AmpC Organisms
General Susceptibility

General Susceptibility

Usually susceptible to fluoroquinolones, TMP/SMX, and aminoglycosides which are appropriate targeted therapy options.

Susceptible to carbapenems.

Usually susceptible to aztreonam.

Using non-carbapenem beta-lactams (i.e. Piperacillin/tazobactam, Ceftriaxone) when reported as susceptible, is likely reasonable for simple infections requiring short duration.

Intrinsic resistance to ampicillin and lower generation cephalosporins.

With exposure to beta-lactams, induction or de-repression can occur and confer resistance to 3rd generation cephalosporins.