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Updated: Jul 14, 2026

Multiplex Therapeutic Drug Monitoring by Isotope-dilution HPLC-MS/MS of Antibiotics in Critical Illnesses
11:17

Multiplex Therapeutic Drug Monitoring by Isotope-dilution HPLC-MS/MS of Antibiotics in Critical Illnesses

Published on: August 30, 2018

When to include polymyxins in the empirical antibiotic regimen in critically ill patients with fever? A decision

Matthew E Falagas1, Petros I Rafailidis

  • 1Alfa Institute of Biomedical Sciences, Athens, Greece. m.falagas@aibs.gr

Shock (Augusta, Ga.)
|May 17, 2007
PubMed

Insights

Polymyxins are crucial in empirical antibiotic regimens for intensive care unit (ICU) patients with fever. Omitting them risks preventable deaths from gram-negative infections, particularly those resistant to other drugs.

Area of Science:

  • Infectious Diseases
  • Critical Care Medicine
  • Pharmacology

Background:

  • Fever in intensive care unit (ICU) patients often indicates infection, necessitating prompt empirical antibiotic treatment.
  • The rise of antimicrobial resistance poses challenges for selecting effective empirical therapies.
  • Polymyxins are reserved for multidrug-resistant gram-negative infections.

Purpose of the Study:

  • To determine the probability of isolating polymyxin-susceptible gram-negative bacteria in ICU patients with fever.
  • To evaluate the impact of including polymyxins in initial empirical antibiotic regimens in the ICU.
  • To inform clinical decision-making regarding empirical antibiotic strategies in critical care.

Main Methods:

  • A mathematical model was developed to estimate the probability of isolating polymyxin-only-susceptible gram-negative bacteria.
  • Data were retrieved from literature reviews and the WHONET Greece database.
  • Probabilities of infection, gram-negative etiology, specific bacterial species, and polymyxin susceptibility were calculated.

Main Results:

  • The overall probability (Ptotal) of isolating a polymyxin-only-susceptible gram-negative bacterium was estimated at 11.7%.
  • Failure to include polymyxins in empirical regimens could lead to 4-5 deaths per 100 ICU patients due to inappropriate treatment.
  • Key contributors to Ptotal included the probability of gram-negative infection (52.3%) and polymyxin-only susceptibility (56.7%).

Conclusions:

  • Polymyxins should be considered for inclusion in empirical antibiotic regimens for ICU patients with fever, especially in settings with high rates of polymyxin-only-susceptible gram-negative bacteria.
  • This strategy can mitigate mortality associated with inappropriate empirical antimicrobial treatment.
  • Hospital-specific data on bacterial susceptibility patterns are crucial for optimizing empirical therapy choices.

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