Clinical results of linezolid in arthroplasty and trauma MRSA related infections.

AIM: To analyse the management of patients treated with linezolid for orthopaedic infections. METHODS: Twenty-two patients with orthopaedic related infections receiving a course of linezolid were reviewed retrospectively. Patients were classified into either post trauma, post arthroplasty and non trauma related infections. A diagnosis of infection was based on clinical findings, positive microbiological specimens, and positive signs of infection on radiological imaging and raised inflammatory markers. Pathogens isolated, inflammatory markers both at presentation and at final follow up, length of linezolid treatment, adverse drug reactions, concomitant anti-microbial therapy, length of hospital stay and any surgical interventions were recorded. RESULTS: Infections were classified as post arthroplasty (n = 10), post trauma surgery (n = 8) or non-trauma related infections (n = 4). Twenty patients (91%) underwent surgical intervention as part of their treatment. The number of required surgical procedures ranged from 1 to 6 (mean = 2.56). Mean total length of stay per admission was 28.5 d (range 1-160 d). Furthermore, the mean duration of treatment with linezolid of patients who had resolution of symptoms was 31 d (range 10-84 d). All patients within this group were discharged on oral linezolid. Pathogens isolated included methicillin resistant Staphylococcus aureus, coagulase negative staphylococci, coliforms, enterococcus, Staphylococcus epidermidis, streptococcus viridans, Escherichia coli, group B streptococcus and pseudomonas. An overall 77% of patients demonstrated resolution of infections at follow-up, with mean C-reactive protein reducing from 123 mg/L to 13.2 mg/L. CONCLUSION: This study demonstrates that the use of linezolid offers excellent efficacy in orthopaedic related infections when used alongside appropriate surgical management.

Anti-inflammatory role and immunomodulation of mesenchymal stem cells in systemic joint diseases: potential for treatment.

INTRODUCTION: Mesenchymal stem cells (MSCs) are multipotent stromal cells characterized by their ability to differentiate into adipocytes, chondrocytes, osteocytes and a number of other lineages. Investigation into their use has increased in recent years as characterization of their immunomodulatory properties has developed, and their role in the pathophysiology of joint disease has been suggested. AREAS COVERED: MSCs demonstrate immunosuppressive functionality by suppressing T- and B-cell responses following activation by cytokines such as IL-6 and IL-1α. They also can be induced to exert pro-inflammatory effects in the presence of acute inflammatory environment due to the actions of TNF-α and IFN-γ. In inflammatory joint diseases such as rheumatoid arthritis, MSCs in bone marrow migrate to joints by a TNF-α-dependent mechanism and may be in part responsible for the disease process. MSCs have also been demonstrated in increased numbers in periarticular tissues in osteoarthritis, which may reflect an attempt at joint regeneration. EXPERT OPINION: Clinical applications for MSCs have shown promise in a number of inflammatory and autoimmune disorders. Future work is likely to further reveal the immunosuppressive characteristics of MSCs, their role in the pathophysiology of joint diseases and provide the basis for new avenues for treatment.