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Serious bacterial infection in recently immunized young febrile infants

Margaret Wolff1, Richard Bachur1

  • 1From the Department of Medicine (MW, RB) and the Division of Emergency Medicine (RB), Children's Hospital Boston, Harvard Medical School, Boston, MA.

Academic Emergency Medicine : Official Journal of the Society for Academic Emergency Medicine
|January 8, 2010
PubMed

Insights

Febrile infants receiving immunizations have a lower risk of serious bacterial infection (SBI), especially within 24 hours. However, urinary tract infections (UTI) remain a risk, warranting urine testing in infants presenting shortly after vaccination.

Area of Science:

  • Pediatrics
  • Infectious Diseases
  • Immunology

Background:

  • Febrile infants without a clear source of infection require careful evaluation for serious bacterial infections (SBI).
  • Recent immunizations can alter the clinical presentation and diagnostic considerations in febrile infants.

Purpose of the Study:

  • To determine the prevalence of SBI in febrile infants aged 6-12 weeks who received immunizations within 72 hours.
  • To compare SBI rates in infants with and without recent immunizations.

Main Methods:

  • Retrospective medical record review of 1,978 febrile infants (age 6-12 weeks) presenting to a pediatric emergency department.
  • Infants categorized into recent immunization (RI) and no recent immunization (NRI) groups based on vaccination within 72 hours prior to presentation.
  • SBI defined by positive blood and/or urine cultures.

Main Results:

  • Overall SBI prevalence was 6.6%.
  • SBI prevalence was lower in infants with recent immunizations (2.8%) compared to those without (7.0%).
  • Infants vaccinated within 24 hours had a significantly lower SBI prevalence (0.6%), with all identified SBIs being UTIs.

Conclusions:

  • The risk of SBI is reduced in the 24 hours following infant immunizations.
  • Urinary tract infections (UTIs) are a significant concern in febrile infants presenting within 24 hours post-immunization.
  • Consider urine testing for febrile infants presenting within 24 hours of vaccination; manage those presenting >24 hours post-vaccination similarly to unvaccinated infants.
Abstract

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