Resolution of Staphylococcus aureus (methicillin-resistant Staphylococcus aureus) osteomyelitis by oral linezolid

The linezolid [1] spectrum of activity has provided a new venue to treat moderate to severe Gram-positive infections orally as well as using the intravenous methods. It has been recommended to avoid prolonged linezolid therapy because of reports of hematological toxicity, especially in thrombocytopenia. We present a case of osteomyelitis that has developed in the presence of vancomycin therapy, but improved when we changed to linezolid. On 8 August 2002, a 71-year-old woman with diabetes mellitus and hypothyroidism was submitted to a second coronary artery bypass graft surgery with a mammary-graft artery to the descending anterior coronary artery and two saphenous-veins grafts to marginal arteries, and also mitral valvuloplasty. Many weeks after this procedure her condition progressed to severe sepsis because of a large bowel ischemia associated with cytomegalovirus infection shown by colonoscopy visualization and biopsy. On this occasion, she further developed a right leg-wound cellulitis caused by Staphylococcus aureus (methicillin-resistant Staphylococcus aureus [MRSA]) that was treated promptly with vancomycin. Recurrence of staphylococcal signs of infection such as endocarditis was detected by transesophagic echocardiography with a vegetation of 0.96 cm shown on left coronary cusp, combined with reactive monoarthritis. After this new occurrence, vancomycin was reinstituted again for 6 weeks longer. Improvement of the endocarditis was achieved but the patient deteriorated due to osteomyelitis in the left femur and sacral region. All of these were detected by gallium-67 citrate scintigraphy in spite of standard vancomycin therapy. Therefore, we changed the therapeutic strategy to oral linezolid (600 mg twice daily) because of some difficulties to maintain safe vascular access [2]. An achievement of good outcome was shown by the second gallium-67 scintigraphy 5 weeks later. Furthermore, long treatment with linezolid was very well tolerated.

In conclusion, control of the bone infection with staphylococcus MRSA after a 5-week course of oral therapy with linezolid was attained. Treatment of osteomyelitis associated with a susceptible bacterial strain (MRSA) with this class of antibiotics taken orally appears to be safe, effective, and yielding a good outcome. Our case report supports the arguments of those who advocate the utilization of this kind of therapy, although there has not yet been consensus in the literature [3].