2009年4月17日 星期五

No More Blood Cultures

Occult Bacteremia in the Postpneumococcal Vaccine Era: No More Blood Cultures
In a study of some 8000 previously healthy, young febrile children with no apparent source of infection, the rate of true-positive blood cultures was only 0.25%.

For decades, the work-up of febrile young children included blood cultures to rule out occult bacteremia. This study assessed the usefulness of this practice in the era of routine childhood immunization with pneumococcal vaccine. Researchers retrospectively reviewed the charts of 8408 previously healthy children (age range, 3–36 months) who presented to a pediatric emergency department in Phoenix between 2004 and 2007 with fever 39°C, had no apparent source of infection, had blood cultures drawn, and were discharged from the ED.

A pediatric infectious diseases specialist determined that 21 blood cultures were true positives (0.25%); of these, 14 grew Streptococcus pneumoniae. Another 159 positive cultures (1.89%) were determined to be contaminants, yielding a ratio of 7.6 contaminants for every 1 true positive culture.

Comment: Routine vaccination for Haemophilus influenzae and pneumococcus has virtually eradicated occult bacteremia in well-appearing febrile children, and the results of this study suggest that blood cultures should no longer be performed in such patients. The complete blood count also is of questionable usefulness in this patient cohort and should not be ordered. Ill-appearing children, whether febrile or not, still warrant an appropriately directed work-up, which might include blood cultures.

— 
Diane M. Birnbaumer, MD, FACEP
Published in Journal Watch Emergency Medicine April 17, 2009

Citation(s): Wilkinson M et al. Prevalence of occult bacteremia in children aged 3 to 36 months presenting to the emergency department with fever in the postpneumococcal conjugate vaccine era. Acad Emerg Med 2009 Mar; 16:220.

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