Final answer:
The key immediate safety measure after a toddler's seizure due to bacterial meningitis is to place them in the side-lying position to maintain a clear airway and prevent aspiration.
Step-by-step explanation:
After a 2-year-old toddler has had a seizure due to bacterial meningitis, the most important safety measure a nurse should institute immediately is to place the child in the side-lying position. This position helps to ensure that the airway remains clear and reduces the risk of aspiration should the child vomit.
Once the toddler is safely positioned, the nurse should proceed to a) monitor the child's vital signs to assess for any immediate medical needs, b) bring suction equipment to the bedside as a precaution for any potential respiration issues, and c) pad the side rails of the crib to prevent injury if another seizure occurs.