The antibacterial activity against MRSA strains and other bacteria of a <500 Da fraction from maggot excretions/secretions of Lucilia sericata (Diptera: Calliphoridae)

The application of Lucilia sericata larvae to chronic, infected wounds results in the rapid elimination of infecting microorganisms, including MRSA. Previously, we demonstrated in vitro antibacterial activity of native excretions/secretions (nES) from L. sericata and partially purified two low mass antibacterial compounds with masses of 0.5-10 kDa and <500 Da. The present study reports the antibacterial effects of the <500 Da fraction (ES<500) on the growth and morphology of a range of bacteria, including 12 MRSA strains. Distinct morphological changes were observed in Bacillus cereus and Escherichia coli following exposure to ES<500. Flow cytometry and confocal microscopy analyses, in conjunction with turbidometric and CFU assays, revealed bacteriostatic activity of nES against S. aureus and E. coli. ES1500 also demonstrated bacteriostatic activity against S. aureus, however, bactericidal activity and the induction of a viable but non-culturable state were observed with ES<500-treated E. coli. (C) 2008 Elsevier Masson SAS. All rights reserved.