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S. anginosus Abscess-Forming — SCE Infectious Diseases MCQ

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ModerateBone & Joint InfectionS. anginosus Abscess-FormingSCE Infectious Diseases

A 55-year-old man with an aortic graft develops a graft infection 6 months after repair. CT shows perigraft inflammation and air. Blood cultures grow Streptococcus anginosus (milleri group). What is the most important feature of S. anginosus group infections?

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Correct answer: A — S. anginosus group has a strong tendency to form abscesses — any S. anginosus/milleri bacteraemia should prompt a search for a deep abscess

The Streptococcus anginosus group (S. anginosus, S. intermedius, S. constellatus — formerly S. milleri group) is uniquely abscessogenic among streptococci. They produce hydrolytic enzymes that facilitate tissue destruction and abscess formation at virtually any body site: liver, brain, lung, peritoneal, spinal, and vascular graft infections. Any blood culture isolate should prompt imaging to identify a deep abscess. Treatment is prolonged IV Benzylpenicillin (or Amoxicillin) plus drainage of any collections. They are generally penicillin-susceptible.

Reference: BSAC 2020 – Streptococcal infections; NICE CKS 2024