Susceptibility of Methicillin Resistant Staphylococcus aureus to Vancomycin using Liposomal Drug Delivery System

Staphylococcus aureus responsible for nosocomial infections is a significant threat to the public health. The increasing resistance of S.aureus to various antibiotics has drawn it to a prime focus for research on designing an appropriate drug delivery system. Emergence of Methicillin Resistant Staphylococcus aureus (MRSA) in 1961, necessitated the use of vancomycin"the drug of last resort"to treat these infections. Unfortunately, S.aureus has already started gaining resistances to vancomycin. Liposome encapsulation of drugs have been earlier shown to provide an efficient method of microbial inhibition in many cases. We have studied the effect of liposome encapsulated vancomycin on MRSA and evaluated the antibacterial activity of the liposome-entrapped drug in comparison to that of the free drug based on the minimum inhibitory concentration (MIC) of the drug. The MIC for liposomal vancomycin was found to be about half of that of free vancomycin. The growth response of MRSA showed that the liposomal vancomycin induced the culture to go into bacteriostatic state and phagocytic killing was enhanced. Administration of the antibiotic encapsulated in liposome thus was shown to greatly improve the drug delivery as well as the drug resistance caused by MRSA.