For serious infections, Carbapenem preferred until susceptibility known, then step down to aminoglycoside, fluoroquinolone, or TMP-SMX if susceptible.

Although beta-lactams may be reported as susceptible, treatment failure with certain beta-lactams may occur due to inducible resistance.

Cefepime and Aztreonam are generally susceptible.

These organisms usually produce inducible beta-lactamase which cause failure of 3rd generation beta-lactam therapy, despite in vitro susceptibility