Treatment with linezolid and rifampicin for 18 months for recurrent infection of a megaprosthesis in a patient with Ewing's sarcoma

Linezolid: a review of safety and tolerability

Linezolid has demonstrated activity against antibiotic-susceptible and antibiotic-resistant aerobic Gram-positive cocci. The availability of intravenous and oral formulations, with near 100% bioavailability of the latter, is hoped to facilitate the management of multiply drug-resistant Gram-positive infections. Linezolid was approved for clinical use in the United States in April 2000 and has subsequently been approved in other countries for the management of community-acquired and nosocomial pneumonia, complicated and uncomplicated skin and soft-tissue infections, and infections caused by methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci, including cases with concurrent bacteremia. Additional studies have demonstrated potential use in febrile cancer patients with neutropenia, and case reports have documented some efficacy in the management of infective endocarditis, tuberculosis, nocardiosis, and in anaerobic infections. Given the potential for significantly increased use of linezolid, a thorough review and update of its tolerability and safety profile is warranted.

Linezolid alone or combined with rifampin against methicillin-resistant Staphylococcus aureus in experimental foreign-body infection

We investigated the activity of linezolid, alone and in combination with rifampin (rifampicin), against a methicillin-resistant Staphylococcus aureus (MRSA) strain in vitro and in a guinea pig model of foreign-body infection. The MIC, minimal bactericidal concentration (MBC) in logarithmic phase, and MBC in stationary growth phase were 2.5, >20, and >20 microg/ml, respectively, for linezolid; 0.01, 0.08, and 2.5 microg/ml, respectively, for rifampin; and 0.16, 0.63, >20 microg/ml, respectively, for levofloxacin. In time-kill studies, bacterial regrowth and the development of rifampin resistance were observed after 24 h with rifampin alone at 1x or 4x the MIC and were prevented by the addition of linezolid. After the administration of single intraperitoneal doses of 25, 50, and 75 mg/kg of body weight, linezolid peak concentrations of 6.8, 12.7, and 18.1 microg/ml, respectively, were achieved in sterile cage fluid at approximately 3 h. The linezolid concentration remained above the MIC of the test organism for 12 h with all doses. Antimicrobial treatments of animals with cage implant infections were given twice daily for 4 days. Linezolid alone at 25, 50, and 75 mg/kg reduced the planktonic bacteria in cage fluid during treatment by 1.2 to 1.7 log(10) CFU/ml; only linezolid at 75 mg/kg prevented bacterial regrowth 5 days after the end of treatment. Linezolid used in combination with rifampin (12.5 mg/kg) was more effective than linezolid used as monotherapy, reducing the planktonic bacteria by >or=3 log(10) CFU (P < 0.05). Efficacy in the eradication of cage-associated infection was achieved only when linezolid was combined with rifampin, with cure rates being between 50% and 60%, whereas the levofloxacin-rifampin combination demonstrated the highest cure rate (91%) against the strain tested. The linezolid-rifampin combination is a treatment option for implant-associated infections caused by quinolone-resistant MRSA.