Staphylococcus aureus normally colonizes about 30 percent healthy population asymptomatically, but it has the potential to causes deep-seated infections. Life threatening diseases like septicemia, Pneumonia and endocarditis. S. aureus is also involved in many toxicoses like food poisoning. Moreover, it is considered as one of the most common causes of nosocomial infection worldwide and its increasing resistance to antibiotic makes it difficult to control spread within the community. The aims of this work was (a) to increase the knowledge about virulence and pathogenesis of S. aureus isolated from sore throat patients (b) validation of traditional herbs as an effective antibacterial remedy that can be used against methicillin resistantS. aureus (c) the effectiveness of these herbs in in vivosetting and finally (d) the toxicological assessment of active herbs. The first part of this thesis comprised of identification and characterization of S. aureus. Isolated from a sore throat patients. The strains were identified using conventional microbiological and molecular methods. The agar disc diffusion method was used to evaluate the antibiotic susceptibility profiling. Virulence-associated genes were detected using PCR while Logistic regression was used to test the likelihood of strains carrying combinations of genes involved in toxin production and/or host immune evasion. Highest resistance was observed against beta-lactam group followed by cephalosporin, lincosamide, tetracycline, macrolides and aminoglycosides. No resistance was observed against vancomycin and linezolid. Among genes involved in host immune evasion, Staphylococcus protein A (spa) was identified most frequently (81%) and proportions of capsular polysaccharides (CP8), clumping factor A (clfA) and intracellular adhesion A (ica A) were 78%, 68.5% and 40% respectively. Intracellular adhesion D (ica D) and capsular polysaccharide 5 (CP5) could not be amplified from any isolate. Toxin genes were present in 43.5% isolates. Staphylococcus enterotoxins genes (SEs) (69 %) were most frequently detected among toxin gene containing isolates, followed by enterotoxin (ETs) (24.09 %) and toxic shock syndrome toxin (TSST-1) (15 %). More than one toxin genes were present in the 32.53% isolates. Host immune evasion and toxin genes were not associated with each other. Coaand spa gene polymorphism and band association analysis revealed that spa negative isolates possess Coa 1200 and 900bp, whereas spa positive isolates contain coa of 650bp and 750bp. The spa, CP8 and sea may be considered molecular targets in designing treatment and control strategies. In the second part in vitro, antibacterial activities of 29 traditional medicinal plants used in respiratory ailments were assessed on multidrug-resistant Gram-positive and Gram-negative bacteria isolated from the sore throat patients and two reference strains. The methanolic, n-hexane and aqueous extracts were screened by the agar well diffusion assay. Bioactive fractions of effective extracts were identified on TLC coupled with bio-autography, while their toxicity was determined using hemolytic assay against human erythrocytes. Qualitative and quantitative phytochemical analysis of effective extracts was also performed. Methanolic extract of 18 plants showed antimicrobial activity against test strains. Adhatoda vasica (ZI = 17–21 mm, MIC: 7.12–62.5 ?g/ml), Althaea officinalis (ZI = 16–20 mm, MIC: 15.62–31.25 ?g/ml), Cordia latifolia (ZI = 16– 20 mm, MIC: 12.62–62.5 ?g/ml), Origanum vulgare(ZI = 20–22 mm, MIC: 3–15.62 ?g/ml), Thymus vulgaris (ZI = 21–25 mm, MIC: 7.81–31.25 ?g/ml) and Ziziphus jujuba (ZI = 14–20 mm, MIC: 7.81–31.25 ?g/ml) showed significant antibacterial activity. Alkaloid fractions of Adhatoda vasica, Cordia latifolia and Origanum vulgare and flavonoid fraction of the Althaea officinalis, Origanum vulgare, Thymus vulgaris and Ziziphus jujuba exhibited antimicrobial activity. Effective plant extracts show 0.93–4.1 % erythrocyte haemolysis. The results obtained from this study provide a scientific rationale for the traditional use of these herbs and emphasized on the in vivo validation of in vitro evaluation. The third part of study comprised of experiments on in vivo validation of in vitro finding. Six plants extract having MIC ≤ 100 μg/ml were selected for their in vivo validation against anti-MRSA activity in an animal model. Efficacy of plant extracts on the course of sore throat was checked by analyzing selected parameters and general health. Two experiments were conducted in this regard. A pilot study was conducted to determine the dose of clinical isolate required to induce clinical infection in mice. The dose at which infection established was used for the main experiment to check the effect of treatments on the progress of infections. In the main trial, after the establishment of infection treatment with plant extracts was given up to 7th-day after wards. Re-isolation, gross lesion scoring and bacterial load in tissues were measured. In addition, hematological parameters were recorded. The quantitative evaluation of bacterial load and blood parameters proved A. vasica and O. vulgare to be the best active plant even in in vivo setting. The fourth part of study comprises of the toxicological assessment of the A. vasica and O. vulgarea recommended dose in human (200 mg/ml/Kg) and double the recommended dose (400 mg/ml/Kg). Extracts were forcibly fed to the Mus musculus for 07 days consecutively and on 08 day blood sample was drawn serum were analyzed for known markers of toxicity including (ALT, AST, ALP, T. bilirubin), (Urea and Creatinine) test. Liver and kidney section were also studied through histology for any toxic effect of both extracts. High dose of both plants induced toxicity which was also supported by histological findings. It is concluded that A. vasica and O. vulgare plants showed and used to isolate broad spectrum antimicrobial compounds that will serve as a novel agent for controlling resistant and highly virulent strains of S. aureus. The plant contains a lot of secondary metabolites that can be explored for the treatment infections condition in place of antibiotics. It may prevent the development of resistance to life saving drugs.