The distribution of group B streptococcal serotypes among isolates obtained in three Australian cities

One hundred and sixty three isolates of group B streptococci from human carrier and disease conditions in Brisbane, Melbourne and Adelaide were serotyped by the Lancefield capillary precipitin test, coagglutination and microimmunodiffusion. Serotypes I and III were most common; serotype III appeared to occur uniformly but serotype Ia varied in distribution. No significant difference was found in serotype distribution among isolates from pregnant and non-pregnant women, or rectal and vaginal swabs; however, type Ia was found to occur significantly more often as an infectious agent than as a commensal (P less than 0.01).