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 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.
Servei de Pneumologia i Allergia Respiratoria, Institut Clínic d'Infeccions i Immunologia, Universitat de Barcelona, Spain.
M B
MB
Drakulovic
T T
TT
Bauer
A
A
Torres
J
J
Gonzalez
M J
MJ
Rodríguez
J
J
Angrill
D000368:Aged; D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015169:Colony Count, Microbial; D003428:Cross Infection / Q000453:epidemiology* / Q000517:prevention & control; D005260:Female; D006090:Gram-Negative Bacteria / Q000302:isolation & purification*; D006094:Gram-Positive Bacteria / Q000302:isolation & purification*; D006801:Humans; D015994:Incidence; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D012124:Respiratory Care Units / Q000706:statistics & numerical data; D012141:Respiratory Tract Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology*; D012307:Risk Factors; D013030:Spain; D015996:Survival Rate; D013997:Time Factors
D000900:Anti-Bacterial Agents