Restriction endonuclease digest patterns of chromosomal DNA from group B beta-haemolytic streptococci.

Scanning densitometry and computer-assisted numerical analysis were used to examine restriction endonuclease digest patterns (RDPs) of chromosomal DNA from 26 infecting strains and 44 vaginal isolates of group B beta-haemolytic streptococci (GBS). At the 95% similarity level, HindIII RDPs of serotype Ia and III strains clustered into four and three RDP types, respectively. Nine of 10 strains from neonates with early-onset septicaemia belonged to two particular RDP types (Ia-3 and III-3). In contrast, serotype III GBS strains from meningitis cases were not characterised by particular RDP types. Associations between RDPs and certain phenotypic characteristics were also found.