Clinical application of urine antigen detection in early onset group B streptococcal disease

The aim of this study was to test the sensitivity and specificity of antigen detection for group B streptococcus (GBS) from the urine of neonates with early onset GBS sepsis. GBS sepsis was defined as early (< 48 hours) signs of sepsis in a neonate colonised with GBS. Neonates of 26 weeks' gestation or more, considered at risk for sepsis, were prospectively investigated for one year. Investigations included culture of superficial swabs to assess colonisation, blood culture, and the Wellcogen Strep B latex particle agglutination test on urine. Of 188 neonates investigated, 17 (9%) had GBS sepsis. The urine antigen test had a sensitivity of 88% and specificity of 98%. The positive predictive value was 79% and the negative predictive value 99%. Blood culture was positive in only five neonates (29%). The annual incidence of GBS sepsis was 4.0 per 1000 and of blood culture positive GBS disease was 1.2 per 1000 live births. Three neonates died. The application of the urine antigen test of clinical neonatal practice is discussed.