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Study of the effect of antimicrobial peptide mimic, CSA-13, on an established biofilm formed by Pseudomonas aeruginosa

25 Feb 2013

Abstract

The formation of a Pseudomonas aeruginosa biofilm, a complex structure enclosing bacterial cells in an extracellular polymeric matrix, is responsible for persistent infections in cystic fibrosis patients leading to a high rate of morbidity and mortality. The protective environment created by the tridimensional structure reduces the susceptibility of the bacteria to conventional antibiotherapy. Cationic steroid antibiotics (CSA)-13, a nonpeptide mimic of antimicrobial peptides with antibacterial activity on planktonic cultures, was evaluated for its ability to interact with sessile cells. Using confocal laser scanning microscopy, we demonstrated that the drug damaged bacteria within an established biofilm showing that penetration did not limit the activity of this antimicrobial agent against a biofilm. When biofilms were grown during exposure to shear forces and to a continuous medium flow allowing the development of robust structures with a complex architecture, CSA-13 reached the bacteria entrapped in the biofilm within 30 min. The permeabilizing effect of CSA-13 could be associated with the death of the bacteria. In static conditions, the compound did not perturb the architecture of the biofilm. This study confirms the potential of CSA-13 as a new strategy to combat persistent infections involving biofilms formed by P. aeruginosa.

Persistent Pseudomonas aeruginosa respiratory infections are linked to the formation of a biofilm and are a common cause of morbidity and mortality in cystic fibrosis patients. The worldwide increase resistance to conventional antibiotics has motived the search for new strategies to combat chronic infections. Confocal laser scanning microscopy was used in this study to demonstrate the ability of the drug to kill bacteria within a complex and robust biofilm. Cationic steroid antibiotics (CSA)-13 offers promising potential to treat not only acute infections caused by planktonic bacteria but also chronic infections involving biofilms.

Date: 
25 February 2013

Click here to view the full article which appeared in MicrobiologyOpen