Prevention of early-onset neonatal group B streptococcal infection: is universal screening by culture universally applicable?

BACKGROUND

Previous assessments of maternal group B Streptococcus carrier rates in women delivering at Shaare Zedek Medical Center ranged between 3.5 and 11% with neonatal sepsis rates of 0.2-0.9/1000 live births. Because of low colonization and disease rates, routine prenatal cultures of GBS were not recommended and intrapartum prophylaxis was mainly based on maternal risk factors.

OBJECTIVES

To determine whether this policy is still applicable.

METHODS

We performed prospective sampling and follow-up of women admitted for labor and delivery between February 2002 and July 2002. Vaginal and rectal cultures were obtained before the first pelvic examination. GBS isolation was performed using selective broth medium and identified by latex agglutination and serotyping. Demographic data were collected by means of a standardized questionnaire. Data on the newborns were collected throughout 2002.

RESULTS

Of the 629 sampled women, 86 had a positive culture and a carrier rate of 13.7%. A borderline significantly higher carriage rate was observed among mothers of North American origin (21% vs. 13.1%, P= 0.048), and a higher attack rate in their infants (3.8/1000 compared with 0.5/1000 live births in our general maternal population, P= 0.002). Eight newborns had early-onset neonatal GBS sepsis (a rate of 0.8/1000 live births), but none of them benefited from intrapartum antibiotic prophylaxis.

CONCLUSIONS

An increased neonatal disease rate was observed in a population with a higher colonization rate than previously seen. In view of the higher carrier rates, we now recommend routine prenatal screening for GBS in our perinatal population.