Antimicrobial Activities of Twenty Lysine-Peptoid Hybrids against Clinically Relevant Bacteria and Fungi

BACKGROUND: This paper describes the antimicrobial activities of 20 lysine-peptoid hybrids against a selection of clinically relevant bacteria and fungi. METHODS: Minimal inhibitory concentrations were determined against methicillin-susceptible Staphylococcus aureus (ATCC 29213), methicillin-resistant S. aureus (ATCC 33591), vancomycin-intermediate S. aureus (ATCC 700699 MU50), vancomycin-resistant Enterococcus faecium (ATCC 700221), Pseudomonas aeruginosa (ATCC 27853), Salmonella typhimurium (clinical isolate), Klebsiella pneumoniae (clinical isolate), amphotericin-B-resistant C. albicans (ATCC 200955) and Cryptococcus neoformans (clinical isolate). RESULTS: The lysine-peptoid hybrids proved to be active against all strains tested, except K. pneumoniae. For each susceptible strain, we identified at least 4 lysine-peptoid hybrids showing excellent activity. The most active compounds displayed minimal inhibitory concentrations ranging from < or =1.6 to 6.25 microM. CONCLUSION: This study demonstrates that lysine-peptoid hybrids show activity against drug-resistant pathogens.