title: Differentiating between live and dead Mycobacterium smegmatis using autofluorescence.
abstract: While there have been research efforts to find faster and more efficient diagnostic techniques for tuberculosis (TB), it is equally important to monitor a patient's response to treatment over time, especially with the increasing prevalence of multi-drug resistant (MDR) and extensively-drug resistant (XDR) TB. Between sputum smear microscopy, culture, and GeneXpert, only culture can verify viability of mycobacteria. However, it may take up to six weeks to grow Mycobacterium tuberculosis (Mtb), during which time the patient may have responded to treatment or the mycobacteria are still viable because the patient has MDR or XDR TB. In both situations, treatment incurs increased patient costs and makes them more susceptible to host-drug effects such as liver damage. Coenzyme Factor 420 (F420) is a fluorescent coenzyme found naturally in mycobacteria, with an excitation peak around 420 nm and an emission peak around 470 nm. Using Mycobacterium smegmatis, we show that live and dead mycobacteria undergo different rates of photobleaching over a period of 2 min. These preliminary experiments suggest that the different photobleaching rates could be used to help monitor a patient's response to TB treatment. In future studies, we propose to describe these experiments with Mtb as both M. smegmatis and Mtb use F420.
authors.affiliation: Department of Bioengineering, Rice University, 6500 Main Street, Houston, TX 77005, United States. Electronic address: Cynthia.Wong@rice.edu.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Wong
authors.affiliation: Department of Pathology and Genomic Medicine, Houston Methodist Research Institute, Houston, TX 77030, United States. Electronic address: NPHa@houstonmethodist.org.
authors.forename: Ngan P
authors.initials: NP
authors.lastname: Ha
authors.affiliation: Department of Bioengineering, Rice University, 6500 Main Street, Houston, TX 77005, United States. Electronic address: Michal.E.Pawlowski@rice.edu.
authors.forename: Michal E
authors.initials: ME
authors.lastname: Pawlowski
authors.affiliation: Department of Pathology and Genomic Medicine, Houston Methodist Research Institute, Houston, TX 77030, United States. Electronic address: EAGraviss@houstonmethodist.org.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Graviss
authors.affiliation: Department of Bioengineering, Rice University, 6500 Main Street, Houston, TX 77005, United States; Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, United States. Electronic address: ttkaczyk@rice.edu.
authors.forename: Tomasz S
authors.initials: TS
authors.lastname: Tkaczyk
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D006801:Humans; D050296:Microbial Viability; D008856:Microscopy, Fluorescence; D009165:Mycobacterium Infections, Nontuberculous / Q000175:diagnosis* / Q000382:microbiology; D020102:Mycobacterium smegmatis / Q000201:enzymology* / Q000302:isolation & purification; D061848:Optical Imaging / Q000379:methods*; D011237:Predictive Value of Tests; D012256:Riboflavin / Q000031:analogs & derivatives* / Q000378:metabolism; D013997:Time Factors
chemical_list: D015415:Biomarkers; C015084:coenzyme F420; D012256:Riboflavin
keywords: Autofluorescence; Microscopy; Mycobacterium; Viability