First report of polymyxin B activity in Klebsiella pneumoniae biofilm.

Considering the clinical importance of biofilm in medical devices and chronic infections, this study aimed to investigate the action of polymyxin B on Klebsiella pneumoniae (K. pneumoniae) biofilm. The experiments were performed using a biofilm formation assay and the interaction of polysorbate 80 was explored. Both inhibition of biofilm formation and reduction of pre-formed biofilm occurred in a concentration-dependent manner with inhibition as high as 56 and 64%, and reduction of pre-formed biofilm as high as 70 and 66%, with and without polysorbate, respectively. The addition of polysorbate enhances the biofilm reduction, but more studies are needed to elucidate this mechanism. Our findings reveal, for the first time, polymyxin B as a potential agent for the treatment of K. pneumoniae biofilm, a current challenge for clinical practice.