Frog Skin May Provide Antimicrobial Peptides Effective Against Multidrug-Resistant Infections

Antimicrobial peptides from the skin of frogs may protect against life-threatening, multidrug-resistant infections such as Pseudomonas aeruginosa say researchers from Italy. They detail their findings in the September 2010 issue of the journal Antimicrobial Agents and Chemotherapy.

P. aeruginosa is an opportunistic pathogen that causes some of the most prevalent life-threatening infections such as eye and ear infections, burn wound infections and lung infections in cystic fibrosis patients. Strains of the bacterium resistant to almost all antibiotics have already emerged causing researchers to seek new drug therapies.

"Unlike other organisms, P. aeruginosa is a pathogen endowed with high intrinsic drug resistance, due in part to many elaborate virulence factors and the formation of a biofilm matrix, which makes it difficult for antibiotics and immune cells to attack," say the researchers.

Membrane-active cationic antimicrobial peptides (CAMPs) are a new class of antibiotics produced by almost all forms of life, however, amphibian skin is one of the richest sources. Although prior studies have shown that these peptides possess potent antimicrobial activity against multidrug-resistant pathogens in a controlled environment, little is known of their effects within a living organism.

Researchers evaluated the antimicrobial activities of different CAMPs from frog skin using the worm model, Caenorhabditis elegans, in which bacterial species such as P. aeruginosa can pass through the mouth, invade the gut and ultimately kill the animal. The process by which the bacterium infects and kills C. elegans is comparable to the infection process in mammals making it an ideal model for observation. Results showed that all of the peptides studied, with the exception of one, increased the survival rate of P. aeruginosa-infected worms compared with those not receiving peptide treatments.

"Besides shedding light on a plausible mode of action in vivo of amphibian CAMPs, our data suggest that esculentin and temporin peptides can serve as attractive molecules for the development of new therapeutic strategies to fight life-threatening infectious diseases," say the researchers.

(D. Uccelletti, E. Zanni, L. Marcellini, C. Palleschi, D. Barra, M.L. Mangoni. 2010. Anti-Pseudomonas activity of frog skin antimicrobial peptides in a Caenorhabditis elegans infection model: a plausible mode of action in vitro and in vivo. Antimicrobial Agents and Chemotherapy, 54. 9: 3853-3860.)

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