In vitro antimicrobial activity of MSI-78, a magainin analog.
MSI-78 is a cationic peptide with broad-spectrum antimicrobial activity and is being developed as a topical agent. We compared the in vitro activity of MSI-78 with those of ofloxacin and other antibiotics against fresh clinical isolates. Based on MIC distribution statistics, strains for which the MSI-78 MIC was < or = 64 micro/ml were assumed to be susceptible for purposes of this report. Of 411 aerobic isolates tested, 91% were susceptible to MSI-78, compared to 91% for ofloxacin and 92% for ciprofloxacin. Only enterococci consistently required > or = 64 microg of MSI-78/ml for inhibition. MSI-78 demonstrated bactericidal activity equivalent to that of ofloxacin. Of 61 anaerobes, 97% were susceptible to MSI-78. Of 10 isolates of Candida albicans, 3 were inhibited by MSI-78 at 24 h. Further studies of this compound appear to be warranted.
Fuchs
P C
PC
The Clinical Microbiology Institute, Wilsonville, Oregon 97070, USA. cmi@hevanet.com
Barry
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AL
Brown
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SD
D000890:Anti-Infective Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides; D006801:Humans; D008826:Microbial Sensitivity Tests; D015242:Ofloxacin / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects*
D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D010455:Peptides; D015242:Ofloxacin; C093828:pexiganan