Anas, KJayasree, P RVijayakumar, TManish Kumar, P R2009-05-282009-05-282008-01-14Anas K, Jayasree PR, Vijayakumar T, Manish Kumar PR. In vitro antibacterial activity of Psidium guajava Linn. leaf extract on clinical isolates of multidrug resistant Staphylococcus aureus. Indian Journal of Experimental Biology. 2008 Jan; 46(1): 41-6http://imsear.searo.who.int/handle/123456789/59885In the present study, antibacterial activity of aqueous and organic extracts of Psidium guajava leaves was evaluated against multidrug resistant (MDR) clinical isolates of Staphylococcus aureus strains collected from hospitals in northern (Malabar region) Kerala. The strains which exhibited resistance against all the antibiotics tested was selected for antibacterial assays. Minimum inhibitory concentration (MIC) for methanolic and aqueous extracts was found to be 625 ug/ml and 7.5 mg/ml, respectively. Minimum bactericidal concentration (MBC) recorded for methanolic and aqueous extracts was 1.25 and 12.5 mg/ml, respectively. Methanolic extract at minimum bactericidal concentration inhibited the growth of MDR strain by 80%. Time-kill assay revealed that methanolic extract (4 mg/ml) killed MDR bacteria within 10 hr. Total polypeptide profiling of bacterial cultures by SDS-PAGE indicated a high degree of protein degradative activity of the extract. Finally, a human RBC based haemolytic assay showed absence of haemolysis even at concentrations higher than that of MBC, advocating thereby its safety in therapeutic use.engAnti-Bacterial Agents --pharmacologyDiffusionDrug Resistance, BacterialElectrophoresis, Polyacrylamide GelErythrocytes --metabolismHemolysisHumansMethanol --chemistryPeptides --chemistryPlant Extracts --pharmacologyPlant Leaves --metabolismStaphylococcal Infections --drug therapyStaphylococcus aureus --metabolismTime FactorsWater --chemistryJournal Article