Summary

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.