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Quick Test posted on 5.1.12:
| Treatment of Infectious Arthritis
| Infectious Arthritis
The three most important therapeutic maneuvers in the management of infectious arthritis are appropriate antibiotics, joint drainage, and joint rest. Smears of the synovial fluid can be useful to select appropriate antibiotic therapy initially. If bacteria are not observed on the Gram stain in a patient who has a purulent joint effusion, antibiotics still should be initiated because of the high risk of an infection being present. A delay in initiating antibiotics significantly increases the likelihood for long-term complications.
The specific antibiotic selected depends on the most likely infecting organism. In infants younger than 1 month, the infecting organisms vary widely, and empirical therapy thus must provide broad-spectrum coverage. A penicillinase-resistant penicillin such as nafcillin or oxacillin plus an aminoglycoside is appropriate. Children younger than 5 years who have been immunized for H. influenzae type B should receive nafcillin, oxacillin, or cefazolin.
In children older than 5 years and in adults, initial therapy with a penicillinase-resistant penicillin is appropriate to provide the necessary coverage against S. aureus. Therapy should be changed to clindamycin, vancomycin, or linezolid if the S. aureus is resistant to methicillin. Preliminary data indicate that children with infectious arthritis can be converted to oral therapy after initial IV therapy. As with osteomyelitis, IV drug abusers require coverage for P. aeruginosa; therefore, combination therapy with an aminoglycoside is needed. The antibiotics selected usually are administered parenterally. Antibiotics administered by this route achieve sufficient concentrations within the synovial fluid; thus, intraarticular antibiotic injections are unnecessary. Although studies to define clearly the appropriate length of therapy have not been conducted, 2 to 3 weeks of antibiotic therapy generally is adequate in nongonococcal infections. Less than 2 weeks of therapy combined with one joint aspiration was effective in closely monitored children with infectious arthritis. Joint fluid cultures usually are no longer positive after 7 days of antibiotics.
Disseminated gonococcal infections often respond quickly to antibiotics. Ceftriaxone 1 g/day for 7 to 10 days is the treatment of choice for adults. After culture and sensitivity results are available, and the organism is determined to be sensitive, therapy can be switched on the fourth day to oral amoxicillin or to doxycycline or tetracycline to complete the 7- to 10-day course. Clinical resolution of signs and symptoms usually is rapid.
Closed-needle aspiration is recommended for all infected joints except the hip. Joint drainage can be repeated daily for 5 to 7 days until effusions no longer reaccumulate. Open drainage is required in hip infections because closed-needle aspiration is difficult and inadequate. During the initial phase of the infection, weight bearing, such as walking, on the joint should be avoided. Passive range-of-motion exercises should be initiated when the pain begins to subside to maintain joint mobility. Approximately one-third of patients with bacterial arthritis have a poor joint outcome, such as severe functional deterioration. Poor joint outcomes are associated with older patients, those with preexisting joint disease, and patients with an infected joint containing synthetic material. Treatment guidelines are useful with septic arthritis of the hip.
| Table 127–2 Characteristics of Acute Infectious Arthritis
| | Feature | Finding | | Peak incidence | Children younger than 16 years | | | Adults older than 50 years | | Clinical findings | Fever of 38-40°C (100.4-104°F) in children; painful swollen joint in the absence of trauma | | | Physical examination: effusion, restriction of joint motion, tenderness, and warmth of joint | | Most commonly affected joints | Knee, hip, ankle, elbow, wrist, and shoulder | | Laboratory findings: | | | Erythrocyte sedimentation rate | Elevated in 90% of cases | | White blood cell count | Elevated in 30-60% of cases | | Left shift | Seen in two-thirds of patients | | Blood culture | Positive in 40% of cases | | Needle aspiration of joint | Gram stain diagnostic in 30-50% of cases. Synovial fluid cultures are positive in 60-80% of cases. Synovial fluid differential reveals 90% polymorphonuclear leukocytes. Synovial fluid glucose decreased relative to serum glucose. Lactic acid levels elevated in nongonococcal infectious arthritis but not in gonococcal infectious arthritis |
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