Select item 2953597211. Factors Mediating Environmental Biofilm Formation by Legionella pneumophila. Abu Khweek A, Amer AO. Front Cell Infect Microbiol. 2018 Feb 27;8:38. doi: 10.3389/fcimb.2018.00038. eCollection 2018. Review. PMID: 29535972 Free PMC Article Similar articles
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Suomennosta tiivistelmästä muutaman sanan ja otan tekstist ä(x) sitaatin samoin yhteenvedosta (Conclusion) .
L. pneumophila on opportunistinen vesiperäinen patogeeni ja legioonalaistautia aiheuttava syytekijä, joka välittyy ihmiseen saastuneitten vesipisaroiden sisäänhengittämisestä. Tämä bakteeri pystyy kolonisoitumaan monenlaisiin ihmisen tekemiin vesijärjestelmiin kuten jäähdytystorneihin, kylpylöihin ja hammasriveihin ja sitä esiintyy laajalti erilaisissa reservoaareissa, piilopaikoissa, mukaanluettuna useat loislajit (protozoa). L- pneumophila pystyy selviämään elossa planktonisissa faaseissa sekä olemaan pinttyneesti elossa monilajisissa biofilmeissä, jotka kattavat vesijärjestelmien sisäpintoja. Legionella pneumophila- biofilmin muodostaminen on bakteeripatogeenille edullista, koska se johtaa pinttyneisyyteen, leviämiseen, hoitoresistensseihin ja virulenssin nousuun. Lisäksi legionelloosipurkauksiin on assosioitunut L. pneumophila-biofilmien olemassaolo vielä laajojen kemiallisten ja fysikaalisten käsitelyjenkin jälkeen.
Mikrobikonsortiossa (yhteistoiminnassa), joka sisältää L. pneumofilaa muiden patogeenien ohella, useat faktorit säätelevät joko positiivisesti tai negatiivisesti L. penumofilan läsnäoloa ja pinttyneisyyttä tässä bakteeriyhteiskunnassa. Biofilmiä muodostava L. pneumofila on kansanterveydessä tärkeä huomioonotettava tekijä ja sillä on vaikutuksensa lääketieteen ja teollisuuden sektoreihin. Kun lähdetään estämään ja juurtamaan pois L. pneumophilaa tai diagnosoimaan ja sairaalahoitamaan tällä bakteerilla infektoituneita, on todellakin kyse biljoonista dollareista hallitusten budjeteissa.
Sentakia
Abstract
- Legionella pneumophila (L. pneumophila) is an opportunistic waterborne pathogen and the causative agent for Legionnaires' disease, which is transmitted to humans via inhalation of contaminated water droplets. The bacterium is able to colonize a variety of man-made water systems such as cooling towers, spas, and dental lines and is widely distributed in multiple niches, including several species of protozoa In addition to survival in planktonic phase, L. pneumophila is able to survive and persist within multi-species biofilms that cover surfaces within water systems. Biofilm formation by L. pneumophila is advantageous for the pathogen as it leads to persistence, spread, resistance to treatments and an increase in virulence of this bacterium. Furthermore, Legionellosis outbreaks have been associated with the presence of L. pneumophila in biofilms, even after the extensive chemical and physical treatments.
- Therefore, understanding the biological and environmental factors that contribute to persistence and physiological adaptation in biofilms: (Look x) etc tex
- In this review, we focus on various factors that contribute to persistence of L. pneumophila within the biofilm consortium, the advantages that the bacteria gain from surviving in biofilms, genes and gene regulation during biofilm formation and finally challenges related to biofilm resistance to biocides and anti-Legionella treatments. KEYWORDS: Legionella pneumophila; Legionellosis; biofilm; planktonic; protozoa
- x) Text
"Biofilms: A Survival Niche in Oligotrophic Environment
Biofilm is a rich environmental niche that harbors
living and dead organisms as well as protozoa and other microflora.
However, in a multispecies biofilm, the bacteria have to compete for the
required nutrients to become an integrated member of the microbial
community. Therefore biofilm-associated bacteria have to seek for the
bacterial neighbors and the environment that best suits their growth and
survival (Watnick and Kolter, 2000). Legionella pneumophila
is exceptionally fastidious and require the mandatory supplementation
of the laboratory media with amino acids and iron to grow (George et al., 1980; Edelstein, 1982). Therefore, survival and growth of L. pneumophila
in oligotrophic environments is puzzling and indicates that the
bacteria are able to utilize the essential nutrient from the bacterial
community located in biofilms. Indeed, establishment of two-species and
multispecies biofilms is one strategy by which L. penumophila
overcome nutrients limitation in the environment. Therefore, adhering to
a pre-established biofilm by other bacteria instead of attaching
directly to the surface as a primary colonizer aids in L. pneumophila survival and incorporation in the biofilm community (Watnick and Kolter, 2000; Stewart et al., 2012).
Even though restricted to certain microbial species,
necrotrophic feeding on the products of dead bacteria and tissues within
the biofilm is likely the primary mode for deriving the required
carbon, nitrogen, and amino acid for multiplication by L. pneumophila (Vervaeren et al., 2006; Taylor et al., 2009). Moreover, heterotrophic bacteria support growth of L. pneumophila on media that does not usually support growth because it is deficient in L-cysteine and ferric pyrophosphate (Wadowsky and Yee, 1983). Consistent with this, L. pneumophila show satellite colonies around some aquatic bacteria including Flavobacterium breve, Pseudomonas spp., Alcaligenes spp., and Acinetobacter spp. Further, L. pneumophila
are able to obtain nutrients directly from algae and to grow on the
extracellular products produced by cyanobacteria under laboratory
conditions (Tison et al., 1980). Further, several algae such as Scenedesmus spp., Chlorella spp., and Gleocystis spp., support the growth of L. pneumophila in basal salt media (Declerck, 2010).
The second mechanism by which L. pneumophila
obtain nutrient in biofilms is through amoeba. Protozoa serve as
habitats that provide the environmental host for survival and
replication of Legionella species in different environmental settings (Rowbotham, 1980; Newsome et al., 1998). Various amoeba such as Acanthamoeba castellanii can use L. pneumophila as a sole food source (Tyndall and Domingue, 1982), but also amoeba contribute to spread of L. pneumophila and protect the bacteria from various adverse effects such as antibacterial agents (Loret and Greub, 2010). Notably, persistence and adaptation of L. pneumophila
in various amoebal hosts has been thought to contribute to pathogenesis
of the bacteria. Intriguingly, biofilm colonization with L. pneumophila can be influenced by several species of protozoa (Rowbotham, 1981; Murga et al., 2001). Indeed, L. pneumophila can parasitize more than 20 species of amoebae, three species of ciliated protozoa and one species of slime mold (Kikuhara et al., 1994; Hägele et al., 2000). Further, it has been shown that multiplication inside the amoeba increased the capacity of L. pneumophila to produce polysaccharides and therefore enhanced its capacity to establish biofilm (Bigot et al., 2013). Further, L. pneumophila is able to grow off the debris from dead amoeba (Temmerman et al., 2006), and outbreaks of L. pneumophila are directly correlated with the biomass of protozoa. Moreover, in the absence of amoeba, biofilm-associated L. pneumophila
numbers did not increase. Instead, bacteria were only able to persist
in the biofilm community and in some cases entered the VBNC state in
order to promote their survival (Declerck, 2010). Recently, increasing evidence suggests that metazoan such as the C. elegans could represent a natural host for L. pneumophila (Brassinga et al., 2010; Hellinga et al., 2015). It has been shown that L. pneumophila survive within biofilm containing protozoan and C. elegans (Rasch et al., 2016). Together, the ability to obtain nutrient in mixed species biofilms as well as to parasitize amoeba and C. elegans enhances the survival and persistence of L. pneumophila. The diversity of organisms in the biofilm consortium provide a diverse pool of nutrients for this fastidious organism.
Factors that Modulate L. pneumophila Biofilm Formation
Role of Cyclic-di-GMP
Cyclic-dimeric diguanylate (c-di-GMP) is a bacterial
second messenger that regulates several processes including bacterial
pathogenesis and biofilm formation (Tamayo et al., 2007; Abu Khweek et al., 2010; Römling et al., 2013; Martinez-Gil and Ramos, 2017). Regulation of biofilm formation by c-di-GMP has been shown for several bacteria (Bobrov et al., 2011; Valentini and Filloux, 2016; Conner et al., 2017). Synthesis of ( etc) Conclusion
Several chemical and physical parameters can influence the behavior of L. pneumophila in biofilms, including the surface, the temperature, carbon and metal concentrations, and the presence of biocides (Wright et al., 1991; Bezanson et al., 1992; Rogers et al., 1994; Donlan et al., 2005; van der Kooij et al., 2005; Liu et al., 2006; Mampel et al., 2006; Pang and Liu, 2006; Piao et al., 2006; Lehtola et al., 2007; Türetgen and Cotuk, 2007; Hindré et al., 2008). Biological factors such as being a member of mixed species biofilm or parasitizing free-living amoeba or nematodes influence biofilm formation by L. pneumophila (Figure 2). Biofilm- associated L. pneumophila is resistant to biocides and Legionellosis outbreaks have been attributed to biofilms.Therefore, it is essential to design new remedies for eradication of L. pneumophila biofilm in different environmental settings. Treatment studies should be performed when the bacterium is in its natural host to determine how the bacteria are protected inside the amoeba and if the passage through the natural hosts modify the resistance. Thus, preventing biofilm formation appears as one strategy to reduce water system contamination.
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