基质辅助激光解析电离飞行时间质谱用于口腔念珠菌菌株鉴定的准确性研究

Diagnostic accuracy of MALDI-TOF mass spectrum in identification of oral Candidiasis isolates

目的:探讨基质辅助激光解析电离飞行时间质谱(matrix assisted laser desorption ionization-time of flight mass spectrometry,MALDI-TOF MS)用于口腔念珠菌菌株鉴定的准确性。方法:本研究分为2部分,第一部分采集170例口腔念珠菌病患者唾液,使用沙保弱琼脂培养基培养48 h,MALDI-TOF MS进行菌种鉴定,以PCR检测结果为金标准,评价MALDI-TOF MS诊断的灵敏度、特异度等诊断学指标。第二部分采集42例口腔念珠菌病患者含漱液,使用液体培养基培养,MALDI-TOF MS鉴定,评价诊断准确性。采用SPSS 18.0软件包对数据进行统计学分析。结果:纳入212例患者,分离临床菌株230株。PCR检测结果显示,白色念珠菌为最常见的口腔念珠菌(65.65%,151/230),其次为光滑念珠菌(11.74%,27/230)。第一部分中,MALDI-TOF MS诊断白色念珠菌的灵敏度为93.33%,特异度为92.73%;诊断非白色念珠菌的灵敏度为83.64%,特异度为89.17%;对所有念珠菌菌株的诊断准确率为90.29%。第二部分结果显示,沙保弱液体培养基培养24 h,MALDI-TOF MS诊断准确率最高(78.42%)。结论:白色念珠菌是口腔念珠菌病最常见的致病菌。MALDI-TOF MS可用于沙保弱固体培养基培养的口腔念珠菌菌种的快速鉴定,诊断准确性高于液体培养基。

PURPOSE:To investigate the diagnostic accuracy of matrix assisted laser desorption ionization-time of flight mass spectrometry(MALDI-TOF MS)in the identification of clinical oral Candida isolates.METHODS:In the first experiment,170 suspected oral candidiasis patients were included.Unstimulated saliva was collected and cultured on solid plate(Sabouraud’s agar)for 48 hours.Clinical isolates were analyzed by both PCR,which was used as golden standard,and MALDI-TOF MS.The diagnostic accuracy of MALDI-TOF MS for both C.albicans and non-C.albicans were investigated.In the second experiment,we tried to identify Candida isolates directly from positive liquid culture in a new cohort of 42 patients.MALDI-TOF MS identification of candida isolates were performed on positive liquid medium cultures directly.The data were analyzed using SPSS 18.0 software package.RESULTS:Totally,230 clinical Candida isolates were isolated from 212 oral candidiasis patients enrolled.Out of the 230 analyzed clinical isolates,C.albicans(65.65%,151/230)was the most frequently isolated species,followed by C.glabrata(11.74%,27/230),and other candida species.The sensitivity and specificity of MALDI-TOF in identification of C.albicans were 93.33%and 92.73%respectively,and those for non-C.albicans were 83.64%and 89.2%respectively.Oral rinse followed by culturing in Sabouraud’s liquid medium for 24 hours yield the diagnostic accuracy of 78.42%in MALDI-TOF MS identification.CONCLUSIONS:C.albicans is the most frequent Candida spp.in oral candidiasis.MALDI-TOF MS is an effective and rapid method for identification of Candida spp.The on-plate based method generate much higher diagnostic accuracy than liquid culture based one.