<i>Pseudomonas aeruginosa</i> cells attached to a surface display a typical proteome early as 20 minutes of incubation

<div><p>Biofilms are present in all environments and often result in negative effects due to properties of the biofilm lifestyle and especially antibiotics resistance. Biofilms are associated with chronic infections. Controlling bacterial attachment, the first step of biofilm formation, is crucial for fighting against biofilm and subsequently preventing the persistence of infection. Thus deciphering the underlying molecular mechanisms involved in attachment could allow discovering molecular targets from it would be possible to develop inhibitors against bacterial colonization and potentiate antibiotherapy. To identify the key components and pathways that aid the opportunistic pathogen <i>Pseudomonas aeruginosa</i> in attachment we performed for the first time a proteomic analysis as early as after 20 minutes of incubation using glass wool fibers as a surface. We compared the protein contents of the attached and unattached bacteria. Using mass spectrometry, 3043 proteins were identified. Our results showed that, as of 20 minutes of incubation, using stringent quantification criteria 616 proteins presented a modification of their abundance in the attached cells compared to their unattached counterparts. The attached cells presented an overall reduced gene expression and characteristics of slow-growing cells. The over-accumulation of outer membrane proteins, periplasmic folding proteins and O-antigen chain length regulators was also observed, indicating a profound modification of the cell envelope. Consistently the sigma factor AlgU required for cell envelope homeostasis was highly over-accumulated in attached cells. In addition our data suggested a role of alarmone (p)ppGpp and polyphosphate during the early attachment phase. Furthermore, almost 150 proteins of unknown function were differentially accumulated in the attached cells. Our proteomic analysis revealed the existence of distinctive biological features in attached cells as early as 20 minutes of incubation. Analysis of some mutants demonstrated the interest of this proteomic approach in identifying genes involved in the early phase of adhesion to a surface.</p></div

Attachment capacity of <i>P</i>. <i>aeruginosa</i> PAO1 reference strains and isogenic mutants.

<p>The attachment capacity of reference strains, mutants and complemented mutants (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0180341#pone.0180341.s011" target="_blank">S9A Table</a>) was assayed after 20 min at 37°C in our glass wool system (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0180341#sec021" target="_blank">materials and methods</a>). Only the attachment capacity of <i>P</i>. <i>aeruginosa</i> PAO1 was presented for reason of clarity, the other reference strains (PAO1-L and MPAO1) showed results similar to those obtained for PAO1. In the same manner, the attachment capacities of the different mutants were not altered by introducing the empty plasmid pUCP20 or pUCP22. For each of the mutants presented herein, the complemented strain displayed an attachment capacity ranging from 80% to 140% of the reference strain (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0180341#pone.0180341.s010" target="_blank">S8 Table</a>). The results corresponded to the average of 3 independent experiments (bar = SD).</p

CT Imaging Assessment of Response to Treatment in Allergic Bronchopulmonary Aspergillosis in Adults With Bronchial Asthma

International audienceBackgroundOne of the major challenges in managing allergic bronchopulmonary aspergillosis (ABPA) remains consistent and reproducible assessment of response to treatment.Research questionWhat are the most relevant changes in computed tomography (CT-scan) parameters over time for assessing response to treatment?Study Design and MethodsIn this ancillary study of a randomized clinical trial (NEBULAMB), asthmatic patients with available CT-scan and without exacerbation during a 4-month ABPA exacerbation treatment period (corticosteroids and itraconazole) were included. Changed CT-scan parameters were assessed by systematic analyses of CT-scan findings at initiation (M0) and end of treatment (M4). CT-scans were assessed by two radiologists blinded to the clinical data. Radiological parameters were determined by selecting those showing significant changes over time. Improvement of at least one, without worsening of the others, defined the radiological response. Agreement between radiological changes, clinical and immunologic responses was likewise investigated.ResultsAmong the 139 originally randomized patients, 132 were included. We identified 5 CT-scan parameters showing significant changes at M4: mucoid impaction extent, mucoid impaction density, centrilobular micronodules, consolidation/ground-glass opacities and bronchial wall thickening (P<0.05). These changes were only weakly associated with one another, except for mucoid impaction extent and density. No agreement was observed between clinical or immunologic and radiological responses, assessed as an overall response, or considering each of the parameters (Cohen’s κ, -0.01 to 0.24).InterpretationChanges in extent and density of mucoid impactions, centrilobular micronodules, consolidation/ground-glass opacities and thickening of the bronchial walls were found to be the most relevant CT-scan parameters to assess radiological response to treatment. A clinical, immunologic and radiological multidimensional approach should be adopted to assess outcomes, probably with a composite definition of response to treatment