OBJECTIVE: The study aimed to describe the patterns and density of early tracheal colonization among intubated patients and to correlate colonization status with levels of antimicrobial peptides and inflammatory cytokines. DESIGN: The was a prospective cohort study.

SETTING: The study was conducted in medical and cardiovascular intensive care units of a tertiary referral hospital.

PATIENTS: Seventy-four adult patients admitted between March 2003 and May 2006 were recruited for the study.

INTERVENTIONS: Tracheal aspirates were collected daily for the first 4 days of intubation using standardized, sterile technique and sent for quantitative culture and cytokines, lactoferrin and lysozyme measurements.

MEASUREMENTS AND MAIN RESULTS: The mean acute physiology and chronic health evaluation (APACHE II) score in this cohort was 24 +/- 7. Proportion of subjects colonized by any microorganism increased over the first 4 days of intubation (47%, 60%, 70%, 70%, P = .08), but density of colonization for bacteria or yeast did not change significantly. No known risk factors predicted tracheal colonization on day 1 of intubation. Several patterns of colonization were observed (persistent, transient, new colonization, and clearance of initial colonization).The most common organisms cultured were Candida albicans and coagulase-negative Staphylococcus. Levels of cytokines, lactoferrin, or lysozyme did not change over time and were not correlated with tracheal colonization status. Four subjects (6%) had ventilator-associated pneumonia.

CONCLUSIONS: The density of tracheal colonization did not change significantly over the first 4 days of intubation in medical intensive care unit patients. There was no correlation between tracheal colonization and the levels of antimicrobial peptides or cytokines. Several different patterns of colonization may have to be considered while planning interventions to reduce airway colonization.