST87 (10%), ST93 (6%), and ST461 and ST1516 (5% each). Several L. pneumophila STs were found to be limited to certain geographical regions. This is the first study to investigate the prevalence and diversity of Legionella in hotels and resorts in Israel during non-outbreak environmental inspections. These findings will inform risk assessment, surveillance, and control measures of TALD.

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Section: Discussionmentioning

confidence: 99%

A Snapshot of the Prevalence and Molecular Diversity of Legionella pneumophila in the Water Systems of Israeli Hotels

Yakunin

Kostyál²,

Agmon

et al. 2020

Pathogens

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“…The same report found that 49% of environmental Lp1 isolated from US facilities with no known disease association were ST1. The clinical and environmental presence of ST1 is not unique to the US but has been reported widely, including in Canada [ 4 – 6 ], England and Wales [ 7 ], mainland Europe [ 8 – 16 ], the Middle East [ 17 , 18 ], Australia [ 19 ], and several countries in Asia [ 20 – 24 ]. It has been proposed that ST1 “Paris” group strains (i.e., isolates with Lp strain Paris-like PFGE and microarray patterns) may represent a homogeneous Lp subpopulation [ 25 ], thus requiring high-resolution genetic analyses to uncover rare polymorphisms among isolates.…”

Section: Introductionmentioning

confidence: 99%

Genomic heterogeneity differentiates clinical and environmental subgroups of Legionella pneumophila sequence type 1

et al. 2018

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Legionella spp. are the cause of a severe bacterial pneumonia known as Legionnaires’ disease (LD). In some cases, current genetic subtyping methods cannot resolve LD outbreaks caused by common, potentially endemic L. pneumophila (Lp) sequence types (ST), which complicates laboratory investigations and environmental source attribution. In the United States (US), ST1 is the most prevalent clinical and environmental Lp sequence type. In order to characterize the ST1 population, we sequenced 289 outbreak and non-outbreak associated clinical and environmental ST1 and ST1-variant Lp strains from the US and, together with international isolate sequences, explored their genetic and geographic diversity. The ST1 population was highly conserved at the nucleotide level; 98% of core nucleotide positions were invariant and environmental isolates unassociated with human disease (n = 99) contained ~65% more nucleotide diversity compared to clinical-sporadic (n = 139) or outbreak-associated (n = 28) ST1 subgroups. The accessory pangenome of environmental isolates was also ~30–60% larger than other subgroups and was enriched for transposition and conjugative transfer-associated elements. Up to ~10% of US ST1 genetic variation could be explained by geographic origin, but considerable genetic conservation existed among strains isolated from geographically distant states and from different decades. These findings provide new insight into the ST1 population structure and establish a foundation for interpreting genetic relationships among ST1 strains; these data may also inform future analyses for improved outbreak investigations.

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“…Cell-SELEX was used to select aptamers binding specifically to lp120292. This strain was selected because it was involved in the Quebec City Outbreak in 2012 47 . To mimic the physiological state of Lp in water system, Lp cells were grown to post-exponential phase and suspended in Fraquil for 24 h at 25 °C to induce starvation and the associated morphological and physiological changes 43,44 .…”

Section: Resultsmentioning

confidence: 99%

Identification of two aptamers binding toLegionella pneumophilawith high affinity and specificity

Saad

Chinerman

Tabrizian

et al. 2019

Preprint

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19Legionella pneumophila (Lp) is a water borne bacterium causing Legionnaires' Disease (LD) in 20 humans. Rapid detection of Lp in water system is essential to reduce the risk of LD outbreaks. 21 The methods currently available require expert skills and are time intensive, thus delaying 22 intervention. In situ detection of Lp by biosensor would allow rapid implementation of control 23 strategies. To this end, a biorecognition element is required. Aptamers are considered promising 24 biorecognition molecules for biosensing. Aptamers are short oligonucleotide sequence folding 25 into a specific structure and are able to bind to specific molecules. Currently no aptamer and thus 26 no aptamer-based technology exists for the detection of Lp. In this study, Systemic Evolution of 27 Ligands through EXponential enrichment (SELEX) was used to identify aptamers binding 28 specifically to Lp. Ten rounds of positive selection and two rounds of counter-selection against 29 two Pseudomonas species were performed. Two aptamers binding strongly to Lp were identified 30 with KD of 116 and 135 nM. Binding specificity of these two aptamers to Lp was confirmed by 31 flow cytometry and fluorescence microscopy. Therefore, these two aptamers are promising 32 biorecognition molecules for the detection of Lp in water systems. 33 34 Key words: Legionella pneumophila, aptamers, SELEX, flow cytometry, fluorescence 35 microscopy, Pseudomonas 36 37 38 Legionella pneumophila (Lp) is a pathogenic Gram-negative bacterium responsible for two types 39 of respiratory diseases, namely the severe pneumonia Legionnaires' Disease (LD) and the milder 40 flu-like Pontiac fever 1 . Lp occurs in both natural and engineered water systems and is one of the 41 most prevalent pathogens in man-made, engineered water systems 2 . Infections occur when the 42 bacteria are aerosolized, and the contaminated aerosols are inhaled; Lp can then infect and replicate 43 inside alveolar macrophages 3 . Modern water systems provide optimal transmission conditions for 44 Lp by generating aerosols 4 . Leading sources of infection are cooling towers, hot water distribution 45 systems, humidifiers, misters, showers, fountains, spa pools and evaporative condensers 5 . 46 47 Outbreaks of LD consistently occur globally and have increased in recent years. The average 48 incidence rate is about 10-15 cases per million people 6 . According to the Centre for Disease 49 Control, incidences of legionellosis have increased by four and a half times between 2000 and 50 2016 7 . The rise in LD outbreaks can be attributed to several factors such as aging infrastructures 51and an aging population who is more vulnerable to such infections, as well as increases in diagnosis 52 and reporting 8,9 . Nevertheless, most LD outbreaks are the consequences of management failure of 53 man-made water systems 10 . Examples of these failures for water distribution systems include 54 keeping the temperature of hot water distribution system below 50°C and allowing water to 55 stagnate 10 . For coolin...

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Molecular Typing of Legionella pneumophila Isolates in the Province of Quebec from 2005 to 2015

Cited by 19 publications

References 50 publications

A Snapshot of the Prevalence and Molecular Diversity of Legionella pneumophila in the Water Systems of Israeli Hotels

A Snapshot of the Prevalence and Molecular Diversity of Legionella pneumophila in the Water Systems of Israeli Hotels

Genomic heterogeneity differentiates clinical and environmental subgroups of Legionella pneumophila sequence type 1

Identification of two aptamers binding toLegionella pneumophilawith high affinity and specificity

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