Snapshot An 82-year-old woman is brought to the emergency room for fevers and altered mental status. She becomes combative and was put in restraints. Her temperature is 102°F (38.9°C) and her blood pressure is 103/74 mmHg. Physical exam shows suprapubic tenderness. Blood and urine cultures are drawn, and urinalysis reveals the presence of leukocyte esterase. Upon further investigation, past medical records show that she has previously been treated for vancomycin-resistant enterococci (VRE). She is started on linezolid. (Urinary tract infection) Introduction Drugs linezolid an oxazolidinone drug Mechanism of action binds to the 23S ribosomal RNA of the 50S subunit and inhibits protein synthesis prevents initiation complex formation with 70S subunit bacteriostatic against enterococci and staphylococci bactericidal against most streptococci Mechanism of resistance mutation of ribosomal RNA to prevent binding Clinical use gram-positive organisms used especially for multi-drug resistant organisms like methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) community-acquired pneumonia skin and soft tissue infections urinary tract infection Adverse effects myelosuppression peripheral neuropathy serotonin syndrome due to the drug’s weak reversible action as a monoamine oxidase inhibitor (MAOI) treat with benzodiazepines or cyproheptadine contraindicated while using MAOIs (phenelzine or isocarboxazid) gastrointestinal upset C. difficile diarrhea