S02.1 MAGGOT EXCRETIONS DECREASE BACTERIAL BIOFILMS ON ORTHOPAEDIC MATERIALS

Abstract

Biofilm formation (BF) in wounds and on biomaterials is a severe complication in trauma and orthopaedic surgery. Maggot therapy is successfully applied in wounds, that are suspected for BF. This study investigated BF by Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella oxytoca, Enterococcus faecalis and Enterobacter cloacae on polyethylene, titanium and stainless steel and tested the effect on BF by maggot excretions/secretions (ES). Comb-forming models of the biomaterials were made to fit into a 96-well microtiter plate. In the wells, a suspension of 2.5 x 105 bacteria/ml and nutrient medium was pipetted. Combs were placed in the wells and incubated for 3, 5, 7, and 9 days at 37°C. The formed biofilms were stained in crystal-violet and eluted in ethanol. The optical density (OD 595 nm) was measured to quantify BF. Then, maggots excretions/secretions (ES) were collected according to a standardized method, added in different concentrations to (non-stained) mature biofilms (7 days), incubated another 24 hours and at last stained and measured. The results showed biofilm reduction by ES on all biomaterials. Biofilms formed by S. aureus were reduced to minima of 40% on PE and SSS (p< 0.001) and 50% on TI (p=0.005). The biofilm reduction for S. epidermidis was even greater on PE, SSS and TI with respectively minima of 8% (p< 0.001), 32% (p< 0.001) and 38% BF (p< 0.001). The quantity of BF by S. aureus and S. epidermidis had a comparable strength (p=ns) and was for both bacteria the greatest on polyethylene and the lowest on titanium (p< 0.001). Klebsiella oxytoca, Enterococcus faecalis and Enterobacter cloacae formed weak biofilms on all materials. Mature BF was reached between 5 to 7 days by S. epidermidis and between 7 to 9 days by S. aureus. Our previous research showed biofilm inhibition and breakdown of Pseudomonas aeruginosa by ES. This study showed that maggot ES also reduce biofilms formed by S. aureus and S. epidermidis which are frequently isolated from biomaterial-associated infections. There may be pharmacologic agents that could be developed from maggot ES. While BF on orthopaedic materials is an increasing problem, this experimental study could indicate a new treatment for BF on infected biomaterials