Activity of cecropin P1 and FA-LL-37 against urogenital microflora

Two mammalian antimicrobial peptides, FA-LL-37 and cecropin P1, were tested for activity against six uropathogens and five Lactobacillus strains by br oth microdilution assay. Both peptides inhibited Escherichia coli at 25 mu M (FA-LL-39), and 1.56 mu M (cecropin P1), Pseudomonas aeruginosa (12.5 mu M, and 25 mu M), and Klebsiella pneumoniae, (50 mu M, and 1.56 mu M), but n ot Enterococcus faecalis and Staphylococcus epidermidis. FA-LL-37 acted bac teriocidally against E. coli and bacteriostatically against the other two G ram-negative organisms. Cecropin P1 was bacteriocidal to all susceptible ba cteria. Lactobacilli were resistant to both peptides, with the exception of poultry isolate Lactobacillus fermentum B-54, which was susceptible to FA- LL-37 at 100 mu M. The differential activities of these peptides toward Gra m-negative uropathogens versus urogenital lactobacilli demonstrate their po tential as a topical treatment for urinary tract infections. In addition, p roduction of such peptides in vivo could be a natural mechanism to aid in t he maintenance of the lactobacilli-dominated urogenital flora at the expens e of pathogens. (C) 2000 Editions scientifiques et medicales Elsevier SAS.