Lee Hyun Seung, Shin Jong Hee, Choi Min Ji, Won Eun Jeong, Kee Seung Jung, Kim Soo Hyun, Shin Myung Geun, Suh Soon Pal
Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
Ann Lab Med. 2017 May;37(3):223-230. doi: 10.3343/alm.2017.37.3.223.
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) allows rapid and accurate identification of clinical yeast isolates. In-tube formic acid/acetonitrile (FA/ACN) extraction is recommended prior to the analysis with MALDI Biotyper, but the direct on-plate FA extraction is simpler. We compared the Biotyper with the VITEK MS for the identification of various clinically relevant yeast species, focusing on the use of the FA extraction method.
We analyzed 309 clinical isolates of 42 yeast species (four common Candida species, Cryptococcus neoformans, and 37 uncommon yeast species) using the Biotyper and VITEK MS systems. FA extraction was used initially for all isolates. If 'no identification' result was obtained following the initial FA extraction, these samples were then retested by using FA (both systems, additive FA) or FA/ACN (Biotyper only, additive FA/ACN) extraction. These results were compared with those obtained by sequence-based identification.
Both systems correctly identified all 158 isolates of the four common Candida species after the initial FA extraction. The Biotyper correctly identified 8.7%, 30.4%, and 100% of 23 C. neoformans isolates after performing initial FA, additive FA, and FA/ACN extractions, respectively, while VITEK MS identified all C. neoformans isolates after the initial FA extraction. Both systems had comparable identification rates of 37 uncommon yeast species (128 isolates), following the initial FA (Biotyper, 74.2%; VITEK MS, 73.4%) or additive FA (Biotyper, 82.0%; VITEK MS, 73.4%).
The identification rate of most common and uncommon yeast isolates is comparable between simple FA extraction/Biotyper method and VITEK MS methods, but FA/ACN extraction is necessary for C. neoformans identification by Biotyper.
基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）能够快速、准确地鉴定临床酵母分离株。在用MALDI Biotyper进行分析之前，建议采用管内甲酸/乙腈（FA/ACN）提取法，但直接在板上进行FA提取更为简单。我们比较了Biotyper和VITEK MS对各种临床相关酵母菌种的鉴定能力，重点关注FA提取方法的使用。
我们使用Biotyper和VITEK MS系统分析了42种酵母菌种的309株临床分离株（4种常见念珠菌属菌种、新型隐球菌以及37种不常见酵母菌种）。最初对所有分离株都采用FA提取法。如果在最初的FA提取后得到“无法鉴定”的结果，那么这些样本随后会通过使用FA（两种系统，添加FA）或FA/ACN（仅Biotyper，添加FA/ACN）提取法重新进行检测。将这些结果与基于序列的鉴定结果进行比较。
在最初的FA提取后，两种系统均正确鉴定出了所有158株4种常见念珠菌属菌种的分离株。在分别进行最初的FA、添加FA和FA/ACN提取后，Biotyper对23株新型隐球菌分离株的正确鉴定率分别为8.7%、30.4%和100%，而VITEK MS在最初的FA提取后鉴定出了所有新型隐球菌分离株。在最初的FA（Biotyper为74.2%；VITEK MS为73.4%）或添加FA（Biotyper为82.0%；VITEK MS为73.4%）提取后，两种系统对37种不常见酵母菌种（128株分离株）的鉴定率相当。
简单的FA提取/Biotyper方法和VITEK MS方法对大多数常见和不常见酵母分离株的鉴定率相当，但通过Biotyper鉴定新型隐球菌需要采用FA/ACN提取法。
