GBS

Chapter 2: Literature review

2.1 History of GBS

In the early 1900’s Streptococcus agalactiae or group B Streptococcus (GBS) was more known for as the causal pathogen for bovine mastitis and held importance in veterinary medicine. However, in 1938 GBS was identified as a human pathogen, related to three fatal cases of puerperal sepsis (Fry R.M., 1938). In 1964, the first study of perinatal GBS infection was published documenting its relationship with negative maternal and neonatal outcomes (Eickoff T.C., Klein J.O., Daly A.K., Ingall D. & Finland M., 1964). This information led to massive researches and studies on GBS.

Initial case series of early onset neonatal sepsis reported case-fatality ratios as high as 50% (Verani et al, 2010) In the

Infants with early onset GBS disease may present with respiratory distress, apnea, or other signs of sepsis within the first 24–48 hours of life (Verani et al, 2010; Baker C.J., 1978). Common clinical syndromes of early-onset disease are sepsis and pneumonia. Early onset infections may, less frequently, lead to meningitis. Due to better neonatal care the case-fatality ratio of early-onset disease has declined from as high as 50% in the 1970s (Baker C.J. & Barrett F.F., 1974) to 4%–6% in recent years (Phares C.R., Lynfield R., Farley M.M., Mohle-Boetani J., Harrison L.H., Petit S., Craig A.S., Zansky S., Gershman K., Stefonek K.R., Albanese B.A., Zell E.R., Schuchat A., Schaffner W. & Schrag S.J., 2008; Schrag et al, 2000). According to Phares et al (2008) and Schrag et al (2000) mortality is higher among preterm infants, with case-fatality rates of approximately 20% to 30% among those ≤33 weeks’ gestation, compared with 2%–3% among full-term infants. In recent years, approximately 70% of cases of EOS are among babies born at term (≥37 weeks’ gestation) (Phares et al,

S. Gibbs, S. Schrag, & A. Schuchat, 2004). Studies on the use of intravenous intrapartum antibiotic prophylaxis to prevent early-onset GBS disease in the infant have been ongoing since the 1980s. Clinical trials and well-designed observational studies have shown that intrapartum antibiotic prophylaxis reduces vertical transmission of GBS, as measured by infant colonization or by reduction in early onset disease (Verani et al, 2010). Although early trials suggested an efficacy of 100% for intrapartum antibiotic prophylaxis to prevent early-onset disease among infants born to women with GBS colonization, more recent studies found the effectiveness to be 86%–89% (Lin FY, Brenner RA, Johnson YR, Azimi P.H., Phillips J.B. 3rd, Regan J.A., Clark P., Weisman L.E., Rhoads G.G., Kong F. & Clemens J.D., 2001; Schrag SJ, Zell ER, Lynfield R, Roome A, Arnold KE, Craig AS, Harrison LH, Reingold A, Stefonek K, Smith G, Gamble M, Schuchat A; Active Bacterial Core Surveillance