Physiological differentiation of viridans streptococci

Area of Science:

• Clinical microbiology
• Bacteriology
• Medical diagnostics

Background:

• Viridans streptococci are a group of bacteria commonly found in the human oral cavity.
• Accurate speciation of clinical isolates is crucial for understanding infection sources and treatment.
• Previous differentiation schemes relied on serological and physiological characteristics with varying success.

Purpose of the Study:

• To evaluate serological and physiological characteristics for differentiating viridans streptococci.
• To develop a reliable speciation scheme for clinical isolates of viridans streptococci.
• To propose a key for identifying human isolates of viridans streptococci.

Main Methods:

• Tested 1227 clinical isolates and 80 stock strains of viridans streptococci.
• Assessed serological reactions and physiological characteristics, focusing on stable enzymatic reactions.
• Included air-tolerant anaerobic streptococcal strains and non-human-associated viridans streptococci.

Main Results:

• Serological reactions were too variable for a reliable differentiation scheme.
• Physiological characteristics, based on enzymatic reactions, successfully speciated nearly 97% of clinical isolates.
• Ten distinct physiological species were identified, with variations in distribution across different clinical sources.

Conclusions:

• A differentiation scheme based on physiological characteristics, particularly enzymatic profiles, is effective for viridans streptococci.
• Serological methods are not suitable for the speciation of this bacterial group.
• A proposed key aids in the differentiation of human isolates of viridans streptococci.