INTERACTION OF CIPROFLOXACIN LOADED LIPOSOMES WITH PSEUDOMONAS-AERUGINOSA CELLS

An antibiotic delivery system has been developed using ciprofloxacin ( CIPRO) encapsulated within sonicated unilamellar vesicles (SUV) of dif ferent lipid compositions composed of dipalmitoylphospatidylcholine (D PPC), L-alpha-phosphatidylcholine (PC), phosphatidylethanolamine (PEA) and cholesterol (CHOL). The interaction of SUV (i.e. liposomes) with Pseudomonas aeruginosa (T12977) cells was studied and the effect of th e liposome encapsulated antibiotic was tested. Encapsulation of CIPRO apparently increased the amount of antibiotic resident in the vicinity of bacteria in aqueous solution at neutral pH. Electrophoretic mobili ty measurements showed that P. aeruginosa cells were negatively charge d. The zeta potential of P. aeruginosa was -11.4 +/- 2.9 mV in phospha te buffered saline at pH 7.0, and the corresponding surface charge den sity was -14.7 +/- 3.9 mC/m2. DPPC liposomes and PC liposomes had mean diameters of 103 +/- 35 nm and 80 +/- 25 nm, respectively. They were electrically neutral or had a small positive charge of +5.0 +/- 3.0 mC /m2 when prepared with PC:CHOL:PEA=5:1:1. The interaction and attachme nt of neutral or positively charged SUV to negatively charged bacteria l cells was studied in an effort to increase the residency of the lipo somes and CIPRO, in the vicinity of the bacterial cells.