FORMATION OF SEROLOGICALLY REACTIVE DEXTRANS BY STREPTOCOCCI FROM SUBACUTE BACTERIAL ENDOCARDITIS

Area of Science:

• Microbiology
• Immunology
• Biochemistry

Background:

• Subacute bacterial endocarditis is often caused by streptococci.
• Streptococci synthesize extracellular polysaccharides like dextran and levan from sucrose.
• Distinguishing between dextran and levan production is important for streptococcal classification.

Purpose of the Study:

• To investigate the production of serologically reactive dextrans by streptococci isolated from patients with subacute bacterial endocarditis.
• To compare dextran and levan synthesis in different streptococcal groups.
• To establish a simple method for differentiating dextran and levan in bacterial cultures.

Main Methods:

• Isolation of streptococci strains from patient blood and human throat/feces samples.
• Synthesis of dextrans from sucrose by bacterial cultures.
• Application of serological tests, supplemented by physical and chemical analyses, to identify and differentiate polysaccharides.
• Comparison of synthesized polysaccharides with known dextran and levan standards.

Main Results:

• 22 out of 48 streptococcal strains from endocarditis patients synthesized serologically reactive dextrans.
• One strain produced both dextran and levan.
• Nine strains of group H streptococci and six strains of Streptococcus salivarius produced dextran and levan, respectively, with distinct serological properties.
• The serological and biochemical methods allowed for reliable differentiation of dextran and levan without isolating pure polysaccharides.

Conclusions:

• Serologically reactive dextran production is common in streptococci associated with subacute bacterial endocarditis.
• A combination of serological, physical, and chemical tests provides an effective method for distinguishing dextran and levan in bacterial cultures.
• Polysaccharide synthesis patterns may be valuable for the differential characterization of non-hemolytic streptococci.