Increasing Incidence of Encapsulated Pseudomonas Aeruginosa Strains

Elston, Harry R.; Hoffman, Kenneth C.

doi:10.1093/ajcp/48.5_ts.519

“…This contrasts with our findings, which were highly reproducible in our hands. The only time we have seen cyanide in late stationary phase was using sealed flasks that prevent loss of cyanide gas by blowing off [15].Previously, mucoid CF isolates have been reported to be deficient in motility (due to inhibition of flagella production), pyocyanin production, elastase and total protease production, and decreased exotoxin A and exoenzyme S production as well as having reduced expression of type III secretion systems and type IV pili [26], [53]–[56]. Here we demonstrate that mucA22 mutation and the consequent increased availability of the sigma factor AlgU leads to a more complex and subtle change in the stationary phase regulation of virulence factor production than previously recognised (Figs.…”

Section: Discussionmentioning

confidence: 99%

The Mucoid Switch in Pseudomonas aeruginosa Represses Quorum Sensing Systems and Leads to Complex Changes to Stationary Phase Virulence Factor Regulation

Ryall

¹

,

Carrara

²

,

Zlosnik

³

et al. 2014

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The opportunistic pathogen Pseudomonas aeruginosa chronically infects the airways of Cystic Fibrosis (CF) patients during which it adapts and undergoes clonal expansion within the lung. It commonly acquires inactivating mutations of the anti-sigma factor MucA leading to a mucoid phenotype, caused by excessive production of the extracellular polysaccharide alginate that is associated with a decline in lung function. Alginate production is believed to be the key benefit of mucA mutations to the bacterium in the CF lung. A phenotypic and gene expression characterisation of the stationary phase physiology of mucA22 mutants demonstrated complex and subtle changes in virulence factor production, including cyanide and pyocyanin, that results in their down-regulation upon entry into stationary phase but, (and in contrast to wildtype strains) continued production in prolonged stationary phase. These findings may have consequences for chronic infection if mucoid P. aeruginosa were to continue to make virulence factors under non-growing conditions during infection. These changes resulted in part from a severe down-regulation of both AHL-and AQ (PQS)-dependent quorum sensing systems. In trans expression of the cAMP-dependent transcription factor Vfr restored both quorum sensing defects and virulence factor production in early stationary phase. Our findings have implications for understanding the evolution of P. aeruginosa during CF lung infection and it demonstrates that mucA22 mutation provides a second mechanism, in addition to the commonly occurring lasR mutations, of down-regulating quorum sensing during chronic infection this may provide a selection pressure for the mucoid switch in the CF lung.

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“…The first P. aeruginosa PS described was alginate due to its prevalence in cystic fibrosis (CF) pulmonary infections, whereby up to 90% of P. aeruginosa clinical isolates overproduce alginate (referred to as mucoid) (60, 93, 94). CF patients are initially colonized by nonmucoid P. aeruginosa (Psl and/or Pel producing) but convert to the mucoid phenotype during the course of infection.…”

Section: Protective Polysaccharidesmentioning

confidence: 99%

Bacterial Extracellular Polysaccharides in Biofilm Formation and Function

Limoli

¹

,

Jones

²

,

Wozniak

³

2015

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Microbes produce a biofilm matrix consisting of proteins, extracellular DNA, and polysaccharides that is integral in the formation of bacterial communities. Historical studies of polysaccharides revealed that their overproduction often alters the colony morphology and can be diagnostic in identifying certain species. The polysaccharide component of the matrix can provide many diverse benefits to the cells in the biofilm, including adhesion, protection, and structure. Aggregative polysaccharides act as molecular glue, allowing the bacterial cells to adhere to each other as well as surfaces. Adhesion facilitates the colonization of both biotic and abiotic surfaces by allowing the bacteria to resist physical stresses imposed by fluid movement that could separate the cells from a nutrient source. Polysaccharides can also provide protection from a wide range of stresses, such as desiccation, immune effectors, and predators such as phagocytic cells and amoebae. Finally, polysaccharides can provide structure to biofilms, allowing stratification of the bacterial community and establishing gradients of nutrients and waste products. This can be advantageous for the bacteria by establishing a heterogeneous population that is prepared to endure stresses created by the rapidly changing environments that many bacteria encounter. The diverse range of polysaccharide structures, properties, and roles highlight the importance of this matrix constituent to the successful adaptation of bacteria to nearly every niche. Here, we present an overview of the current knowledge regarding the diversity and benefits that polysaccharide production provides to bacterial communities within biofilms.

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“…Significance, structure, and regulation-The first P. aeruginosa PS described was alginate due to its prevalence in cystic fibrosis (CF) pulmonary infections, whereby up to 90% of P. aeruginosa clinical isolates overproduce alginate (referred to as mucoid) (60,93,94). CF patients are initially colonized by nonmucoid P. aeruginosa (Psl and/or Pel producing) but convert to the mucoid phenotype during the course of infection.…”

Section: Alginatementioning

confidence: 99%

Bacterial Extracellular Polysaccharides in Biofilm Formation and Function

Limoli

¹

,

Jones

²

,

Wozniak

³

2015

View full text Add to dashboard Cite

Microbes produce a biofilm matrix consisting of proteins, extracellular DNA, and polysaccharides that is integral in the formation of bacterial communities. Historical studies of polysaccharides revealed that their overproduction often alters the colony morphology and can be diagnostic in identifying certain species. The polysaccharide component of the matrix can provide many diverse benefits to the cells in the biofilm, including adhesion, protection, and structure. Aggregative polysaccharides act as molecular glue, allowing the bacterial cells to adhere to each other as well as surfaces. Adhesion facilitates the colonization of both biotic and abiotic surfaces by allowing the bacteria to resist physical stresses imposed by fluid movement that could separate the cells from a nutrient source. Polysaccharides can also provide protection from a wide range of stresses, such as desiccation, immune effectors, and predators such as phagocytic cells and amoebae. Finally, polysaccharides can provide structure to biofilms, allowing stratification of the bacterial community and establishing gradients of nutrients and waste products. This can be advantageous for the bacteria by establishing a heterogeneous population that is prepared to endure stresses created by the rapidly changing environments that many bacteria encounter. The diverse range of polysaccharide structures, properties, and roles highlight the importance of this matrix constituent to the successful adaptation of bacteria to nearly every niche. Here, we present an overview of the current knowledge regarding the diversity and benefits that polysaccharide production provides to bacterial communities within biofilms.

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Increasing Incidence of Encapsulated Pseudomonas Aeruginosa Strains

Cited by 22 publications

References 0 publications

The Mucoid Switch in Pseudomonas aeruginosa Represses Quorum Sensing Systems and Leads to Complex Changes to Stationary Phase Virulence Factor Regulation

The Mucoid Switch in Pseudomonas aeruginosa Represses Quorum Sensing Systems and Leads to Complex Changes to Stationary Phase Virulence Factor Regulation

Bacterial Extracellular Polysaccharides in Biofilm Formation and Function

Bacterial Extracellular Polysaccharides in Biofilm Formation and Function

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