Staphylococcus aureus exotoxin has limited and transient effects on cochlear electrophysiology

Seven ears of Sprague-Dawley rats were exposed to 20 μl Staphylococcus aureus exotoxin suspension by injection via the tympanic membrane into the round window niche. Another 6 ears were exposed to 20 μl broth as controls. ABR was performed in the interval 2-31.5 kHz immediately before and 1, 2, 5, 7 and 10 days after the exposure. Although threshold changes could be found in the toxin-exposed group but not the control group in the frequency range 10-20 kHz, there were only statistically significant threshold changes at 31.5 kHz - on the 1st, 2nd, 5th, and 7th days after the exotoxin injection. S. aureus exotoxin has minor transient but reversible effects on the inner ear, causing chiefly high-frequency threshold and latency changes.