Upon the observation of an increase in teicoplanin resistance rates in coagulase negative staphylococci (CoNS) isolates determined by the automated system, we aimed to compare the automated system and gradient test methods with the gold standard broth microdilution method. In addition, the effect of standard antimicrobial susceptibility guidelines on teicoplanin susceptibility test results in CoNS was investigated. A total of 81 CoNS isolates, 52 resistant and 29 susceptible to teicoplanin determined by automated system (Phoenix, Becton Dickinson, USA), were tested. The minimum inhibitory concentration (MIC) values were determined by gradient test (M.I.C. Evaluators, OXOID, UK) and broth microdilution methods. Susceptibility categories were determined according to EUCAST and CLSI criteria and the results were compared. Among 29 isolates found to be susceptible by automated system, one isolate was found resistant by gradient and broth microdilution tests. Of the 52 resistant isolates determined by automated system, 12 (23%) were found to be resistant by gradient test and 22 (42.3%) were resistant by broth microdilution. According to CLSI criteria, no resistant isolates were detected by broth microdilution and six isolates were intermediately susceptible while, two isolates were detected to be resistant and five isolates were found to be intermediately susceptible by the gradient test. In conclusion, compared to microdilution, teicoplanin resistance was detected at a higher rate in CoNS isolates by the automated system used. On the other hand, the gradient test method which is frequently used for confirmation was not reliable in MIC values close to the EUCAST breakpoint values (4 μg/mL). In addition, lower resistance rates were observed when the CLSI breakpoints were used in gradient test and broth microdilution methods.

观察到通过自动化系统确定的凝固酶阴性葡萄球菌（CoNS）分离株中替考拉宁耐药率的增加，我们旨在比较自动化系统和梯度测试方法与金标准肉汤微量稀释法。此外，还研究了标准抗菌药物敏感性指南对CoNS中替考拉宁药物敏感性测试结果的影响。通过自动化系统（Phoenix，Becton Dickinson，美国）测定了总共81种CoNS分离株，52种耐药性和29种对替考拉宁敏感的菌株。最小抑菌浓度（MIC）值通过梯度测试（MIC Evaluators，OXOID，UK）和肉汤微量稀释法确定。根据EUCAST和CLSI标准确定敏感性类别，并比较结果。在29个被自动化系统检测到的分离株中，通过梯度和肉汤微稀释测试发现一个分离株具有抗性。通过自动化系统确定的52株抗性分离株中，通过梯度试验发现12株（23％）具有抗性，通过肉汤微稀释法发现22株（42.3％）具有抗性。根据CLSI标准，通过肉汤微量稀释未检测到抗性分离株，并且六个分离株中等敏感，而通过梯度试验检测到两个分离株具有抗性，发现五个分离株中等敏感。总之，与微量稀释相比，通过使用的自动化系统在CoNS分离物中检出的替考拉宁耐药性更高。另一方面，经常用于确认的梯度测试方法在MIC值接近EUCAST断点值（4μg/ mL）时不可靠。此外，将CLSI断点用于梯度测试和肉汤微稀释方法时，观察到较低的耐药率。