scholarly journals The rapid in vivo evolution of Pseudomonas aeruginosa in ventilator-associated pneumonia patients leads to attenuated virulence

Open Biology ◽  
2017 ◽  
Vol 7 (9) ◽  
pp. 170029 ◽  
Author(s):  
Ke Wang ◽  
Yi-qiang Chen ◽  
May M. Salido ◽  
Gurjeet S. Kohli ◽  
Jin-liang Kong ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Opportunistic Pathogen ◽  
Ventilator Associated Pneumonia ◽  
Loss Of Function ◽  
Short Term ◽  
Airway Infections ◽  
Evolutionary Trajectories ◽  
Human Airways ◽  
Late Stages

Pseudomonas aeruginosa is an opportunistic pathogen that causes severe airway infections in humans. These infections are usually difficult to treat and associated with high mortality rates. While colonizing the human airways, P. aeruginosa could accumulate genetic mutations that often lead to its better adaptability to the host environment. Understanding these evolutionary traits may provide important clues for the development of effective therapies to treat P. aeruginosa infections. In this study, 25 P. aeruginosa isolates were longitudinally sampled from the airways of four ventilator-associated pneumonia (VAP) patients. Pacbio and Illumina sequencing were used to analyse the in vivo evolutionary trajectories of these isolates. Our analysis showed that positive selection dominantly shaped P. aeruginosa genomes during VAP infections and led to three convergent evolution events, including loss-of-function mutations of lasR and mpl , and a pyoverdine-deficient phenotype. Specifically, lasR encodes one of the major transcriptional regulators in quorum sensing, whereas mpl encodes an enzyme responsible for recycling cell wall peptidoglycan. We also found that P. aeruginosa isolated at late stages of VAP infections produce less elastase and are less virulent in vivo than their earlier isolated counterparts, suggesting the short-term in vivo evolution of P. aeruginosa leads to attenuated virulence.

scholarly journals Instantaneous Within-Patient Diversity of Pseudomonas aeruginosa Quorum-Sensing Populations from Cystic Fibrosis Lung Infections

2009 ◽  
Vol 77 (12) ◽  
pp. 5631-5639 ◽  
Author(s):  
Cara N. Wilder ◽  
Gopal Allada ◽  
Martin Schuster
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Loss Of Function ◽  
Selective Forces ◽  
Lung Infections

ABSTRACT In the opportunistic pathogen Pseudomonas aeruginosa, acyl-homoserine lactone (acyl-HSL) quorum sensing (QS) regulates biofilm formation and expression of many extracellular virulence factors. Curiously, QS-deficient variants, often carrying mutations in the central QS regulator LasR, are frequently isolated from infections, particularly from cystic fibrosis (CF) lung infections. Very little is known about the proportion and diversity of these QS variants in individual infections. Such information is desirable to better understand the selective forces that drive the evolution of QS phenotypes, including social cheating and innate (nonsocial) benefits. To obtain insight into the instantaneous within-patient diversity of QS, we assayed a panel of 135 concurrent P. aeruginosa isolates from eight different adult CF patients (9 to 20 isolates per patient) for various QS-controlled phenotypes. Most patients contained complex mixtures of QS-proficient and -deficient isolates. Among all patients, deficiency in individual phenotypes ranged from 0 to about 90%. Acyl-HSL, sequencing, and complementation analyses of variants with global loss-of-function phenotypes revealed dependency upon the central QS circuitry genes lasR, lasI, and rhlI. Deficient and proficient isolates were clonally related, implying evolution from a common ancestor in vivo. Our results show that the diversity of QS types is high within and among patients, suggesting diverse selection pressures in the CF lung. A single selective mechanism, be it of a social or nonsocial nature, is unlikely to account for such heterogeneity. The observed diversity also shows that conclusions about the properties of P. aeruginosa QS populations in individual CF infections cannot be drawn from the characterization of one or a few selected isolates.

scholarly journals Genome-Wide Survey of Pseudomonas aeruginosa PA14 Reveals a Role for the Glyoxylate Pathway and Extracellular Proteases in the Utilization of Mucin

2017 ◽  
Vol 85 (8) ◽  
Author(s):  
Jeffrey M. Flynn ◽  
Chi Phan ◽  
Ryan C. Hunter
Keyword(s):  
Pseudomonas Aeruginosa ◽  
High Throughput Sequencing ◽  
Opportunistic Pathogen ◽  
Virulence Determinants ◽  
Extracellular Proteases ◽  
Biofilm Growth ◽  
Content Type ◽  
Airway Infections ◽  
Glyoxylate Pathway

ABSTRACT Chronic airway infections by the opportunistic pathogen Pseudomonas aeruginosa are a major cause of mortality in cystic fibrosis (CF) patients. Although this bacterium has been extensively studied for its virulence determinants, biofilm growth, and immune evasion mechanisms, comparatively little is known about the nutrient sources that sustain its growth in vivo. Respiratory mucins represent a potentially abundant bioavailable nutrient source, although we have recently shown that canonical pathogens inefficiently use these host glycoproteins as a growth substrate. However, given that P. aeruginosa, particularly in its biofilm mode of growth, is thought to grow slowly in vivo, the inefficient use of mucin glycoproteins may be relevant to its persistence within the CF airways. To this end, we used whole-genome fitness analysis, combining transposon mutagenesis with high-throughput sequencing, to identify genetic determinants required for P. aeruginosa growth using intact purified mucins as a sole carbon source. Our analysis reveals a biphasic growth phenotype, during which the glyoxylate pathway and amino acid biosynthetic machinery are required for mucin utilization. Secondary analyses confirmed the simultaneous liberation and consumption of acetate during mucin degradation and revealed a central role for the extracellular proteases LasB and AprA. Together, these studies describe a molecular basis for mucin-based nutrient acquisition by P. aeruginosa and reveal a host-pathogen dynamic that may contribute to its persistence within the CF airways.

scholarly journals Complete Genome Sequence of Pseudomonas aeruginosa Strain AA2 (LMG 27630), an Early Isolate Recovered from the Airway of a German Cystic Fibrosis Patient

2020 ◽  
Vol 9 (26) ◽  
Author(s):  
Andrea Sass ◽  
Tom Coenye
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Respiratory Tract ◽  
Cystic Fibrosis Patient ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Opportunistic Pathogen ◽  
Content Type ◽  
Airway Infections ◽  
Early Isolate

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen that is able to cause various infections, including airway infections in cystic fibrosis patients. Here, we present the complete closed and annotated genome sequence of P. aeruginosa AA2, an isolate obtained early during infection of the respiratory tract of a German cystic fibrosis patient.

scholarly journals GidA Posttranscriptionally Regulates rhl Quorum Sensing in Pseudomonas aeruginosa

2009 ◽  
Vol 191 (18) ◽  
pp. 5785-5792 ◽  
Author(s):  
Rashmi Gupta ◽  
Timothy R. Gobble ◽  
Martin Schuster
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Flavin Adenine Dinucleotide ◽  
Skim Milk ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Trna Modification ◽  
Loss Of Function ◽  
Novel Genes ◽  
Lasa Protease

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa utilizes two interconnected acyl-homoserine lactone quorum-sensing (acyl-HSL QS) systems, LasRI and RhlRI, to regulate the expression of hundreds of genes. The QS circuitry itself is integrated into a complex network of regulation by other factors. However, our understanding of this network is still unlikely to be complete, as a comprehensive, saturating approach to identifying regulatory components has never been attempted. Here, we utilized a nonredundant P. aeruginosa PA14 transposon library to identify additional genes that regulate QS at the level of LasRI/RhlRI. We initially screened all 5,459 mutants for loss of function in one QS-controlled trait (skim milk proteolysis) and then rescreened attenuated candidates for defects in other QS phenotypes (LasA protease, rhamnolipid, and pyocyanin production) to exclude mutants defective in functions other than QS. We identified several known and novel genes, but only two novel genes, gidA and pcnB, affected all of the traits assayed. We characterized gidA, which exhibited the most striking QS phenotypes, further. This gene is predicted to encode a conserved flavin adenine dinucleotide-binding protein involved in tRNA modification. Inactivation of the gene primarily affected rhlR-dependent QS phenotypes such as LasA, pyocyanin, and rhamnolipid production. GidA affected RhlR protein but not transcript levels and also had no impact on LasR and acyl-HSL production. Overexpression of rhlR in a gidA mutant partially restored QS-dependent phenotypes. Taken together, these results indicate that GidA selectively controls QS gene expression posttranscriptionally via RhlR-dependent and -independent pathways.

scholarly journals The Pseudomonas aeruginosa PrrF Small RNAs Regulate Iron Homeostasis during Acute Murine Lung Infection

2017 ◽  
Vol 85 (5) ◽  
Author(s):  
Alexandria A. Reinhart ◽  
Angela T. Nguyen ◽  
Luke K. Brewer ◽  
Justin Bevere ◽  
Jace W. Jones ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Small Rnas ◽  
Iron Homeostasis ◽  
Critical Role ◽  
Opportunistic Pathogen ◽  
Lung Infection ◽  
Content Type ◽  
The Individual

ABSTRACT Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that requires iron for virulence. Iron homeostasis is maintained in part by the PrrF1 and PrrF2 small RNAs (sRNAs), which block the expression of iron-containing proteins under iron-depleted conditions. The PrrF sRNAs also promote the production of the Pseudomonas quinolone signal (PQS), a quorum sensing molecule that activates the expression of several virulence genes. The tandem arrangement of the prrF genes allows for expression of a third sRNA, PrrH, which is predicted to regulate gene expression through its unique sequence derived from the prrF1-prrF2 intergenic (IG) sequence (the PrrHIG sequence). Previous studies showed that the prrF locus is required for acute lung infection. However, the individual functions of the PrrF and PrrH sRNAs were not determined. Here, we describe a system for differentiating PrrF and PrrH functions by deleting the PrrHIG sequence [prrF(ΔHIG)]. Our analyses of this construct indicate that the PrrF sRNAs, but not PrrH, are required for acute lung infection by P. aeruginosa. Moreover, we show that the virulence defect of the ΔprrF1-prrF2 mutant is due to decreased bacterial burden during acute lung infection. In vivo analysis of gene expression in lung homogenates shows that PrrF-mediated regulation of genes for iron-containing proteins is disrupted in the ΔprrF1-prrF2 mutant during infection, while the expression of genes that mediate PrrF-regulated PQS production are not affected by prrF deletion in vivo. Combined, these studies demonstrate that regulation of iron utilization plays a critical role in P. aeruginosa's ability to survive during infection.

In vivo efficacy and pharmacokinetics of biapenem in a murine model of ventilator-associated pneumonia with Pseudomonas aeruginosa

2012 ◽  
Vol 18 (4) ◽  
pp. 472-478 ◽  
Author(s):  
Koichi Yamada ◽  
Katsunori Yanagihara ◽  
Yosuke Harada ◽  
Yoshitomo Morinaga ◽  
Nobuko Araki ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Murine Model ◽  
Ventilator Associated Pneumonia ◽  
In Vivo Efficacy

scholarly journals Selective Sweeps and Parallel Pathoadaptation Drive Pseudomonas aeruginosa Evolution in the Cystic Fibrosis Lung

mBio ◽  
2015 ◽  
Vol 6 (5) ◽  
Author(s):  
Julio Diaz Caballero ◽  
Shawn T. Clark ◽  
Bryan Coburn ◽  
Yu Zhang ◽  
Pauline W. Wang ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Evolutionary Dynamics ◽  
Genomic Analysis ◽  
Opportunistic Pathogen ◽  
Ancestral Population ◽  
Selective Sweeps ◽  
Short Term ◽  
Evolutionary Patterns ◽  
Content Type

ABSTRACT Pulmonary infections caused by Pseudomonas aeruginosa are a recalcitrant problem in cystic fibrosis (CF) patients. While the clinical implications and long-term evolutionary patterns of these infections are well studied, we know little about the short-term population dynamics that enable this pathogen to persist despite aggressive antimicrobial therapy. Here, we describe a short-term population genomic analysis of 233 P. aeruginosa isolates collected from 12 sputum specimens obtained over a 1-year period from a single patient. Whole-genome sequencing and antimicrobial susceptibility profiling identified the expansion of two clonal lineages. The first lineage originated from the coalescence of the entire sample less than 3 years before the end of the study and gave rise to a high-diversity ancestral population. The second expansion occurred 2 years later and gave rise to a derived population with a strong signal of positive selection. These events show characteristics consistent with recurrent selective sweeps. While we cannot identify the specific mutations responsible for the origins of the clonal lineages, we find that the majority of mutations occur in loci previously associated with virulence and resistance. Additionally, approximately one-third of all mutations occur in loci that are mutated multiple times, highlighting the importance of parallel pathoadaptation. One such locus is the gene encoding penicillin-binding protein 3, which received three independent mutations. Our functional analysis of these alleles shows that they provide differential fitness benefits dependent on the antibiotic under selection. These data reveal that bacterial populations can undergo extensive and dramatic changes that are not revealed by lower-resolution analyses. IMPORTANCE Pseudomonas aeruginosa is a bacterial opportunistic pathogen responsible for significant morbidity and mortality in cystic fibrosis (CF) patients. Once it has colonized the lung in CF, it is highly resilient and rarely eradicated. This study presents a deep sampling examination of the fine-scale evolutionary dynamics of P. aeruginosa in the lungs of a chronically infected CF patient. We show that diversity of P. aeruginosa is driven by recurrent clonal emergence and expansion within this patient and identify potential adaptive variants associated with these events. This high-resolution sequencing strategy thus reveals important intraspecies dynamics that explain a clinically important phenomenon not evident at a lower-resolution analysis of community structure.

scholarly journals LasR-deficient Pseudomonas aeruginosa variants increase airway epithelial mICAM-1 expression and enhance neutrophilic lung inflammation

2021 ◽  
Vol 17 (3) ◽  
pp. e1009375
Author(s):  
Lisa C. Hennemann ◽  
Shantelle L. LaFayette ◽  
Julien K. Malet ◽  
Perrine Bortolotti ◽  
Tianxiao Yang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Lung Inflammation ◽  
Airway Epithelial Cells ◽  
Model Systems ◽  
Infection Model ◽  
Airway Epithelial ◽  
Loss Of Function ◽  
Lung Function Decline ◽  
Neutrophilic Inflammation ◽  
Airway Infections

Pseudomonas aeruginosa causes chronic airway infections, a major determinant of lung inflammation and damage in cystic fibrosis (CF). Loss-of-function lasR mutants commonly arise during chronic CF infections, are associated with accelerated lung function decline in CF patients and induce exaggerated neutrophilic inflammation in model systems. In this study, we investigated how lasR mutants modulate airway epithelial membrane bound ICAM-1 (mICAM-1), a surface adhesion molecule, and determined its impact on neutrophilic inflammation in vitro and in vivo. We demonstrated that LasR-deficient strains induce increased mICAM-1 levels in airway epithelial cells compared to wild-type strains, an effect attributable to the loss of mICAM-1 degradation by LasR-regulated proteases and associated with enhanced neutrophil adhesion. In a subacute airway infection model, we also observed that lasR mutant-infected mice displayed greater airway epithelial ICAM-1 expression and increased neutrophilic pulmonary inflammation. Our findings provide new insights into the intricate interplay between lasR mutants, LasR-regulated proteases and airway epithelial ICAM-1 expression, and reveal a new mechanism involved in the exaggerated inflammatory response induced by lasR mutants.

scholarly journals Pseudomonas aeruginosa Forms Biofilms in Acute Infection Independent of Cell-to-Cell Signaling

2007 ◽  
Vol 75 (8) ◽  
pp. 3715-3721 ◽  
Author(s):  
J. Andy Schaber ◽  
W. Jeffrey Triffo ◽  
Sang Jin Suh ◽  
Jeffrey W. Oliver ◽  
Mary Catherine Hastert ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Colonization ◽  
Acute Infection ◽  
Opportunistic Pathogen ◽  
Confocal Scanning Laser Microscopy ◽  
Chronic Infections ◽  
Signaling Mechanism ◽  
Confocal Scanning Laser

ABSTRACT Biofilms are bacterial communities residing within a polysaccharide matrix that are associated with persistence and antibiotic resistance in chronic infections. We show that the opportunistic pathogen Pseudomonas aeruginosa forms biofilms within 8 h of infection in thermally injured mice, demonstrating that biofilms contribute to bacterial colonization in acute infections as well. Using light, electron, and confocal scanning laser microscopy, P. aeruginosa biofilms were visualized within burned tissue surrounding blood vessels and adipose cells. Although quorum sensing (QS), a bacterial signaling mechanism, coordinates differentiation of biofilms in vitro, wild-type and QS-deficient P. aeruginosa strains formed similar biofilms in vivo. Our findings demonstrate that P. aeruginosa forms biofilms on specific host tissues independently of QS.

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