Lollar Daniel I, Rodil Maridi, Herbert Benoit, Burlew Clay Cothren, Pieracci Fredric M
Denver Health Medical Center , Denver, Colorado.
Surg Infect (Larchmt). 2016 Apr;17(2):187-90. doi: 10.1089/sur.2014.159. Epub 2015 Dec 31.
Choice of empiric antibiotic(s) for early ventilator associated pneumonia (VAP) involves weighing the risks of potential infection with multi-drug resistant (MDR) pathogens against those of over-exposure to broad-spectrum agents. Although early VAP is believed to be rarely caused by MDR pathogens, the overall incidence of all methicillin resistant Staphylococcus aureus (MRSA) infections is increasing. We questioned if MRSA VAP is becoming more common and if these infections were occurring earlier in the patient's hospital course. We hypothesized that 1) early (2-4 d from intubation) VAP caused by MRSA is relatively uncommon and 2) those patients with early VAP because of MRSA had risk factors associated with a MDR organism infection.
Bronchoscopies with lavage (BALs) from patients admitted to our SICU from 2010-2013 were reviewed. MRSA VAP was defined as growth of ≥10(5) cfu/mL from BAL. Multi-drug resistant risk factors included a previous MRSA infection or positive nasal swab, antibiotic use within 90 d, hospitalization for >5 d, hemodialysis, homelessness, intravenous drug use, and men having sex with men.
In the 3-y period, there were 438 cases of VAP. Forty-seven specimens from 43 patients had quantitative microbiologic confirmation of MRSA VAP for an overall prevalence of 10.7%. Of patients with early VAP, three of 106 (2.8%) were MRSA positive. Culture results were graphed according to ventilator days ( Fig. 1 ). The median days ventilated at the time of MRSA VAP were 8 d (range 2-81). All of the early MRSA VAP patients had identifiable risk factors for MRSA infection. The negative predictive value for patients not having a risk factor was one.
These data suggest that the incidence of MRSA VAP is stable. Those patients with early MRSA VAP demonstrated traditional MDR risk factors. Patients without risk factors in the early time period could effectively be ruled out from having MRSA VAP and likely do not require empiric MRSA coverage.
早期呼吸机相关性肺炎（VAP）经验性抗生素的选择需要权衡多重耐药（MDR）病原体潜在感染风险与过度暴露于广谱抗菌药物的风险。虽然普遍认为早期VAP很少由MDR病原体引起，但耐甲氧西林金黄色葡萄球菌（MRSA）感染的总体发生率正在上升。我们质疑MRSA-VAP是否正变得更常见，以及这些感染是否在患者住院病程中更早出现。我们假设：1）由MRSA引起的早期（插管后2 - 4天）VAP相对不常见；2）那些因MRSA导致早期VAP的患者具有与MDR病原体感染相关的危险因素。
回顾性分析2010年至2013年入住我院外科重症监护病房（SICU）患者的支气管镜灌洗（BAL）标本。MRSA-VAP定义为BAL中培养出≥10⁵cfu/mL的MRSA。MDR危险因素包括既往MRSA感染或鼻腔拭子阳性、90天内使用过抗生素、住院超过5天、血液透析、无家可归、静脉吸毒以及男男性行为。
在这3年期间，共有438例VAP病例。43例患者的47份标本经定量微生物学证实为MRSA-VAP，总体患病率为10.7%。在早期VAP患者中，106例中有3例（2.8%）MRSA阳性。根据机械通气天数绘制培养结果图（图1）。MRSA-VAP发生时的机械通气天数中位数为8天（范围2 - 81天）。所有早期MRSA-VAP患者均具有可识别的MRSA感染危险因素。无危险因素患者的阴性预测值为1。
这些数据表明MRSA-VAP的发生率稳定。那些早期MRSA-VAP患者表现出传统的MDR危险因素。早期无危险因素的患者可有效排除MRSA-VAP，可能不需要经验性覆盖MRSA。
