Are most ICU infections really nosocomial? A prospective observational cohort study in mechanically ventilated...

Area of Science:

• Infectious Diseases
• Critical Care Medicine
• Microbiology

Background:

• Accurate classification of intensive care unit (ICU) infections is crucial for effective patient management and infection control.
• Traditional classification methods, such as the 48-hour time cutoff, may not accurately distinguish between acquired and endogenous infections.
• The concept of microbial carriage offers a potential alternative for understanding infection origins.

Purpose of the Study:

• To compare the 48-hour time cutoff with the carrier state criterion for classifying ICU infections.
• To determine a more appropriate time cutoff for classifying infections in line with the carrier state concept.

Main Methods:

• A prospective cohort study enrolled 117 patients requiring mechanical ventilation for at least three days.
• Surveillance cultures of throat and rectum were obtained on admission and twice weekly.
• Infections were classified using both the 48-hour cutoff and the carrier state criterion, with a nine-day cutoff also evaluated.

Main Results:

• Using the 48-hour cutoff, 80% of infections were classified as ICU-acquired.
• The carrier state criterion identified 60% of infections as endogenous (originating from imported microorganisms).
• A nine-day cutoff was found to be a better indicator of ICU-acquired infections compared to the 48-hour cutoff.

Conclusions:

• The 48-hour cutoff overestimates the rate of ICU-acquired infections.
• The carrier state criterion provides a more accurate classification of infection origins in the ICU.
• Monitoring microbial carriage is a more realistic approach for classifying ICU infections.