Biofilm infections between Scylla and Charybdis: interplay of host antimicrobial peptides and antibiotics

The aim of this study is to improve the anti-biofilm activity of antibiotics. We hypothesized that the antimicrobial peptide (AMP) complex of the host's immune system can be used for this purpose and examined the assumption on model biofilms. FLIP7, the AMP complex of the blowfly containing a combination of defensins, cecropins, diptericins and proline-rich peptides was isolated from the hemolymph of bacteria-challenged maggots. The complex interaction with antibiotics of various classes was studied in biofilm and planktonic cultures of , , , and by the checkerboard method using trimethyl tetrazolium chloride cell viability and crystal violet biofilm eradication assays supplemented with microscopic analysis. We found that FLIP7 demonstrated: high synergy (fractional inhibitory concentration index