ISBN: 978-83-60043-10-3 - eurobic9

E. Feese, R.A. Ghiladi
Eurobic9, 2-6 September, 2008, Wrocław, Poland
O14. Exploring New Treatment Options for Tuberculosis:
Photodynamic Inactivation of Mycobacterium Smegmatis
Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, 27695-8204, Raleigh, NC,
United States,
e-mail: efeese@ncsu.edu
Tuberculosis (TB) is one of the leading causes of death due to a single disease with 9.2 million new infections
and 1.7 million deaths reported for 2006 alone. Efforts to control TB infection have been hampered by the rise of
multiple-drug resistant strains, thereby necessitating research into new treatment options. Herein, we explore the
feasibility of photodynamic inactivation (PDI) as an alternative approach to the current antibiotic-based
tuberculosis treatments. Non-pathogenic Mycobacteria smegmatis was employed as a surrogate for
M. tuberculosis and the reduction in colony forming units (CFU) was examined as a function of the
photosensitizer (PS) concentration and light dose. Several commercially available photosensitizers were
examined at micromolar to nanomolar concentrations. The most promising results were achieved using the
cationic tetrakis-(1-methyl-4-pyridinio)porphyrin (146 nM), showing a 5-6 log unit reduction of CFU after
irradiation (400-700 nm) for 5 minutes at 60 mW/cm 2 s. Longer irradiation times resulted in no CFUs being
detected. Generally, positively charged photosensitizers showed PDI against M. smegmatis, whereas negatively
charged PS were ineffective. Further data obtained using other photosensitizers, along with a comparison to
analogous experiments with E. coli, will be presented. The data show that mycobacteria can be
photodynamically inactivated, suggesting that PDI may be an attractive treatment option for drug-resistant
tuberculosis.
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