Lab method
Bile solubility test
Pneumococcus dissolves in bile; viridans does not
High-yield clue
Bile-soluble alpha-hemolytic colonies point to Streptococcus pneumoniae, while viridans streptococci stay insoluble.
Overview
A differentiation test that uses bile salts (sodium deoxycholate) to distinguish Streptococcus pneumoniae from other alpha-hemolytic streptococci by triggering its self-lysis.
Classification
- Differential biochemical concept
- Applied to alpha-hemolytic cocci
- Reads colony/broth clearing
Lab & identification clues
- Bile salts activate pneumococcal autolysin (LytA)
- Positive = colony dissolves/broth clears
- Pairs with optochin sensitivity for pneumococcus
- Viridans streptococci are bile-insoluble
Associations
- Separates S. pneumoniae from viridans group
- Study pairing with capsule and Quellung vocabulary
- Alpha-hemolysis identification context
Commonly confused with
- Optochin test
- Viridans streptococci
Frequently asked questions
What is Bile solubility test?
A differentiation test that uses bile salts (sodium deoxycholate) to distinguish Streptococcus pneumoniae from other alpha-hemolytic streptococci by triggering its self-lysis.
What is the high-yield clue for Bile solubility test?
Bile-soluble alpha-hemolytic colonies point to Streptococcus pneumoniae, while viridans streptococci stay insoluble.
What is Bile solubility test associated with?
Bile solubility test is associated with Separates S. pneumoniae from viridans group, Study pairing with capsule and Quellung vocabulary, and Alpha-hemolysis identification context.
What is Bile solubility test commonly confused with?
Bile solubility test is commonly confused with Optochin test and Viridans streptococci.
Original concept summary for coursework. Sources checked: OpenStax Microbiology 2e and NCBI Bookshelf Medical Microbiology; reviewed 2026-06. Describes vocabulary and interpretation concepts only; not a lab protocol and not for handling specimens or identifying patient isolates.