Soil as a source of Legionella pneumophila sequence type 47

Schalk, J.A.C.; Euser, Sjoerd M.; Heijnsbergen, Eri van; Bruin, Jacob P.; Boer, Jeroen W. Den; Husman, Ana Maria de Roda

doi:10.1016/j.ijid.2014.05.009

Cited by 12 publications

(15 citation statements)

References 9 publications

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“…However, of the three STs most frequently observed in clinical samples in the United Kingdom and Wales, only one strain (ST47) was isolated once from an outbreak-unrelated environmental sample (8). Also in France (21), the Netherlands (15,22), the United States (13), and Canada (4), ST47 and ST62 were not or were only incidentally observed in environmental samples. Contrastingly, L. pneumophila SG1 ST1, the most frequently isolated environmental ST, accounts for a relatively small proportion of the clinical isolates (8,13,15), suggesting that ST1 strains are less virulent than strains of ST47, ST62, and a number of other STs.…”

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confidence: 99%

Multiplication of Legionella pneumophila Sequence Types 1, 47, and 62 in Buffered Yeast Extract Broth and Biofilms Exposed to Flowing Tap Water at Temperatures of 38°C to 42°C

Kooij

Brouwer-Hanzens

Veenendaal

et al. 2016

Appl Environ Microbiol

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Legionella pneumophila proliferates in freshwater environments at temperatures ranging from 25 to 45°C. To investigate the preference of different sequence types (ST) for a specific temperature range, growth of L. pneumophila serogroup 1 (SG1) ST1 (environmental strains), ST47, and ST62 (disease-associated strains) was measured in buffered yeast extract broth (BYEB) and biofilms grown on plasticized polyvinyl chloride in flowing heated drinking water originating from a groundwater supply. The optimum growth temperatures in BYEB were approximately 37°C (ST1), 39°C (ST47), and 41°C (ST62), with maximum growth temperatures of 42°C (ST1) and 43°C (ST47 and ST62). In the biofilm at 38°C, the ST47 and ST62 strains multiplied equally well compared to growth of the environmental ST1 strain and an indigenous L. pneumophila non-SG1 strain, all attaining a concentration of approximately 10 7 CFU/cm ؊2 . Raising the temperature to 41°C did not impact these levels within 4 weeks, but the colony counts of all strains tested declined (at a specific decline rate of 0.14 to 0.41 day ؊1 ) when the temperature was raised to 42°C. At this temperature, the concentration of Vermamoeba vermiformis in the biofilm, determined with quantitative PCR (qPCR), was about 2 log units lower than the concentration at 38°C. In columns operated at a constant temperature, ranging from 38 to 41°C, none of the tested strains multiplied in the biofilm at 41°C, in which also V. vermiformis was not detected. These observations suggest that strains of ST47 and ST62 did not multiply in the biofilm at a temperature of >41°C because of the absence of a thermotolerant host. IMPORTANCEGrowth of Legionella pneumophila in tap water installations is a serious public health concern. The organism includes more than 2,100 varieties (sequence types). More than 50% of the reported cases of Legionnaires' disease are caused by a few sequence types which are very rarely detected in the environment. Strains of selected virulent sequence types proliferated in biofilms on surfaces exposed to warm (38°C) tap water to the same level as environmental varieties and multiplied well as pure culture in a nutrient-rich medium at temperatures of 42 and 43°C. However, these organisms did not grow in the biofilms at temperatures of >41°C. Typical host amoebae also did not multiply at these temperatures. Apparently, proliferation of thermotolerant host amoebae is needed to enable multiplication of the virulent L. pneumophila strains in the environment at elevated temperatures. The detection of these amoebae in water installations therefore is a scientific challenge with practical implications. T he genus Legionella currently includes ca. 63 (sub)species (https://www.dsmz.de), at least 20 of which have been implicated in legionellosis (1). Legionella pneumophila is responsible for more than 90% of the reported cases of Legionnaires' disease (LD) in Europe (2), the United States (3), Canada (4), and Japan (5). This species includes 15 polyclonal serogroups (SGs). Most of the cli...

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confidence: 99%

Multiplication of Legionella pneumophila Sequence Types 1, 47, and 62 in Buffered Yeast Extract Broth and Biofilms Exposed to Flowing Tap Water at Temperatures of 38°C to 42°C

Kooij

Brouwer-Hanzens

Veenendaal

et al. 2016

Appl Environ Microbiol

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“…As L. pneumophila cycles through over at least 15 species of diverse protozoa in the environment (Rowbotham, ; Fields, ; Solomon et al , ; Molmeret et al , ), acquisition of LME‐1 would likely confer a costly host range switch under environmental conditions of sufficient host diversity. Note that this could occur within freshwater, the typical habitat of L. pneumophila (Fliermans et al , ), as Dictyostelium species have been observed in lakes and sediment (O'Dell, ; Richards et al , ; Somboonna et al , ; Shanan et al , ); at the same time, L. pneumophila has also been isolated from soil (Wallis and Robinson, ; Schalk et al , ; van Heijnsbergen et al , ), a long‐established habitat of D. discoideum (Singh, ). While D. discoideum is generally thought of within the context of a laboratory model for Legionella infection, these data suggest that further scrutiny should be placed on the natural association of L. pneumophila and D. discoideum in the environment.…”

Section: Discussionmentioning

confidence: 99%

Active and adaptive Legionella CRISPR‐Cas reveals a recurrent challenge to the pathogen

Rao

Guyard

Peláz

et al. 2016

Cellular Microbiology

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SummaryClustered regularly interspaced short palindromic repeats with CRISPR‐associated gene (CRISPR‐Cas) systems are widely recognized as critical genome defense systems that protect microbes from external threats such as bacteriophage infection. Several isolates of the intracellular pathogen Legionella pneumophila possess multiple CRISPR‐Cas systems (type I‐C, type I‐F and type II‐B), yet the targets of these systems remain unknown. With the recent observation that at least one of these systems (II‐B) plays a non‐canonical role in supporting intracellular replication, the possibility remained that these systems are vestigial genome defense systems co‐opted for other purposes. Our data indicate that this is not the case. Using an established plasmid transformation assay, we demonstrate that type I‐C, I‐F and II‐B CRISPR‐Cas provide protection against spacer targets. We observe efficient laboratory acquisition of new spacers under ‘priming’ conditions, in which initially incomplete target elimination leads to the generation of new spacers and ultimate loss of the invasive DNA. Critically, we identify the first known target of L. pneumophila CRISPR‐Cas: a 30 kb episome of unknown function whose interbacterial transfer is guarded against by CRISPR‐Cas. We provide evidence that the element can subvert CRISPR‐Cas by mutating its targeted sequences – but that primed spacer acquisition may limit this mechanism of escape. Rather than generally impinging on bacterial fitness, this element drives a host specialization event – with improved fitness in Acanthamoeba but a reduced ability to replicate in other hosts and conditions. These observations add to a growing body of evidence that host range restriction can serve as an existential threat to L. pneumophila in the wild.

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“…Strikingly, since the start of the National Legionella Outbreak Detection Programme in the Netherlands in 2002, this ST was only found three times in the environment during outbreak investigations, which concerned outdoor whirlpools that were involved in two combined outbreaks of LD and Pontiac fever and one solitary case of LD. As all three whirlpools were located outside, it was hypothesized that the outdoor environment was an influence, and after further investigation, L. pneumophila ST47 was isolated from a soil sample from the garden of the most recent outbreak ( 19 ). It was suggested that the ST47 strain was transmitted from garden soil to the whirlpool by wind or by people entering the whirlpool with soil on their feet.…”

Section: Introductionmentioning

confidence: 99%

Presence and Persistence of Viable, Clinically Relevant Legionella pneumophila Bacteria in Garden Soil in the Netherlands

Heijnsbergen

Deursen

Bouwknegt

et al. 2016

Appl Environ Microbiol

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Garden soils were investigated as reservoirs and potential sources of pathogenic Legionella bacteria. Legionella bacteria were detected in 22 of 177 garden soil samples (12%) by amoebal coculture. Of these 22 Legionella-positive soil samples, seven contained Legionella pneumophila. Several other species were found, including the pathogenic Legionella longbeachae (4 gardens) and Legionella sainthelensi (9 gardens). The L. pneumophila isolates comprised 15 different sequence types (STs), and eight of these STs were previously isolated from patients according to the European Working Group for Legionella Infections (EWGLI) database. Six gardens that were found to be positive for L. pneumophila were resampled after several months, and in three gardens, L. pneumophila was again isolated. One of these gardens was resampled four times throughout the year and was found to be positive for L. pneumophila on all occasions. IMPORTANCE Tracking the source of infection for sporadic cases of Legionnaires' disease (LD) has proven to be hard. L. pneumophila ST47, the sequence type that is most frequently isolated from LD patients in the Netherlands, is rarely found in potential environmental sources. As L. pneumophila ST47 was previously isolated from a garden soil sample during an outbreak investigation, garden soils were investigated as reservoirs and potential sources of pathogenic Legionella bacteria. The detection of viable, clinically relevant Legionella strains indicates that garden soil is a potential source of Legionella bacteria, and future research should assess the public health implication of the presence of L. pneumophila in garden soil.

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Soil as a source of Legionella pneumophila sequence type 47

Cited by 12 publications

References 9 publications

Multiplication of Legionella pneumophila Sequence Types 1, 47, and 62 in Buffered Yeast Extract Broth and Biofilms Exposed to Flowing Tap Water at Temperatures of 38°C to 42°C

Multiplication of Legionella pneumophila Sequence Types 1, 47, and 62 in Buffered Yeast Extract Broth and Biofilms Exposed to Flowing Tap Water at Temperatures of 38°C to 42°C

Active and adaptive Legionella CRISPR‐Cas reveals a recurrent challenge to the pathogen

Presence and Persistence of Viable, Clinically Relevant Legionella pneumophila Bacteria in Garden Soil in the Netherlands

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