ABSTRACT
Objective To study the efficacy of linezolid on gram positive bacterial infection in elderly patients and risk factors associated with thrombocytopenia.Methods A retrospective analysis of 50 elderly patients treated with intravenous linezolid for gram-positive bacterial infection from January 2008 to October 2010 was conducted.Clinical data and bacteriological responses were assessed.Efficacy of linezolid on infection and risk factors associated with thrombocytopenia in elderly patients were analyzed.Results The average duration of treatment was (13±2) d,the efficacy rate was 74 ％ and the bacteriological eradication rate was 69 ％ (18/26).Thrombocytopenia occurred in 24 patients during the treatment,and the average platelet count was significantly reduced compared with pretreatment[(146±87) 109/L vs.(239± 114) 109/L,t=3.888,P=0.000)].Thromhocytopenia was associated with the baseline platelet count and the mean time of linezolid treatment.Based on a Logistic regression analysis,the baseline platelet count ＜ 200 × 109/L was identified as the only significant risk factor for linezolid-associated thrombocytopenia in elderly patients (OR =0.244,95％CI:0.068-0.874,P=0.030).The mean platelet count was decreased significantly after 7 days of treatment,and decreased to the lowest value 1-2 days after the end of therapy.Conclusions Linezolid is effective and safe for the elderly with gram-positive bacterial infection,especially hospital acquired methicillin-resistant staphylococcus aureus infection.Linezolid has little effect on liver and renal function in elderly patients,but it can cause thrombocytopenia,which is associated with baseline platelet count and the mean time of linezolid treatment.Platelet counts should be monitored during treatment and measures should be taken to prevent hemorrhagic tendencies.