I'm just an MS2 and currently procrastinating, but I'm thinking Cipro also.
Gentamycin is an aminoglycoside, which are IV only. Same with Vancomycin, IV only (isn't absorbed p.o., but can be used for pseudomembranous colitis). Amphotericin B is IV, but not sure if it's only IV. Still my gut tells me it's not used p.o. or IM
That leaves Cipro as the only one I'm sure can be admin other than IV