Initial bacterial colonization in patients admitted to a respiratory intensive care unit: bacteriological pattern and risk factors

Respiration. 2001;68(1):58-66. doi: 10.1159/000050464.


Background: Colonization is an important risk factor for consecutive infection, but little is known about incidence and initial pattern on admission to respiratory intensive care units (RICU).

Objective: To study the bacterial colonization during the first 24 h after admission to a RICU.

Methods: Endotracheal aspirates, gastric juice, and pharyngeal and rectal swabs of 55 consecutive patients were cultured (45 men, age 66 +/- 14 years, APACHE II 20.1 +/- 5.6, no parenchymal infection). All samples were taken within the first 24 h after admission to a RICU. Potentially pathogenic microorganisms were grouped as community (c-PPM) and hospital acquired (h-PPM), and risk factors for colonization of each body site as well as for overall colonization (all sites excluding rectum) were identified by logistic regression analysis.

Results: The trachea was colonized in 18% of the intubated patients with c-PPMs and in 11% with h-PPMs. Candida spp. were the most frequent c-PPMs isolated from trachea, pharynx, and stomach (excluding rectal swabs), and Pseudomonas aeruginosa was the most frequently isolated h-PPM in trachea. The incidence of overall colonization was 49% for c-PPMs (predominantly Escherichia coli) and 18% for h-PPMs (predominantly P. aeruginosa). Admission to the hospital > or = 48 h before ICU admission was an independent risk factor of colonization with h-PPMs in univariate (33 vs. 7%, p = 0.015) and multivariate analyses (odds ratio 7.2, 95% CI 1.4-38.3; p = 0.0197).

Conclusions: Colonization of the trachea with c-PPMs was already present in every 5th and with h-PPMs in every 10th intubated patient during the first 24 h of RICU admission even in the absence of parenchymal infections. Hospitalization more than 48 h prior to RICU admission was a risk factor of colonization with h-PPMs.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Analysis of Variance
  • Anti-Bacterial Agents / pharmacology
  • Colony Count, Microbial
  • Cross Infection / epidemiology*
  • Cross Infection / prevention & control
  • Female
  • Gram-Negative Bacteria / isolation & purification*
  • Gram-Positive Bacteria / isolation & purification*
  • Humans
  • Incidence
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Multivariate Analysis
  • Prospective Studies
  • Respiratory Care Units / statistics & numerical data
  • Respiratory Tract Infections / diagnosis
  • Respiratory Tract Infections / epidemiology*
  • Respiratory Tract Infections / microbiology*
  • Risk Factors
  • Spain
  • Survival Rate
  • Time Factors


  • Anti-Bacterial Agents