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Outpatient pediatric blood cultures: time to positivity
K L McGowan1, J A Foster, S E Coffin
1Division of Immunologic and Infectious Diseases, Children's Hospital of Philadelphia, Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA. mcgowan@email.chop.edu
Insights
Most pediatric blood cultures with pathogens turn positive within 24 hours. This finding aids clinicians in making timely patient management decisions for suspected bacteremia or sepsis.
Area of Science:
- Pediatric Infectious Diseases
- Clinical Microbiology
- Diagnostic Bacteriology
Background:
- Blood cultures are crucial for diagnosing bloodstream infections in children.
- Prompt identification of pathogens is essential for effective treatment and patient management.
- Continuously monitoring blood culture systems offer potential for faster results.
Purpose of the Study:
- To determine the time to positivity for blood cultures in immunocompetent children not on antibiotics.
- To evaluate the utility of continuously monitoring blood culture systems in a pediatric setting.
- To provide data supporting clinical decision-making based on blood culture turnaround times.
Main Methods:
- Prospective study of 10,200 blood cultures from pediatric patients (infants to 24 years) over 47 months.
- Exclusion criteria included antibiotic use, central lines, prosthetic devices, and oncology follow-up.
- Utilized a continuously monitoring blood culture instrument to record time to positivity.
Main Results:
- 6.97% of cultures were positive; 36.3% yielded pathogens, 52% contaminants.
- 87% of pathogen-positive cultures were detected within 24 hours.
- 95% of critical pediatric pathogens (e.g., S. pneumoniae, N. meningitidis) were identified in <24 hours.
Conclusions:
- The majority of clinically significant pediatric bloodstream infections are detected within 24 hours.
- Time to positivity data can aid emergency department and clinic clinicians in patient management.
- Faster detection supports decisions regarding patient disposition and resource utilization.
Objective:
Using a continuously monitoring blood culture system, we determined the time to positivity of blood cultures performed on immunocompetent infants and children who were not receiving antibiotics at the time of culture.
Study Design:
This study was conducted prospectively using blood cultures taken in the emergency department and outpatient clinics of an urban pediatric teaching hospital from February 1, 1993, through December 31, 1996. Cultures were excluded if obtained from patients receiving antibiotics, patients with a central line, patients with prosthetic devices, or those being followed by the oncology division. Our measures included: 1) recording the time to positive culture obtained by using a continuously monitoring blood culture instrument, 2) patient information derived from the hospital computer system concerning antibiotic use and the presence of indwelling central venous catheters and prosthetic devices, and 3) a chart review of 10% of patients from whom positive cultures were obtained.
Results:
During the 47-month study period, 10 200 single bottle blood cultures were obtained, 711 (6.97%) of which became positive. Patients ranged in age from <1 week to 24 years (mean: 2.00 years). Two hundred fifty-eight cultures (36.3%) contained only pathogens, 370 (52%) contained only skin contaminants, and 83 (11.7%) contained a mixture of contaminant and pathogen. Of the 258 cultures containing only pathogens, 14% were positive by 12 hours, 87% by 24 hours, 92% by 36 hours, 95% by 48 hours, 98% by 60 hours, and 99.7% by 72 hours. Ninety-five percent of critical pediatric pathogens including Streptococcus pneumoniae, Salmonella and other Enterobacteriaceae, Neisseria meningitidis, and groups A and B streptococci were detected in <24 hours.
Conclusion:
Because 87% of all cultures containing pathogens were detected within the first 24 hours of incubation, this study can assist emergency department, clinic, and primary care clinicians when making critical decisions concerning patients on whom blood cultures were obtained. Data on time to positivity of blood cultures can be used in conjunction with clinical status to support clinicians in making patient management decisions. Use of short stay (
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