Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
BMC Infect Dis. 2011 Oct 19;11:279. doi: 10.1186/1471-2334-11-279.
The high prevalence of methicillin-resistant S. aureus (MRSA) has led clinicians to select antibiotics that have coverage against MRSA, usually vancomycin, for empiric therapy for suspected staphylococcal infections. Clinicians often continue vancomycin started empirically even when methicillin-susceptible S. aureus (MSSA) strains are identified by culture. However, vancomycin has been associated with poor outcomes such as nephrotoxicity, persistent bacteremia and treatment failure. The objective of this study was to compare the effectiveness of vancomycin versus the beta-lactam antibiotics nafcillin and cefazolin among patients with MSSA bacteremia. The outcome of interest for this study was 30-day in-hospital mortality.
This retrospective cohort study included all adult in-patients admitted to a tertiary-care facility between January 1, 2003 and June 30, 2007 who had a positive blood culture for MSSA and received nafcillin, cefazolin or vancomycin. Cox proportional hazard models were used to assess independent mortality hazards comparing nafcillin or cefazolin versus vancomycin. Similar methods were used to estimate the survival benefits of switching from vancomycin to nafcillin or cefazolin versus leaving patients on vancomycin. Each model included statistical adjustment using propensity scores which contained variables associated with an increased propensity to receive vancomycin.
267 patients were included; 14% (38/267) received nafcillin or cefazolin, 51% (135/267) received both vancomycin and either nafcillin or cefazolin, and 35% (94/267) received vancomycin. Thirty (11%) died within 30 days. Those receiving nafcillin or cefazolin had 79% lower mortality hazards compared with those who received vancomycin alone (adjusted hazard ratio (HR): 0.21; 95% confidence interval (CI): 0.09, 0.47). Among the 122 patients who initially received vancomycin empirically, those who were switched to nafcillin or cefazolin (66/122) had 69% lower mortality hazards (adjusted HR: 0.31; 95% CI: 0.10, 0.95) compared to those who remained on vancomycin.
Receipt of nafcillin or cefazolin was protective against mortality compared to vancomycin even when therapy was altered after culture results identified MSSA. Convenience of vancomycin dosing may not outweigh the potential benefits of nafcillin or cefazolin in the treatment of MSSA bacteremia.
耐甲氧西林金黄色葡萄球菌（MRSA）的高患病率导致临床医生选择覆盖耐甲氧西林金黄色葡萄球菌的抗生素，通常是万古霉素，用于疑似葡萄球菌感染的经验性治疗。临床医生经常在培养物鉴定出甲氧西林敏感金黄色葡萄球菌（MSSA）菌株后继续使用万古霉素进行经验性治疗。然而，万古霉素与肾毒性、持续性菌血症和治疗失败等不良后果有关。本研究的目的是比较万古霉素与β-内酰胺类抗生素萘夫西林和头孢唑林在 MSSA 菌血症患者中的疗效。本研究的感兴趣结局为 30 天院内死亡率。
本回顾性队列研究纳入了 2003 年 1 月 1 日至 2007 年 6 月 30 日期间入住一家三级保健机构的所有成年住院患者，这些患者的血培养为 MSSA 阳性，并接受了萘夫西林、头孢唑林或万古霉素治疗。使用 Cox 比例风险模型评估比较萘夫西林或头孢唑林与万古霉素的独立死亡率风险。使用相似的方法估计从万古霉素转换为萘夫西林或头孢唑林与继续使用万古霉素相比，切换治疗的生存获益。每个模型都使用包含与接受万古霉素的倾向增加相关的变量的倾向评分进行统计学调整。
共纳入 267 例患者；14%（38/267）接受了萘夫西林或头孢唑林，51%（135/267）接受了万古霉素和萘夫西林或头孢唑林，35%（94/267）接受了万古霉素。30 例（11%）在 30 天内死亡。接受萘夫西林或头孢唑林治疗的患者死亡率危险比接受单独万古霉素治疗的患者低 79%（调整后的危险比（HR）：0.21；95%置信区间（CI）：0.09，0.47）。在 122 例最初接受万古霉素经验性治疗的患者中，转换为萘夫西林或头孢唑林（66/122）的患者死亡率危险比（调整 HR：0.31；95% CI：0.10，0.95）比继续使用万古霉素的患者低 69%。
与万古霉素相比，接受萘夫西林或头孢唑林治疗可降低死亡率，即使在培养结果鉴定出 MSSA 后改变治疗。万古霉素给药的便利性可能不及萘夫西林或头孢唑林在治疗 MSSA 菌血症中的潜在益处。
