The authors of this research note that Group B streptococcus is the most common cause of neonatal sepsis in high-income countries, acquired either from the mother or from environmental sources.  Case fatality is high, even with antibiotic therapy, and it is also an important cause of preterm delivery, antepartum and intrapartum stillbirth, and puerperal sepsis.  Prophylaxis, with antibiotics given to pregnant women with risk factors or known carriage of the bacteria, has been implemented in most high-income countries since the late 1990s, but has been difficult to implement in many low- and middle-income countries.

Despite widespread use of intrapartum antibiotic prophylaxis, group B streptococcus remains a leading cause of morbidity and mortality in infants in Europe, the Americas, and Australia. The purpose of the current research was to determine the current global burden of invasive disease and case fatality in infants aged 0-89 days, and estimate the distribution of serotypes in invasive disease specimens.

A search of Medline, Embase, and Wholis databases located 74 relevant studies – 56 reporting incidence, 29 reporting case fatality, and 19 reporting serotype distribution.  An additional search for serotype data was conducted (going as far back as Jan 1980) and located a further 38 articles.  The majority of studies involved high-income countries; only 5 low-income countries were represented (contributing 5% weight to the meta-analysis).  The main overall findings of the study were as follows:

• 47 (69%) studies reported use of intrapartum antibiotic prophylaxis; this proportion was higher in Europe (22 [92%] of 24) and the Americas (13 [81%] of 16) than in the eastern Mediterranean (one [25%] of four) and Africa (one [17%] of six).

• Mean incidence of group B streptococcus in infants aged 0-89 days was 0.53 per 1000 livebirths (95% CI 0.44-0.62) and the mean case fatality ratio was 9.6% (95% CI 7.5-11.8).  The studies were very heterogeneous in both the overall analysis and within regions (p<0.0001).

• The incidence of early-onset (day 0-6) group B streptococcus (0.43 per 1000 livebirths [95% CI 0.37-0.49]) and case fatality (12.1%, [6.2-18.3]) were higher than late-onset disease (0.24 per 1000 livebirths [0.17-0.30 and case fatality of 6•8% [4.3-9.4]).

• Studies reporting use of any intrapartum antibiotic prophylaxis had a lower incidence of early-onset group B streptococcus (0.23 per 1000 livebirths [95% CI 0.13-0.59]) than studies in which patients did not use prophylaxis (0.75 per 1000 livebirths [0.58-0.89]).

• The most frequently identified serotype was III (48.9%) in all regions with available data

The authors conclude that more studies are required to accurately estimate the global burden of group B streptococcus, especially in low-income countries, and they judge their overall estimate of incidence to be an underestimate of the global incidence.  Based on their findings, they say that a vaccine incorporating five serotypes (Ia, Ib, II, III V) could prevent over 85% of global group B streptococcal disease in infants aged below 3 months.