AESCULIN bile Test Kit for 30 tests

​The Liofilchem® Aesculin Bile Test is a rapid biochemical assay used for the differentiation of Enterococci and Lancefield Group D Streptococci (Streptococcus bovis group) from other streptococcal species. The test determines the ability of microorganisms to hydrolyze aesculin in the presence of 40% bile, a key diagnostic feature for identifying Group D streptococci and Enterococci.

Upon hydrolysis, aesculin is split into aesculetin and glucose. The resulting aesculetin reacts with ferric ions in the medium to form a dark brown or black complex, indicating a positive result. This test is intended as an aid in bacterial identification and must be used in conjunction with other confirmatory microbiological methods.

Key Features

• Rapid and reliable biochemical differentiation of Enterococci and Group D Streptococci.
• Visual color change (brown/black) indicates aesculin hydrolysis.
• High selectivity — utilizes bile and sodium azide to inhibit non-target bacteria.
• Ready-to-use format: pre-dosed tubes with desiccated substrates and selective agents.
• Simple and safe procedure suitable for routine diagnostic microbiology.
• Quality-controlled formulation ensuring reproducibility and accuracy.
• Stable shelf life: 12 months at 2–8 °C in original packaging.

Principle of the Test

Certain bacteria possess the ability to hydrolyze the glycoside aesculin into aesculetin and glucose. Only a few microorganisms, such as Enterococci, Lancefield Group D Streptococci, and Lactococci, can perform this hydrolysis in the presence of 40% bile.

The liberated aesculetin then reacts with ferric ions in the test medium to produce a dark brown or black phenolic complex, signifying a positive result.

Kit Contents

• 30 Tubes of Liofilchem® Aesculin Bile Test
  (Each tube contains desiccated nutritive components, aesculin, ferric salts, bile, and sodium azide.)

Additional Materials Required (Not Included)

• Inoculating loop or sterile swab
• Micropipette or sterile pipettes
• Culture media
• Physiological saline (0.85%)
• Quality control organisms

Specimen Collection and Preparation

• Collect samples in sterile containers or swabs.
• Process promptly following standard microbiological protocols.
• Use pure cultures for reliable results.
• Refer to appropriate microbiology guidelines for detailed specimen handling procedures.

Test Procedure

1. Remove required test tubes from refrigerated storage and allow them to reach room temperature.
2. Add 0.3 mL of physiological saline to each test tube.
3. Using a sterile loop, inoculate the tube with one or more well-isolated colonies from a fresh (18–24 h) culture.
4. Incubate at 35 ± 2 °C for up to 24 hours.
5. Observe the tubes after 4 hours, and continue checking periodically for color change.
6. Run positive and negative controls alongside test samples.

Interpretation of Results

Quality Control Recommendations

For internal quality assurance, recommended control strains include:

• Positive control: Enterococcus faecalis ATCC® 29212
• Negative control: Streptococcus pyogenes ATCC® 19615

Storage and Stability

• Store at 2–8 °C in the original sealed packaging.
• Avoid exposure to heat or rapid temperature fluctuations.
• Do not use if desiccant indicator has changed color or if deterioration is evident.
• Shelf Life: 1 year from manufacturing date under recommended conditions.

Technical Specifications

Ordering Information

The Liofilchem® Aesculin Bile Test offers a rapid and reliable method for identifying Enterococci and Group D Streptococci based on aesculin hydrolysis in the presence of bile. Its ready-to-use tube format, high selectivity, and clear visual endpoint make it an essential biochemical test for clinical, veterinary, and food microbiology laboratories.