Laser-induced microbial reduction in acute bacterial rhinosinusitis

This study was designed to assess laser-induced manipulation on bacterial load and host in an animal model of acute bacterial rhinosinusitis (ABRS). An animal study using 12 rabbits followed an elaborated efficient in vitro model. ABRS was created by packing the nose with a sponge soaked in solution containing pathogenic microorganisms. Eight infected animals were randomly allocated to two separate groups, each being exposed to different laser therapies. Two healthy animals served as treatment controls, and one animal without ABRS and treatment was observed.

ABRS was confirmed histologically, radiologically, and bacteriologically. Two days after bacterial inoculation, packing was removed and nasal passages were treated by laser irradiation. Two laser modalities were tested. A near infrared (NIR) 940-nm diode laser with diffuser fiber tip was used in four rabbits. A photosensitizer (methylene blue 0.01 or 0.05%) and 635-nm laser combination was used in the second cohort. Nasal cultures were obtained before and after the laser treatments. Animals were killed 5-10 days after laser treatment and bacteriological/histological results were analyzed.

An average 2 log reduction in bacterial colony counts was achieved with both laser methods compared with control. Histological studies showed tissue integrity preservation without significant damage to nasal mucosa.

Significant bacterial reduction was achieved with both NIR laser and photograph activated therapies in an animal study of ABRS. This pilot study shows an innovative method of bacterial killing without host tissue damaging and may have potential future clinical application.