Indole test

The sputum test refers to some bacteria such as Escherichia coli, Proteus, Vibrio cholerae, etc., which can decompose tryptophan in the culture medium (靛 matrix), and react with p-dimethylaminobenzaldehyde in the reagent. When the rose mites are formed and red, the sputum test is positive.

Basic Information

Specialist classification: growth and development check classification: biochemical examination

Applicable gender: whether men and women apply fasting: fasting

Analysis results:

Below normal:

Normal value:

Above normal:

There is no color change around the bacterial print or negative for the light yellow.

A liquid that turns red under pentanol or xylene is a positive reaction. Red was positive on the cotton wool. The bacteria were stained blue and were positive.

Tips: Keep a good working habit before you check, pay attention to normal eating habits. Normal value

The normal flora of the gastrointestinal tract can be divided into aerobic bacteria, facultative anaerobic bacteria and anaerobic bacteria. The most dominant are anaerobic bacteria, which account for 99% of the total bacterial population, of which only Bacteroides and Bifidobacteria account for 90%, while Lactobacilli and Bifidobacteria can be with us for the rest of our lives. The types and proportions of these normal flora are normal.

Clinical significance

Some bacteria can decompose tryptophan and can react with dimethylaminobenzaldehyde to form red rose mites, so the strain can be identified based on whether the bacteria can decompose tryptophan to produce sputum.

Abnormal result

The internal environment of the intestine is not in dynamic equilibrium, and the proportion of normal bacteria is out of balance. Symptoms such as stomach acid, bloating, diarrhea, abdominal pain, falling, pus and bloody stools can cause gastrointestinal bleeding, perforation, and cancer, such as stomach cancer and colon cancer.

Positive results may be diseases: chronic diarrhea, children's abdominal pain precautions

Taboo before the test: To maintain good work habits, pay attention to normal eating habits.

Requirements for inspection: Actively cooperate with the doctor.

Inspection process


1. The fresh slant culture of the test bacteria inoculated with the inoculation loop in the Deng Hei's peptone solution, and cultured at 37 ° C for 24 to 48 hours (may be extended for 4 to 5 days). Add 2 to 3 ml of pentanol or xylene to the culture solution, shake well, and let stand for a while, then add 2 ml of the reagent along the tube wall. A liquid that turns red under pentanol or xylene is a positive reaction.

2, you can also put a large amount of absorbent cotton, drop two drops of Ou Lishi reagent, and then add two drops of high potassium sulfate (K2S2O4) saturated aqueous solution in the same place, placed in the test tube containing the culture solution, from the liquid surface About half an inch, when the water bath in the beaker is boiled, red is positive on the cotton wool. This method is slightly complicated, but the reagent is accurate and accurate, because the reagent is added to the liquid, and both sputum and skatole are positive, and in this method, only 吲哚 (which can be volatilized) is positive.

3. The filter paper may also be wetted with 1% dimethyl benzene propylene formaldehyde in 10% concentrated HCl solution, and then a pure culture of a ring agar scraped off with an inoculating ring is applied to the filter paper. The bacteria were stained blue and positive, and there was no color change around the bacterial print or negative yellow.

Not suitable for the crowd

Inappropriate crowd: temporarily unknown.

Adverse reactions and risks

Generally, this examination does not have too many adverse reactions and does not have much influence on the body.