Serotyping and bacteriophage typing of group B streptococci.

Three hundred and eighty-two human streptococcal strains of serogroup B, collected from different sources and from different parts of Norway have been serotyped and phagetyped . The results of serotyping show a predominance of serotype Ia; 150 strains belonged to this type. Only 32 strains belonged to serotype III, a serotype well-known as the dominating cause of neonatal septicemia and meningitis (11, 23). The other serotypes were evenly represented. The phagetyping was performed by the procedure and with phages described by Stringer (19). The strains were lysed by phages at a frequency of 70%. A total of 145 strains (38%) was lysed by one or two phages, while 124 strains (32%) were typable by different phage patterns. When combined with serotyping, phagetyping of group B streptococci is an important tool in characterizing these microbes for epidemiological and other purposes.