摘要：This study was carried out to determine the prevalence and proportional distribution of the potentially pathogenic species Streptococcus anginosus, S. intermedius and S. constellatus at sites within the human mouth. The samples from 162 different subjects included supragingival plaque and saliva (18 subjects), subgingival samples (14 subjects) and mouthrinsings (130 subjects). All three species were recovered on nalidixic acid sulphamethazine selective agar at rates comparable with those obtained on a non-selective medium (Columbia blood agar). S. anginosus was the most frequently isolated of the three species, being found in 6.10 per cent of subjects examined, while S. intermedius and S. constellatus were recovered from 53 per cent and 13 per cent of subjects respectively. S. anginosus was recovered more frequently and in higher numbers at all oral sites examined than the other two species. S. constellatus was isolated least often and in lower numbers, except in the subgingival samples where it occurred as frequently and in similar numbers to S. intermedius. The majority of sites harboured S. anginosus and S. intermedius either singly or together, whilst the combination S. intermedius with S. constellatus or all three species together, occurred rarely. Sites most frequently harboured only a single phenotype of a species (78 percent of S. anginosus, 83 per cent of S. intermedius and 91 percent of S. constellatus yielding sites). Two phenotypes of a species were found together much less frequently and three phenotypes were rarely detected from a single site. Of the 129 isolates of S. anginosus recovered during this study, only three (2 per cent) were of the so-called broadly fermentative biotype (which ferment mannitol and raffinose), previously associated with urogenital sources.Keywords - Streptococcus anginosus, S. intermedius, S. constellatus, Oral cavity
