In vitro and in vivo photodynamic therapy of otitis media in gerbils.
OBJECTIVE
The aim of this study was to evaluate the antibacterial effects of photodynamic therapy (PDT) on common bacteria causing otitis media with effusion (OME).


METHODS
An in vitro study was carried out using a hematoporphyrin derivative sensitizer (Photogem; Lemonosov Institute of Fine Chemical, Moscow, Russia) and a 632-nm diode laser on Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae. The presence of colony-forming units of the bacteria was examined, the microscopic structures of the bacteria were examined by transmission electron microscopy (TEM), and flow cytometry of the bacteria was performed. An in vivo PDT study was performed using gerbils. S. pneumoniae or H. influenzae were injected into bullae. The Photogem was injected into the bullae 2 days later when OME developed, and transcanal irradiation with the 632-nm diode laser (90 J) was performed. Middle ear and bulla were washed with Dulbecco's phosphate buffered saline (DPBS) and the washed DPBS was cultured. The presence of bacterial colonies was examined.


RESULTS
The PDT was effective in killing all three kinds of bacteria. TEM showed damaged bacterial cell membranes and cytoplasmic structures, and the flow cytometry showed a lower number of viable bacteria in the PDT group compared to the control group. PDT was effective in killing S. pneumoniae in 87% of the infected bullae with OME, whereas it was effective in eradicating H. influenzae in 50% of the infected bullae with OME.


CONCLUSIONS
The results of these studies demonstrated that PDT may be effective to treat otitis media. PDT may have clinical implications in the treatment of otitis media that is resistant to antibiotic therapy.
Jung
Jae Yun
JY
Department of Otolaryngology-Head & Neck Surgery and Medical Laser Research Center, Dankook University College of Medicine, Cheonan, Korea.
Kwon
Pil Seung
PS
Ahn
Jin Chul
JC
Ge
Ruifeng
R
Suh
Myung-Whan
MW
Rhee
Chung-Ku
CK
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D005849:Gerbillinae; D006415:Hematoporphyrins / Q000627:therapeutic use; D066298:In Vitro Techniques; D010034:Otitis Media with Effusion / Q000188:drug therapy* / Q000382:microbiology; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use
D006415:Hematoporphyrins; D017319:Photosensitizing Agents