Monitoring genome evolution ex vivo: reversible chromosomal integration of a 106 kb plasmid at two tRNALys gene loci in sequential Pseudomonas aeruginosa airway isolates The GenBank accession numbers for the sequences reported in this paper are AF285416–AF285426.

Introduction: We previously reported that extracellular vesicles (EVs) released during Escherichia coli bacterial pneumonia were inflammatory, and administration of high molecular weight hyaluronic acid (HMW HA) suppressed several indices of acute lung injury (ALI) from Escherichia coli pneumonia by binding to these inflammatory EVs. The current study was undertaken to study the therapeutic effects of HMW HA in ex vivo perfused human lungs injured with Pseudomonas aeruginosa (PA)103 bacterial pneumonia. Methods: For lungs with baseline alveolar fluid clearance (AFC)<10%/h, HMW HA 1 or 2 mg was injected intravenously after 1 h (N = 4-9), and EVs released during PA pneumonia were collected from the perfusate over 6 h. For lungs with baseline AFC>10%/h, HMW HA 2 mg was injected intravenously after 1 h (N = 6). In vitro experiments were conducted to evaluate the effects of HA on inflammation and bacterial phagocytosis. Results: For lungs with AFC<10%/h, administration of HMW HA intravenously significantly restored AFC and numerically decreased protein permeability and alveolar inflammation from PA103 pneumonia but had no effect on bacterial counts at 6 h. However, HMW HA improved bacterial phagocytosis by human monocytes and neutrophils and suppressed the inflammatory properties of EVs released during pneumonia on monocytes. For lungs with AFC>10%/h, administration of HMW HA intravenously improved AFC from PA103 pneumonia but had no significant effects on protein permeability, inflammation or bacterial counts. Discussion: In the presence of impaired alveolar epithelial transport capacity, administration of HMW HA improved the resolution of pulmonary edema from Pseudomonas PA103 bacterial pneumonia.

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Adaptive resistance of Pseudomonas aeruginosa induced by aminoglycosides and killing kinetics in a rabbit endocarditis model.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.41.4.823 ◽

1997 ◽

Vol 41 (4) ◽

pp. 823-826 ◽

Cited By ~ 40

Author(s):

Y Q Xiong ◽

J Caillon ◽

M F Kergueris ◽

H Drugeon ◽

D Baron ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Single Dose ◽

Ex Vivo ◽

Day Treatment ◽

Total Daily Dose ◽

Once Daily ◽

Adaptive Resistance ◽

Dosing Regimens

Adaptive resistance following the first exposure to aminoglycosides is a recently described in vitro phenomenon in Pseudomonas aeruginosa and other aerobic gram-negative bacilli. We investigated the in vivo relevance of adaptive resistance in P. aeruginosa following a single dose of amikacin in the experimental rabbit endocarditis model. Rabbits with P. aeruginosa endocarditis received either no therapy (control) or a single intravenous (i.v.) dose of amikacin (80 mg/kg of body weight) at 24 h postinfection, after which they were sacrificed at 5, 8, 12, 16, or 24 h postdose. Excised aortic vegetations were subsequently exposed ex vivo to amikacin at 2.5, 5, 10 or 20 times the MIC for 90 min. In vivo adaptive resistance was identified when amikacin-induced pseudomonal killing within excised aortic vegetations was less in animals receiving single-dose amikacin in vivo than in vegetations from control animals not receiving amikacin in vivo. Maximal adaptive resistance occurred between 8 and 16 h after the in vivo amikacin dose, with complete refractoriness to ex vivo killing by amikacin seen at 12 h postdose. By 24 h postdose, bacteria within excised vegetations had partially recovered their initial amikacin susceptibility. In a parallel treatment study, we demonstrated that amikacin given once daily (but not twice daily) at a total dose of 80 mg/kg i.v. for 1-day treatment significantly reduced pseudomonal densities within aortic vegetations versus those in untreated controls. When therapy was continued for 3 days with the same total daily dose (80 mg/kg/day), amikacin given once or twice daily significantly reduced intravegetation pseudomonal densities versus those in controls. However, amikacin given once daily was still more effective than the twice-daily regimen. These data confirm the induction of aminoglycoside adaptive resistance in vivo and further support the advantages of once-daily aminoglycoside dosing regimens in the treatment of serious pseudomonal infections.

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Chestnut Honey and Bacteriophage Application to Control Pseudomonas aeruginosa and Escherichia coli Biofilms: Evaluation in an ex vivo Wound Model

Frontiers in Microbiology ◽

10.3389/fmicb.2018.01725 ◽

2018 ◽

Vol 9 ◽

Cited By ~ 20

Author(s):

Ana Oliveira ◽

Jéssica C. Sousa ◽

Ana C. Silva ◽

Luís D. R. Melo ◽

Sanna Sillankorva

Keyword(s):

Escherichia Coli ◽

Pseudomonas Aeruginosa ◽

Ex Vivo ◽

Wound Model

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DNA Binding: a Novel Function of Pseudomonas aeruginosa Type IV Pili

Journal of Bacteriology ◽

10.1128/jb.187.4.1455-1464.2005 ◽

2005 ◽

Vol 187 (4) ◽

pp. 1455-1464 ◽

Cited By ~ 96

Author(s):

Erin J. van Schaik ◽

Carmen L. Giltner ◽

Gerald F. Audette ◽

David W. Keizer ◽

Daisy L. Bautista ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Dna Binding ◽

Biofilm Formation ◽

Quaternary Structure ◽

Natural Transformation ◽

Ex Vivo ◽

Specific Binding ◽

Type Iv Pili ◽

Type Iv ◽

Bacteriophage Infection

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa produces multifunctional, polar, filamentous appendages termed type IV pili. Type IV pili are involved in colonization during infection, twitching motility, biofilm formation, bacteriophage infection, and natural transformation. Electrostatic surface analysis of modeled pilus fibers generated from P. aeruginosa strain PAK, K122-4, and KB-7 pilin monomers suggested that a solvent-exposed band of positive charge may be a common feature of all type IV pili. Several functions of type IV pili, including natural transformation and biofilm formation, involve DNA. We investigated the ability of P. aeruginosa type IV pili to bind DNA. Purified PAK, K122-4, and KB-7 pili were observed to bind both bacterial plasmid and salmon sperm DNA in a concentration-dependent and saturable manner. PAK pili had the highest affinity for DNA, followed by K122-4 and KB-7 pili. DNA binding involved backbone interactions and preferential binding to pyrimidine residues even though there was no evidence of sequence-specific binding. Pilus-mediated DNA binding was a function of the intact pilus and thus required elements present in the quaternary structure. However, binding also involved the pilus tip as tip-specific, but not base-specific, antibodies inhibited DNA binding. The conservation of a Thr residue in all type IV pilin monomers examined to date, along with the electrostatic data, implies that DNA binding is a conserved function of type IV pili. Pilus-mediated DNA binding could be important for biofilm formation both in vivo during an infection and ex vivo on abiotic surfaces.

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Expression of ExsA in trans Confers Type III Secretion System-Dependent Cytotoxicity on Noncytotoxic Pseudomonas aeruginosa Cystic Fibrosis Isolates

Infection and Immunity ◽

10.1128/iai.69.1.538-542.2001 ◽

2001 ◽

Vol 69 (1) ◽

pp. 538-542 ◽

Cited By ~ 55

Author(s):

Denis Dacheux ◽

Ina Attree ◽

Bertrand Toussaint

Keyword(s):

Cystic Fibrosis ◽

Pseudomonas Aeruginosa ◽

Transcriptional Activation ◽

Type Iii Secretion ◽

Ex Vivo ◽

Type Iii Secretion System ◽

Secretion System ◽

Type Iii ◽

In Trans

ABSTRACT Twelve Pseudomonas aeruginosa cystic fibrosis isolates that are not able to exert a type III secretion system (TTSS)-dependent cytotoxicity towards phagocytes have been further studied. The strains, although possessing TTSS genes and exsA, which encodes a positive regulator of the TTSS regulon, showed no transcriptional activation of the exsCBA regulatory operon. The expression of exsA in trans restored the in vitro secretion of TTSS proteins and ex vivo cytotoxicity.

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