A male client has been receiving the antibiotic gentamicin sulfate, IV piggyback every 12 hours for several days. Which observation by the nurse indicates that the client may be experiencing an adverse effect of gentamicin? Reference Range: White Blood Cell [5,000 to 10,000/mm3 (5 to 10 10^9/L)]

A. Hearing has decreased: Gentamicin is an aminoglycoside antibiotic known for its potential to cause ototoxicity, leading to hearing loss, tinnitus, or balance disturbances. Early signs of auditory damage, such as decreased hearing, must be promptly recognized because ototoxicity can be irreversible if the drug is not discontinued or adjusted quickly. B. White blood cell count of 6,000/mm³ (6 × 10⁹/L): A WBC count within the range of 5,000 to 10,000/mm³ is considered normal. A value of 6,000/mm³ does not suggest bone marrow suppression or infection-related complications and is not an indicator of gentamicin toxicity. C. Decreased blood urea nitrogen: Gentamicin is more commonly associated with nephrotoxicity, which typically leads to increased BUN and creatinine levels due to kidney injury. A decreased BUN level would not suggest an adverse reaction to gentamicin and would not be expected. D. Reports of photophobia: Photophobia is not a recognized adverse effect of gentamicin. Visual disturbances like photophobia are more commonly associated with other medications or conditions, not aminoglycoside toxicity.