Comparison of a rapid enzyme-linked immunosorbent assay test and the Gram stain for detection of group B streptococcus in high-risk antepartum patients.

Early-onset neonatal sepsis with group B streptococci is a major problem in the management of high-risk obstetrics. Intrapartum treatment of the colonized mother reduces neonatal acquisition; however, many high-risk patients are delivered before culture results are available. This study prospectively evaluated a new enzyme-linked immunosorbent assay and the Gram stain for their accuracy in rapid detection of group B streptococci in 131 high-risk patients. Twenty positive cultures for group B streptococci were identified in the study population and were used as the control for test comparisons. The enzyme-linked immunosorbent assay test was 60% sensitive, whereas the Gram stain was 45% sensitive. The enzyme-linked immunosorbent assay showed an increase in sensitivity as the colony count increased; however, two cases of severe neonatal sepsis occurred in patients with low colony counts and both had enzyme-linked immunosorbent assay negative results. In conclusion, the need for a rapid sensitive test for group B streptococci detection still exists.