Factors that predict preexisting colonization with antibiotic-resistant gram-negative bacilli in patients admitted to a pediatric intensive care unit

Objective. To predict which patients hospitalized in a pediatric intensive care unit (ICU) are colonized with antibiotic-resistant Gram- negative rods on admission. Methods. Consecutive children admitted to a pediatric ICU over a 6-month period were entered into the study. A questionnaire soliciting information regarding the child's medical history and home environment was completed by the parent or guardian. Nasopharyngeal and rectal cultures were obtained on each of the first 3 days of ICU admission, and organisms resistant to ceftazidime or tobramycin were identified. Only clonally distinct organisms, as confirmed by pulsed field gel electrophoresis, were analyzed. The association between identification of colonization with an antibiotic-resistant Gram-negative rod within 3 days of ICU admission and factors included in the questionnaire was tested by χ² or t test. Results. In 64 (8.8%) of 727 admissions, an antibiotic-resistant Gram-negative bacillus was isolated within the first 3 ICU days. More than half were identified on the day of admission. Colonization was associated with two factors related to the patient's medical history, namely, number of past ICU admissions (1.98 vs .87) and administration of intravenous antibiotics within the past 12 months (67.9% vs 28.2%). No association was found between colonization and exposure to oral antibiotics. In addition, factors related to the child's environment were also associated with presumed importation of an antibiotic-resistant Gram-negative rod into the ICU. Specifically, residence in a chronic care facility was strongly associated with colonization (28.3% vs 2.6%); exposure to a household contact who had been hospitalized in the past 12 months also predicted colonization (41.7% vs 18.5%). Conclusions. These data suggest that a profile can be established characterizing children colonized with resistant Gram-negative bacilli before admission to a pediatric ICU. Infection control measures may help to contain these potentially dangerous bacteria once they have been introduced into the unit.