Time to identification of positive bacterial cultures in infants under three months of age hospitalized to rule out sepsis

OBJECTIVE: To calculate the culture incubation required to determine bacteremia or meningitis in infants younger than three months of age hospitalized from the community following a full septic work-up for fever without focus. DESIGN: Retrospective chart review. SETTING: Large, urban, paediatric tertiary care hospital. PATIENTS: All previously healthy infants younger than three months of age with positive blood and/or cerebrospinal fluid (CSF) cultures admitted from the emergency department to the general paediatric and infectious disease wards from January 1990 to December 1996. METHODS: The charts of all patients with positive blood and CSF cultures (excluding coagulase-negative staphylococcus) were reviewed to determine the time at which the positive culture was identified. Organisms were considered pathogenic if a clinical decision was made to treat the organism with a therapeutic course of antibiotics. RESULTS: Of 1235 infants admitted, 5.5% were bacteremic and 1.9% had bacterial meningitis. In 34% of patients, the period between the arrival of the culture in the laboratory to the initial reporting of a positive result was greater than 24 h but less than 48 h, and in 2% of patients (treated as pathogens but likely contaminants) greater than 48 h. The most common organism cultured (in 31% of patients) was Escherichia coli. CONCLUSIONS: With the present culture technique, most, if not all, clinically significant positive blood and CSF results are reported by 48 h of culture incubation.