RAPID DETECTION OF MYCOBACTERIUM TUBERCULOSIS IN LUNG TISSUE USING A FIBER OPTIC BIOSENSOR

Abstract

ABSTRACT There is no rapid diagnostic technique at medical examiners' offices to determine if a decedent is infected with Mycobacterium tuberculosis. Present diagnostic testing requires at least 1 month for results. The RAPTOR, a portable, automated fiber optic evanescent wave biosensor, was used as the platform to develop more rapid assays to detect M. tuberculosis from lung tissue. Positive biosensor detection was obtained 80% of the time at cell concentrations of 106 cells/mL, 96% of the time at 107 cells/mL, and 99% of the time at 108 cells/mL of live attenuated M. tuberculosis (ATCC 25177) suspended in phosphate‐buffered saline with 0.1% Tween 20 (PBST). Live attenuated M. tuberculosis suspended in PBST and seeded into decedent lung tissue was tested using the RAPTOR. Positive detection was obtained 96% of the time at 107 cells/mL and 100% of the time at 108 cells/mL. Detection of M. tuberculosis in lung tissue homogenate was possible within 3 h.PRACTICAL APPLICATIONSDevelopment of a rapid method to detect Mycobacterium tuberculosis from lung tissue at autopsy would be a significant benefit to medical examiners' offices and pathologists worldwide. Rapid diagnosis would enable those possibly exposed to an infected decedent to be informed of M. tuberculosis infection in a timely manner. Biosensor assays on seeded lung tissue show it is possible to detect M. tuberculosis in 3 h using the RAPTOR biosensor, instead of 1 month using current, conventional tests, when there are 107 or more cells in the assay sample. Tuberculous cavities may contain 107–109 activelymultiplying organisms. Sample preparation and assay protocols involve common laboratory practices and could easily and quickly be learned and implemented by laboratory staff. The RAPTOR is user friendly and could be used by medical examiner staff at time of need. The biosensor assay may also have potential applications for use on biopsy tissue from living individuals who have heavy pulmonary or disseminated infections by M. tuberculosis.