''Streptococcus intermedius'' is an aerotolerant anaerobic commensal bacterium and a member of the
''Streptococcus anginosus'' group. The ''S. anginosus'' group, occasionally termed “''Streptococcus milleri'' group” (SMG) display hemolytic and serologic diversity, yet share core physiological traits. Despite being commensal organisms, members of the ''S. anginosus'' group display wide pathogenic potential. ''S. intermedius'' has been isolated from patients with periodontitis and fatal purulent infections, especially brain and liver abscesses.
[Claridge, J. E., III, S. Attorri, D. M. Musher, J. Hebert, and S. Dunbar. 2001. ''Streptococcus intermedius'', ''Streptococcus constellatus'', and Streptococcus ''anginosus'' (“''Streptococcus milleri'' group”) are of different clinical importance and are not equally associated with abscess. Clin. Infect. Dis. 32:1511–1515.][Whiley, R. A., D. Beighton, T. G. Winstanley, H. Y. Fraser, and J. M. Hardie. 1992. ''Streptococcus intermedius'', ''Streptococcus constellatus'', and ''Streptococcus anginosus'' (the ''Streptococcus milleri'' group): association with different body sites and clinical infections. J. Clin. Microbiol. 30:243–244.]
Researchers identified the isolates to species that led to 118 cases of infection due to SMG using 16S rRNA gene sequence and biochemical tests. This study, done in 2002 used identification of clinical isolates recovered and stored at the Microbiology Laboratory, Veterans Affairs Medical Center, Houston during 1989–1999. In summary, different strains were characterized as belonging to the ''Streptococcus milleri'' group. ''S. intermedius'' was found to be the least commonly isolated member of the SMG (14 of 122 isolates). The majority of which (12 or 86%) were recovered from an abscess or from a site associated with an abscess (blood abscess). Therefore 86% of isolates of this species were attributed to an abscess. Data from the study support observations that members of the SMG have a tendency to cause abscesses, however they do not cause them with equal frequency. ''S. intermedius'' were more likely to cause deep-seated abscess and was found as a solitary isolate in specimens obtained.
References
External links
Type strain of ''Streptococcus intermedius'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
Streptococcaceae
{{lactobacilli-stub