Streptococcus anginosus group
From IDWiki
Background
Microbiology
- Catalase negative, variably hemolytic Gram-positive cocci within the viridans group streptococci
- Contains Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius
- S. anginosus has two subspecies: S. anginosus subsp. anginosus and S. anginosus subsp. whileyi
- S. constellatus has three subspecies: S. constellatus subsp. constellatus, S. constellatus subsp. pharyngis, and S. constellatus subsp. viborgensis
- Have a buttered popcorn smell on plate
- Normal flora of oral cavity, throat, stool, and vagina
- Identified using three rapid tests:
- Voges-Proskaur (VP) test for acetoin production
- Arginine hydrolysis
- Failure to ferment sorbitol
Clinical Manifestations
- Tendency to form abscesses, unlike other streptococci, which can be polymicrobial with anaerobes and Enterobacterales
- Infections can range in severity, and include pharyngitis, dental abscess, skin and soft tissue infection, pneumonia, empyema, lung abscess, brain abscess, liver abscess, and kidney abscess
Investigations
- Presence of bacteremia without focus should prompt investigations to identify an occult abscess
- The HANDOC score can assess need for echocardiography
Management
- Typically treated with ceftriaxone or other third-generation cephalosporin pending susceptibilities
- If found in an abscess, should be considered polymicrobial and treated with concomitant metronidazole
- Clindamycin resistance is high, approximately 20-30%
