万古霉素对医院获得性肺炎中甲氧西林耐药金葡菌的最低抑菌浓度及其与预后的关系

Association between the minimum inhibitory concentration of vancomycin against methicillin-resistant Staphylococcus aureus and the clinical outcome in patients with hospital-acquired pneumonia

目的研究耐甲氧西林金葡菌(MRSA)医院获得性肺炎(HAP)中万古霉素对MRSA的最低抑菌浓度(MIC)分布、MIC值与预后的关系以及高MIC值MRSA菌株感染的危险因素。方法选择应用万古霉素治疗的MRSA HAP,采用E试验法测定MRSA菌株的MIC值,分析比较不同MIC值菌株感染患者的临床资料。结果本研究共纳入患者82例,43例(52.4%)MRSA菌株具有较高的MIC值;在基础疾病状态无明显统计学差异情况下,低MIC值和高MIC值患者万古霉素应用7 d后病原菌未清除率分别为15.4%和37.2%(P=0.026);万古霉素应用3 d后临床治疗无效率分别为25.6%和44.2%(P=0.079);28 d内肺炎复发率分别为5.7%和20.5%(P=0.129);万古霉素治疗前90 d内MRSA感染史与高MIC值MRSA感染发生明显相关(P=0.033)。结论高MIC值MRSA HAP患者万古霉素应用3 d后临床治疗无效率、7 d后病原菌未清除率及28 d内肺炎复发率高于低MIC值患者,万古霉素治疗前90 d内有MRSA感染史是HAP中高MIC值MRSA菌株感染的独立危险因素。

Objective To analyze the distribution of vancomycin minimum inhibitory concentrations （MICs） in methicillin-resist ant Staphylococcus aureus （MRSA） isolates and the efficacy of vancomycin relative to vaneomycin MICs in patients with hospi- tal acquired MRSA pneumonia, and identify the risk factors of high vancomycin MICs. Methods This study involved hospital acquired MRSA pneumonia treated with vancomycin. Vancomycin MICs were determined using E-test. The patients were as signed to high vancomycin MIC group （MIC 〉1 mg/L） or low vancomycin MIC group （MIC≤1 mg/L）. The clinical charac- teristics of these two patient groups were compared. Results Eighty-two patients were included in this study. Forty-three （52.4%） isolates showed high vancomycin MICs. There was no significant difference between the two patients groups in terms of baseline characteristics. Mierobiologic failure rate after 7 days of vancomycin treatment was 15.4% and 37.2% in the low- and high MIC groups, respectively （P = 0. 026）. Clinical failure after 3 days of treatment （25.6% versus 44.2%, P = 0. 079） and relapse rate of MRSA pneumonia within 28 days （5.7Y0 versus 20. 5%, P = 0. 129） was significantly higher in the high MIC group than in the low MIC group. Prior MRSA in fection within 90 days of vancomycin treatment （P = 0. 033） was significantly associated with high vancomycin MIC val- ue. Conclusions Hospital acquired pneumonia caused by MRSA with high vancomycin MIC show a higher clinical failure after 3 days of vancomycin treatment, microbiologic failure and re- lapse of MRSA pneumonia within 28 days compared with those caused by MRSA with low vancomycin MIC. Patients with a history of MRSA infection within 90 days before vancomycin treatment should be considered as an independent risk factor of hospital-acquired pneumonia caused by MRSA strains with high vancomycin MIC.