Institution of universal screening for Group B streptococcus (GBS) from a risk management protocol results in reduction of early‐onset GBS disease in a tertiary obstetric unit

Abstract

To determine the effect of institution of a universal screening protocol as per CDC 2002 guidelines had on the incidence of early-onset Group B streptococcal (GBS) and non-GBS disease in a tertiary obstetric unit. A prospective study with historical control data reporting the incidence of early-onset GBS and non-GBS disease following institution of a universal screening strategy at John Hunter Hospital, Newcastle, Australia. We compared the incidence of early-onset GBS and non-GBS disease during prescreening (1994-2002) with screening period (2004 to June 2006). The outcome measure was the incidence of early-onset GBS disease. We specifically reported the number of women needed to treat (NNT) with antibiotics and the number of women needed to screen. The incidence of early-onset GBS and non-GBS during the prescreening period was 0.84/1000 and 0.94/1000 live births, respectively. After institution of universal screening, the incidence was 0.00/1000 and 0.72/1000 live births, respectively. This is a statistically significant reduction in early-onset GBS disease by 84% (chi(2) = 5.75; P = 0.016). There was no difference in non-GBS disease (chi2 = 0.14; P = 0.71). The NNT is 1191 and we needed to screen 5704 women to prevent one case of early-onset GBS disease. Screening for GBS rather than by assessing risk factors has significantly reduced the incidence of early-onset GBS disease in our unit. Despite low incidence of early-onset GBS prior to screening period, we still found a significant decrease in early-onset GBS disease after institution of universal screening protocol. These results support the screening-based approach at 34-37 weeks gestation.