title: Detection of group B streptococcal bacteremia in simulated intrapartum antimicrobial prophylaxis.
abstract: 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.
authors.affiliation: Maxwell Finland Laboratory for Infectious Diseases, Boston University School of Medicine and Boston Medical Center, Boston, MA, 02118, USA. khsu@bu.edu
authors.forename: Katherine K
authors.initials: KK
authors.lastname: Hsu
authors.forename: Stephen I
authors.initials: SI
authors.lastname: Pelton
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Shapiro
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D019072:Antibiotic Prophylaxis; D016470:Bacteremia / Q000175:diagnosis / Q000188:drug therapy*; D015169:Colony Count, Microbial; D017077:Culture Media, Conditioned; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008826:Microbial Sensitivity Tests; D016544:Patient Simulation; D011247:Pregnancy; D011295:Prenatal Care; D011336:Probability; D012116:Resins, Plant; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000188:drug therapy* / Q000517:prevention & control*; D013292:Streptococcus agalactiae / Q000187:drug effects* / Q000302:isolation & purification*
chemical_list: D017077:Culture Media, Conditioned; D012116:Resins, Plant; D000667:Ampicillin