Effect of nystatin on Guinea Pigs' inner ear

Nystatin is a topical antifungal agent. Its wide spectrum of action and low cost make it a treatment of choice. Though it is safe for external ear use, no study has proven its safety in cases of tympanic membrane perforation (TMP). We aim to test the safety of Nystatin when applied directly to the middle ear of a Guinea Pig model. We performed an experimental study with 18 Hartley Guinea Pigs that were divided into two groups. All tympanic membranes were perforated at the beginning of the study. Exposing one group to Nystatin and the other to the ototoxic Neomycin, we compared results of auditory brainstem response testing at three intervals. Each animals' contralateral ear was used as a negative control. At the end, we performed a histological analysis of the animals' cochleae using a scanning electron microscope (SEM). Average hearing loss in the Nystatin group was 13.0 dB which was similar to the results obtained in the negative control group (13.1 dB). Average hearing loss in the Neomycin group was 39.3 dB, which represents a statistically significant difference (P < 0.001). SEM evaluation revealed intact cochlear hair cell architecture in the Nystatin and normal saline groups, whereas significant hair cell losses were noted in the Neomycin group was noted. Nystatin does not cause hearing impairment or cochlear hair cell damage when exposed directly to the middle ear of a Guinea Pig model. It is therefore a safe treatment option for otomycosis with presence of TMP.