Introduction

Infection is a major cause of perinatal morbidity and mortality (Christensen, 1982; Ohlsson et al., 1987). The aetiology of neonatal septicemia varies with geographical location and changes over time (Nyhan & Fousek, 1958; Ohlsson & Serenius, 1981; Ohlsson et al., 1986). From the 1960s onwards, Group B beta-haemolytic streptococcus (GBS) has been one of the most common causes of neonatal infectious morbidity and mortality in the USA (Eickhoffet al., 1964; Franciosi et al., 1973; McCracken, 1973), Canada (Allardice et al., 1982), the UK (Reid, 1975; Lloyd & Reid, 1976), Europe (Cayeux, 1972, Bergqvist, 1974; Bergqvist et al., 1978; Schroder & Paust, 1979; Speer et al., 1985; Vesikari et al., 1989) and Australia (Fliegner & Garland, 1990). GBS causes significant maternal perinatal morbidity (Institute of Medicine, 1985), bacteriuria in pregnancy (Hastings et al., 1986) as well as urinary tract (Munoz et al., 1992) and other infections in the adult non-pregnant population (Opal et al., 1988; Schwartz et al., 1991).

Historical background

Rebecca Lancefield described in 1933 a serological method for differentiating the haemolytic streptococci into a number of groups (Lancefield, 1933). At that time most severe streptococcal infections in the puerperium were caused by streptococci belonging to Group A (Charles & Larsen, 1986). In 1935 GBS was reported as a cause of mild puerperal infection (Lancefield & Hare, 1935), followed by a report of three cases of fatal GBS puerperal infection (Fry, 1938). GBS was subsequently confirmed as an important pathogen in the perinatal period (Nyhan & Fousek, 1958; Eickhoffet al., 1964; Franciosi et al., 1973; Hood et al., 1961).

The organism

The GBS, or Streptococcus agalactiae, is a Gram-positive diplococcus. The majority of strains (99%) are beta-haemolytic.