I'd imagine it's not much different in Central and South America based on my travels. You can walk into any pharmacy and show them the word "amoxicillin" and they'll give you a 2 week course.
Edit: a word
Edit: a word
BTW, in my experience Brazilian doctors prescribe antibiotics a lot less than American doctors.
Others just walk to the pharmacy store and narrate the symptoms to the pharmacist. Typically: Sore throat, a little fever etc. Then they state their budget(10-20 rupees), the pharmacist gives two tablets of Azithromycin.