Isolation and characterization of group B streptococci from genito-urinary tracts in Japan

The prevalence of group B streptococci in urine specimens submitted from both inpatients and outpatients to the Clinical Microbiology Laboratory were investigated. Out of 3,780 urine specimens, forty-seven strains were identified as group B streptococci, and clinical features revealed that the isolation ratio from outpatients was higher than that from inpatients, and that the majority of isolates were from female urine. Whereas the isolation ratios of group B streptococci from vaginal swabs were 2.9% in 377 pregnant women at 37-40 weeks of gestation, and 4.8% in 335 non-pregnant women. Also, the newborns delivered from mothers tested were investigated. Only two cases were positive in ear, pharyngeal and/or nasal swabs, but no clinical manifestation was observed. An alternative nomenclature system of group B streptococci based on the serological classification of both heat-labile protein and heat-stable polysaccharide antigens was evaluated for the clinical isolates and compared with the original Lancefield's procedure. The results indicated that the method described will provide a simple and reasonable technique for serotyping of group B streptococci.