Medication Summary
Antimicrobial therapy is dictated by the results of a Gram stain and the clinical characteristics of the host. If the results of a Gram stain of synovial fluid identify no organism, empiric therapy is initiated on the basis of the clinical characteristics of the host. Mycobacterial and fungal infections are treated with agents appropriate to the causative pathogen.
Antibiotics
Class Summary
Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.
Nafcillin
Nafcillin is used as initial therapy for possible penicillin G–resistant streptococcal or staphylococcal infections. In a patient with severe infections, it should be given parenterally at first, then orally as the patient's condition warrants. Because of the risk thrombophlebitis, particularly in elderly patients, parenteral administration should be continued for a short period (1-2 days) only.
Ceftriaxone (Rocephin)
Ceftriaxone is a third-generation cephalosporin with broad-spectrum gram-negative activity; it has lower efficacy against gram-positive organisms and higher efficacy against resistant organisms. It arrests bacterial growth by binding to 1 or more penicillin-binding proteins (PBPs).
Ciprofloxacin (Cipro, Cipro XR)
Ciprofloxacin inhibits bacterial DNA synthesis and thus growth. It is active against gram-negative rods and may be administered with nafcillin.
Vancomycin
Vancomycin is active against Staphylococcus epidermidis. To avoid toxicity, the current recommendation is to assay vancomycin trough levels after the third dose in a sample drawn 0.5 hours before the next dose. Dose adjustment is possible in patients with renal impairment; the adjustment should be based on creatinine clearance.
Antitubercular agents
Class Summary
Antitubercular agents are used when therapy for tuberculous arthritis is indicated.
Isoniazid
Isoniazid offers the best combination of effectiveness, low cost, and minor adverse effects. Coadministration of pyridoxine is recommended if peripheral neuropathies develop secondary to isoniazid therapy. Prophylactic pyridoxine 6-50 mg/day is recommended.
Rifampin (Rifadin)
Rifampin is given in combination with at least 1 other antituberculous drug (eg, isoniazid); it inhibits DNA-dependent bacterial but not mammalian RNA polymerase. Cross-resistance may occur. Treat for 6-9 months or until 6 months have elapsed since conversion to a negative sputum culture result.
Antifungals, Systemic
Class Summary
These agents are used when fungal arthritis, such as candidal arthritis, is documented.
Amphotericin B lipid complex (Abelcet)
Amphotericin B is produced from a strain of Streptomyces nodosus; it can be fungistatic or fungicidal. This agent binds to sterols (eg, ergosterol) in the fungal cell membrane, causing intracellular components to leak, with subsequent fungal cell death.
Fluconazole (Diflucan)
Fluconazole is a synthetic oral antifungal (broad-spectrum bistriazole) that selectively inhibits fungal cytochrome P-450 and sterol C-14 alpha-demethylation. It is suggested for use in combination with amphotericin.
