Synergism between maggot excretions and antibiotics

Maggots are successfully used to treat severe, infected wounds. This study investigated whether maggot excretions/secretions influence the antibacterial activity of different antibiotics. Minimal inhibitory concentrations and minimal bactericidal concentrations (MBC) were determined of gentamicin and flucloxacillin for Staphylococcus aureus, of penicillin for Streptococcus pyogenes, of amoxicillin and vancomycin for Enterococcus faecalis, of gentamicin for Enterobacter cloacae, and of gentamicin, tobramycin, and ciprofloxacin for Pseudomonas aeruginosa by checkerboard titration. A range of concentrations of antibiotics in combination with excretions/secretions was examined to investigate the potential of maggot excretions/secretions to affect antibacterial activity. The results showed a dose-dependent increase of the antibacterial effect of gentamicin in the presence of excretions/secretions on S. aureus. Minimal concentrations and MBC of gentamicin decreased, respectively, 64- and 32-fold. The MBC of flucloxacillin and excretions/secretions against S. aureus were also decreased. The other antibiotic and excretions/secretions combinations exerted an indifferent effect. Excretions/secretions alone did not have any antibacterial effect. The synergism between gentamicin and maggot excretions/secretions could be of direct importance in clinical practice, because it could allow the use of lower doses of gentamicin and thus minimize the risk of gentamicin-related side effects.