Pérez-Sancho Marta, Vela Ana I, Horcajo Pilar, Ugarte-Ruiz María, Domínguez Lucas, Fernández-Garayzábal José F, de la Fuente Ricardo
VISAVET Health Surveillance Centre (Pérez-Sancho, Vela, Ugarte-Ruiz, Fernández-Garayzábal, Domínguez), Complutense University, Madrid, Spain.
Animal Health Department, Veterinary Faculty (Vela, Horcajo, Fernández-Garayzábal, Domínguez, de la Fuente), Complutense University, Madrid, Spain.
J Vet Diagn Invest. 2018 Nov;30(6):813-820. doi: 10.1177/1040638718805537. Epub 2018 Oct 3.
Staphylococcus aureus encompasses 2 subspecies ( aureus and anaerobius) with significant differences in their epidemiology and pathogenicity. We evaluated the suitability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the rapid identification of both subspecies using a panel of 52 S. aureus isolates (30 subsp. anaerobius and 22 subsp. aureus) recovered from different origins, countries, and years. The on-board library identification system correctly identified 42 of 52 (81%) S. aureus isolates at the species level with score values >2.0. Limited performance was observed for differentiation of S. aureus subspecies (particularly subsp. anaerobius). Visual inspection of MALDI-TOF MS profiles identified 5 subspecies-specific mass peaks ( m/ z 3430 and 6861 in S. aureus subsp. anaerobius, and m/ z 4046, 6890, and 8093 in S. aureus subsp. aureus) with 100% sensitivity and specificity values, which is potentially useful for differentiating these subspecies. The suitability of 3 models, Genetic Analysis (GA), Quick Classifier (QC), and Supervised Neural Network, for automatic identification of both subspecies was evaluated using the Recognition Capability (RC) and Cross Validation (CV) values provided by the on-board ClinProTools software. The GA and QC models reached RC and CV values of 100%. Both models were externally validated using a panel of 26 S. aureus isolates of both subspecies, with both models correctly classifying all isolates of both subspecies. MALDI-TOF MS coupled with ClinProTools software represents a rapid and simple approach for S. aureus subspecies discrimination.
金黄色葡萄球菌包括两个亚种（金黄色亚种和厌氧亚种），它们在流行病学和致病性方面存在显著差异。我们使用从不同来源、国家和年份分离出的52株金黄色葡萄球菌（30株厌氧亚种和22株金黄色亚种）评估了基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）对这两个亚种进行快速鉴定的适用性。车载文库鉴定系统在物种水平上正确鉴定了52株金黄色葡萄球菌中的42株（81%），得分值>2.0。在区分金黄色葡萄球菌亚种（特别是厌氧亚种）方面观察到性能有限。对MALDI-TOF MS图谱的目视检查确定了5个亚种特异性质量峰（金黄色葡萄球菌厌氧亚种中的m/z 3430和6861，以及金黄色葡萄球菌金黄色亚种中的m/z 4046、6890和8093），其灵敏度和特异性值均为100%，这可能有助于区分这些亚种。使用车载ClinProTools软件提供的识别能力（RC）和交叉验证（CV）值评估了3种模型（遗传分析（GA）、快速分类器（QC）和监督神经网络）对这两个亚种的自动识别适用性。GA和QC模型的RC和CV值均达到100%。使用一组26株两个亚种的金黄色葡萄球菌分离株对这两种模型进行了外部验证，两种模型均正确分类了两个亚种的所有分离株。MALDI-TOF MS与ClinProTools软件相结合代表了一种快速、简单的金黄色葡萄球菌亚种鉴别方法。
