Like most things in clinical medicine, practical knowledge does not necessarily come from reviewing books. You'll find that most people think in terms of disease coverage, not pathogen coverage (i.e. what antibiotic is good for uncomplicated UTI vs. what covers E. coli and S. saprophyticus). You pretty much have to do an ID month (always a good idea no matter what medical field you are going into) if you want to learn the nuances of antibiotic use, pick up cool tricks (continuous infusion vanc), and get experience using things you wouldn't normally touch (carbipenems, colistin, aminoglycosides, etc.).
Wow, I managed a post about antibiotics without starting a flame war with another specialty. :]