Final answer:
The appropriate action for the medical assistant is to not use the sterile instruments without dates and report the issue. They should reprocess the instruments through the autoclave and label them correctly to ensure patient safety.
Step-by-step explanation:
If a medical assistant finds packages of autoclave sterile instruments with no dates on the packages, the most appropriate action to take would be to not use the instruments and to report this issue to their supervisor. This is because without a date, there is no way to verify the {}sterility of the instruments. Sterile items are typically dated to indicate until when the item can be considered sterile and safe to use.
It is imperative for patient safety that any instruments used are not only sterilized but also handled and stored correctly after sterilization, which includes proper labeling and dating. The absence of a date may indicate a breach in protocol and could potentially put patients at risk of infection. The medical assistant should reprocess the instruments through an autoclave and ensure they are correctly labeled this time before they are used in any medical procedure.