During two clinical trials involving the treatment of 835 outpatients with infected
diabetic foot ulcers, 2515 bacterial isolates, including 2337 aerobes and 178 anaerobes, were grown from cultures of the
ulcers. The in vitro susceptibility of these isolates was determined to
pexiganan, a
peptide anti-infective evaluated in these clinical trials, and to other classes of
antibiotics.
Pexiganan demonstrated broad spectrum antimicrobial activity against Gram-positive and Gram-negative aerobes and anaerobes. The MIC90 values for the most common species among 1735 Gram-positive aerobes isolated, such as Staphylococcus aureus,
coagulase-negative staphylococci, Group A streptococci, and Group B streptococci, were 16 micrograms/mL or less. Of 602 Gram-negative aerobes tested, the MIC90 values for
pexiganan were 16 micrograms/mL or less for Acinetobacter, Pseudomonas, Stenotrophomonas, Citrobacter, Enterobacter, Escherichia, Klebsiella, and Flavobacterium species.
Pexiganan had a MIC90 of 4 to 16 micrograms/mL against the anaerobic isolates of Bacteroides, Peptostreptococcus, Clostridium, and Prevotella species. Importantly,
pexiganan did not exhibit cross-resistance with other commonly used
antibiotics, including
beta-lactams,
quinolones,
macrolides, and
lincosamides. The broad spectrum in vitro antimicrobial activity of
pexiganan against clinical isolates from infected
diabetic foot ulcers supports its potential as a local
therapy for infected
diabetic foot ulcers.