scholarly journals Transcriptome analyses and biofilm-forming characteristics of a clonal Pseudomonas aeruginosa from the cystic fibrosis lung

2008 ◽  
Vol 57 (12) ◽  
pp. 1454-1465 ◽  
Author(s):  
Jim Manos ◽  
Jonathan Arthur ◽  
Barbara Rose ◽  
Pholawat Tingpej ◽  
Carina Fung ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Microarray Data ◽  
Reference Strain ◽  
Differentially Expressed Gene ◽  
Differentially Expressed ◽  
Strain Pao1 ◽  
Eastern Australia ◽  
Forming Characteristics ◽  
Insight Into

Transmissible Pseudomonas aeruginosa clones potentially pose a serious threat to cystic fibrosis (CF) patients. The AES-1 clone has been found to infect up to 40 % of patients in five CF centres in eastern Australia. Studies were carried out on clonal and non-clonal (NC) isolates from chronically infected CF patients, and the reference strain PAO1, to gain insight into the properties of AES-1. The transcriptomes of AES-1 and NC isolates, and of PAO1, grown planktonically and as a 72 h biofilm were compared using PAO1 microarrays. Microarray data were validated using real-time PCR. Overall, most differentially expressed genes were downregulated. AES-1 differentially expressed bacteriophage genes, novel motility genes, and virulence and quorum-sensing-related genes, compared with both PAO1 and NC. AES-1 but not NC biofilms significantly downregulated aerobic respiration genes compared with planktonic growth, suggesting enhanced anaerobic/microaerophilic growth by AES-1. Biofilm measurement showed that AES-1 formed significantly larger and thicker biofilms than NC or PAO1 isolates. This may be related to expression of the gene PA0729, encoding a biofilm-enhancing bacteriophage, identified by PCR in all AES-1 but few NC isolates (n=42). Links with the Liverpool epidemic strain included the presence of PA0729 and the absence of the bacteriophage gene cluster PA0632–PA0639. No common markers were found with the Manchester strain. No particular differentially expressed gene in AES-1 could definitively be ascribed a role in its infectivity, thus increasing the likelihood that AES-1 infectivity is multi-factorial and possibly involves novel genes. This study extends our understanding of the transcriptomic and genetic differences between clonal and NC strains of P. aeruginosa from CF lung.

scholarly journals A Cystic Fibrosis Epidemic Strain of Pseudomonas aeruginosa Displays Enhanced Virulence and Antimicrobial Resistance

2005 ◽  
Vol 187 (14) ◽  
pp. 4908-4920 ◽  
Author(s):  
Prabhakar Salunkhe ◽  
Catherine H. M. Smart ◽  
J. Alun W. Morgan ◽  
Stavroula Panagea ◽  
Martin J. Walshaw ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Resistance ◽  
Reference Strain ◽  
Efflux Pump ◽  
Epidemic Strain ◽  
Strain Pao1 ◽  
The United Kingdom ◽  
Infection Episode

ABSTRACT The Liverpool epidemic strain (LES) of Pseudomonas aeruginosa is a transmissible aggressive pathogen of cystic fibrosis (CF) patients. We compared transcriptome profiles of two LES isolates with each other and with a laboratory and genetic reference strain (PAO1) after growth to late exponential phase and following exposure to oxidative stress. Both LES isolates exhibited enhanced antimicrobial resistances linked to specific mutations in efflux pump genes. Although transcription of AmpC β-lactamase was up-regulated in both, one LES isolate contained a specific mutation rendering the ampC gene untranslatable. The virulence-related quorum-sensing (QS) regulon of LES431, an isolate that caused pneumonia in the non-CF parent of a CF patient, was considerably up-regulated in comparison to either isolate LES400, associated with a chronic CF infection, or strain PAO1. Premature activation of QS genes was detected in isolates from both non-CF parents and the CF patient in a previously reported infection episode. LES isolates lacking the up-regulated QS phenotype contained different frameshift mutations in lasR. When fed to Drosophila melanogaster, isolate LES431 killed the fruit flies more readily than either isolate LES400 or strain PAO1, indicating that virulence varies intraclonally. The LES may represent a clone with enhanced virulence and antimicrobial resistance characteristics that can vary or are lost due to mutations during long-term colonization but have contributed to the successful spread of the lineage throughout the CF population of the United Kingdom.

scholarly journals Mutations in β-Lactamase AmpC Increase Resistance of Pseudomonas aeruginosa Isolates to Antipseudomonal Cephalosporins

2015 ◽  
Vol 59 (10) ◽  
pp. 6248-6255 ◽  
Author(s):  
M. Berrazeg ◽  
K. Jeannot ◽  
Véronique Yvette Ntsogo Enguéné ◽  
I. Broutin ◽  
S. Loeffert ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Reference Strain ◽  
Binding Pocket ◽  
Amino Acid Substitutions ◽  
Substrate Binding Pocket ◽  
Strain Pao1 ◽  
Gram Negative ◽  
Content Type ◽  
Omega Loop ◽  
New Mutations

ABSTRACTMutation-dependent overproduction of intrinsic β-lactamase AmpC is considered the main cause of resistance of clinical strains ofPseudomonas aeruginosato antipseudomonal penicillins and cephalosporins. Analysis of 31 AmpC-overproducing clinical isolates exhibiting a greater resistance to ceftazidime than to piperacillin-tazobactam revealed the presence of 17 mutations in the β-lactamase, combined with various polymorphic amino acid substitutions. When overexpressed in AmpC-deficientP. aeruginosa4098, the genes coding for 20/23 of these AmpC variants were found to confer a higher (2-fold to >64-fold) resistance to ceftazidime and ceftolozane-tazobactam than did the gene from reference strain PAO1. The mutations had variable effects on the MICs of ticarcillin, piperacillin-tazobactam, aztreonam, and cefepime. Depending on their location in the AmpC structure and their impact on β-lactam MICs, they could be assigned to 4 distinct groups. Most of the mutations affecting the omega loop, the R2 domain, and the C-terminal end of the protein were shared with extended-spectrum AmpCs (ESACs) from other Gram-negative species. Interestingly, two new mutations (F121L and P154L) were predicted to enlarge the substrate binding pocket by disrupting the stacking between residues F121 and P154. We also found that the reported ESACs emerged locally in a variety of clones, some of which are epidemic and did not require hypermutability. Taken together, our results show thatP. aeruginosais able to adapt to efficacious β-lactams, including the newer cephalosporin ceftolozane, through a variety of mutations affecting its intrinsic β-lactamase, AmpC. Data suggest that the rates of ESAC-producing mutants are ≥1.5% in the clinical setting.

scholarly journals Use of suppression subtractive hybridization to examine the accessory genome of the Liverpool cystic fibrosis epidemic strain of Pseudomonas aeruginosa

2006 ◽  
Vol 55 (6) ◽  
pp. 677-688 ◽  
Author(s):  
Catherine H. M. Smart ◽  
Martin J. Walshaw ◽  
C. Anthony Hart ◽  
Craig Winstanley
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Suppression Subtractive Hybridization ◽  
Sequence Data ◽  
Pcr Amplification ◽  
Subtractive Hybridization ◽  
Epidemic Strain ◽  
Strain Pao1 ◽  
The Uk ◽  
Specific Sequences

The Liverpool epidemic strain (LES) of Pseudomonas aeruginosa has been highly successful at colonizing cystic fibrosis (CF) patients throughout the UK, has replaced previously established strains in CF patients, has caused infections of non-CF parents of CF patients, and can cause greater morbidity in CF than other strains of P. aeruginosa. Using suppression subtractive hybridization (SSH) to identify strain-specific sequences, a diagnostic test for the LES based on PCR amplification of SSH sequence PS21 had previously been developed. In this study, the SSH sequence database of LES was substantially increased, using both extension of previous sequences and new rounds of subtraction. Of 92 SSH sequences identified as present in the LES but absent from strain PAO1, 25 were assessed for prevalence amongst a strain panel consisting mainly of LES and non-LES CF isolates. Preliminary analysis of genome sequence data indicated that all SSH sequences that were LES specific or found only rarely in other strains of P. aeruginosa were present on one of three contigs. All of the SSH sequences screened were either unstable amongst LES isolates or were not completely LES specific. Rare false positives were found with the PS21 test. The authors suggest that a second PCR assay designed to detect SSH sequence LESF9 can be used to confirm the identity of the most prevalent CF epidemic lineage in the UK.

scholarly journals Evolution of Bacterial “Frenemies”

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Sophie E. Darch ◽  
Carolyn B. Ibberson ◽  
Marvin Whiteley
Keyword(s):  
Cystic Fibrosis ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Community Assembly ◽  
Microbial Interactions ◽  
Microbial Interaction ◽  
Microbial Dynamics ◽  
Lung Infections ◽  
Insight Into ◽  
Polymicrobial Infections

ABSTRACT Chronic polymicrobial infections are associated with increased virulence compared to monospecies infections. However, our understanding of microbial dynamics during polymicrobial infection is limited. A recent study by Limoli and colleagues (D. H. Limoli, G. B. Whitfield, T. Kitao, M. L. Ivey, M. R. Davis, Jr., et al., mBio 8:e00186-17, 2017, https://doi.org/10.1128/mBio.00186-17 !) provides insight into a mechanism that may contribute to the coexistence of Pseudomonas aeruginosa and Staphylococcus aureus in the cystic fibrosis (CF) lung. CF lung infections have frequently been used to investigate microbial interactions due to both the complex polymicrobial community and chronic nature of these infections. The hypothesis of Limoli et al. is that the conversion of P. aeruginosa to its mucoidy phenotype during chronic CF infection promotes coexistence by diminishing its ability to kill S. aureus. Highlighting a new facet of microbial interaction between two species that are traditionally thought of as competitors, this study provides a platform for studying community assembly in a relevant infection setting.

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