Here, we demonstrated the in vitro and in vivo antibacterial and anti-biofilm activities of melittin, a peptide derived from honeybee venom, against uropathogenic Escherichia coli (UPEC) resistant to quinolones. The minimum inhibitory concentration (MIC) of melittin varied from 0.5 to 8 μM. The bactericidal effect was considered rapid and potent (ranging from 3.0 to 6.0 h after incubation) against a quinolone-resistant and Extended Spectrum Beta-lactamase (ESBL)-producing UPEC strain. Prior exposure to melittin did not reduce the MIC of the quinolones tested, but it decreased the MIC of ceftizoxime by 8-fold due to its ability to form pores in the membrane. Furthermore, melittin disrupted mature biofilms (39.58% at 32 μM) and inhibited the adhesion of this uropathogen to the surfaces of urethral catheter. These results show that melittin is a promising molecule that can be incorporated into invasive urethral medical devices to prevent urinary infections caused by multidrug-resistant UPECs.
Keywords: Escherichia coli; antimicrobial peptides; biofilm; urethral catheter; urinary tract infections.