Final answer:
Aminoglycoside toxicity is indicated by hearing loss and a rising serum creatinine level, showing effects of ototoxicity and nephrotoxicity respectively.
Step-by-step explanation:
The nurse administering aminoglycoside therapy must closely monitor the patient for signs of toxicity. The conditions indicating aminoglycoside toxicity include ototoxicity, which manifests as hearing loss, and nephrotoxicity, indicated by a rising serum creatinine level. These drugs, which include medications like streptomycin and gentamicin, are known to be damaging to both the ears (leading to hearing loss) and the kidneys (leading to altered renal function as evidenced by increased creatinine levels).