Suppurative arthritis must be distinguished from Lyme disease, osteomyelitis, suppurative bursitis, fasciitis, myositis, cellulitis, and soft tissue abscesses. Psoas muscle abscess often presents with fever and pain on hip flexion and rotation. Juvenile idiopathic arthritis, Kawasaki disease, Henoch-Schönlein purpura, other rheumatic disorders, and Crohn’s disease must be differentiated from infectious arthritis. In most of these diseases, the presence of symmetric or multiple joint involvement
Infants (younger Group B Ampicillin plus than 2 months of streptococci aminoglycoside age)
Staphylococcus Nafcillin (or oxacillin), aureus vancomycin
Older infants and S. aureus Nafcillin (or oxacillin), children
Kingella kingae Penicillin G, nafcillin (or oxacillin) or cefotaxime
Neisseria Ceftriaxone gonorrhoeae: *The incidence of invasive infections caused by H. influenzae type b has diminished greatly with universal childhood Hib vaccination.
often excludes infectious arthritis. Suppurative bursitis with Staphylococcus aureus occurs most often in older boys and men and is usually a consequence of trauma or, less commonly, a complication of bacteremia.
Initial antibiotic therapy for infectious arthritis is based on the likely organism for the age of the child and the Gram stain of joint fluid. Suppurative arthritis of the hip joint, especially, or shoulder joint necessitates prompt surgical drainage. With insertion of the joint capsule below the epiphysis in these balland-socket joints, increased pressure in the joint space can adversely affect the vascular supply to the head of the femur or humerus, leading to avascular necrosis. Infections of the knee may be treated with repeated arthrocenteses, in addition to appropriate parenteral antibiotics.
Several antimicrobial agents provide adequate antibiotic levels in joint spaces (Table 118-3). Initial therapy for neonates should include antibiotics with activity against S. aureus, group B streptococcus, and aerobic gram-negative rods, such as nafcillin and cefotaxime. Initial therapy for children 3 months to 5 years old should include antibiotics with activity against S. aureus. Addition of appropriate antibiotics should be considered if the child is unimmunized against Haemophilus influenzae type b (Hib). Confirmed methicillin-susceptible S. aureus infections are best treated with nafcillin or oxacillin, and methicillin-resistant S. aureus infections are best treated with clindamycin, if susceptible, or vancomycin otherwise.
The duration of therapy depends on clinical resolution offever and pain and decline of the ESR and CRP. Infectionwith virulent organisms, such as S. aureus, usually necessitates treatment for at least 21 days. Treatment may bechanged to oral antibiotics if adherence can be ensured. Oral agents with excellent activity against S. aureus that are often used to complete therapy include cephalexin, clindamycin,amoxicillin-clavulanate, dicloxacillin, and ciprofloxacin (forpatients >18 years).