Some Gram negative bacilli produce "broad-spectrum" beta-lactamases that can hydrolyze penicillins and cephalosporins. Treatment of such organisms can often be challenging.
"SPICE" organisms is a colloquial acronym for Gram negative bacteria that have inducible, chromosomal beta-lactamase genes known as AmpC. While resistance may not be detectable initially, it can appear after a period of exposure to beta-lactam antibiotics.
"SPICE" organisms include Serratia, Providencia, (Indole positive) Proteus species, Citrobacter, Enterobacter, Hafnia, Acinetobacter, Morganella, and rarely Pseudomonas.
Use of penicillins (with or without beta-lactamase inhibitors) and cephalosporins should generally be avoided. Options for therapy (pending susceptibilities) include: nitrofurantoin (for cystitis only), TMP-SMX, carbapenems, aminoglycosides and fluoroquinolones.
