ESBL- Extended Spectrum Beta-Lactamase producing organisms

Resistant to ampicillin and most cephalosporins (eg, ceftriaxone).

Reliably susceptible to carbapenems.

Many are susceptible to piperacillin-tazobactam and amoxicillin-clavulanate.

Viable treatment option if isolate is susceptible, and infection source is biliary or urinary.

Variable susceptibility to fluoroquinolones, TMP-SMX, and aminoglycosides.