Montaño Aleyda M, Robledo Carlos, Galvis-Ayala Julián C, Jimenez J Natalia, Brunel Romain, Robledo Jaime
Laboratorio Medico de Referencia, Medellín, Colombia.
Grupo de Investigación en Microbiología Básica y Aplicada, Escuela de Microbiología, MICROBA, Universidad de Antioquia, Medellín, Colombia.
Eur J Clin Microbiol Infect Dis. 2025 Jun;44(6):1443-1453. doi: 10.1007/s10096-025-05097-6. Epub 2025 Apr 3.
To determine diagnostic validity of MALDI-TOF MS (VITEK MS) system for detecting Klebsiella pneumoniae carbapenemases (KPC)-type carbapenemases by identifying the 11,109 Da peak in the mass spectrum generated for species identification as compared to RAPIDEC CARBA NP, and the modified carbapenemase inactivation method (mCIM) and the EDTA-modified carbapenem inactivation method (eCIM) in a collection of isolates previously characterized as KPC positive or negative.
210 Enterobacterales clinical strains previously characterized having bla gene, the pKpQIL plasmid and the Tn4401a transposon were evaluated, including 34 positive controls carbapenemase-producing Klebsiella pneumoniae associated with Tn4401a, 30 Enterobacterales bla positive of unknown plasmid background, and 146 negative controls. Accuracy and agreement were established for Vitek MS, RAPIDEC CARBA NP, and mCIM/eCIM) tests; ROC curves were compared among these tests.
The 11,109 Da peak was detected in 100% of KPC Tn4401a positive isolates using Vitek MS, sensitivity of 100% (95% CI 98.53-100), specificity of 95.5% (95% CI 91.7-99.4), positive predictive value (PPV) of 85.0 (95% CI 72.7-97.3), negative predictive value (NPV) of 100% (95% CI 99.6-100) and positive Likelihood Ratio (PLR) of 22.3 (10.2-48.8). Agreement between the three tests was 93.3% Kappa index of 0.90 (95% CI 0.83-0.97, p ≤ 0.05). ROC curves showed areas under the curve (AUCs) of 0.95, 0.96 and 0.96 for the VITEK MS, RAPIDEC CARBA NP and the mCIM/eCIM tests, respectively.
Detection of the 11,109 Da peak by Vitek MS confirms the presence of KPC-type carbapenemase, allowing rapid and simultaneous detection with species identification; a negative result does not rule out the presence of the enzyme and may require additional tests.
通过将质谱图中11,109 Da峰与RAPIDEC CARBA NP以及改良碳青霉烯酶灭活方法（mCIM）和乙二胺四乙酸改良碳青霉烯酶灭活方法（eCIM）相比较，来确定基质辅助激光解吸电离飞行时间质谱（VITEK MS）系统检测肺炎克雷伯菌碳青霉烯酶（KPC）型碳青霉烯酶的诊断有效性，这些比较基于一组先前已鉴定为KPC阳性或阴性的分离株。
对210株先前已鉴定具有bla基因、pKpQIL质粒和Tn4401a转座子的肠杆菌科临床菌株进行评估，包括34株与Tn4401a相关的产碳青霉烯酶肺炎克雷伯菌阳性对照、30株质粒背景未知的肠杆菌科bla阳性菌株以及146株阴性对照。确定了Vitek MS、RAPIDEC CARBA NP和mCIM/eCIM检测的准确性和一致性；比较了这些检测的ROC曲线。
使用Vitek MS在100%的KPC Tn4401a阳性分离株中检测到11,109 Da峰，灵敏度为100%（95%可信区间98.53 - 100），特异性为95.5%（95%可信区间91.7 - 99.4），阳性预测值（PPV）为85.0（95%可信区间72.7 - 97.3），阴性预测值（NPV）为100%（95%可信区间99.6 - 100），阳性似然比（PLR）为22.3（10.2 - 48.8）。三种检测方法之间的一致性为93.3%，Kappa指数为0.90（95%可信区间0.83 - 0.97，p≤0.05）。ROC曲线显示VITEK MS、RAPIDEC CARBA NP和mCIM/eCIM检测的曲线下面积（AUC）分别为0.95、0.96和0.96。
Vitek MS检测到11,109 Da峰可确认KPC型碳青霉烯酶的存在，能够在进行菌种鉴定的同时实现快速检测；阴性结果不能排除该酶的存在，可能需要进一步检测。
