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Milleri group streptococcus--a stepchild in the viridans family

Y Siegman-Igra1, Y Azmon, D Schwartz

  • 1Infectious Diseases Unit, Tel-Aviv Sourasky Medical Center, 6 Weizman str., Tel-Aviv, 64239, Israel. yardena.igra@gmail.com

European Journal of Clinical Microbiology & Infectious Diseases : Official Publication of the European Society of Clinical Microbiology
|March 7, 2012
PubMed

Insights

Milleri group streptococci, primarily Streptococcus anginosus, frequently cause pyogenic infections and bloodstream invasion. Accurate species identification is crucial for effective treatment of these common bacteria, especially in urinary tract infections.

Area of Science:

  • Clinical Microbiology
  • Infectious Diseases
  • Bacteriology

Background:

  • Milleri group streptococci are part of the viridans streptococci, often implicated in pyogenic infections.
  • Understanding their specific pathogenic roles and disease spectrum is essential for clinical management.
  • Previous studies have not fully elucidated the differential roles of the three species within this group.

Purpose of the Study:

  • To comprehensively review the pathogenic role and spectrum of disease caused by milleri group streptococci.
  • To specifically investigate bloodstream invasion and potential differences among the three species.
  • To highlight the clinical significance of accurate species-level identification.

Main Methods:

  • Retrospective analysis of all milleri group streptococci isolates from a tertiary care hospital over 37 months.
  • Identification to the species level using an automated system.
  • Correlation of isolates with patient data, infection sites, and clinical outcomes.

Main Results:

  • Streptococcus anginosus comprised 82% of the 245 patient-unique isolates.
  • Non-urinary isolates were associated with pyogenic infections, predominantly from the gastrointestinal tract, with 28 cases of bacteremia.
  • Streptococcus constellatus showed a higher relative representation in bacteremia; no other species-site associations were detected. Urinary isolates caused UTIs or were nonsignificant bacteriuria.

Conclusions:

  • Milleri group streptococci are common in clinical settings and possess distinct pathogenic roles compared to other viridans streptococci.
  • Their consistent association with pyogenic processes necessitates immediate species identification when found in blood.
  • These bacteria also play a significant role in urinary tract infections, an underappreciated clinical niche.

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