Photodynamic Inactivation of Moraxella catarrhalis

Moraxella catarrhalis의 광역학적 비활성화

The aim of this study was to evaluate the bacterial effects of Moraxella catarrhalis in otitis media with effusion (OME) by photodynamic therapy (PDT). Bacterial suspensions (10000 CFU/mL) were prepared. The colony forming units (CFU) of Moraxella catarrhalis have been measured after an application of photogem plus 632 nm diode laser irradiation. One ml of the bacterial suspensions have been incubated in the dark for 3h with various concentrations of photogem ($0.625{\sim}5.0_{\mu}g/mL$) and then irradiated with 632 nm diode laser ($15J/cm^2$). After, the PDT Moraxella catarrhalis suspensions ($50{\mu}L$) were inoculated on chocolate agar plate and cultured in the dark at $37^{\circ}C$, 5% $CO_2$ condition for 18h. The colony forming units off the bacteria were measured. Also transmission electron microscopy (TEM) was employed to evaluate the effect of otitis media pathogens by PDT. The nucleus of Moraxella catarrhalis was stained using green fluorescent nucleic acid dye thiazole orange and the fluorescence intensity of the nucleus was measured by flow cytometry. The PDT was effective in killing Moraxella catarrhalis at the photogem dose of $5.0_{\mu}g/mL$, respectively, As assessed by flow cytometry analysis the fluorescence intensity of the nucleus got lower after PDT. TEM result appeared to able to cause damage to the bacterial membranes. On the basis of these findings, bacterial photodynamic therapy with photogem can be considered to be a promising new therapeutic approach for OME.