Treatment of osteomyelitis and septic arthritis with cefazolin.

Sixteen cases of severe osteomyelitis and septic arthritis caused by staphylococci, streptococci, gonococci, and a variety of gram-negative bacilli were treated with 4 to 8 g of parenteral cefazolin per day; nine received subsequent therapy with oral cephalexin or ampicillin. Of 16 infections, 15 were apparently cured. Cefazolin concentrations in those patients were: serum (peak), 25 to 216 micrograms/ml; synovial fluid, 24 to 46 micrograms/ml; and bone, 3.2 to 10.6 micrograms/g. Bacterial pathogens had minimal inhibitory concentrations of cefazolin of 2 micrograms or less per ml and seemed to be eradicated from foci of infection during therapy. One infection in a diabetic patient did not respond; despite high concentrations of cefazolin in serum, no detectable antibiotic was present in her infected metatarsal, and the infecting Escherichia coli (minimal inhibitory concentration, 16 micrograms/ml) was not eradicated during therapy. Concentrations of cefazolin in bone in 10 uninfected patients who received 1-g intramuscular doses prophylactically before surgery were also measured. Concentrations in bones from those who had normal renal function ranged from less than 0.6 to 2.8 micrograms/g.