OTOTOXICITY OF VANCOMYCIN - AN EXPERIMENTAL-STUDY IN GUINEA-PIGS

Vancomycin (V) - a polypeptide antibiotic - is the drug of choice in severe infections with multiresistant staphylococcus spp. Due to the multimorbidity of the patients receiving V, the interactions with known ototoxic agents and the lack of an audiometric documentation, earlier clinical reports of V-associated hearing loss must be carefully interpreted. To elucidate this topic, a controlled animal study considering nonspecific effects was performed. 40 albino guinea pigs with positive Preyer's reflex and normal hearing were used. The hearing function was controlled by means of brainstem auditory evoked potentials before and after intraperitoneal administration of V (75, 150, 300 mg/kg b.w. for 11-17 days), gentamicin (60 mg/kg b.w. for 26 days), neomycin (100 mg/kg b.w. for 17 days) and sodium chloride solution. The cochleas were dissected for hair cell counting by the surface preparation technique. Additionally, the serum concentrations of V were measured. As a result there was no significant difference in hearing loss between the controls and the animals treated with 75 and 150 mg V; toxic doses of 300 mg V led to a certain threshold elevation after click stimuli, but not after trapezoid stimuli of 1, 4 and 8 kHz. On the other hand, the aminoglycosides as a positive control caused an obvious hearing loss after click and trapezoid stimuli, which was correlated to the amount of outer hair cell loss. Renal damage could be excluded by histological examination of the kidneys and estimation of creatinine in serum. Therefore, treatment with moderate doses of V comparable to clinical conditions does not exhibit a specific ototoxicity as compared to the aminoglycosides. However, serum levels of V should be controlled as a safety measure in older patients and in patients with impaired renal function.