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Occult Bacteremia in the Post-H. influenzae Era.

Before widespread use of Haemophilus influenzae type b (Hib) vaccine, Hib was a frequent and dreaded cause of occult bacteremia in febrile, relatively well-appearing young children. Because Hib is now virtually eliminated, this study takes another look at the risk of occult bacteremia in highly febrile infants.

From 1993 through 1996, the emergency department at Children's Hospital in Boston evaluated almost 12,000 children between 3 and 36 months of age with temperatures of 39.0 degreesC or higher and no apparent source for their fever (except otitis media), who were well enough to be sent home. In blood cultures obtained from 79 percent of the children, a total of 149 (1.6 percent) contained pathogenic bacteria. The most common were Streptococcus pneumoniae (92 percent), salmonella species (5 percent), and Neisseria meningitidis (1 percent). Rates of bacteremia increased significantly with increasing temperature, white blood cell count (WBC), absolute neutrophil count, and absolute band count.

Comment: In contrast to previous reports, which suggested that 3 percent to 5 percent of well-appearing, febrile children have occult bacteremia, this study found an incidence of 1.6 percent, with S. pneumoniae the most common agent. The clinician must decide empirically what WBC cut-off value makes sense when deciding whether to treat infants at risk for occult bacteremia with antibiotics. The authors feel that 18,000 is a reasonable choice.

— RA Dershewitz

Published in Journal Watch General Medicine August 7, 1998

Citation(s):

Lee GM and Harper MB. Risk of bacteremia for febrile young children in the post-Haemophilus influenzae type b era. Arch Pediatr Adolesc Med 1998 Jul 152 624-628.

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