Ototoxicity of Vistamycin

Abstract

Vistamycin (VSM) is a new aminoglycoside antibiotic produced by Streptomyces ribosidificus and effective against gram positive and negative bacteria. The present experimental study was made on 63 guinea pigs to compare the ototoxicity of VSM with those of Kanamycin (KM) and Dihydrostreptomycin (DHSM). These guinea pigs of Hartley strain (300g at the start of injection) were divided into 6 groups. Dosis of the administered antibiotics and number of the animals in each group were as follows: VSM 200mg/kg group (14), VSM 400mg/kg group (12), KM 200mg/kg group (14), KM 400mg/kg group (10). DHSM 200mg/kg group (10) and DHSM 400mg/kg group (3). Each antibiotic was injected intramuscularly for 28 days. Before, during and after the injection of these antibiotics, Preyer's pinna reflex test was carried out with audiometer with frequency range from 500Hz to 10, 000Hz. After the last injection the animals underwent vital perfusion with physiological saline solution and then with Wittmaack's fixative. Bilateral temporal bones were removed from the skull and fixed in the same fixative further for several days. According to the conventional method, serial celloidin horizontal sections were prepared and stained with hematoxylin-eosin. Histopathological examination revealed that the loss of the most sensitive outer hair cells of the organ of Corti occurred less frequently as well as less extensively in the guinea pigs received VSM at the dosis of 200mg/kg or 400mg/kg than in the animals received KM at the same dosis. DHSM was less ototoxic than the another two antibiotics at the dosis of 200mg/kg.The present study indicated that VSM is less ototoxic than KM.