Final answer:
The treatment of PKU focuses on preventing toxic levels of phenylalanine by adhering to a modified diet low in this amino acid and steering clear of aspartame-containing products.
Step-by-step explanation:
The goal of treatment for an infant with phenylketonuria (PKU) is to prevent the buildup of phenylalanine to toxic levels in the body, which can cause severe damage to the central nervous system and brain. Early diagnosis and treatment with a modified diet that is low in phenylalanine are essential to reduce the severity of symptoms such as delayed neurological development and intellectual disability. It is also important to avoid products containing aspartame, as these can release high levels of phenylalanine when broken down by the body.