Patients fitted with urinary bladder and vascular catheters are subject to bacterial infections and biofilm formation. These infections are mostly caused by coagulase-positive and coagulase-negative staphylococci. Vancomycin (VCM) remains the frontline intravenous antibiotic for the treatment of catheter-related bacteremia. Liposomes are appealing drug carrier systems, especially against colonized microorganisms.
In the present study, VCM-loaded propylene glycol liposomes were prepared by the ethanol injection method The liposomes were characterized pharmaceutically and microbiologically. Pharmaceutical attributes included colloidal properties, entrapment efficiency (EE%), release, and stability. Microbiological tests included the determination of Minimum Inhibitory Concentration (MIC) by two methods, antibiofilm efficacy using the microtiter plate model, including assessment of Minimum Biofilm Inhibitory Concentration (MBIC), Minimum Biofilm Eradicating Concentration (MBEC), and biofilm formation induction by vancomycin sub-minimum inhibitory concentrations. Antibiofilm efficacy was also assessed using the catheter segments model. VCM liposomes showed vesicle size in the nanorange (219.49 ± 20.21 nm), low PDI (0.282 ± 0.044), negative zeta potential (-4.78), and EE% (52.84±1.5%) that proved stable with no drug leakage after 3 months of storage at 4°C. It also showed a slower release profile compared to the free VCM. The antibacterial and antibiofilm efficacy of VCM liposomes compared to free VCM increased by 2–8 folds, calculated from the observed extent of reduction in MIC, MBIC, and MBEC of liposome-loaded VCM compared to free VCM. Results of catheter segment experiments indicated the potential usefulness of VCM liposomes in antibiotic lock solutions for managing biofilms on medical devices and implants.