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

Background: Colonization is an important risk factor for consecutive infect ion, but little is known about incidence and initial pattern on admission t o respiratory intensive care units (RICU). Objective: To study the bacteria l colonization during the first 24 h after admission to a RICU. Methods: En dotracheal 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 with in the fi rst 24 h after admission to a RICU. Potential iv pathogenic microorgani sms were grouped as community (c-PPM) and hospital acquired (h-PPM), and ri sk factors for colonization of each body site as well as for overall coloni zation tall sites excluding rectum) were identified by logistic regression analysis. Results: The trachea was colonized in 18% of the intubated patien ts 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 trac hea. The incidence of overall colonization was 49% for c-PPMs (predominantl y Escherichia com and 18% for h-PPMs (predominantly P. aeruginosa). Admissi on to the hospital greater than or equal to 48 h before ICU admission was a n 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 alre ady present in every 5th and with h-PPMs in every 10th intubated patient du ring the first 24 h of RICU admission even in the absence of parenchymal in fections. Hospitalization more than 48 h prior to RICU admission was a risk factor of colonization with h-PPMs. Copyright(C)2001 S. Karger AG,Basel.