not related to antibiotics, but in most cold/flu medicines....
I guess Phenylpropanolamine (PPA) is suspected in the deaths of many people.
http://www.fda.gov/cder/drug/infopage/ppa/
PPA was a terrific medicine. My favorite cold medicine was Tavist D which contained PPA. Everything that had PPA then was just reformulated and the manufacturers put in Sudafed (Pseudoephedrine) instead. It was taken off the market several years ago because it was linked to hemmorhagic strokes in overweight women in their 30s and 40s (think I'm remembering that right).