Idelevich Evgeny A, Hoy Matthias, Görlich Dennis, Knaack Dennis, Grünastel Barbara, Peters Georg, Borowski Matthias, Becker Karsten
Institute of Medical Microbiology, University Hospital MünsterMünster, Germany.
Institute of Biostatistics and Clinical Research, University of MünsterMünster, Germany.
Front Microbiol. 2017 Jun 14;8:1064. doi: 10.3389/fmicb.2017.01064. eCollection 2017.
We developed a methodology for antimicrobial susceptibility testing (AST) based on the BacterioScan216R laser scattering technology, using methicillin resistance in and vancomycin resistance in enterococci as exemplar for important resistance phenotypes. Fifty methicillin-resistant (MRSA) and 50 methicillin-susceptible (MSSA) , as well as 50 vancomycin-resistant enterococci (VRE) and 50 vancomycin-susceptible enterococci (VSE) isolates were used for the study. Optimal test conditions were derived by investigating the effects of inoculum size, medium, incubation temperature and broth filtration. We proposed four different statistical approaches for rapid discrimination between resistant and susceptible bacteria. The statistical approach based on raw measurements of bacterial concentrations delivered sensitivity of 100% and specificity of 94% for discrimination between MRSA and MSSA already after 3 hours of incubation. Categorical agreement of ≥90% was achieved after 140 min with this approach. Differentiation between VRE and VSE was possible with 98% sensitivity and 92% specificity after 3 hours, using a sophisticated statistical approach based on concentration slopes derived from the raw concentration measurements. This approach provided categorical agreement of ≥90% after 165 min. The sensitivity and specificity estimates were confirmed by leave-one-out cross validation. In conclusion, the phenotypic AST methods developed in this study are promising for rapid detection of MRSA and VRE. The development and application of this technology would allow early detection of the resistant pathogens, thus facilitating swift change to the targeted antimicrobial treatment as well as timely initiation of appropriate infection control measures. Further studies are warranted to validate this approach for the detection of other resistance phenotypes, including direct testing from clinical specimens.
我们基于BacterioScan216R激光散射技术开发了一种抗菌药物敏感性测试（AST）方法，以耐甲氧西林金黄色葡萄球菌和肠球菌中的耐万古霉素作为重要耐药表型的范例。本研究使用了50株耐甲氧西林金黄色葡萄球菌（MRSA）、50株甲氧西林敏感金黄色葡萄球菌（MSSA），以及50株耐万古霉素肠球菌（VRE）和50株万古霉素敏感肠球菌（VSE）分离株。通过研究接种量、培养基、培养温度和肉汤过滤的影响得出了最佳测试条件。我们提出了四种不同的统计方法用于快速区分耐药菌和敏感菌。基于细菌浓度原始测量值的统计方法在孵育3小时后对MRSA和MSSA的区分灵敏度达到100%，特异性为94%。使用这种方法在140分钟后分类一致性达到≥90%。使用基于原始浓度测量得出的浓度斜率的复杂统计方法，在3小时后区分VRE和VSE的灵敏度为98%，特异性为92%。这种方法在165分钟后分类一致性达到≥90%。通过留一法交叉验证确认了灵敏度和特异性估计值。总之，本研究中开发的表型AST方法在快速检测MRSA和VRE方面很有前景。该技术的开发和应用将有助于早期检测耐药病原体，从而促进迅速转向针对性抗菌治疗以及及时启动适当的感染控制措施。有必要进一步开展研究以验证该方法用于检测其他耐药表型，包括直接从临床标本进行检测。
