In vitro susceptibility to pexiganan of bacteria isolated from infected diabetic foot ulcers

During two clinical trials involving the treatment of 835 out patients with infected diabetic foot ulcers, 2515 bacterial isolates, including 2337 aer obes and 178 anaerobes, were grown from cultures of the ulcers. The in vitr o susceptibility of these isolates was determined to pexiganan, a peptide a nti-infective evaluated in these clinical trials, and to other classes of a ntibiotics. Pexiganan demonstrated broad spectrum antimicrobial activity ag ainst Gram-positive and Guam-negative aerobes and anaerobes. The MIC90 valu es for the most common species among 1735 Gram-positive aerobes isolated, s uch as Staphylococcus aureus, coagulase-negative staphylococci, Group A str eptococci, and Group B streptococci, were 16 mu g/mL or less. Of 602 Gram-n egative aerobes tested, the MIC90 values for pexiganan were 16 mu g/mL ou l ess for Acinetobacter, Pseudomonas, Stenotrophomonas, Citrobacter, Enteroba cter, Escherichia, Klebsiella, and Flavobacterium species. Pexiganan had a MIC90 of 4 to 16 mu g/mL against the anaerobic isolates of Bacteroides, Pep tostreptococcus, Clostridium, and Prevotella species. Importantly pexiganan did not exhibit cross-resistance with other commonly used antibiotics, inc luding beta-lactams, quinolones, macrolides, and lincosamides. The broad sp ectrum in vitro antimicrobial activity of pexiganan against clinical isolat es from infected diabetic foot ulcers supports its potential as a local the rapy for infected diabetic foot ulcers. (C) 1999 Elsevier Science Inc.