there are no reasons why you can't take an anitbiotic with AAS. most are metabolized thru the kidneys while the others are metabolized thru the liver. these drugs are routinely given to patients with chronic kidney and liver diseases only with dose adjustments. i would assume that you are a healthy individual and should have no problem. the garggling idea would probably work well with viral infections (most common) since antibiotics do not treat these, however if you tested positive for "strep" you probably need medication.
on another note, some antibiotics may compete for binding sites on the proteins that carry Anabolic Androgenic Steroids (AAS) in the blood, displacing them. this may actually increase the blood levels of these drugs, which would not be a bad thing i suppose.