Montgomery Sandra, Roman Kiana, Ngyuen Lan, Cardenas Ana Maria, Knox James, Tomaras Andrew P, Graf Erin H
Children's Hospital of Philadelphia, Infectious Disease Diagnostics Laboratory, Philadelphia, Pennsylvania, USA.
Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
J Clin Microbiol. 2017 Jun;55(6):1802-1811. doi: 10.1128/JCM.00027-17. Epub 2017 Mar 29.
Urinary tract infections are one of the most common reasons for health care visits. Diagnosis and optimal treatment often require a urine culture, which takes an average of 1.5 to 2 days from urine collection to results, delaying optimal therapy. Faster, but accurate, alternatives are needed. Light scatter technology has been proposed for several years as a rapid screening tool, whereby negative specimens are excluded from culture. A commercially available light scatter device, BacterioScan 216Dx (BacterioScan, Inc.), has recently been advertised for this application. Paired use of mass spectrometry (MS) for bacterial identification and automated-system-based susceptibility testing straight from the light scatter suspension might provide dramatic improvement in times to a result. The present study prospectively evaluated the BacterioScan device, with culture as the reference standard. Positive light scatter specimens were used for downstream rapid matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) MS organism identification and automated-system-based antimicrobial susceptibility testing. Prospective evaluation of 439 urine samples showed a sensitivity of 96.5%, a specificity of 71.4%, and positive and negative predictive values of 45.1% and 98.8%, respectively. MALDI-TOF MS analysis of the suspension after density-based selection yielded a sensitivity of 72.1% and a specificity of 96.9%. Antimicrobial susceptibility testing of the samples identified by MALDI-TOF MS produced an overall categorical agreement of 99.2%. Given the high sensitivity and negative predictive value of results obtained, BacterioScan 216Dx is a reasonable approach for urine screening and might produce negative results in as few as 3 h, with no downstream workup. Paired rapid identification and susceptibility testing might be useful when MALDI-TOF MS results in an organism identification, and it might decrease the time to a result by more than 24 h.
尿路感染是就医的最常见原因之一。诊断和最佳治疗通常需要进行尿培养，从收集尿液到得出结果平均需要1.5至2天，这会延误最佳治疗。因此需要更快且准确的替代方法。光散射技术作为一种快速筛查工具已被提出数年，通过该技术可将阴性标本排除在培养之外。一种市售的光散射设备BacterioScan 216Dx（BacterioScan公司）最近已被宣传用于此应用。将质谱（MS）用于细菌鉴定，并直接从光散射悬浮液进行基于自动化系统的药敏试验，可能会显著缩短得出结果的时间。本研究以前瞻性方式评估了BacterioScan设备，并以培养作为参考标准。光散射阳性标本用于下游的快速基质辅助激光解吸电离飞行时间（MALDI-TOF）质谱微生物鉴定和基于自动化系统的抗菌药敏试验。对439份尿液样本的前瞻性评估显示，敏感性为96.5%，特异性为71.4%，阳性预测值和阴性预测值分别为45.1%和98.8%。基于密度选择后的悬浮液进行MALDI-TOF质谱分析，敏感性为72.1%，特异性为96.9%。通过MALDI-TOF质谱鉴定的样本进行抗菌药敏试验，总体分类一致性为99.2%。鉴于所获得结果的高敏感性和阴性预测值，BacterioScan 216Dx是一种合理的尿液筛查方法，可能在短短3小时内得出阴性结果，且无需下游检查。当MALDI-TOF质谱得出微生物鉴定结果时，配对的快速鉴定和药敏试验可能会有所帮助，并且可能将得出结果的时间缩短超过24小时。
