Background. Ventilator-associated pneu-monia (VAP) still remains a common de-vice-associated hospital acquired infection in pediatric and adult intensive care units. The aim of our study was to determine ways of microbial transmission to the low-er airways in intubated patients admitted to a single tertiary-care pediatric intensive care unit.
Methods. This was a prospective obser-vational study. A total of 284 sample sets (oropharyngeal swabs, swabs from the lu-men of the proximal tip of an endotracheal tube, and bronchoalveolar lavage samples) were collected from 62 consecutive pedi-atric patients intubated for > 24 hours. Pulsed-field gel electrophoresis was per-formed on all isolated pathogens, which were later identified by MALDI biotyper (MALDI-TOF mass spectrometry).
Results. Overall colonization rates were high and did not differ significantly at different time points in the oropharynx (75%–100%) and the lower airways (50%–76.5%). The endotracheal tube was colo-nized at lower rates: on day 1–3 (28.8%), on day 4–6 (52.7%), on day 7–9 (61.8%) and on day 10-12 (52.9%) (P < 0.001). A total of 191 matched sample sets from the lower airways and at least one site above were collected from 46 (74.2%) patients. In the oropharynx-lower airways group,
Candida spp. (76.9%) and upper airway bacteria (63.2%); in the endotracheal tube-lower airway group, S. aureus (15.7%) and upper airway bacteria (21.1%); in the oropharynx-endotracheal tube-lower air-way group, Enterobacteriaceae (70.8%) prevailed (P < 0.001). The mean survival (entrance) time to lower airways for the Acinetobacter / Pseudomonas / Steno-trophomonas group was 8.28 ± 0.81 days; for the Enterobacteriaceae group, 5.63 ± 0.41; and for Candida spp. group, 3.00 ± 0.82 days (P < 0.005).
Conclusions. Oropharyngeal contamina-tion of the lower airways is the most im-portant route of colonization. Different pathogens enter the lower airways at dif-ferent time intervals from the insertion of an endotracheal tube.