Aerosolized Vancomycin in Methicillin-Resistant Staphylococcus Aureus Pneumonia Under Mechanical Ventilation

Inclusion Criteria: * Nosocomial or severe community-acquired pneumonia due to Methicillin-Resistant Staphylococcus aureus * Must be mechanically ventilated in intensive care unit Exclusion Criteria: * Non-bacterial pneumonia, such as viral, fungal, tuberculosis infections * Underlying respiratory condition: bronchiectasis, post-tuberculosis, chronic obstructive pulmonary disease or asthma * Complicated pneumonia, such as empyema, parapneumonic effusion requiring chest tube or drainage * Already or previous treated with intravenous vancomycin (Not pneumonia) * Adverse reaction due to inhaled ventolin before treatment of aerosolized vancomycin * Hypersensitivity of vancomycin or glycopeptide antibiotics * Positive culture of Enterococcus in respiratory specimen * Pregnant or Breast-feeding patient * Immunocompromised hosts: more than 1mg/kg of corticosteroid users for more than 3 months, transplantation recipients, AIDS patients * Another aerosolized antibiotics within 48 hours of study enrollment * Not adherent to mechanical ventilation protocol of this study * Not arterial line monitoring * Vancomycin minimum inhibitory concentration \>= 2㎍/㎖ of cultured Staphylococcus aureus