How can a possible infection be treated after a dog bite?

Depends on severity. I assume you are talking about increasing pain, redness and warmth around the site of a dog bite, not rabies or tetanus! if the bite was sutured, suture removal might be important, even if it is earlier than expected. Antibiotics by mouth, or, in serious cases, intravenously might be needed, as well. This is nothing to fool around with; see a doctor asap!
Antibiotics. Dog bites can cause significant infections. Proper physical examination with a doctor, cleaning as indicated, and antibiotics would be indicated if the bite is deep or in a concerning location. Must see a doctor to determine treatment.