Sepsis and Antimicrobials


Sepsis is a very frequently encountered issue in ICU, and as such basic awareness of management principles is key.

Sepsis can be defined as “life threatening organ dysfunction caused by a dysregulated host response to infection”.

The most recently published (Sepsis 3) defines organ dysfunction as a SOFA or qSOFA score of ≥2. The qSOFA score can be conducted at the bedside (the SOFA score is more complex to calculate) and assigns 1 point to each of:

  • Systolic BP < 100
  • GCS < 15
  • Respiratory Rate > 22.

These same guidelines define septic shock as sepsis + persistent hypotension requiring vasopressors and a lactate > 2 mmol/L despite adequate volume resuscitation.

Aside from supportive care, the management of sepsis involves early recognition, correct antimicrobial usage, and adequate source control.

Important considerations in a septic patient who is clinically deteriorating include:

  • Inadequate (or no) source control
  • Incorrect antimicrobials (or developing resistance)
  • Development of organ dysfunction related to sepsis (e.g. a septic cardiomyopathy).

Source Control

This can be defined as the physical methods used to control/remove the foci of infection and restore physiological function. In an unstable or deteriorating patient source control should not be delayed. Plans and timing for source control should form part of an ICU admission plan.

For source control to occur, there has to be a diagnosis of the presumed source. Therefore, one should have a low threshold for diagnostic imaging (e.g. abdominal CT) if the infective source is not obviously apparent. This could include repeat imaging to assess interval changes in a deteriorating patient.

Forms of source control include:

  • Drainage of infected fluid collections
    • i.e.  I + D of an abscess, ICC for empyema, cholecystostomy for obstructed gall bladder or nephrostomy for obstructed kidney
  • Debridement of solid tissue
    • i.e. soft tissue debridement in necrotising fasciitis
  • Definitive measures to correct an anatomical disruption (that would result in ongoing contamination) and optimise physiological function
    • i.e. bowel resection for perforation
  • Removal of foreign body or medical device
    • i.e. removal of long-term venous access line or joint metalwork


Using the right antimicrobials in the right way at the right time is key in their success. Antimicrobials is the encompassing term for antibiotics, anti-fungals and anti-virals. An understanding against of how microbes are classified and which organisms certain antibiotics work against is important. LITFL has an excellent antimicrobial compendium.

When prescribing antimicrobials (and in particular antibiotics), always:

  • Consider whether they are necessary now. For example, a stable patient with a single isolated fever should have investigations (appropriate cultures and imaging) but may not require immediate administration of a broad-spectrum antibiotic.
  • Follow local guidelines, as these will take into account local microbiomes and resistance patterns. Guidelines should also provide information as to dosing and monitoring in the critically unwell patients (in particular those with renal failure or on dialysis).
  • Review previous microbiology results to see if atypical organisms have been grown in the past.
  • Check allergy status and clarify (if able) the nature of the reaction. People may classify an unpleasant side effect (e.g. nausea) as an allergy.

Resistance is an increasingly important issue. Antimicrobial stewardship is an important part of ICU practice. This includes:

  • Regular pharmacy / ID ward rounds to help guide practice and use.
  • Stopping antibiotics as soon as possible (and setting a review date when initially prescribed).
  • Switching from IV to oral when able (improving clinically and likely to have normal GI absorption).
  • Using the narrowest spectrum we can on the basis of available microbiology results (e.g. switching to flucloxacillin in a septic cellulitis if sensitive staphylococcal infection is proven).

Some clinically important groups of antibiotic resistance include:

  • Consider MRSA in patients with invasive lines or medical devices in situ, this may require initial treatment with vancomycin until blood cultures are negative for MRSA.
  • Extended Spectrum Beta-lactamases (ESBL) are resistant to broad spectrum penicillins and third generation cephalosporin. These often present as UTIs and need carbapenems.
  • The “ESCAPPM group” – these are G-ve rods (Enterobacter, Serratia, Citrobacter, Aeromonas, Proteus, Providencia, Morganella Morganii) that have rapidly inducible beta-lactamase production so will require carbapenems or 4th generation cephalosporins.

In a clinically deteriorating patients then sometimes anti-fungals may be required. This will be often guided by senior clinicians and infectious diseases but would be considered in immunosuppressed patients (included those with prolonged antimicrobial usage), or those with fungal growth on cultures. Normally candida would need to be cultured from multiple sources on multiple occasions.

References and Further Reading

The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)

Classification of Micro-Organisms

Author: George Walker