Dataset Information

Characterization of the virulence of Pseudomonas aeruginosa strains causing ventilator-associated pneumonia.

ABSTRACT:

Background

The objective of this study was to evaluate the virulence of P. aeruginosa ventilator-associated pneumonia (VAP) strains (cases) in terms of biofilm production and other phenotypic and genotypic virulence factors compared to P. aeruginosa strains isolated from other infections (controls).

Methods

Biofilm production was tested to assess biomass production and metabolic activity using crystal violet binding assay and XTT assay, respectively. Pigment production (pyocyanin and pyoverdine) was evaluated using cetrimide agar. Virulence genes were detected by conventional multiplex PCR and virulence was tested in an in vivo model in Galleria mellonella larvae.

Results

We did not find statistically significant differences between VAP and no-VAP strains (p >?0.05) regarding biofilm production. VAP strains had no production of pyocyanin after 24?h of incubation (p =?0.023). The distribution of virulence genes between both groups were similar (p?>?0.05). VAP strains were less virulent than non-VAP strains in an in vivo model of G. mellonella (p ConclusionThe virulence of VAP-Pseudomonas aeruginosa does not depend on biofilm formation, production of pyoverdine or the presence of some virulence genes compared to P. aeruginosa isolated from non-invasive locations. However, VAP strains showed attenuated virulence compared to non-VAP strains in an in vivo model of G. mellonella.

SUBMITTER: Alonso B

PROVIDER: S-EPMC7706020 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Publications

Characterization of the virulence of Pseudomonas aeruginosa strains causing ventilator-associated pneumonia.

Alonso Beatriz B Fernández-Barat Laia L Di Domenico Enea Gino EG Marín Mercedes M Cercenado Emilia E Merino Irene I de Pablos Manuela M Muñoz Patricia P Guembe María M

BMC infectious diseases 20201201 1

<h4>Background</h4>The objective of this study was to evaluate the virulence of P. aeruginosa ventilator-associated pneumonia (VAP) strains (cases) in terms of biofilm production and other phenotypic and genotypic virulence factors compared to P. aeruginosa strains isolated from other infections (controls).<h4>Methods</h4>Biofilm production was tested to assess biomass production and metabolic activity using crystal violet binding assay and XTT assay, respectively. Pigment production (pyocyanin ...[more]

PMID: 33261585

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Project description:BackgroundProbiotics could prevent Pseudomonas aeruginosa colonization in lower respiratory tract (LRT) and reduced P. aeruginosa ventilator-associated pneumonia (VAP) rate. Recent studies also suggested that probiotics could improve lung inflammation in mice infected with P. aeruginosa. It seems that microbiota regulation may be a potential therapy for P. aeruginosa VAP patients. However, we know less about the LRT microbial composition and its correlation with prognosis in P. aeruginosa VAP patients. This study aimed to characterize LRT microbiota in P. aeruginosa VAP patients and explore the relationship between microbiota and patient prognosis.MethodsDeep endotracheal secretions were sampled from subjects via intubation. Communities were identified by 16S ribosomal RNA gene sequencing. The relationship between microbiota and the prognosis of P. aeruginosa VAP patients were evaluated. Clinical pulmonary infection score and the survival of intensive care unit were both the indicators of patient prognosis.ResultsIn this study, the LRT microbial composition of P. aeruginosa VAP patients was significantly different from non-infected intubation patients, and showed significant individual differences, forming two clusters. According to the predominant phylum of each cluster, these two clusters were named Pro cluster and Fir-Bac cluster respectively. Patients from Pro cluster were dominated by Proteobacteria (adj.P < 0.001), while those from Fir-Bac cluster were dominated by Firmicutes, and Bacteroidetes (both adj.P < 0.001). These two varied clusters (Pro and Fir-Bac cluster) were associated with the patients' primary disease (χ2-test, P < 0.0001). The primary disease of the Pro cluster mainly included gastrointestinal disease (63%), and the Fir-Bac cluster was predominantly respiratory disease (89%). During the two-week dynamic observation period, despite the use of antibiotics, the dominant genera and Shannon diversity of the LRT microbiota did not change significantly in patients with P. aeruginosa VAP. In prognostic analysis, we found a significant negative correlation between Lactobacillus and clinical pulmonary infection score on the day of diagnosis (P = 0.014); but we found no significant difference of microbial composition between survivors and non-survivors.ConclusionsLRT microbial composition was diversified among P. aeruginosa VAP patients, forming two clusters which were associated with the primary diseases of the patients.

Project description:Ventilator-associated pneumonia is an important clinical manifestation of the nosocomial pathogen Pseudomonas aeruginosa. We characterized the correlates of protection with MEDI3902, a bispecific human IgG1 monoclonal antibody that targets the P. aeruginosa type 3 secretion system PcrV protein and the Psl exopolysaccharide, in a rabbit model of ventilator-associated pneumonia using lung-protective, low-tidal-volume mechanical ventilation. Rabbits infused with MEDI3902 prophylactically were protected, whereas those pretreated with irrelevant isotype-matched control IgG (c-IgG) succumbed between 12 and 44 h postinfection (100% survival [8/8 rabbits] versus 0% survival [8/8 rabbits]; P < 0.01 by log rank test). Lungs from rabbits pretreated with c-IgG, but not those pretreated with MEDI3902, had bilateral, multifocal areas of marked necrosis, hemorrhage, neutrophilic inflammatory infiltrate, and diffuse fibrinous edema in alveolar spaces. All rabbits pretreated with c-IgG developed worsening bacteremia that peaked at the time of death, whereas only 38% of rabbits pretreated with MEDI3902 (3/8 rabbits) developed such high-grade bacteremia (two-sided Fisher's exact test, P = 0.026). Biomarkers associated with acute respiratory distress syndrome were evaluated longitudinally in blood samples collected every 2 to 4 h to assess systemic pathophysiological changes in rabbits pretreated with MEDI3902 or c-IgG. Biomarkers were sharply increased or decreased in rabbits pretreated with c-IgG but not those pretreated with MEDI3902, including the ratio of arterial oxygen partial pressure to the fraction of inspired oxygen of <300, hypercapnia or hypocapnia, severe lactic acidosis, leukopenia, and neutropenia. Cytokines and chemokines associated with acute respiratory distress syndrome were significantly downregulated in lungs from rabbits pretreated with MEDI3902, compared with c-IgG. These results suggest that MEDI3902 prophylaxis could have potential clinical utility for decreasing the severity of P. aeruginosa ventilator-associated pneumonia.

Dataset Information

Characterization of the virulence of Pseudomonas aeruginosa strains causing ventilator-associated pneumonia.

Background

Methods

Results

Publications

Characterization of the virulence of Pseudomonas aeruginosa strains causing ventilator-associated pneumonia.

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