Neonatal group B streptococcal infection in Mallorca, Spain.

Early onset infection in neonates caused by group B Streptococcus and the prevalence of colonization by this microorganism in a group of 1,003 pregnant women and their neonates were studied. The capsular serotypes of the colonizing and infecting bacterial isolates and the components of C protein expressed were determined. Except for serotype IV, all the currently recognized capsular serotypes (including serotype V) were found. Among the colonizing strains, serotypes III, Ia, and Ib were almost equally represented and accounted for 82% of the isolates. Serotype III was predominantly found in cases of infection (55%), and serotypes Ia and V were also found in such cases. C protein was not detected in serotype III isolates, but alpha and/or beta components of this protein were found in isolates of all other serotypes. Neonatal infection and colonization due to this microorganism were observed in 1.2 cases per 1,000 live births and in 7.1% of pregnant women. Host factors for infection, such as low birth weight, premature delivery, and prolonged rupture of membranes, were uncommon. The level of specific antibodies to serotype III was also quantitated; lower levels were found in infected children and their mothers than in healthy infants and pregnant women. Further similar studies in Spain are necessary so that preventive measures can be planned.