Institute of Medical Microbiology, University Hospital Münster, Domagkstr. 10, 48149 Münster, Germany.
Institute of Biostatistics and Clinical Research, University of Münster, Schmeddingstraße 56, 48149 Münster, Germany.
Int J Antimicrob Agents. 2018 Feb;51(2):221-226. doi: 10.1016/j.ijantimicag.2017.10.009. Epub 2017 Oct 27.
Delays in appropriate antimicrobial treatment contribute to increased mortality of septic patients. We aimed to develop a methodology for detection of carbapenem resistance in Gram-negative bacteria directly from positive blood cultures (BCs). Initially, meropenem-resistant Enterobacteriaceae (n = 13) and Pseudomonas aeruginosa (n = 32) isolates as well as the same numbers of meropenem-susceptible isolates were used to establish the detection of carbapenem resistance from agar cultures. Growth-based phenotypic detection of meropenem resistance was performed by a laser scattering (LS) method using a BacterioScan™216R instrument. A subset of the strain collection consisting of meropenem-susceptible and -resistant isolates (each comprising seven P. aeruginosa and three Klebsiella pneumoniae) was used for determination of carbapenem resistance directly from positive BCs. Lysis/centrifugation and filtration/dilution methods were investigated for processing of positive BCs. Four different statistical approaches to discriminate between susceptible and resistant bacteria in real-time were applied and were compared regarding their sensitivity and specificity. After 3 h and 4 h of incubation, respectively, detection of carbapenem resistance in Enterobacteriaceae (sensitivity, 100%; specificity, 100%) and P. aeruginosa (sensitivity, 100%; specificity, ≥90%) agar cultures was attainable. Detection of carbapenem resistance directly from positive BCs was achievable with 100% sensitivity and 100% specificity after 4 h and 5 h, respectively, applying lysis/centrifugation and filtration/dilution methods. In conclusion, LS technology combined with lysis/centrifugation and appropriate statistical real-time analyses represents a promising option for rapid detection of carbapenem resistance in Gram-negative rods directly from positive BCs.
适当的抗菌治疗的延迟导致败血症患者的死亡率增加。我们旨在开发一种从阳性血培养物（BC）中直接检测革兰氏阴性菌碳青霉烯耐药的方法。最初，使用耐美罗培南的肠杆菌科（n=13）和铜绿假单胞菌（n=32）分离株以及相同数量的美罗培南敏感分离株来建立琼脂培养物中检测碳青霉烯耐药的方法。使用 BacterioScan™216R 仪器的激光散射（LS）方法进行基于生长的美罗培南耐药表型检测。由美罗培南敏感和耐药分离株（每个包含 7 株铜绿假单胞菌和 3 株肺炎克雷伯菌）组成的菌株集合的子集用于直接从阳性 BC 中确定碳青霉烯耐药性。研究了裂解/离心和过滤/稀释方法用于处理阳性 BC。应用了四种不同的统计方法来实时区分敏感菌和耐药菌，并比较了它们的敏感性和特异性。分别孵育 3 小时和 4 小时后，可在肠杆菌科（敏感性，100%；特异性，100%）和铜绿假单胞菌（敏感性，100%；特异性，≥90%）琼脂培养物中检测到碳青霉烯耐药。分别采用裂解/离心和过滤/稀释方法，孵育 4 小时和 5 小时后，可从阳性 BC 中直接检测到碳青霉烯耐药，其敏感性和特异性均为 100%。结论，LS 技术结合裂解/离心和适当的统计实时分析代表了从阳性 BC 中直接快速检测革兰氏阴性杆菌碳青霉烯耐药的有前途的选择。
