Sequential microbiological monitoring of tracheal aspirates in intubated patients admitted to a pediatric intensive care unit

Abstract

To evaluate, sequentially, tracheal aspirates from patients admitted to a pediatric intensive care unit and to associate these pathogens with length of hospital stay, previous use of antimicrobial therapy and diagnoses of ventilator-associated pneumonia. The study population consisted of patients admitted to a pediatric intensive care unit, between November 2002 and December 2003, on ventilator support. Three tracheal aspirates were collected serially from each patient. The first tracheal aspirate sample was obtained 6 hours after admission to the intensive care unit and the remaining samples were collected after 48 and 96 hours. One hundred patients aged from one day to 14 years were assessed. Positive tracheal cultures were observed to have increased in the three tracheal aspirate samples collected from each patient for Pseudomonas aeruginosa, from 6 to 22% (p = 0.002), and to have decreased for Staphylococcus aureus, from 23 to 8% (p = 0.009). Isolation of Candida spp increased for the subset that had received previous antimicrobial therapy (p < 0.05). Sixteen (23.5%) out of 68 patients admitted without pneumonia developed ventilator-associated pneumonia. Positive tracheal aspirate cultures were obtained in 10 out of 16 of these patients: six were positive for Staphylococcus aureus (three associated with Acinetobacter baumanii), two for Klebsiella spp (one associated with Enterobacter spp), one for Pseudomonas aeruginosa and one for Candida spp. Sequential evaluation of tracheal aspirates may be useful to track changes in bacterial flora at pediatric intensive care units.