利用飛行質譜儀作Mycobacterium avium之快速鑑定及區別

Abstract

M. avium is a well known etiological agent for immuno-compromised patients, especially for those with HIV infection. Rapid, accurate discrimination between M. avium and other Mycobacterium species is essential for appropriate therapeutic management and timely intervention for infection control. Identification and speciation of M. avium is both time consuming and labor intensive by traditional bacteriological methods. From our previous report [Yi et al., (1998) Use of Fluorescein Labelled Antibody and Fluorescence Activated Cell Sorter for Rapid Identification of Mycobacterium species. Biochem. Biophy. Res. Commu. 250: 403-408.], we have used Flow Cytometry for rapid identification of Mycobacterium species. As we mentioned in the text, however, identification of Mycobacterium to the species level can be achieved only depending on the availability of species-specific antibody. In this article, a rapid method involving intact cell mass spectrometry (ICMS) is presented that shows promise for identification, typing and discrimination of M. avium from other Mycobacterium species. In ICMS, cells from a bacterial colony are emulsified in a chemical matrix, added to a sample probe, dried and analysed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). This technique analyses proteins from intact and disrupted bacteria yielding spectra consisting of 16 peaks from 5000 to 17500, which represent the mass:charge (m:z) ratios. Each peak corresponds to a molecular fragment released from the cell surface during laser desorption. Specimens can be prepared in a few seconds from plate cultures and a spectrum can be obtained within 10 min. Our results show that MALDI-TOF-MS is applicable for rapid identification and differentiation of M. avium from, and thus shows its potential for clinical M. avium identification, or for epidemiological studies.