【最新热点】社区获得性肺炎过度抗MRSA，竟达30倍！！！原创 2016-06-24 SIFIC热点团队 SIFIC官微
编者按 bianzhean 耐甲氧西林金黄色葡萄球菌（MRSA）是医院感染和社区感染的主要致病菌之一，呈世界分布，并有局部暴发流行。近年来，MRSA呈迅速上升趋势，准确快速的检测对防止MRSA传播和抗菌药物合理使用具有十分重要的意义。目前，表型水平的MRSA快速检测法和基因水平的MRSA快速检测法均有其局限性，尚不能普及使用。由于MRSA的诊断技术限制，临床医生往往只能够经验性使用抗菌药物来进行治疗，从而造成严重的抗菌药物过度使用，具体请阅读下文。
[size=1.8em]诊断问题导致耐甲氧西林金黄色葡萄球菌药物过度使用30倍 Diagnosis Problems Blamed for 30-fold Overuse of MRSA Drugs作者：Janis C. Kelly 检索：唐文瑞 翻译：唐文瑞 编写：陈志锦 审核：陈志锦 研究人员在5月8日《临床感染性疾病》在线版杂志上发表的一篇文章称，目前用于住院患者的《耐甲氧西林金黄色葡萄球菌（MRSA）临床指南》，导致了肺炎病人接受的抗MRSA药物治疗是理论需要的30倍以上，因为除了使用抗MRSA药物经验性治疗社区获得性肺炎外，临床医生没有更好的选择。
由田纳西州那什维尔范德堡大学医学中心急诊医学副教授、公共卫生硕士的威斯利·塞尔夫主导的多中心前瞻性监测研究显示，社区获得性肺炎入院的成人中MRSA患病率为0.7%，但将近三分之一（29.8%）的社区获得性肺炎的病人使用了万古霉素或利奈唑胺这些抗MRSA类抗生素。 精确的MRSA社区获得性肺炎临床预测模型被视为不太可能 作者写道：“尽管近来大家对MRSA社区获得性肺炎的危险因素识别和临床预测模型的发展产生了巨大的兴趣，但是我们的结果表明，由于普通MRSA的非特异性特征（合并流感病毒感染，多肺叶浸润）和个别非典型症状（大咯血，肺空洞），不太可能开发出能精确地鉴别入院中MRSA社区获得性肺炎的临床预测模型。” 这导致了抗MRSA治疗的广泛过度使用，因为临床医生没有快速可靠的方法来区分非MRSA社区获得性肺炎与潜在致命性MRSA感染。
塞尔夫博士的团队利用研究社区获得性肺炎住院患者的肺炎社区病原学数据来记录这些问题。这项分析包括2010年1月1日至2012年6月30日期间，伊利诺州芝加哥的三个医院和那什维尔的两个医院登记的病人。入选标准包括：年龄大于18岁、因急性呼吸系统感染入院和肺炎的影像学证据。排除标准包括：最近住院史，非功能独立的疗养院住户以及肺部其他问题，比如囊性纤维化、癌症、气管造口术、最近干细胞移植、闭塞性细支气管炎、或者CD4计数小于200/mm^3的HIV。
2259名患者作为研究对象，接受了细菌和病毒中的至少一种诊断试验。
这项分析显示，1.6%的病人的社区获得性肺炎由金黄色葡萄球菌引起，包括0.7%的MRSA和1.0%的MSSA。研究人员按年龄组18~49岁、50~64岁、65~79岁和≥80岁调查了社区获得性肺炎的MRSA患病率，每个年龄段的患病率均不到1%。 支持重症监护患者经验性抗MRSA药物治疗 未入住ICU的病人中MRSA社区获得性肺炎的患病率较低，为0.1%。该数据得到现在《美国传染病协会和美国胸科协会社区获得性肺炎指南》的支持，所以这个指南不推荐给普通病人常规使用抗MRSA抗生素。在ICU的病人中，MRSA社区获得性肺炎的患病率为2.7%。 与MSSA的病人或者非金黄色葡萄球菌感染的社区获得性肺炎患者相比， MRSA社区获得性肺炎的病人更可能入住ICU，平均住院时间更长，更可能需要机械通气，且院内死亡率更高。研究人员建议，对于社区获得性肺炎的危重病人，在等待诊断试验结果的同时，应该考虑经验性抗MRSA治疗。
亟需金黄色葡萄球菌快速检测，以降低抗MRSA药物的过度使用 研究者得出结论，“虽然MRSA社区获得性肺炎病人的疾病严重程度普遍很高，但临床和流行病学特征与非金黄色葡萄球菌社区获得性肺炎明显重叠，尤其是肺炎链球菌的社区获得性肺炎，从而使得鉴别临床肺炎类型的病因变得困难。MRSA的低患病率加上缺乏独特临床症状使得经验性抗MRSA抗生素的精确定位治疗变得困难。能够快速准确鉴别金黄色葡萄球菌诊断试验的发展能够极大的提高当前对社区获得性肺炎的管理，以降低抗MRSA抗生素的过度使用。”
英文原文Current clinical guidelines for identifying methicillin-resistant Staphylococcus aureus (MRSA) at hospital admission are resulting in 30 times more patients with pneumonia being treated with anti-MRSA drugs than theoretically necessary because clinicians have no better options than empiric anti-MRSA therapy for many patients with community-acquired pneumonia (CAP), researchers report in an article published online May 8 in Clinical Infectious Diseases.
The multicenter, prospective surveillance study led by Wesley H. Self, MD, MPH, associate professor of emergency medicine, Vanderbilt University Medical Center, Nashville, Tennessee, showed a MRSA prevalence of 0.7% in adults hospitalized for CAP but treatment of 29.8%, nearly one third of patients with CAP, with the anti-MRSA antibiotics vancomycin or linezolid.
Accurate Clinical Prediction Model for MRSA CAP Seen as Unlikely
The authors write, "Although the identification of risk factors and development of clinical prediction models for MRSA CAP have generated great interest recently, our results suggest it is unlikely that a clinical prediction model could be developed that accurately identifies MRSA CAP at hospital admission due to the nonspecificity of common MRSA features (influenza coinfection, multilobar infiltrates) and uncommon occurrence of more specific features (massive hemoptysis, cavitary pneumonia)."
This has resulted in widespread overuse of anti-MRSA therapy because clinicians have no quick and reliable way to differentiate between non-MRSA CAP and potentially fatal MRSA.
Dr Self's team documented these problems using data from the Etiology of Pneumonia in the Community (EPIC) study of patients hospitalized for CAP. The analysis included patients enrolled between January 1, 2010, and June 30, 2012, at three hospitals in Chicago, Illinois, and two in Nashville. Eligibility criteria included age older than 18 years, hospital admission for acute respiratory infection, and radiographic evidence of pneumonia. Exclusion criteria included recent hospitalization, nursing home resident not functionally independent, and various conditions such as cystic fibrosis, cancer, tracheostomy, recent stem cell transplant, bronchiolitis obliterans, or HIV with CD4 count lower than 200 mm3.
The study population of 2259 patients underwent at least one diagnostic test for both bacteria and viruses.
The analysis showed that 1.6% of patients had CAP caused by S aureus, including 0.7% with MRSA and 1.0% with methicillin-susceptible S aureus (MSSA). The researchers examined prevalence of MRSA CAP by age group (18-49, 50-64, 65-79, and ≥80 years) and it was less than 1% in each age group.
Empirical Anti-MRSA Therapy Supported for Intensive Care Patients
The low prevalence (0.1%) of MRSA CAP among patients not admitted to an intensive care unit provides support for the current Infectious Diseases Society of America and American Thoracic Society CAP guidelines, which do not recommend routine anti-MRSA antibiotics for patients admitted to a general medical floor. Among patients admitted to an intensive care unit, MRSA CAP prevalence was 2.7%.
Patients with MRSA CAP were more likely to be admitted to an intensive care unit, had longer median hospital stays, were more likely to require mechanical ventilation, and had higher in-hospital mortality than patients with MSSA or who had CAP without S aureus. The authors advise that empirical anti-MRSA therapy for critically ill patients with CAP be considered while awaiting the results of diagnostic testing.
Rapid Test for S aureus Needed to Reduce Overuse of anti-MRSA Drugs
The authors conclude, "While MRSA CAP patients generally had high severity of illness, clinical and epidemiologic characteristics overlapped substantially with non-S. aureus CAP, particularly pneumococcal CAP, making it difficult to distinguish between etiologic types of pneumonia clinically. Low prevalence of MRSA combined with a lack of highly distinctive clinical features make accurate targeting of empirical anti-MRSA antibiotics very difficult. Development of diagnostic tests capable of rapidly and accurately identifying S. aureus could greatly improve the current approach to CAP management and reduce overuse of anti-MRSA antibiotics." 摘自：http://www.medscape.com/viewarticle/864909
[本文图片来源于互联网，如有侵权请告知] 图文编辑：宋小船 审稿：马嘉睿 高晓东
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