AmpC Organisms

General Susceptibility

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

Susceptible to carbapenems and cefepime

Using some beta-lactams (i.e. Ceftriaxone) when reported as susceptible, is likely reasonable for simple infections requiring short duration (ie UTI)

Intrinsic resistance to ampicillin and lower generation cephalosporins.

Do not use ceftriaxone for serious infections such as bacteremia or osteomyelitis even if test susceptible in the laboratory. With exposure to beta-lactams, induction or de-repression can occur and confer resistance to third generation cephalosporins.