Clinical results of linezolid in arthroplasty and trauma 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 nontrauma 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.

Biomechanical characteristics of bone in streptozotocin-induced diabetic rats:An in-vivo randomized controlled experimental study

AIM: To investigate the in vivo effects of type Ⅰdiabetes on the mechanical strength of tibial bone in a rodent model.METHODS: The biomechanical effect of diabetes on the structural integrity of the tibia in streptozotocin induced diabetic Wistar rats was analysed. Induction of diabetes was achieved by an intra-peritoneal injection and confirmed by measuring serial blood glucose levels(> 150 mg/d L). After 8 wk the tibiae were harvested and compared to a control group. Biomechanical analysis of harvested tibiae was performed using a threepoint bending technique on a servo hydraulic MTS 858 MiniB ionix frame. Maximum force applied to failure(N), stiffness(N × mm) and energy absorbed(N/mm) were recorded and plotted on load displacement curves. A displacement control loading mode of 1 mm/min was selected to simulate quasi-static loading conditions. Measurements from load-displacement curves were directly compared between groups.RESULTS: Fourteen streptozotocin induced diabetic Wistar rats were compared against nineteen non-diabetic controls. An average increase of 155.2 g in body weight was observed in the control group compared with only 5 g in the diabetic group during the experimental study period. Levels of blood glucose increased to 440.25 mg/d L in the diabetic group compared to 116.62 mg/d L in the control group.The biomechanical results demonstrate a highly significant reduction in the maximum load to failure from 69.5 N to 58 N in diabetic group compared to control(P = 0.011). Energy absorption to fracture was reduced from 28.2 N in the control group to 23.5 N in the diabetic group(P = 0.082). No significant differences were observed between the groups for bending stiffness.CONCLUSION: Streptozotocin-induced diabetes in rodents reduces the maximum force and energy absorption to failure of bone, suggesting a predisposition for fracture risk.