Detection of group B streptococcal bacteremia in simulated intrapartum antimicrobial prophylaxis

Diagn Microbiol Infect Dis. 2003 Jan;45(1):23-7. doi: 10.1016/s0732-8893(02)00480-7.


The diagnostic value of negative blood cultures from neonates whose mothers receive intrapartum antimicrobial prophylaxis for prevention of perinatal group B streptococcal disease is uncertain. We investigated whether blood culture medium containing resin designed to adsorb antibiotic improved group B streptococcal detection following simulated intrapartum antimicrobial prophylaxis. Group B streptococcus (Streptococcus agalactiae) was preincubated with varying antibiotic concentrations before inoculation into BACTEC Peds Plus resin-containing medium, BACTEC Standard, or Trek ESP 80A. In the presence of 10 mcg/mL ampicillin, detection of both low (<500 CFU/mL) and high (>500 CFU/mL) S. agalactiae inocula ranged between 75-100% of resin-containing medium bottles; detection rates in both non-resin-containing media were lower. When S. agalactiae was detected, it was detected sooner with resin-containing medium. The addition of gentamicin to ampicillin did not affect sensitivity of resin-containing medium for S. agalactiae. In our model, resin-containing medium more consistently and more rapidly detected S. agalactiae than did either of two non-resin-containing media, in the presence of antibiotic levels likely present in fetal sera following intrapartum antimicrobial prophylaxis.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ampicillin / pharmacology*
  • Antibiotic Prophylaxis*
  • Bacteremia / diagnosis
  • Bacteremia / drug therapy*
  • Colony Count, Microbial
  • Culture Media, Conditioned
  • Female
  • Humans
  • Infant, Newborn
  • Microbial Sensitivity Tests
  • Patient Simulation
  • Pregnancy
  • Prenatal Care
  • Probability
  • Resins, Plant
  • Sensitivity and Specificity
  • Streptococcal Infections / drug therapy*
  • Streptococcal Infections / prevention & control*
  • Streptococcus agalactiae / drug effects*
  • Streptococcus agalactiae / isolation & purification*


  • Culture Media, Conditioned
  • Resins, Plant
  • Ampicillin