Occult Bacteremia: Should We Look for the Needle in the Haystack?

BACKGROUND

Once a well-recognized entity, occult bacteremia (OB) is no longer a significant or serious bacterial infection. First following the introduction of the Haemophilus influenzae type B vaccine and now with the implementation of the conjugate pneumococcal vaccine (PCV), the number of cases has declined significantly. This has led to a change in many published guidelines to avoid taking blood cultures in fully vaccinated children presenting with fever. In Israel, the introduction of the PCV13 is now widespread.

OBJECTIVES

To assess the incidence and outcome of OB, specifically by Streptococcus pneumoniae, in a single large pediatric medical center.

METHODS

We conducted a retrospective review of all cases of pneumococcal bacteremias in the years 2008-2013 and specifically those considered occult.

RESULTS

Of 355 cases of bacteremia diagnosed during the study period, 164 were caused by S. pneumoniae and 20 (12.8%) were considered occult. None of the OB cases had any complications. OB was not found in children over the age of 36 months. There was a change in the serotypes involving pneumococcal OB.

CONCLUSIONS

OB is uncommon in the PCV-vaccinated population and the serotypes involved have changed.