Antimicrobial Photodynamic Therapy on Drug-resistant Pseudomonas aeruginosa-induced Infection. An In Vivo Study

• Published in: Photochemistry and photobiology 2012-05, Vol.88 (3), p.590-595
• Main Authors: Hashimoto, Maria C. E., Prates, Renato A., Kato, Ilka T., Núñez, Silvia C., Courrol, Lília C., Ribeiro, Martha S.
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents - pharmacology; Anti-Bacterial Agents - therapeutic use; Bacteremia; Burns; Disease Models, Animal; Drug resistance; Drug Resistance, Microbial; Female; Gram-negative bacteria; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Photochemistry; Photochemotherapy; Photodynamic therapy; Photosensitizing Agents - pharmacology; Photosensitizing Agents - therapeutic use; Pseudomonas aeruginosa; Pseudomonas aeruginosa - drug effects; Pseudomonas aeruginosa - isolation & purification; Pseudomonas Infections - drug therapy; Pseudomonas Infections - microbiology; Rodents; Survival Analysis
• ISSN: 0031-8655; 1751-1097
• DOI: 10.1111/j.1751-1097.2012.01137.x

Pseudomonas aeruginosa is considered one of the most important pathogens that represent life‐threatening risk in nosocomial environments, mainly in patients with severe burns. Antimicrobial photodynamic therapy (aPDT) has been effective to kill bacteria. The purpose of this study was to develop a burn wound and bloodstream infection model and verify aPDT effects on it. In vitro, we tested two wavelengths (blue and red LEDs) on a clinical isolate of P. aeruginosa strain with resistance to multiple antibiotics using HB:La+3 as photosensitizer. Verapamil® associated to aPDT was also studied. In vivo, P. aeruginosa‐infected burned mice were submitted to aPDT. Bacterial counting was performed on local infection and bloodstream. Survival time of animals was also monitored. In this study, aPDT was effective to reduce P. aeruginosa in vitro. In addition, Verapamil® assay showed that HB:La+3 is not recognized by ATP‐binding cassete (ABC) efflux pump mechanism. In the in vivo study, aPDT was able to reduce bacterial load in burn wounds, delay bacteremia and keep the bacterial levels in blood 2–3 logs lower compared with an untreated group. Mice survival was increased on 24 h. Thus, this result suggests that aPDT may also be a novel prophylactic treatment in the care of burned patients. This study reports a potential use of antimicrobial photodynamic therapy (aPDT) to delay bacteremia and increase life expectancy. We developed a mouse model of P. aeruginosa‐infected burns to investigate the effects of aPDT in situ and in the bloodstream. Infected mice without treatment died in 18 h. APDT was able to reduce bacterial load in burn wounds, retard bacteremia and keep the bacterial levels in blood 2–3 logs lower compared with untreated group. Mice survival was increased by 24 h. Put together, these findings suggest that aPDT could be a new prophylactic approach in the care of burned patients.