Final answer:
A manufacturer must report to the FDA within 15 calendar days if it receives information about a serious adverse event, such as acute sepsis, related to an approved device not previously listed in the package insert.
Step-by-step explanation:
When a physician reports to a manufacturer that a patient was hospitalized with acute sepsis after treatment with an approved device and this side effect is not listed in the package insert, the manufacturer must report this event to the FDA no later than 15 calendar days. This requirement is in place to ensure that any unexpected serious or fatal adverse events related to drug usage are promptly communicated to the FDA for further investigation and public safety measures. The reporting system helps to maintain postmarket safety surveillance, ensuring the ongoing evaluation of drugs and devices even after they have been approved to be marketed.