Detection of Legionella pneumophila in biofilms containing a complex microbial consortium by gas chromatography-mass spectrometry analysis of genus-specific hydroxy fatty acids

Walker, Jimmy

doi:10.1016/0378-1097(93)90259-5

Cited by 17 publications

(21 citation statements)

References 10 publications

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“…The bacteria are more easily detected from swab samples of biofilm than from flowing water, suggesting that the majority of the legionellae are biofilm associated (235). A limited number of studies have attempted to characterize the bacteria's interaction within these complex ecosystems (236,237,282). These studies have evaluated the effect of temperature and surface materials on the growth of L. pneumophila as well as the effect of biocides on sessile legionellae.…”

Section: Association With Biofilmsmentioning

confidence: 99%

Legionella and Legionnaires' Disease: 25 Years of Investigation

2002

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There is still a low level of clinical awareness regarding Legionnaires' disease 25 years after it was first detected. The causative agents, legionellae, are freshwater bacteria with a fascinating ecology. These bacteria are intracellular pathogens of freshwater protozoa and utilize a similar mechanism to infect human phagocytic cells. There have been major advances in delineating the pathogenesis of legionellae through the identification of genes which allow the organism to bypass the endocytic pathways of both protozoan and human cells. Other bacteria that may share this novel infectious process are Coxiella burnetti and Brucella spp. More than 40 species and numerous serogroups of legionellae have been identified. Most diagnostic tests are directed at the species that causes most of the reported human cases of legionellosis, L. pneumophila serogroup 1. For this reason, information on the incidence of human respiratory disease attributable to other species and serogroups of legionellae is lacking. Improvements in diagnostic tests such as the urine antigen assay have inadvertently caused a decrease in the use of culture to detect infection, resulting in incomplete surveillance for legionellosis. Large, focal outbreaks of Legionnaires' disease continue to occur worldwide, and there is a critical need for surveillance for travel-related legionellosis in the United States. There is optimism that newly developed guidelines and water treatment practices can greatly reduce the incidence of this preventable illness

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Section: Association With Biofilmsmentioning

confidence: 99%

Legionella and Legionnaires' Disease: 25 Years of Investigation

2002

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“…The direct¯uorescent antibody technique has proved to be very useful for detecting L. pneumophila in natural aquatic systems (Fliermans et al, 1981;Alary and Joly, 1992). A gas chromatographic± mass spectrometric method, based on unique 3-hydroxy and 2,3-dihydroxy fatty acids of the L. pneumophila lipopolysaccharides, has been used to detect L. pneumophila in bio®lms in potable water containing a complex microbial consortium (Walker et al, 1993). Various molecular methods have also been developed for detecting Legionella.…”

Section: Detection and Disinfectionmentioning

confidence: 99%

Legionella: from environmental habitats to disease pathology, detection and control

Atlas

1999

Environmental Microbiology

210

148

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Studies on Legionella show a continuum from environment to human disease. Legionellosis is caused by Legionella species acquired from environmental sources, principally water sources such as cooling towers, where Legionella grows intracellularly in protozoa within biofilms. Aquatic biofilms, which are widespread not only in nature, but also in medical and dental devices, are ecological niches in which Legionella survives and proliferates and the ultimate sources to which outbreaks of legionellosis can be traced. Invasion and intracellular replication of L. pneumophila within protozoa in the environment play a major role in the transmission of Legionnaires' disease. Protozoa provide the habitats for the environmental survival and reproduction of Legionella species. L. pneumophila proliferates intracellularly in various species of protozoa within vacuoles studded with ribosomes, as it also does within macrophages. Growth within protozoa enhances the environmental survival capability and the pathogenicity (virulence) of Legionella. The growth requirements of Legionella, the ability of Legionella to enter a viable non‐culturable state, the association of Legionella with protozoa and the occurrence of Legionella within biofilms complicates the detection of Legionella and epidemiological investigations of legionellosis. Polymerase chain reaction (PCR) methods have been developed for the molecular detection of Legionella and used in environmental and epidemiological studies. Various physical and chemical disinfection methods have been developed to eliminate Legionella from environmental sources, but gaining control of Legionella in environmental waters, where they are protected from disinfection by growing within protozoa and biofilms, remains a challenge, and one that must be overcome in order to eliminate sporadic outbreaks of legionellosis.

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“…Opportunistic pathogens that have been isolated from biofilms in potable water systems include Mycobacterium avium, Pseudomonas aeruginosa, Klebsiella spp., Legionella spp., and Flavobacterium spp. (29,39,50). Payment et al (31) suggested that approximately 35% of gastrointestinal infections could be associated with the consumption of apparently potable water.…”

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confidence: 99%

Shear Rate Moderates Community Diversity in Freshwater Biofilms

Rickard

McBain

Stead

et al. 2004

Appl Environ Microbiol

150

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The development of freshwater multispecies biofilms at solid-liquid interfaces occurs both in quiescent waters and under conditions of high shear rates. However, the influence of hydrodynamic shear rates on bacterial biofilm diversity is poorly understood. We hypothesized that different shear rates would significantly influence biofilm diversity and alter the relative proportions of coaggregating and autoaggregating community isolates. In order to study this hypothesis, freshwater biofilms were developed at five shear rates (<0.1 to 305 S ؊1 ) in a rotating concentric cylinder reactor fed with untreated potable water. Eubacterial diversity was assessed by denaturing gradient gel electrophoresis (DGGE) and culturing on R2A agar. Fifty morphologically distinct biofilm strains and 16 planktonic strains were isolated by culturing and identified by partial 16S rRNA gene sequencing, and their relatedness was determined by the construction of a neighbor-joining phylogenetic tree. Phylogenetic and DGGE analyses showed an inverse relationship between shear rate and bacterial diversity. An in vitro aggregation assay was used to assess the relative proportions of coaggregating and autoaggregating species from each biofilm. The highest proportion of autoaggregating bacteria was present at high shear rates ( Microorganisms colonize a wide range of environments as spatially organized, taxonomically diverse, multispecies biofilm communities (1,20,44). In potable water distribution systems, many bacterial species, including members of the Proteobacteria, Actinobacteria, low-GϩC-content gram-positive bacteria, and Cytophaga-Flavobacterium-Bacterioides group, readily adhere to surfaces to form multispecies biofilms (29,41). The abilities of these taxonomically diverse organisms to attach to surfaces and codevelop within multispecies biofilms are imperative for their survival and persistence within flowing environments (4,33,44). Few published articles have described the effect of shear on the bacterial composition and diversity of freshwater biofilms. Evidence is emerging, however, that at high fluid velocities with associated high shear rates, multispecies communities are less diverse than those developed at lower shear rates (9,23,35,42). In order to adhere to surfaces or surface-attached cells and subsequently to form biofilms, bacteria in high-velocity flowing systems must overcome shear stress at the fluid-surface interface (7, 11). Attachment is facilitated by the expression of cell surface polymers that alter cell surface properties (3, 15). Properties that enhance attachment include increases in whole-cell hydrophobicity (14) and the abilities to coaggregate (25, 36) and autoaggregate (17). Recently, it was shown, using a simple recirculating tank model (35), that freshwater biofilms formed at high shear rates contained a high proportion of bacterial species that were not detectable in the surrounding fluid phase. In addition, a larger proportion of biofilm strains than of their planktonic counterparts were able to coaggr...

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Detection of Legionella pneumophila in biofilms containing a complex microbial consortium by gas chromatography-mass spectrometry analysis of genus-specific hydroxy fatty acids

Cited by 17 publications

References 10 publications

Legionella and Legionnaires' Disease: 25 Years of Investigation

Legionella and Legionnaires' Disease: 25 Years of Investigation

Legionella: from environmental habitats to disease pathology, detection and control

Shear Rate Moderates Community Diversity in Freshwater Biofilms

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