Horizontal transmission of group B streptococcus in a neonatal intensive care unit

G roup B streptococcal (GBS) sepsis is a leading cause of mor- bidity and mortality in the neonatal population (1). A significant reduction has been seen in the incidence of early-onset GBS sepsis (defined as zero to seven days of age) from 1.7 cases per 1000 live births in 1993 to 0.31 cases per 1000 live births in 2005 (2). This reduction was due to the introduction of routine prenatal screening and maternal intrapartum antibiotic prophylaxis (2). However, the incidence of late-onset GBS disease (defined as seven to 89 days of age) has remained static and is now higher than early-onset GBS disease, averaging 0.35 cases per 1000 live births (1,2). The transmission of late-onset GBS sepsis is hypothesized to occur through multiple mechanisms such as persistent neonatal mucous membrane colonization, contamination of shared equipment via other infected neonates and through infected maternal breast milk (3-10). Currently, no preventive strategy has been shown to effectively reduce the incidence of late-onset GBS sepsis. The present case report describes probable acquisition of GBS disease through horizontal transmission in a neonatal intensive care unit based on the clinical and microbiological picture as well as the confirmation of strain based on antibiotic resistance patterns and pulsed-field gel electrophoresis.