Septic Arthritis

A 35-year-old male presents with acute onset knee pain, swelling, and inability to bear weight. Examination reveals a hot, tense joint with restricted movement. Synovial fluid analysis shows WBC 85,000/μL with 92% neutrophils, glucose 18 mg/dL (serum 110 mg/dL), protein 6.2 g/dL, and positive Gram stain for cocci. Which of the following is NOT a typical feature of septic arthritis?

In a series of 100 cases of acute bacterial septic arthritis in a tertiary care hospital in Delhi, the knee joint was involved in 48 cases, hip in 22 cases, ankle in 15 cases, and shoulder in 10 cases. What is the most common site of septic arthritis?

A 28-year-old woman with a history of intravenous drug use presents with a 5-day history of left shoulder pain, swelling, and fever (38.2°C). Synovial fluid obtained by arthrocentesis shows WBC 62,000/μL (90% neutrophils), glucose 22 mg/dL (serum 110 mg/dL), protein 5.8 g/dL, and Gram stain is negative. Blood cultures are pending. She is allergic to penicillin (anaphylaxis). What is the most appropriate immediate antibiotic regimen?

A 38-year-old man from rural Maharashtra presents to the emergency department with a 3-day history of severe left knee pain, swelling, and inability to bear weight. He has a fever of 38.9°C and reports a puncture wound to the knee from a contaminated nail 5 days ago. On examination, the knee is grossly swollen, warm, and tender; passive range of motion is severely restricted. Synovial fluid analysis shows WBC 85,000/μL (95% neutrophils), protein 6.2 g/dL, glucose 18 mg/dL (serum glucose 110 mg/dL), and Gram stain shows Gram-positive cocci in clusters. What is the most appropriate next step in management?

A 68-year-old woman with rheumatoid arthritis on methotrexate and prednisolone presents with acute onset of left hip pain and fever (39.2°C) for 3 days. She denies recent trauma or surgery. Hip examination shows severe pain on internal rotation and flexion, with guarding. Synovial fluid obtained by ultrasound-guided aspiration shows: WBC 72,000/μL (88% neutrophils), glucose 18 mg/dL (serum 95 mg/dL), protein 5.8 g/dL, Gram stain negative, and culture pending. Inflammatory markers are elevated (CRP 12 mg/dL, ESR 68 mm/hr). What is the most likely organism?