Biofilm formation in wounds and on biomaterials is increasingly recognized as a problem. It therefore is important to focus on new strategies for eradicating severe biofilm-associated infections. The beneficial effects of maggots (Lucilia sericata) in wounds have been known for centuries. We hypothesized sterile maggot excretions and secretions (ES) could prevent, inhibit, and break down biofilms of Pseudomonas aeruginosa (PAO1) on different biomaterials. Therefore, we investigated biofilm formation on polyethylene, titanium, and stainless steel. Furthermore, we compared the biofilm reduction capacity of Instar-1 and Instar-3 maggot ES and tested the temperature tolerance of ES. After biofilms formed in M63 nutrient medium on comb-forming models of the biomaterials, ES solutions in phosphate-buffered saline or M63 were added in different concentrations. PAO1 biofilms adhered tightly to polyethylene and titanium but weakly to stainless steel. Maggot ES prevent and inhibit PAO1 biofilm formation and even break down existing biofilms. ES still had considerable biofilm reduction properties after storage at room temperature for 1 month. ES from Instar-3 maggots were more effective than ES from Instar-1 maggots. These results may be relevant to patient care as biofilms complicate the treatment of infections associated with orthopaedic implants.

Complement activation is needed to restore tissue injury; however, inappropriate activation of complement, as seen in chronic wounds can cause cell death and enhance inflammation, thus contributing to further injury and impaired wound healing. Therefore, attenuation of complement activation by specific inhibitors is considered as an innovative wound care strategy. Currently, the effects of several complement inhibitors, for example, the C3 inhibitor compstatin and several C1 and C5 inhibitors, are under investigation in patients with complement-mediated diseases. Although (pre)clinical research into the effects of these complement inhibitors on wound healing is limited, available data indicate that reduction of complement activation can improve wound healing. Moreover, medicine may take advantage of safe and effective agents that are produced by various microorganisms, symbionts, for example, medicinal maggots, and plants to attenuate complement activation. To conclude, for the development of new wound care strategies, (pre)clinical studies into the roles of complement and the effects of application of complement inhibitors in wound healing are required.

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BackgroundBiofilm-associated infections in trauma surgery are difficult to treat with conventional therapies. Therefore, it is important to develop new treatment modalities. Maggots in captured bags, which are permeable for larval excretions/secretions, aid in healing severe, infected wounds, suspect for biofilm formation. Therefore we presumed maggot excretions/secretions would reduce biofilm formation.Questions/purposesWe studied biofilm formation of Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella oxytoca, Enterococcus faecalis, and Enterobacter cloacae on polyethylene, titanium, and stainless steel. We compared the quantities of biofilm formation between the bacterial species on the various biomaterials and the quantity of biofilm formation after various incubation times. Maggot excretions/secretions were added to existing biofilms to examine their effect.MethodsComb-like models of the biomaterials, made to fit in a 96-well microtiter plate, were incubated with bacterial suspension. The formed biofilms were stained in crystal violet, which was eluted in ethanol. The optical density (at 595 nm) of the eluate was determined to quantify biofilm formation. Maggot excretions/secretions were pipetted in different concentrations to (nonstained) 7-day-old biofilms, incubated 24 hours, and finally measured.ResultsThe strongest biofilms were formed by S. aureus and S. epidermidis on polyethylene and the weakest on titanium. The highest quantity of biofilm formation was reached within 7 days for both bacteria. The presence of excretions/secretions reduced biofilm formation on all biomaterials. A maximum of 92% of biofilm reduction was measured.ConclusionsOur observations suggest maggot excretions/secretions decrease biofilm formation and could provide a new treatment for biofilm formation on infected biomaterials.