Quorum-sensing-regulated virulence factors in Pseudomonas aeruginosa are toxic to Lucilia sericata maggots

1 Statens Serum Institut ABMP, Artillerivej 5, Copenhagen S, Denmark 2 Copenhagen Wound Healing Center, Bispebjerg Hospital, Bispebjerg bakke 23, Copenhagen NV, Denmark 3 University of Copenhagen Faculty of Health Sciences, Blegdamsvej 3B, 2200 Copenhagen N, Denmark Maggot debridement therapy (MDT) is widely used for debridement of chronic infected wounds; however, for wounds harbouring specific bacteria limited effect or failure of the treatment has been described. Here we studied the survival of Lucilia sericata maggots encountering Pseudomonas aeruginosa PAO1 in a simple assay with emphasis on the quorum-sensing (QS)-regulated virulence. The maggots were challenged with GFP-tagged P. aeruginosa wild-type (WT) PAO1 and a GFP-tagged P. aeruginosa lasR rhlR ( RR) QS-deficient mutant in different concentrations. Maggots were killed in the presence of WT PAO1 whereas the challenge with the QS mutant showed a survival reduction of 25 % compared to negative controls. Furthermore, bacterial intake by the maggots was lower in the presence of WT PAO1 compared to the PAO1 RR mutant. Maggot excretions/secretions (ES) were assayed for the presence of QS inhibitors; only high doses of ES showed inhibition of QS in P. aeruginosa . Thus P. aeruginosa was shown to be toxic to L. sericata maggots. This, coupled to the preferential feeding by the maggots and reduced ingestion of P. aeruginosa , could explain MDT failure in wounds colonized by P. aeruginosa. Wounds heavily colonized with P. aeruginosa should be a counterindication for MDT unless used in combination with a pre-treatment with other topical therapeutics targeting P. aeruginosa . Correspondence A. S. Andersen aea{at}ssi.dk Abbreviations: ES, excretions/secretions; MDT, maggot debridement therapy; QS, quorum sensing; QSI, quorum sensing inhibiting; SSI, Statens Serum Institut; PON1, paraoxonase-1