Causes of Antibiotic Failure - Differential Diagnosis Framework Diagnosis: • Non-Infectious: Malignant, Autoimmune, Drug-related (NMS, serotonin syndrome, antichol, toxin), Tissue Inflammation (pancreatitis), Drug withdrawal, Pseudo-cellulitis / "CAP" mimic, VTE • Wrong Bug: Atypical bacteria: Viral, Fungal, Parasite Natural History: • Too Soon: Can take 48 hrs for infections to improve • Too Aggressive: MRSA bacteremia, Toxin-mediated, Ongoing source • Predisposition to Infections: Obstruction/Anatomical abnormality, Aspiration, Immunocompromise Treatment: • Antibiotic: Spectrum (MRSA/ESBL), Not taking/absorbing? Wrong dose? • Tissue: Source control (abscess, lines, osteo, endocarditis), Tissue penetration (CNS, prostate, ocular), Tissue activity (daptomycin in lungs) Mimics / Secondary Process: • Secondary to Treatment: Drug side effect/reaction (ie SJS, DIHS, drug fever, Jarish Herxheimer rxn), Secondary infection (C diff) • Hospital-Acquired Infection: IV catheter (CLABSI or thrombophlebitis), HAP, Blood stream, C. Difficile, COVID-19 • Unrelated Infection: Esp in immunocompromised hosts Dr. Ann Marie Kumfer @AnnKumfer #Antibiotic #Failure #Differential #Diagnosis
