Time to detection of bacterial cultures in infants aged 0 to 90 days.

Objective: To determine the time to detection (TTD) of positive results on blood, urine, and cerebrospinal fluid (CSF) cultures taken during the evaluation for serious bacterial infection (SBI) in otherwise healthy infants aged 0 to 90 days.

Methods: This study was a retrospective chart review of infants aged 0 to 90 days with positive blood, urine, or CSF cultures drawn during evaluation for SBI in the emergency department or inpatient setting. The TTD of positive culture results, reason for testing, and age of the infant were recorded.

Results: A total of 283 charts were reviewed related to 307 positive culture results. Of the 101 positive results on blood culture, 38% were true pathogens with a mean TTD of 13.3 hours; 97% were identified in < or = 36 hours. Blood cultures with TTD > or = 36 hours were 7.8 times more likely to be contaminants compared with those with TTD < 36 hours. Of 192 positive results on urine culture, 58% were true pathogens with a mean TTD of 21 hours; 95% were identified in < or = 36 hours. Fifty percent of 14 positive CSF culture results were true pathogens with a mean TTD of 28.9 hours; 86% were identified in < or = 36 hours. When data for infants < or = 28 days of age were analyzed separately, TTD followed the same patterns for positive blood and urine culture results as seen in all infants aged 0 to 90 days.

Conclusions: In certain clinical situations, the inpatient observation period for infants under evaluation for SBI may be decreased to 36 hours.