Depends on what strain of RI your snake has - the vet would have to take a swab to examine and determine what antibiotic will best work with your snake's particular strain.
Culture THEN antibiotics. Antibiotics cannot be bought without a prescription from your veterinarian. Common antibiotics used for RI treatment in reptiles are Baytril(enrofloxacin), Amiglyde(amikacin), and Fortaz(ceftazidime). Fortaz is NOT cheap, so be forwarned if the culture comes back and it needs to be used.
--Becky--
?.? Normals, 1.0 100% Het Pied Classic Jungle, 1.0 Yellow Hypo, 0.1 100% Het Butterscotch Hypo, 0.1 100% Het VPI Hypo, 0.1 100% Het Yellow Hypo, 1.0 Enchi, 1.1 Yellowbellies, 0.1 YB Granite, 1.0 Black Pastel, 1.0 Lemon Pastel, 0.1 50% Possible Het Banded Albino, 0.1 Spider, 1.0 Fire, 0.2 Granite