A 65-year-old man comes to the physician because of a 3 day history of pain and swelling in his left knee. He also reports nausea and feeling weak earlier today. He has a long-standing history of rheumatoid arthritis (RA) and has had several previous episodes of "fluid in the knee." He currently takes methotrexate and sulfasalazine for his RA. Tumor necrosis factor inhibitor therapy was prescribed two years ago but was discontinued after six months due to frequent sinus infections and exacerbation of his congestive heart failure. His other medical problems include hypertension, hypercholesterolemia, colonic polyps, essential tremor, congestive heart failure, and a remote history of asbestos exposure. His other medications include furosemide, propranolol, lisinopril, aspirin, and simvastatin.
His temperature is 37.2 C (99 F), blood pressure is 110/70 mm Hg, pulse is 88/min, and respirations are 16/min. He has no jugular venous distention. His heart sounds are normal and his lungs are clear. Musculoskeletal examination is notable for extensive deformities in the hands due to long-standing arthritis. His right knee is normal. The left knee is tender and swollen and he is unable to extend it due to pain.
Joint aspiration yields 20 cc of synovial fluid. Laboratory results are as follows:

Which of the following is the most appropriate next step in management?

Question

A 65-year-old man comes to the physician because of a 3 day history of pain and swelling in his left knee.  He also reports nausea and feeling weak earlier today.  He has a long-standing history of rheumatoid arthritis (RA) and has had several previous episodes of "fluid in the knee."  He currently takes methotrexate and sulfasalazine for his RA.  Tumor necrosis factor inhibitor therapy was prescribed two years ago but was discontinued after six months due to frequent sinus infections and exacerbation of his congestive heart failure.  His other medical problems include hypertension, hypercholesterolemia, colonic polyps, essential tremor, congestive heart failure, and a remote history of asbestos exposure.  His other medications include furosemide, propranolol, lisinopril, aspirin, and simvastatin.
His temperature is 37.2 C (99 F), blood pressure is 110/70 mm Hg, pulse is 88/min, and respirations are 16/min.  He has no jugular venous distention.  His heart sounds are normal and his lungs are clear.  Musculoskeletal examination is notable for extensive deformities in the hands due to long-standing arthritis.  His right knee is normal.  The left knee is tender and swollen and he is unable to extend it due to pain.
Joint aspiration yields 20 cc of synovial fluid.  Laboratory results are as follows:

Which of the following is the most appropriate next step in management?

Quizplus · Accepted Answer

This patient's clinical presentation (e.g., sudden onset of knee joint swelling, nausea, weakness, and inability to move joint) and synovial fluid analysis (increased cell count with 88% neutrophils) are suspicious for a septic joint. Damaged joints (e.g., rheumatoid arthritis) serve as a nidus for infection and can predispose to septic arthritis. However, many rheumatoid arthritis (RA) patients with septic arthritis do not present acutely and may not have fever, chills, or peripheral leukocytosis. This is particularly common in elderly patients, which often leads to a delayed diagnosis. Although RA alone can present as "pseudoseptic arthritis" with florid acute synovitis and marked synovial fluid leukocytosis, septic arthritis must be excluded first. Diagnosis is usually suggested by synovial fluid showing elevated leukocytes (50,000-150,000 cells/µL), positive Gram stain, and positive fluid culture. However, synovial fluid Gram stain can be negative in 20-30% of septic arthritis cases, especially with gram-negative bacteria. Blood cultures are positive in 50% of patients and must always be obtained prior to antibiotic therapy. Treatment consists of IV antibiotics and joint drainage. This patient should be monitored clinically and started on IV antibiotics until culture results return. (Choice A) Colchicine would be effective in treating gouty arthritis, but the lack of crystals in this patient's synovial fluid makes this diagnosis unlikely. (Choice B) Intraarticular steroid injection should not be performed until infection is excluded. Repeated steroid injections are an important risk factor for septic arthritis. (Choice D) Prednisone is effective in RA flare-up, but infectious arthritis should be excluded first. (Choice E) TNF antagonists may be used cautiously in class 1 and 2 congestive heart failure (CHF), but are contraindicated in class 3 and 4 CHF. Since the patient had CHF exacerbation with a TNF antagonist, it would be inappropriate to restart the medication. In addition, TNF antagonists are not useful in acute joint inflammation. Educational objective: Septic arthritis occurs more commonly in patients with comorbidities (e.g., diabetes, HIV) or conditions such as rheumatoid arthritis, severe osteoarthritis, or prosthetic joints. Patients typically present with monoarthritis with restricted motion and synovial fluid showing an elevated WBC count with positive Gram stain (although it can be negative in 20-30% of cases). Treatment involves IV antibiotics and joint drainage. __________ References: Management of the nontraumatic hot swollen joint. (http://www.ncbi.nlm.nih.gov/pubmed/21730866) Diagnosing acute monoarthritis in adults: a practical approach for the family physician (http://www.ncbi.nlm.nih.gov/pubmed/12887114) Approach to septic arthritis. (http://www.ncbi.nlm.nih.gov/pubmed/21916390)

A 65-Year-Old Man Comes to the Physician Because of a 3