Synovial fluid and plasma concentrations of tedizolid in patients with osteoarthritis infected with Staphylococcus aureus effectively determined with fluorescence detection.

BACKGROUND: Tedizolid is a new oxazolidinone antibiotic with high potency for the treatment of infections caused by methicillin-resistant Staphylococcus aureus and other species. CASE PRESENTATION: Two patients with osteoarthritis (women aged 79 and 73 years, cases 1 and 2, respectively) infected with S. aureus were successfully treated with tedizolid after administration of 200 mg once daily via intravenous infusion. The synovial fluid and plasma concentrations of tedizolid during surgery in case 1 at day 7 were 2.1 and 1.6 µg/mL, respectively, yielding a ratio of synovial fluid/plasma of 130%. Those in case 2 at day 2 were 2.9 and 3.3 µg/mL, respectively, corresponding to a ratio of synovial fluid/plasma of 88%. CONCLUSIONS: These results imply very similar concentrations of tedizolid in the synovial fluid and plasma of osteoarthritis patients with acute S. aureus infection.

Plasma and synovial fluid concentrations of linezolid in patients with knee osteoarthritis infected with Staphylococcus aureus.

BACKGROUND: Linezolid is a new oxazolidinone antibiotic used for infections caused by methicillin-resistant Staphylococcus and other species. CASE PRESENTATION: Two cases of knee osteoarthritis with acute infection were successfully treated using linezolid. The plasma and synovial fluid concentrations of linezolid in two patients [women aged 69 and 73 years (cases 1 and 2)] with knee osteoarthritis infected with Staphylococcus aureus were measured after they were administered 600 mg twice daily by intravenous infusion. The plasma linezolid concentrations during knee surgery in case 1 at day 5 and in case 2 at day 2 were 19.6 and 15.6 µg/mL, respectively. The synovial fluid concentrations of linezolid in samples taken during surgery in case 1 and case 2 were 14.9 and 17.0 µg/mL, respectively; these values corresponded to ratios of synovial fluid/plasma of 76 and 109%. Possible metabolite 2-hydroxylated linezolid potentially mediated by cytochrome P450 2 J2 was not detected in the plasma or synovial fluid samples under the current clinical setting after multiple doses. CONCLUSIONS: These results implied nearly equivalent concentrations of linezolid in plasma and synovial fluid of clinical patients with knee osteoarthritis acutely infected with Staphylococcus aureus.