MedCompanion

Empiric Therapy for Resistant Organisms

Cheat sheet for common resistant pathogens. Caveat: take drug penetration, allergies, concomitant medications, and local susceptibility into account.

OrganismEmpiric antibiotics
MRSAVancomycin (target AUC 400–600), Daptomycin (NOT for PNA), Linezolid (good for PNA, IV→PO), Ceftaroline
VREDaptomycin (high-dose 8–10 mg/kg), Linezolid
ESBL E. coli / KlebsiellaCarbapenem (meropenem, ertapenem). Avoid pip-tazo for severe ESBL infections (MERINO trial).
AmpC (Enterobacter, Serratia, Citrobacter, Providencia, Morganella, Hafnia)Cefepime; carbapenem if severe. Avoid 3rd-gen cephalosporins (ceftriaxone) — inducible resistance.
CRE (carbapenem-resistant Enterobacterales)Ceftazidime-avibactam, meropenem-vaborbactam, imipenem-relebactam, cefiderocol. Call ID.
MDR PseudomonasCeftolozane-tazobactam, ceftazidime-avibactam, cefiderocol. Call ID.
Stenotrophomonas maltophiliaTMP-SMX (first-line). Levofloxacin or minocycline as alternatives.

Adapted from UCSF CODA Bugs & Drugs (Karandikar & Rubio, 2026) and IDSA antimicrobial stewardship resources.