Antepartum screening for group B Streptococcus by three FDA-cleared molecular tests and effect of shortened enrichment culture on molecular detection rates

Neonatal Streptococcus agalactiae infections cause significant morbidity and mortality, and antenatal screening is recommended. We compared three U.S. Food and Drug Administration (FDA)-cleared nucleic acid amplification tests (NAATs) to culture using 314 vaginal/rectal swabs after 18 to 24 h (recommended period) and 4 to 8 h (shortened period) of broth enrichment. Agreement of the NAATs with each other was high (97.1% to 98.4%), but culture was less sensitive than all NAATs (67% to 73%). A shortened period of broth culture enrichment resulted in 1 false-negative result in 68 (1.5%). The NAATs performed comparably and were more sensitive than culture.