What is the recommended treatment for a patient with septic arthritis caused by gram-negative diplococci?

Treatment of Gonococcal Septic Arthritis

You should prescribe ceftriaxone 1 g IV or IM every 24 hours for this patient with gonococcal septic arthritis, and also add azithromycin 1 g orally as a single dose to cover concurrent chlamydial infection. 1

Rationale for Ceftriaxone Selection

The clinical presentation—acute monoarticular arthritis with gram-negative diplococci on synovial fluid Gram stain—is pathognomonic for disseminated gonococcal infection (DGI) with septic arthritis. 1

• Ceftriaxone is the CDC-recommended first-line treatment for DGI and gonococcal septic arthritis, with no reported treatment failures using this regimen. 1
• The synovial fluid WBC count of 70,000/µL with gram-negative diplococci confirms bacterial septic arthritis requiring immediate antimicrobial therapy. 2
• This patient requires hospitalization given the purulent synovial effusion and systemic signs (fever, tachycardia, leukocytosis). 1

Treatment Protocol

Initial parenteral therapy:

• Ceftriaxone 1 g IV or IM every 24 hours should be continued for 24-48 hours after clinical improvement begins. 1
• After improvement, transition to oral cefixime 400 mg twice daily to complete at least 1 week of total antimicrobial therapy. 1

Mandatory concurrent chlamydial coverage:

• Add azithromycin 1 g orally as a single dose, as patients with DGI should be treated presumptively for concurrent C. trachomatis infection unless appropriate testing excludes it. 1, 3
• This patient's risk factors (two male sexual partners, no barrier contraception implied) make concurrent chlamydial infection highly likely. 1

Joint Drainage Requirements

Arthrocentesis or surgical drainage is essential:

• Evacuation of purulent material must accompany antibiotic therapy for septic arthritis. 4, 5, 2
• Repeated arthrocentesis may be sufficient for gonococcal hip infections, which respond better than non-gonococcal bacterial arthritis. 6
• The Infectious Diseases Society of America recommends immediate joint drainage or debridement combined with prompt empiric antibiotic therapy. 4, 5

Why Other Options Are Incorrect

Azithromycin alone (option b) is inadequate—it treats chlamydia but has no reliable activity against N. gonorrhoeae and would not adequately treat septic arthritis. 1

Nafcillin (option c) targets gram-positive organisms like Staphylococcus aureus, not gram-negative diplococci. 2

Piperacillin-tazobactam (option d) is unnecessarily broad-spectrum when the Gram stain clearly identifies gram-negative diplococci, and it is not the guideline-recommended agent for gonococcal infections. 1

Vancomycin (option e) covers only gram-positive organisms (particularly MRSA) and has no activity against gram-negative bacteria. 4, 5, 2

Critical Management Considerations

Timing is crucial:

• Antimicrobials should be initiated within 1 hour of recognition, as each hour of delay decreases survival by approximately 7.6% in septic patients. 5
• However, obtain synovial fluid culture before starting antibiotics if this causes no substantial delay. 5

Partner notification:

• Both sexual partners must be evaluated and treated for gonorrhea and chlamydia to prevent reinfection. 1, 3
• The patient should abstain from sexual intercourse until therapy is completed and symptoms resolve. 3

Duration and monitoring:

• Total treatment duration is typically 7 days for uncomplicated gonococcal arthritis. 1
• Monitor ESR and CRP levels to guide response to therapy. 5
• Narrow therapy once culture sensitivities return, though ceftriaxone will likely remain appropriate. 5

Common Pitfalls to Avoid

• Do not delay antibiotics for imaging studies—the clinical presentation and Gram stain are sufficient to initiate treatment. 5
• Do not use fluoroquinolones empirically for gonococcal infections due to widespread resistance, though they may be used after susceptibility testing confirms sensitivity. 1, 7
• Do not forget chlamydial co-treatment—up to 50% of patients with gonorrhea have concurrent chlamydial infection. 1
• Do not rely on antibiotics alone—joint drainage is mandatory for successful treatment of septic arthritis. 4, 5, 2