1. Potent antimicrobial peptides against Legionella pneumophila and its environmental host, Acanthamoeba castellanii
Margot Schlusselhuber, Vincent Humblot, Sandra Casale, Christophe Méthivier, Julien Verdon, Matthias Leippe, Jean-Marc Berjeaud Appl Microbiol Biotechnol. 2015 Jun;99(11):4879-91. doi: 10.1007/s00253-015-6381-z. Epub 2015 Jan 16.
Legionella pneumophila, the major causative agent of Legionnaires' disease, is most often found in the environment in close association with free-living amoebae, leading to persistence, spread, biocide resistance, and elevated virulence of the bacterium. In the present study, we evaluated the anti-Legionella and anti-Acanthamoeba activities of three alpha-helical antimicrobial peptides (AMPs), namely, NK-2, Ci-MAM-A24, and Ci-PAP-A22, already known for the extraordinary efficacy against other microbes. Our data represent the first demonstration of the activity of a particular AMP against both the human facultative intracellular pathogen L. pneumophila and its pathogenic host, Acanthamoeba castellanii. Interestingly, the most effective peptide, Ci-MAM-A24, was also found to reduce the Legionella cell number within amoebae. Accordingly, this peptide was immobilized on gold surfaces to assess its antimicrobial activity. Surfaces were characterized, and activity studies revealed that the potent bactericidal activity of the peptide was conserved after its immobilization. In the frame of elaborating anti-Legionella surfaces, Ci-MAM-A24 represents, by its direct and indirect activity against Legionella, a potent peptide template for biological control of the bacterium in plumbings.
2. The antimicrobial peptide Ci-MAM-A24 is highly active against multidrug-resistant and anaerobic bacteria pathogenic for humans
Henning Fedders, Rainer Podschun, Matthias Leippe Int J Antimicrob Agents. 2010 Sep;36(3):264-6. doi: 10.1016/j.ijantimicag.2010.04.008.
Ci-MAM-A24, a synthetic antimicrobial peptide derived from a peptide precursor from immune cells of the marine invertebrate Ciona intestinalis, has been shown to be potently active against representatives of Gram-positive and Gram-negative bacteria by permeabilising their cytoplasmic membrane. In the present study, the activity of Ci-MAM-A24 against different bacterial pathogens frequently causing therapeutic problems was tested. In particular, the killing capacity of Ci-MAM-A24 against clinically important anaerobic bacteria as well as multiresistant aerobic strains such as meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci, extended-spectrum beta-lactamase-producers and multiple-resistant Pseudomonas aeruginosa strains was monitored. Virtually all strains proved to be highly susceptible to Ci-MAM-A24 at low concentrations [minimum bactericidal concentration (MBC)<10 microg/mL].
3. Potent antimicrobial peptides with selectivity for Bacillus anthracis over human erythrocytes
Raymond M Dawson, Marc A Fox, Helen S Atkins, Chun-Qiang Liu Int J Antimicrob Agents. 2011 Sep;38(3):237-42. doi: 10.1016/j.ijantimicag.2011.05.006. Epub 2011 Jul 8.
In this study, 39 antimicrobial peptides, most with documented low haemolytic activity and potent efficacy against Gram-negative and Gram-positive bacteria, were evaluated for their haemolytic activity against human red blood cells as well as their antimicrobial activity against Escherichia coli, Burkholderia thailandensis, Bacillus globigii and Bacillus anthracis. The majority of the peptides had a minimum inhibitory concentration (MIC) of 30 and could be considered as candidates for further development for potential medical countermeasures against anthrax. Although B. globigii has often been used as a non-pathogenic simulant for B. anthracis, in this study it was found that the sensitivity of B. globigii to peptides was not a reliable predictor of the sensitivity of B. anthracis to the same peptides.
