temporin and Cross-Infection

Due to the widespread resistance of bacteria to the available drugs, the discovery of new classes of antibiotics is urgently needed, and naturally occurring antimicrobial peptides (AMPs) are considered promising candidates for future therapeutic use. Amphibian skin is one of the richest sources of such AMPs. In the present study we compared the in vitro bactericidal activities of five AMPs from three different species of anurans against multidrug-resistant clinical isolates belonging to species often involved in nosocomial infections (Staphylococcus aureus, Enterococcus faecium, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Acinetobacter baumannii). The peptides tested were temporins A, B, and G from Rana temporaria; the fragment from positions 1 to 18 of esculentin 1b [Esc(1-18)] from Rana esculenta; and bombinin H2 from Bombina variegata. When they were tested in buffer, all the peptides were bactericidal against all bacterial species tested (three strains of each species) at concentrations ranging from 0.5 to 48 microM, with only a few exceptions. The temporins were found to be more active against gram-positive bacteria, especially when they were assayed in human serum; Esc(1-18) showed fast and strong bactericidal activity, within 2 to 20 min, especially against the gram-negative species, which were killed by Esc(1-18) at concentrations ranging from 0.5 to 1 microM; bombinin H2 displayed similar bactericidal activity toward all isolates. Interestingly, while the activities of the temporins and bombinin H2 were almost completely inhibited in the presence of 20% human serum, the activity of Esc(1-18) against the gram-negative species was partially preserved in the presence of 40% serum. This property renders this peptide an attractive molecule for use in the development of new compounds for the treatment of infectious diseases.

Topics: Amino Acid Sequence; Amphibian Proteins; Animals; Antimicrobial Cationic Peptides; Anura; Cross Infection; Drug Resistance, Multiple, Bacterial; Gram-Negative Bacteria; Gram-Positive Bacteria; Humans; Microbial Sensitivity Tests; Molecular Sequence Data; Proteins; Ranidae

To study the in vitro activity of temporin A, a basic, highly hydrophobic, antimicrobial peptide amide derived from the skin of the European red frog Rana temporaria, alone and in combination with co-amoxiclav, imipenem, ciprofloxacin, linezolid and vancomycin, against 42 nosocomial isolates of Enterococcus faecalis. Fourteen of these were resistant to vancomycin.. Antimicrobial activity of temporin A was measured by MIC, MBC and time-kill studies and by the chequerboard titration method.. All isolates were inhibited at concentrations of 1 to 16 mg/L. Combination studies carried out with E. faecalis ATCC 29212 and ATCC 51299 demonstrated synergy only when the peptide was combined with co-amoxiclav and imipenem.. Our findings show that temporin A is active against E. faecalis and that its activity could be enhanced when it is combined with other antimicrobial agents.

Topics: Anti-Bacterial Agents; Antimicrobial Cationic Peptides; Cross Infection; Drug Interactions; Enterococcus faecalis; Humans; Microbial Sensitivity Tests; Proteins