Department of Applied Sciences, Northumbria University, Newcastle upon Tyne, UK.
J Appl Microbiol. 2014 Apr;116(4):1010-9. doi: 10.1111/jam.12418. Epub 2014 Jan 6.
A novel method has been developed that allows successful differentiation between Clostridium difficile culture-positive and culture-negative stool samples based on volatile organic compound (VOC) evolution and detection by headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME-GC-MS).
The method is based on the activation of p-hydroxyphenylacetate decarboxylase produced by Cl. difficile and the detection of a specific VOC, that is 2-fluoro-4-methylphenol from an enzyme substrate. In addition, other VOCs were good indicators for Cl. difficile, that is isocaproic acid and p-cresol, although they could not be used alone for identification purposes. One hundred stool samples were tested, of which 77 were positive by culture. Detection using HS-SPME-GC-MS allowed confirmation of the presence of Cl. difficile within 18 h with a sensitivity and specificity of 83·1 and 100%, respectively.
It is recommended that this new approach could be used alongside conventional methods for Cl. difficile detection, including toxin detection methods, which would allow any false-negative results to be eliminated.
The ability to identify Cl. difficile-positive stool samples by the analysis of VOCs could allow the development of a VOC detection device which could allow rapid diagnosis of disease and hence prompt treatment with appropriate antibiotics.
开发了一种新方法，可基于挥发性有机化合物（VOC）的演变和通过顶空固相微萃取结合气相色谱-质谱（HS-SPME-GC-MS）进行的检测，成功区分艰难梭菌培养阳性和培养阴性粪便样本。
该方法基于艰难梭菌产生的对羟基苯乙酸脱羧酶的激活，以及从酶底物中检测到特定的 VOC，即 2-氟-4-甲基苯酚。此外，其他 VOC 也是艰难梭菌的良好指标，即异亮氨酸和对甲酚，尽管它们不能单独用于鉴定目的。测试了 100 个粪便样本，其中 77 个通过培养呈阳性。使用 HS-SPME-GC-MS 进行检测可在 18 小时内确认艰难梭菌的存在，其灵敏度和特异性分别为 83.1%和 100%。
建议将这种新方法与艰难梭菌检测的常规方法（包括毒素检测方法）一起使用，以消除任何假阴性结果。
通过分析 VOC 来识别艰难梭菌阳性粪便样本的能力可以开发出一种 VOC 检测装置，从而可以快速诊断疾病，并及时使用适当的抗生素进行治疗。
