ICU Antimicrobial Strategy
This section is deliberately different from the medication library. It starts with the clinical syndrome, then walks through immediate therapy, cultures, source control, resistance risk, de-escalation and duration. Dosing remains linked to the verified medication monographs.
The ICU antimicrobial sequence
The framework does not replace the local antibiogram, local formulary, microbiology advice or patient-specific dosing. It is designed to prevent two common ICU errors: inadequate initial therapy in high-risk infection and unnecessary persistence of broad therapy after the diagnosis becomes clearer.
Quick empiric starts for common ICU syndromes
These are adult empiric starting examples, not universal order sets. Match the choice to acquisition setting, allergy, prior cultures, local susceptibility, organ function and the suspected source; open the full framework for when to broaden, what to add and when to narrow.
Syndrome-Based Strategy
Sepsis / Septic Shock — Source Not Yet Known
A severity-first empiric strategy that covers likely pathogens without reflexive maximal-spectrum therapy in every patient, then narrows aggressively as source and microbiology become clearer.
Severe Community-Acquired Pneumonia in the ICU
Severe CAP strategy focused on prompt pneumococcal/atypical coverage, selective MRSA/Pseudomonas expansion and rapid microbiology-driven narrowing.
Hospital-Acquired & Ventilator-Associated Pneumonia
Empiric HAP/VAP therapy built around local antibiogram risk, early respiratory sampling and rapid removal of unnecessary MRSA/dual gram-negative coverage.
Complicated Intra-Abdominal Infection / Abdominal Sepsis
Antibiotics are adjuncts to source control: cover enteric gram-negatives and anaerobes, add enterococcal/MRSA or resistant coverage only when the clinical setting justifies it.
Urosepsis & Complicated Urinary Tract Infection
Severity-driven therapy paired with urgent relief of obstruction and early narrowing to urine/blood susceptibility results.
Suspected Bacterial Meningitis / Encephalitis
Do not delay CNS-active empiric therapy for imaging or lumbar puncture; tailor coverage to age, immune state, post-neurosurgical exposure and encephalitis risk.
Necrotizing Soft-Tissue Infection
Surgery first: use broad empiric polymicrobial/MRSA coverage plus toxin-suppressive therapy when streptococcal/clostridial disease is suspected, then narrow after operative cultures.
Catheter-Related Bloodstream Infection
Paired cultures, organism-specific line removal decisions and targeted therapy—without reflexively labeling every positive culture as CLABSI.
Severe / Fulminant Clostridioides difficile Infection
Severity recognition, enteral anti-C. difficile therapy, adjunctive IV therapy for fulminant disease, ileus-aware delivery and early surgical consultation.
Suspected Infective Endocarditis in the ICU
Obtain multiple blood-culture sets, define native/prosthetic/device context, start empiric therapy according to acuity and epidemiology, then pivot rapidly to organism-specific therapy plus surgical decision-making.
Aspiration Pneumonitis vs Aspiration Pneumonia
Separates chemical aspiration injury from bacterial aspiration pneumonia so antibiotics are not given reflexively after every witnessed aspiration.
Empyema & Complicated Parapneumonic Infection
Pleural infection strategy built around prompt antibiotics plus effective pleural drainage rather than antibiotics alone.
Healthcare-Associated Ventriculitis / EVD or Shunt Infection
Device-associated CNS infection strategy emphasizing CSF microbiology, neurosurgical source control and agents with reliable CNS activity.
Brain Abscess & Intracranial Empyema
Intracranial suppurative infection strategy prioritizing urgent imaging, neurosurgical source control and source-specific antibacterial coverage.
Acute Cholangitis & Biliary Sepsis
Biliary sepsis strategy in which decompression of an obstructed infected biliary tree is central to survival.
Spontaneous Bacterial Peritonitis
Cirrhosis-associated SBP strategy emphasizing immediate diagnostic paracentesis, prompt therapy and distinction from secondary peritonitis.
Staphylococcus aureus Bacteremia
High-risk bloodstream infection pathway: repeat cultures, source control, endocarditis evaluation and search for metastatic infection.
Enterococcus Bacteremia
Enterococcal bloodstream infection strategy that distinguishes E. faecalis/E. faecium, evaluates endovascular and abdominal/urinary sources, and avoids unnecessary broad therapy.
Gram-Negative Bacteremia
Source-first gram-negative bloodstream infection strategy emphasizing source control, resistance phenotype and short-course therapy for uncomplicated responding infection.
Severe Influenza & Viral Pneumonia
Viral pneumonia strategy that prioritizes early influenza antivirals, bacterial coinfection assessment and avoidance of unnecessary antibiotics/steroids.
Staphylococcal / Streptococcal Toxic Shock Syndrome
Shock-plus-source strategy requiring immediate resuscitation, source control and antitoxin-active therapy in addition to definitive antibacterial coverage.
Septic Arthritis, Vertebral Osteomyelitis & Epidural Abscess
Deep bone/joint infection pathway centered on urgent source sampling, neurologic assessment and source control rather than prolonged blind broad-spectrum therapy.
Infected Pancreatic Necrosis
Necrotizing pancreatitis strategy that avoids prophylactic antibiotics for sterile necrosis and uses a delayed step-up source-control approach when infection is established.
Cardiac Implantable Electronic Device Infection
Pacemaker/ICD infection strategy requiring blood cultures, endocarditis evaluation and device extraction when infection criteria are met.
Meningococcal Disease & Exposure Prophylaxis
Fulminant meningococcal sepsis/meningitis management plus droplet precautions and rapid public-health prophylaxis for true close contacts.
Immunocompromised Host
Febrile Neutropenia / Neutropenic Sepsis
Immediate antipseudomonal therapy with selective gram-positive, resistant-organism and antifungal expansion based on instability, source and duration of neutropenia.
Pneumocystis jirovecii Pneumonia
Severe PJP strategy using host context, PCR/organism burden, TMP-SMX therapy and adjunctive steroids when established hypoxemia criteria are met in HIV-associated disease.
Cytomegalovirus Disease in the Immunocompromised ICU Patient
CMV strategy distinguishing viremia/reactivation from tissue-invasive disease and incorporating host-specific thresholds and antiviral toxicity.
Severe HSV / VZV Infection
Time-critical antiviral strategy for HSV encephalitis, disseminated HSV and severe/disseminated VZV in critically ill patients.
Tuberculosis in the ICU
Critical TB pathway emphasizing airborne isolation, rapid molecular diagnosis, organ-specific treatment constraints and recognition of meningitis/pericardial disease.
Invasive Fungal Infection
Candidemia & Invasive Candidiasis
Echinocandin-first strategy for most critically ill adults, paired with line/source control, repeat blood cultures and susceptibility-informed step-down.
Invasive Aspergillosis in the ICU
Risk-based strategy for invasive pulmonary aspergillosis in immunocompromised and selected critically ill patients, integrating CT, fungal diagnostics and mold-active therapy.
Mucormycosis in the ICU
Time-critical invasive mold strategy centered on liposomal amphotericin B, urgent surgical assessment and reversal of predisposing factors.
Candiduria — When to Treat and When Not to Treat
Prevents overtreatment of Candida colonization in urine while identifying high-risk patients and true Candida urinary infection.