The effect of topical doxycycline in the prevention of experimental tympanosclerosis.

Abstract

The aim of this study is to determine the effectiveness of topical doxycycline used in the process of experimental myringosclerosis and tympanosclerosis. A prospective experimental animal study. Experimental tympanosclerosis was accomplished in 25 healthy adult guinea pigs by inoculation with 2.5 x 10(7) colony-forming units of type-3 Streptococcus pneumoniae microorganisms followed by bilateral myringotomy. While the animals' right ears received a topical doxycycline treatment daily, their left ears were left untreated and used as controls. Otomicroscopic examination was carried out weekly and healing tympanic membranes were remyringotomized. After a 6-week follow-up, the temporal bones of 24 of 25 animals were removed and light-microscopy examination was done regarding tympanic membrane myringosclerosis and middle ear mucosal sclerosis. Myringosclerosis was noticed to a lesser extent in the doxycycline-treated group when compared to the untreated control group. Light microscopy evaluation revealed a difference in the area and thickness of the sclerotic plaques of myringosclerosis of the tympanic membranes in the doxycycline-treated group and the control group, being significantly smaller and thinner in the treated group (P < .001, P < .04, respectively). Similarly, the area and thickness of the sclerotic plaques in the middle ear mucosa were significantly smaller and thinner in the doxycycline treated group (P < .001, P < .03). This study demonstrated that the potent matrix metallo-proteinase inhibitor doxycycline plays a preventive role in the development of experimentally induced tympanosclerosis.