Oral antibiotic therapy for skeletal infections of children. I. Antibiotic concentrations in suppurative synovial fluid

To evaluate the feasibility of oral antibiotic treatment for pyogenic arthritis, one or more oral doses of antibiotics were substituted for the drugs being used for parenteral therapy. Synovial fluid and serum specimens obtained at randomized times after an oral dose of ampicillin, cephalexin, cloxacillin, dicloxacillin, or penicillin G were assayed for antibiotic content and antibacterial activity. Seventy specimens from 21 infants and children were studied. Peak synovial fluid concentrations were greater than 60% of peak serum concentrations with all drugs tested and there was adequate inhibitory activity against bacteria commonly causing arthritis. The degree of antibiotic binding to serum protein had no apparent effect on the degree of penetration into pyogenic synovial fluid.