Boattini Matteo, Guarrasi Luisa, Comini Sara, Ricciardelli Guido, Casale Roberto, Cavallo Rossana, Costa Cristina, Bianco Gabriele
Department of Public Health and Paediatrics, University of Torino, Turin, Italy.
Microbiology and Virology Unit, University Hospital Città Della Salute E Della Scienza Di Torino, Turin, Italy.
Eur J Clin Microbiol Infect Dis. 2025 Apr;44(4):827-837. doi: 10.1007/s10096-025-05039-2. Epub 2025 Jan 22.
To evaluate diagnostic performance of four diagnostic methods for rapid determination of methicillin resistance in S. aureus positive blood cultures (BCs).
Clinical and spiked BCs were subjected to the evaluation of the following methods and protocols: a. Eazyplex MRSA Plus loop-mediated isothermal amplification (LAMP) assay directly from BC fluid; b. MALDI-TOF MS subtyping on BC pellet extracted with Rapid Sepsityper protocol and on 4-h short-term subculture; c. Clearview™ Culture Colony PBP2a SA immunochromatography assay on BC pellet and on 4-h short-term subculture; d. EUCAST RAST cefoxitin screen test performed directly from BC and including reading times at 4-h, 6-h and 16-20-h.
Eazyplex MRSA plus exhibited the best performance, showing 100% sensitivity, specificity, positive predictive value, and negative predictive value, followed by PBP2a SA Culture Colony Clearview assay and EUCAST RAST cefoxitin screen. MALDI-TOF MS subtyping showed the lowest diagnostic accuracy (59.8 and 65.7% directly from BC and from 4-h subculture, respectively). In detail, sensitivity and specificity ranged from 24.3% to 20.4% and from 88.9% to 98.3% for protocols performed from BC pellet and 4-h subculture, respectively.
The Eazyplex MRSA Plus and the immunochromatographic Clearview™ PBP2a SA Culture Colony methods can provide reliable results within 1 h from the start of positive BC processing. MALDI TOF MS subtyping showed unacceptable specificity by performing analysis from BC pellets, while its sensitivity depends on the prevalence of PSM-positive MRSA strains. The EUCAST RAST, based on disc diffusion, showed excellent performance with a time-to-result of at least 4 h.
评估四种诊断方法对金黄色葡萄球菌阳性血培养物（BCs）中耐甲氧西林情况进行快速测定的诊断性能。
对临床血培养物和加标血培养物进行以下方法和方案的评估：a. 直接从血培养物液体中进行Eazyplex MRSA Plus环介导等温扩增（LAMP）检测；b. 采用快速细菌离心试剂盒提取法从血培养物沉淀中以及在4小时短期传代培养物上进行基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）分型；c. 在血培养物沉淀和4小时短期传代培养物上进行Clearview™ 培养菌落PBP2a SA免疫层析检测；d. 直接从血培养物中进行欧洲抗菌药物敏感性试验委员会（EUCAST）快速自动化筛选试验（RAST）头孢西丁筛选试验，包括在4小时、6小时和16 - 20小时读取结果。
Eazyplex MRSA plus表现出最佳性能，敏感性、特异性、阳性预测值和阴性预测值均为100%，其次是PBP2a SA培养菌落Clearview检测和EUCAST RAST头孢西丁筛选试验。MALDI-TOF MS分型显示诊断准确性最低（直接从血培养物和4小时传代培养物中进行检测时，分别为59.8%和65.7%）。详细而言，从血培养物沉淀和4小时传代培养物中进行检测的方案，其敏感性范围为24.3%至20.4%，特异性范围为88.9%至98.3%。
Eazyplex MRSA Plus和免疫层析Clearview™ PBP2a SA培养菌落方法可在阳性血培养物处理开始后1小时内提供可靠结果。通过对血培养物沉淀进行分析，MALDI TOF MS分型显示出不可接受的特异性，而其敏感性取决于PSM阳性耐甲氧西林金黄色葡萄球菌菌株的流行率。基于纸片扩散法的EUCAST RAST表现出色，但结果报告时间至少为4小时。
