Baytril plus or minus amoxicillin are the most common empirical (medical guess) antibiotics for AP. Clavamox or azithromycin are also reasonable. If she is getting repeated bouts of AP and none of the antibiotics are knocking it out she may benefit from either a transtracheal wash (which can be done with the pet awake) or Bronchoalveolar lavage (ie. obtaining material from deep in the lungs to culture and find out what antibiotic would probably work best) – BAL requires anesthesia. good that you are using albuterol in the nebulizer and coupage.
Sometimes we just can’t GUESS which antibiotic. Also, as you probably know 4-6 weeks is the minimal time for administration of the antibiotics and in chronic cases we may need to treat for several months.
There are a few injectable antibiotics that can be administered via nebulizer but, you want to know that they are REALLY needed, as they can be damaging to the kidneys.