Department of Pharmacy, Mobile Infirmary Medical Center, Mobile, AL, USA.
Department of Pharmacotherapy and Translational Research, University of Florida, Jacksonville, FL, USA.
Am J Health Syst Pharm. 2021 May 24;78(Supplement_2):S57-S61. doi: 10.1093/ajhp/zxab109.
Previous studies indicate that the polymerase chain reaction (PCR) nasal assay for methicillin-resistant Staphylococcus aureus (MRSA) has a consistently high (>95%) negative predictive value (NPV) in ruling out MRSA pneumonia; however, optimal timing of PCR assay specimen and respiratory culture collection is unclear.
A study including 736 patients from a community hospital system was conducted. Patients were included if they had undergone MRSA nasal screening with a PCR assay and had documented positive respiratory culture results.
In the full cohort, the MRSA PCR nasal screen assay was demonstrated to have an NPV of 94.9% (95% confidence interval [CI], 92.8%-96.5%) in ruling out MRSA-positive respiratory cultures. When evaluating the NPV by level of care (ie, where the MRSA PCR nasal assay sample was collected), no significant difference between values for samples collected in an intensive care unit vs medical/surgical units was identified (NPV [95%CI], 94.9% [92.7%-96.6%] vs 95.3% [88.4%-98.7%]). Additionally, NPV remained high with use of both invasive (NPV [95%CI], 96.8% [92.7%-99.0%]) and noninvasive (NPV [95%CI], 94.5% [91.7%-96.2%]) respiratory sampling methods. Finally, when evaluating the effect of time between MRSA PCR nasal screening and respiratory sample collection, we found high NPVs for all evaluated timeframes: within 24 hours, 93.8% (90.1%-96.4%); within 25 to 48 hours, 98.6% (92.7%-100.0%); within 49 hours to 7 days, 95.7% (91.4%-98.3%); within 8 to 14 days, 92.9% (85.1%-97.3%); and after more than 14 days, 95.5% (84.5%-99.4%).
We report high NPVs for up to 2 weeks between specimen collections, which allows clinicians to use a negative MRSA PCR nasal screen assay to rule out MRSA pneumonia, potentially leading to decreased exposure to MRSA-active antibiotics.
先前的研究表明，聚合酶链反应（PCR）鼻腔检测耐甲氧西林金黄色葡萄球菌（MRSA）对排除 MRSA 肺炎具有一致的高（>95%）阴性预测值（NPV）；然而，PCR 检测标本和呼吸道培养物采集的最佳时间尚不清楚。
对来自社区医院系统的 736 例患者进行了一项研究。如果患者接受了 MRSA 鼻腔筛查的 PCR 检测，并且有阳性的呼吸道培养结果记录，则将其纳入研究。
在全队列中，MRSA PCR 鼻腔筛查检测在排除 MRSA 阳性呼吸道培养物方面的 NPV 为 94.9%（95%置信区间[CI]，92.8%-96.5%）。当按护理级别评估 NPV（即，采集 MRSA PCR 鼻腔检测样本的位置）时，在重症监护病房和医疗/外科病房采集的样本之间未发现 NPV 值有显著差异（NPV[95%CI]，94.9%[92.7%-96.6%] vs 95.3%[88.4%-98.7%]）。此外，使用有创（NPV[95%CI]，96.8%[92.7%-99.0%]）和无创（NPV[95%CI]，94.5%[91.7%-96.2%]）呼吸道采样方法时，NPV 仍保持较高水平。最后，当评估 MRSA PCR 鼻腔筛查与呼吸道样本采集之间的时间间隔的影响时，我们发现所有评估时间框架的 NPV 均较高：在 24 小时内，93.8%（90.1%-96.4%）；在 25 至 48 小时内，98.6%（92.7%-100.0%）；在 49 小时至 7 天内，95.7%（91.4%-98.3%）；在 8 至 14 天内，92.9%（85.1%-97.3%）；在 14 天以上时，95.5%（84.5%-99.4%）。
我们报告了标本采集之间长达 2 周的高 NPV，这使得临床医生可以使用阴性的 MRSA PCR 鼻腔筛查检测来排除 MRSA 肺炎，从而可能减少接触 MRSA 活性抗生素。
