Ciprofloxacin-Eluting Nanofibers Inhibits Biofilm Formation by Pseudomonas aeruginosa and a Methicillin-Resistant Staphylococcus aureus

Pseudomonas aeruginosa and Staphylococcus aureus are commonly associated with hospital-acquired infections and are known to form biofilms. Ciprofloxacin (CIP), which is normally used to treat these infections, is seldom effective in killing cells in a biofilm. This is mostly due to slow or weak penetration of CIP to the core of biofilms. The problem is accentuated by the release of CIP below MIC (minimal inhibitory concentration) levels following a rapid (burst) release. The aim of this study was to develop a drug carrier that would keep CIP above MIC levels for an extended period. Ciprofloxacin was suspended into poly(D,L-lactide) (PDLLA) and poly(ethylene oxide) (PEO), and electrospun into nanofibers (CIP-F). All of the CIP was released from the nanofibers within 2 h, which is typical of a burst release. However, 99% of P. aeruginosa PA01 cells and 91% of S. aureus Xen 30 cells (a methicillin-resistant strain) in biofilms were killed when exposed to CIP-F. CIP levels remained above MIC for 5 days, as shown by growth inhibition of the cells in vitro. The nanofibers were smooth in texture with no bead formation, as revealed by scanning electron and atomic force microscopy. A single vibration peak at 1632 cm-1, recorded with Fourier transform infrared spectroscopy, indicated that CIP remained in crystal form when incorporated into PDLLA: PEO. No abnormalities in the histology of MCF-12A breast epithelial cells were observed when exposed to CIP-F. This is the first report of the inhibition of biofilm formation by CIP released from PDLLA: PEO nanofibers.