The activity of antimicrobial peptide S-thanatin is independent on multidrug-resistant spectrum of bacteria

In this study, the activity of S-thanatin (an analog of antimicrobial peptide derived from thanatin) against different bacterial pathogens frequently which can cause therapeutic problems was tested. The result showed minimal inhibitory concentrations (MICs) of S-thanatin against all isolates of the Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes, Klebsiella ornithinolytica and Klebsiella oxytoca were in the range of 4-16 μg/ml, no matter which antibiotic the bacterial was resistant or susceptible, while almost all MICs to Gram-positive bacterial were >128 μg/ml except Enterococcus faecium. S-thanatin was more effective toward Gram-negative strains, especially for Enterobacter and Klebsiella. The MICs of S-thanatin were no significantly different in the same species regardless of antibiotic sensitive or -resistant isolates to single or multiple antibiotic (P > 0.05). Likewise, no notable difference could be observed between E. coli, K. pneumoniae, E. cloacae, E. aerogenes, K. ornithinolytica which were sensitive to S-thanatin (P > 0.05). It was implied that the antimicrobial activity of S-thanatin was independent on multi-drug resistance spectrum of bacteria.