Antianaerobic activity of a cecropin---melittin peptide

OBJECTIVE: Several small, 15-residue peptides that contain portions of the amino acid sequences of both cecropin A and melittin have previously been shown to have broad-spectrum antibacterial activities against aerobic microorganisms, with no undesirable hemolytic properties. It would also be useful to know what effect these hybrid peptides have on anaerobic bacteria. METHODS: The minimum inhibitory concentrations of one hybrid, CA(1--7)M(2--9)NH2, were compared with those of seven other antimicrobial agents against 111 clinical anaerobic strains; Bacteroides fragilis, 24 strains; other Bacteroides fragilis group, 14 strains; other Bacteroides species, 13 strains; Fusobacterium nucleatum, six strains; Clostridium difficile, 22 strains; Clostridium perfringens, 10 strains, Propionibacterium spp., nine strains; and anaerobic cocci, 13 strains. RESULTS: Ninety per cent of strains belonging to the B. fragilis group, fusobacteria, propionibacteria and peptostreptococci were inhibited by 4 mg/L CA(1--7)M(2--9)NH2, and the antimicrobial activity was approximately in the same range as that of chloramphenicol. CONCLUSION: This investigation showed that the antimicrobial spectrum of this cecropin---melittin hybrid also includes anaerobic organisms.