Streptococci and aerococci associated with systemic infection in man

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Clinical Bacteriology

Background:

• Streptococci and aerococci are significant causes of systemic human infections.
• Understanding the specific taxa involved in different infections like endocarditis and purulent diseases is crucial for effective treatment and prevention.

Purpose of the Study:

• To classify a large collection of streptococcal and aerococcal isolates from human systemic infections.
• To determine the prevalence and associations of different streptococcal taxa with specific conditions, particularly endocarditis.
• To investigate demographic and clinical factors influencing streptococcal infections.

Main Methods:

• Cultural and biochemical tests were used to classify 820 streptococci and aerococci isolates.
• Isolates were sourced from patients with systemic infections, including endocarditis, purulent diseases, and bacteremia.
• Statistical analysis compared the frequency of streptococcal taxa in endocarditis versus non-endocarditis cases and analyzed demographic data.

Main Results:

• Dextran-forming streptococci (e.g., Streptococcus mutans, S. bovis I, S. sanguis) showed higher ratios in endocarditis cases compared to non-dextran-forming taxa.
• Alpha-hemolytic streptococci predominated in younger patients (<35 years), while other taxa increased with age.
• Streptococcus milleri was the most common isolate from internal organ purulent lesions, associated with abscesses and meningitis.

Conclusions:

• Dextran production is a significant factor associated with streptococcal endocarditis.
• Age and sex are important demographic factors influencing the type and incidence of streptococcal infections.
• Previous heart damage is a primary predisposing factor for endocarditis, while other factors are relevant for different streptococcal diseases.