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Infections due to Lancefield group F and related Streptococci (S. milleri, S. anginosus)
Abstract:
We can no longer accept classification of streptococci solely on the basis of hemolytic reactions or Lancefield agglutinations. While the "viridans" streptococci cannot be serologically differentiated, physiological separation of the species offers a satisfactory method of classifying human isolates. We review the microbiology of Lancefield group F and related streptococci (S. milleri, S. anginosus), emphasizing microbial ecology and current taxonomic considerations. A series of 28 patients infected with these organisms is presented. There was a striking male predominance in the series (6:1) as well as an obvious association with underlying diseases and/or antecedent trauma. The most remarkable feature of these pathogens is their predilection for abscess formation, confirming their overdue recognition as the most common "viridans" streptococcus recovered from abscesses within internal organs. We observed purulent disease of the nervous and skeletal systems, oral cavity, lung and pleural space, abdomen and subcutaneous tissues. Microbial synergy (i.e. polymicrobic infection) was not a requisite for abscess formation. Four of the five deaths in this series occurred in patients 60 years of age of older. Some degree of variability in antimicrobial susceptibility was noted, so speciation alone may not always provide sufficient information on which to base a therapeutic decision.
Insights
Classification of "viridans" streptococci requires physiological separation, not just serology. These bacteria frequently cause abscesses, especially in males with underlying conditions, and show variable antimicrobial susceptibility.
Area of Science:
- Microbiology
- Bacteriology
- Taxonomy
Background:
- Traditional classification of streptococci using hemolytic reactions or Lancefield agglutinations is insufficient.
- Serological differentiation of
- viridans
- streptococci is not feasible.
- Physiological separation of species provides a reliable method for classifying human isolates.
Observation:
- Lancefield group F and related streptococci, including Streptococcus milleri and Streptococcus anginosus, are reviewed.
- A series of 28 patients infected with these streptococci revealed a male predominance (6:1) and associations with underlying diseases or trauma.
- These pathogens demonstrate a strong predilection for forming abscesses in various internal organs and tissues.
Findings:
- Streptococci of Lancefield group F and related species are the most common
- viridans
- streptococci found in internal organ abscesses.
- Abscess formation by these bacteria can occur without microbial synergy (polymicrobial infection).
- Purulent diseases were observed in the nervous system, skeletal system, oral cavity, lungs, abdomen, and subcutaneous tissues.
Implications:
- The findings underscore the need for accurate speciation of these streptococci beyond traditional methods.
- Variable antimicrobial susceptibility highlights that speciation alone may not guide therapeutic decisions.
- Recognizing these streptococci as common causes of abscesses is crucial for clinical management, particularly in older patients where mortality was observed.