Prevention of perinatal group B streptococcal disease: screening during a pregnancy

The prevention of perinatal group B streptococcal (GBS) disease is based on the screening of all pregnant women at 35-37 weeks’ gestation for vaginal and rectal GBS colonization. The colonized women receive intrapartum antibiotic prophylaxis. Our study reports the different rates of maternal GBS colonization between April 2008 and March 2011. We have collected 3430 samples by swabbing both the lower vagina and rectum and we have employed two different laboratory methods: direct agar plating and selective enrichment broth. The rates of maternal GBS colonization increased from 10.5% during 2008-2009, to 12.2% during 2009-2010 and to 14.4% during 2010-2011, when we have introduced the Todd Hewitt broth. Our results show that the use of an enrichment broth improves detection of GBS carriers women.