A 62-year-old man in ICU for severe sepsis with CKD stage 3 reports worsening hearing loss and tinnitus after 4 days of treatment. Which medication is the most likely cause?

• A. Vancomycin
• B. Ciprofloxacin
• C. Gentamicin
• D. Amikacin

Answer: (C)

Ototoxicity risk with certain antibiotics, particularly aminoglycosides, is the key idea here. Gentamicin is a classic example of an aminoglycoside that can damage inner ear hair cells, leading to sensorineural hearing loss and tinnitus. This damage tends to be dose- and duration-dependent and is more likely when drug clearance is impaired, such as in chronic kidney disease. In this patient, four days of therapy in the ICU with CKD stage 3 means higher and more prolonged exposure to the drug, making gentamicin the most likely culprit for the new hearing changes.

Vancomycin can cause nephrotoxicity and, less commonly, ototoxicity, but the association and typical presentation are not as strong as with aminoglycosides in this context. Ciprofloxacin is not a typical cause of ototoxicity, though unusual tinnitus can occur rarely. Amikacin is another aminoglycoside and can cause ototoxicity as well, but in exam scenarios gentamicin is the more common/recognized culprit for this presentation, especially given the duration and renal impairment.