Bactericidal effect of photodynamic therapy using Na-pheophorbide a: evaluation of adequate light source.
OBJECTIVE
To evaluate the efficacy of photodynamic therapy (PDT) against methicillin resistant-Staphylococcus aureus (MRSA) by selecting different light sources for irradiation and combining them with the photosensitizer Na-Pheophorbide a (Na-Phde a).


BACKGROUND
The treatment of drug-resistant bacterial infection is a serious issue. Recently, as a new clinical approach against septic arthritis, an experimental in vivo and in vitro model for the inactivation of MRSA by PDT using the photosensitizer Na-Phde a has been developed.


METHODS
Na-Phde a solution (280 micromol/L) was mixed with MRSA strain bacterial inoculum. After 60 minutes, light was irradiated for 30 minutes using the following light sources: GaA1p semiconductor laser (300 mW, 670 nm), halogen lamp (75 W), xenon lamp (300 W) and fluorescent lamp (27 W). Bacterial growth was evaluated after 24 hours incubation in a blood agar culture.


RESULTS
The semiconductor laser and halogen lamp groups showed perfect bactericidal effects after PDT. The xenon lamp and fluorescent lamp groups showed partial bactericidal effects.


CONCLUSIONS
The results of this experiment showed that PDT using the combination of Na-Phde a with a semiconductor laser or halogen lamp showed a better bactericidal performance than with xenon or fluorescent lamps. These findings indicated that PDT using Na-Phde a could be a useful treatment for septic arthritis and soft tissue infection.
Yamamoto
Toru
T
Nihon University School of Medicine, Department of Orthopaedic Surgery, Tokyo, Japan.
Iriuchishima
Takanori
T
Aizawa
Shin
S
Okano
Tatsumasa
T
Goto
Bunsei
B
Nagai
Yu
Y
Horaguchi
Takashi
T
Ryu
Junnosuke
J
Saito
Akiyoshi
A
D001170:Arthritis, Infectious / Q000188:drug therapy; D002734:Chlorophyll / Q000031:analogs & derivatives* / Q000494:pharmacology; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D010778:Photochemotherapy / Q000295:instrumentation / Q000379:methods*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D018461:Soft Tissue Infections / Q000188:drug therapy; D013203:Staphylococcal Infections / Q000188:drug therapy*
D011838:Radiation-Sensitizing Agents; D002734:Chlorophyll; C032623:pheophorbide a