For the reason that the potential risk for long-term orthopedic sequelae caused by the rapid joint destruction, septic arthritis should be considered a true pediatric emergency requiring a high index of clinical suspicion, early joint drainage, and prompt administration of adequate antimicrobial therapy. The initial antibiotics therapy should be administered through the parenteral route. The penetration of most antibiotics into inflamed joint effusions is sufficient providing that an adequate serum level is achieved. Therefore, antibiotics do not need to be injected intra-articularly; furthermore, this is contraindicated because of the possibility of inducing chemical synovitis.35
The choice of the initial antibiotic therapy should be guided by the results of the Gram stain examination of the fluid, age of the patient, clinical picture, presence of specific risk factors (such as immunodeficiency), potential exposures to organisms such as B. burgdorferi or brucellae, and the local prevalence of antibiotic resistance in organisms such as S. aureus. Once the pathogen is identified and antibiotic susceptibility is determined, antibiotic therapy should be adjusted accordingly. If no pathogen is isolated but the patient is responding adequately, therapy should be continued with the drug chosen originally. If no improvement is noted the possibility of an uncommon infectious etiology or a non infectious process should be entertained and a more extensive clinical and laboratory evaluation, including reaspiration and, eventually, a synovial biopsy should be considered.1
In the newborn, an antistaphylococcal penicillin, such as oxacillin or nafcillin (150–200 mg/kg per 24 hours divided q6h), in combination with a third generation cephalosporin, such as cefotaxime (150–200 mg/kg per 24 hours divided q8h), provide adequate empiric antimicrobial coverage (pending culture and antibiotic susceptibility results). In premature babies with long-term indwelling intravenous catheters, vancomycin (10–15 mg/kg per 24 hours divided in 1–3 doses, according to weight and age) instead of the penicillinase-resistant penicillins is recommended to cover nosocomial coagulase-negative staphylococci.
In preschool age children up to 5 years of age, options include cefuroxime (200–300 mg/kg per 24 hours divided q8h), cefotaxime, or ceftriaxone because each adequately covers gram-positive pathogens such as methicillin-susceptible S. aureus, β-hemolytic streptococci, pneumococci, as well as gram-negative organisms such as H. influenzae type b, K. kingae, N. meningitidis, and most of the Enterobacteriaceae. In children older than 5 years of age, gram-positive bacteria constitute the vast majority of isolates. Anti staphylococcal antibiotics alone would provide adequate coverage pending culture results, unless N. gonorrhoeae is suspected, in which case, addition of ceftriaxone is recommended. In areas where CA-MRSA organisms are prevalent, vancomycin (40–60 mg/kg per 24 hours divided q6h) or clindamycin (30–40 mg/kg per 24 hours divided tid-qid) should be administered, although resistance to the latter has been detected in a few isolates.12 Experience with the use of linezolid for CA-MRSA is limited but the drug appears to be effective for the treatment of suppurative arthritis.53 The use of quinopristin/dalfopristin and daptomycin as alternative drugs for skeletal infections caused by CA-MRSA has not been adequately evaluated in children, and emergence of resistance to the latter drug in the course of therapy for osteomyelitis has been reported.54
Immunocompromized hosts should be given broad-spectrum antibiotics to cover a large variety of common as well as rarer opportunistic organisms. Combinations of vancomycin with ceftazidime (150–200 mg/kg per 24 hours divided q4–6h) or combinations of piperacillin-clavulanate (300–400 mg/kg per 24 hours divided q6–8h) or ticarcillin-clavulanate (200–300 mg/kg per 24 hours divided q4–6h) with an aminoglycoside are currently recommended.1 When joint infections are caused by direct penetrating wounds or bites, anti anaerobic antibiotic coverage with clindamycin should be added. S. aureus arthritis and infections caused by Enterobacteriaceae require 4 weeks of therapy, whereas arthritis caused by other organisms may be adequately treated for a total 2 weeks.
Children with Lyme arthritis may receive oral medications such as amoxicillin, doxycycline (if older than 8 years of age), or cefuroxime initially. If symptoms fail to improve substantially and the diagnosis is certain, ceftriaxone may be used. In children aged 8 years or older, brucellar arthritis is best treated with a combination of oral doxycycline (2–4 mg/kg per 24 hours, up to a maximum of 200 mg/d, divided q12h), and rifampin (15–20 mg/kg/day, maximum 600–900 mg/d, in 1 or 2 divided doses) for 6 weeks. In children younger than 8 years, oral trimethoprim-sulfamethoxazole (10 mg/kg per 24 hours of trimethoprim hours, maximum 480 mg/d, divided q12h and sulfamethoxazole, 50 mg/kg/d, maximum 2.4 g/d) should be used instead of doxycycline.55
Once the patient's condition has improved and surgical procedures are no longer necessary (usually within 1 week), the initial parenteral antimicrobial therapy may be shifted to oral drugs for infections involving the knee, ankle, and other small joints. The synovial fluid antibiotic concentrations after oral administration routinely exceed the serum concentrations by 60% or more.56 Prerequisites for oral therapy include control of infection and inflammation and compliance with planned therapy and monitoring. For the oral regimen of β-lactam antibiotics, a dosage 2–3 times higher than that used for more benign infections is needed.1 In the past, it was recommended to assess the adequacy of the antibiotic dosage and absorption of the drug in patients with osteomyelitis and septic arthritis treated with sequential parenteral-oral antibiotic therapy. The peak bactericidal activity at the steady state (after the third dose of oral antibiotics) was measured in the serum and finding of a level of 1:8 or greater was considered adequate.1 A recent study has suggested that determining antibiotic levels may be unnecessary and patients with staphylococcal osteomyelitis may be safety managed with judicious clinical evaluation and serial CRP determinations.57 Further experience with this simplified treatment approach and with its use in children with septic arthritis or infections caused by other organisms is required before it can be universally recommended.
The appropriate duration of antimicrobial therapy for septic arthritis is not clear but should be individualized based on the organism isolated and the clinical and laboratory response. Minimum criteria for discontinuing antibiotic therapy include resolution of signs and symptoms of infection and normalization of the CRP level. The CRP peaks on the second day of therapy and is normal within 7–9 days. In contrast, the ESR rises slowly over several days, peaks in the first week, and then normalizes slowly during the next 3–4 weeks. Since the CRP increases and decreases much more quickly than ESR, measuring the CRP may be more useful in determining response to therapy. CRP values that remain high or increase again during therapy require careful investigation. Waiting for normalization of the ESR may be an overly conservative therapeutic end point. Most infections require 2 weeks of therapy but septic arthritis caused by S. aureus or gram negative organisms require at least 3 weeks of therapy. Children with associated osteomyelitis should be treated for 4 weeks since a shorter duration of therapy may be inadequate for the treatment of osteomyelitis.
Lyme arthritis is treated with a 4-week course of oral amoxicillin or doxycycline, depending on age. Fewer than 10% of children fail an oral regimen but children with incomplete response to oral antibiotic therapy require intravenous ceftriaxone or penicillin for 14–21 days. Surgical irrigation of the joint is not usually required. Up to 50% of children with Lyme arthritis will have a recurrent episode of arthritis within 6 months of initial treatment.33 Recurrences can be treated with non-steroidal anti-inflammatory agents. The frequency and duration of recurrences, which occur more commonly in females and in older children,34 diminish over time. Patients who receive intra-articular steroids prior to antibiotic treatment for Lyme arthritis appear to have a longer time to resolution of the arthritis.34 Repeating Lyme serologic tests during recurrences does not alter management. Chronic arthritis rarely develops in children with Lyme arthritis.
Gonococcal arthritis should be treated with intravenous ceftriaxone or other broad-spectrum cephalosporins. Skin lesions may continue to develop during the first two days of therapy. Treatment may be switched to oral fluoroquinolones or, if penicillin-susceptible organisms are isolated, amoxicillin to complete 7–10 days of total therapy. Surgical irrigation of the joint is not routinely required. Sexually active adolescents should be evaluated for other sexually transmitted diseases, including C. trachomatis. Prepubertal children require evaluation for sexual abuse.
Results of a recent double-blind placebo-controlled study conducted among 123 children with joint infections in Costa Rica have shown that adding intravenous dexamethasone (0.6 mg/kg per 24 hours divided q8h) for 4 days to appropriate antibiotic and surgical therapy significantly reduced the duration of symptoms and residual dysfunction compared to placebo, supporting the role played by the host's immune response in the degradation of the joint cartilage.58 These promising results need to be confirmed before the administration of corticosteroids can be routinely recommended in patients with septic arthritis.
Because of the deleterious effect of infected synovial fluid on the cartilage layer, removal of the accumulated exudate is recommended. A seminal study conducted by Nelson and Koontz59 in 1966 concluded that needle aspirations (single or multiple, as clinically required) were preferable over open drainage as the initial management of infected joints, and these results have been later confirmed by others. The hip and shoulder are the exceptions to this rule because increased intracapsular pressure of undrained fluid may compromise the vascular supply, resulting in necrosis of the femoral or humeral heads. It has been recently suggested that repeated ultrasound-guided aspirations and irrigation may spare the need for surgical drainage,60 but this conservative approach should be confirmed by additional experience. The indications for surgery in the management of pediatric septic arthritis are summarized in Table 48–6.
Table 48–6. Indications for Open Surgical Drainage of a Septic Joint ||Download (.pdf)
Table 48–6. Indications for Open Surgical Drainage of a Septic Joint
- Arthritis of the hip or shoulder
- Presence of large amounts of fibrin, debris or loculation within the joint space
- Rapid reaccumulation of fluid despite repeat aspirations
- Presence of a foreign body
- Arthritis not responding to medical treatment within 3 days
- Adjacent osteomyelitis
- Arthritis in a patient with rheumatoid arthritis
- Arthritis of the sternoclavicular joint