<i>Pseudomonas aeruginosa</i> is an opportunistic pathogen found ubiquitously in the environment and commonly associated with airway infection in patients with cystic fibrosis.<i>P. aeruginosa</i> strain PAO1 is one of the most commonly used laboratory-adapted research strains and is a standard laboratory-adapted strain in multiple laboratories and strain banks worldwide.
Twenty-four hour biofilms formed by the P. aeruginosa strain PAO1 and cystic fibrosis (CF) isolates were tested for susceptibility to oxyclozanide and tobramycin killing using BacTiter-Glo™ and cfu.
While a reduction in cell growth was observed after 8 h of CORM application, either no effect or even a slight increase in cell densities and the amount of biofilm was observed after 24 h. This variation could be partly explained by differences in bacterial virulence traits: while CF isolates showed attenuated <i>in vivo</i> virulence and growth compared to strain PAO1, they formed much more biofilm, which could have potentially protected them from the CORM.
By exploiting this unstable phenotype, we isolated 34 spontaneous nonmucoid variants arising from the mucoid strain PDO300, a PAO1 derivative containing the <i>mucA22</i> allele commonly found in mucoid CF isolates.
In the present study, we evaluate the volatile metabolites produced by P. aeruginosa (PAO1)-infected, RSV-infected, co-infected, or uninfected CF bronchial epithelial (CFBE) cells, in vitro.
In the present work, P. aeruginosa strain PAO1, and four multidrug resistant (MDR) isolates from chronically infected CF individuals, were grown as 48-hour biofilms in a static biofilm slide chamber model.
This study demonstrates the effect of CAP on the whole proteome of Pseudomonas aeruginosa PAO1 biofilms, which is a dominant pathogen in cystic fibrosis and medical device-related infections.
Here, we demonstrate that GaPPIX is indeed capable of inhibiting the growth of clinical <i>P. aeruginosa</i> strains under iron-deplete conditions, as those encountered by bacteria during infection, and that GaPPIX inhibition is reversed by iron.Using <i>P. aeruginosa</i> PAO1 as model organism, we show that GaPPIX enters cells through both the heme-uptake systems <i>has</i> and <i>phu</i>, primarily <i>via</i> the PhuR receptor which plays a crucial role in <i>P. aeruginosa</i> adaptation to the CF lung.
We investigated this by performing both SWATH mass spectrometry and data-dependent SPS-MS3 of TMT-labeled peptides to profile the proteomes of two P. aeruginosa CF isolates, PASS2 and PASS3, and a laboratory reference strain, PAO1, grown under hypoxic stress (O<sub>2</sub> < 1%) in media that mimic the nutrient components of the CF lung.
PAO1 exoproducts also dampened F508del-CFTR rescue by VRT-325 or Vx-809 correctors in CF cells, whereas PAO1Δ<i>lasR</i> had no impact.Importantly, treatment of <i>P. aeruginosa</i> cultures with a quorum sensing inhibitor (HDMF) prevented the negative effect of <i>P. aeruginosa</i> exoproducts on wt-CFTR and preserved CFTR rescue by correctors in CF AEC.
The CF isolates showed marked differences in membrane protein expression in comparison with PAO1 including up-regulation of drug resistance proteins (MexY, MexB, MexC) and down-regulation of chemotaxis and aerotaxis proteins (PA1561, PctA, PctB) and motility and adhesion proteins (FliK, FlgE, FliD, PilJ).
These variations indicate significant differences between the metabolism and physiology of P. aeruginosa CF isolates and PAO1 that cannot be detected at the genome level alone.
A PAO1ΔoprD mutant was complemented with the oprD genes from five carbapenem-resistant CF strains exhibiting very low amounts of mutated OprD porins in their outer membrane despite wild-type levels of oprD transcripts.
We demonstrated using promoter::fusion clones of P. aeruginosa PAO1 and clinical strains collected from CF patients that OpdQ was transcriptionally repressed under low oxygen but increased in the presence of nitrate.
To test this hypothesis, the reference strain PAO1 and clonal pairs of CF clinical hypermutable and wild-type P. aeruginosa strains belonging to different genotypes were subjected to competition experiments in vitro and in a mouse model of chronic infection.
Infection with the P. aeruginosa strain PAO1 up-modulated the expression of 14 (27%) genes in IB3-1 cells and 15 (29%) genes in CF primary respiratory epithelia grown at an air-liquid interface, including chemokines (IL-8, growth-regulated Gro-α/β/γ proteins, and granulocyte chemotactic peptide-2 [GCP-2]), proinflammatory cytokines (IL-1α/β, IL-6, and TNF-α), and the intercellular adhesion molecule-1, nuclear factor kB1, toll like receptor 2, and human defensin B4 genes, confirming that bronchial epithelium is an important source of inflammatory mediators.
The results demonstrate that a mucoid CF isolate of P. aeruginosa responds to biofilm-associated growth and [Ca2+] in a fashion similar to strain PAO1, but that strain-specific differences may allow this CF isolate to successfully colonize the pulmonary environment.
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.
Using strain PAO1 whole genome DNA microarrays, we assessed the genomic variation in P. aeruginosa strains isolated from young children with CF (6 months to 8 years of age) as well as from the environment.
AM and DC were susceptible to cell death induced by the laboratory PA isolates PAO1, PAK and PA103, as well as a mucoid derivative of PAO1 and PA isolates derived from sputum of individuals with CF.
We examined the induction of apoptosis in response to Pseudomonas aeruginosa PAO1 in normal cells and several cystic fibrosis (CF) and corrected cell lines.
In this report, we show that mutations in the muc loci, (muc-2, muc-22, and muc-23, in the standard genetic P. aeruginosa strain PAO, as well as a mapped muc allele in an isolate from a cystic fibrosis patient) affect transcription of algD and algR.