A new investigation suggests that universal vaccination with a heptavalent pneumococcal conjugate vaccine (PCV7) has vastly reduced the incidence of occult bacteremia in highly febrile young children-most often caused by Streptococcus pneumoniae.
Investigators conducted a retrospective study of 329 children between 2 and 36 months old who visited the emergency department or urgent care center of a children's hospital with a temperature at least as high as 39° C. These children had a blood culture performed and were discharged. Visits to the hospital were made between December 2001-about 1 year after PCV7 began to be used routinely-and March 2003.
More often than not, the fact that a culture was positive was attributable to a contaminant. Indeed, only three cultures yielded a pathogenic bacterium-in all cases, S pneumoniae. One patient was infected with an S pneumoniae serotype that is not included in PCV7; another had two episodes of pneumococcal occult bacteremia one month apart and had not received PCV7 (Stoll ML et al: Arch Pediatr Adolesc Med 2004;158:671).