The utility of tracheal aspirate cultures in the immediate neonatal period

Determine the contemporary incidence of pathogenic tracheal aspirate (TA) cultures when obtained within 12 h of birth, and to associate TA culture results with specific clinical conditions that increase the risk of infection.

A retrospective study over a 6-month period of admissions to a single outborn neonatal intensive care unit when a TA sample was collected within 12 h of birth (n=139).

In total, 9 of 139 (6.5%) TA cultures were positive for pathogenic bacterial growth. Maternal fever (relative risk (RR)=7.7, P<0.04) and clinical chorioamnionitis (RR=6.4, P<0.02) were significantly associated with pathogenic TA culture results. Infants with a pathogenic TA culture had lower white blood cell counts (7,500 vs 13,900 mm(-3), P<0.05) when compared with infants with a negative culture. In eight of the nine patients with pathogenic cultures, either the mother or the infant received antibiotics before TA sample collection.

Early TA culture is a helpful tool in diagnosing pneumonia, especially in certain clinical scenarios, including maternal fever, clinical chorioamnionitis and leukopenia. Administration of antibiotics before sample collection does not seem to preclude culture growth.