Infectious Diseases and Sepsis
Core concepts
Recognize sepsis as life-threatening organ dysfunction from infection, quantified by SOFA or bedside qSOFA, and septic shock as persistent hypotension requiring vasopressors with elevated lactate despite fluids. Emphasize the Surviving Sepsis bundle: cultures before antibiotics, early broad-spectrum antibiotics, balanced fluid resuscitation, and lactate-guided reassessment. Understand source control (drainage, debridement, line removal). Know common ICU pathogens, empiric regimens, and antimicrobial stewardship. Recognize specific syndromes: ventilator-associated pneumonia, catheter-related bloodstream infection, Clostridioides difficile, and necrotizing soft tissue infection.
Traps
Do not delay antibiotics to obtain cultures in an unstable patient - draw cultures rapidly but do not wait. Lactate clearance matters more than a single value. A normal white count does not exclude sepsis. Recognize that vasopressors may be started peripherally while central access is obtained. Do not miss fungal or atypical pathogens in immunocompromised patients.
Worked example
A patient with fever, hypotension, and lactate 4 mmol/L after 30 mL/kg crystalloid remains on norepinephrine. This is septic shock. Obtain blood cultures, give broad-spectrum antibiotics within the hour, add norepinephrine to target MAP ≥65, and aggressively pursue source control (imaging, drainage). Rule of thumb: every hour of delayed appropriate antibiotics in septic shock increases mortality.