Sepsis, Infection and Antimicrobial Stewardship
This domain tests whether you can recognise sepsis early, resuscitate within the hour, and then take antibiotics away again. The Board favours SOFA and qSOFA, the hour-1 bundle, source control and de-escalation.
Definitions that carry marks
Sepsis-3 defines sepsis as life-threatening organ dysfunction caused by a dysregulated host response to infection, operationalised as a SOFA rise of 2 points or more. qSOFA (respiratory rate 22 or more, systolic pressure 100 or less, GCS below 15) is a prompt to look harder, not a diagnostic test. Septic shock requires vasopressors to keep MAP at 65 mmHg or above plus lactate above 2 mmol/L despite adequate fluid resuscitation; the old category of severe sepsis is gone.
The first hour
Measure lactate, take blood cultures before antibiotics if this causes no delay, give broad-spectrum antibiotics, start 30 mL/kg crystalloid for hypotension or lactate of 4 mmol/L or more, and start vasopressors to reach MAP 65. Antibiotics within one hour for shock or high likelihood of sepsis. Source control - drain the abscess, remove the infected line - within 6-12 hours. Re-measure lactate; clearance predicts survival better than a single value.
Stewardship in practice
Review antibiotics at 48-72 hours with culture results: de-escalate, narrow, or stop. Typical duration is 5-7 days for most infections when source control is achieved. Pharmacokinetics matters in the critically ill - give a loading dose, use extended or continuous infusion of beta-lactams, use once-daily aminoglycosides, and target vancomycin AUC rather than trough alone. Do not treat asymptomatic bacteriuria, candiduria or tracheal colonisation. Oral vancomycin or fidaxomicin for Clostridioides difficile.
Worked example
A 72-year-old with pyelonephritis: lactate 4.6, MAP 58 after 30 mL/kg. Take cultures, give ceftriaxone according to local resistance patterns, start noradrenaline, and obtain urgent imaging for obstruction. At 48 hours she is afebrile, cultures grow a susceptible E. coli, lactate 1.2 - narrow to the susceptibility report and plan 7 days total. Repeating broad-spectrum coverage to be safe is the wrong answer.
Traps
Equating fever with sepsis. Delaying antibiotics for lumbar puncture or imaging. Continuing empirical carbapenems without culture justification. Forgetting that lactate rises with beta-agonists, seizures and liver failure, so trend it rather than worshipping it.