Restriction endonuclease analysis of human and bovine group B streptococci for epidemiologic study

Group B streptococci, a frequent cause of neonatal sepsis and meningitis, postpartum endometritis, and bovine mastitis, may be acquired by several modes of transmission. Detailed epidemiologic study is hampered by the lack of a sufficiently discriminatory typing system, especially for type III and nontypable strains. We examined 54 epidemiologically well-characterized strains by restriction endonuclease analysis (REA) and compared the results with those obtained by serotyping. REA patterns were inspected without knowledge of the epidemiological or serotyping data. Among 21 type Ia, Ia/c, and Ib/c isolates, we found 10 REA patterns; among 5 type II and IIc isolates, we found 5 REA patterns; among 13 type III isolates, we found 6 REA patterns; and among 15 nontypable human and animal isolates, we found 7 different REA patterns. Double digestion of type III isolates with EcoRI and BglII helped us to distinguish the isolates. In total, 28 REA patterns were found in six serotype groups and one nontypable group. Some geographically and epidemiologically separate isolates had identical REA patterns, suggesting dissemination of a limited number of clones. We conclude that REA is a promising tool for detailed epidemiological study of group B streptococci.