Sugar fermentation test

The sugar fermentation test is a test for the ability of microorganisms to utilize various carbon sources, the principle being that different microorganisms have different enzyme systems. Most bacteria use sugar as a carbon source, but they have great differences in their ability to break down sugars. Some bacteria can break down certain sugars to produce organic acids (such as lactic acid, acetic acid, propionic acid, etc.) and gases (such as hydrogen, methane, carbon dioxide, etc.). Some bacteria produce only acid and do not produce gas. Basic Information Specialist classification: growth and development check classification: pathogenic microbiological examination Applicable gender: whether men and women apply fasting: not fasting Tips: Before taboos: Maintain healthy eating habits and skin hygiene. Normal value It is normal for various tests of pathogenic bacteria, such as color reactions, to be negative. Pay attention to false positives, so you should control the variable method to exclude. Clinical significance Abnormal results differ in the ability of bacteria to break down sugars and metabolites. For example, Escherichia coli can ferment glucose and lactose; while Salmonella typhimurium can ferment glucose, but can not ferment lactose. Even if both bacteria can ferment the same sugar, the results are not the same. For example, Escherichia coli has formate dehydrogenase, which can further decompose the formic acid produced by glucose fermentation into CO2 and H2, so it produces acid and produces gas; Salmonella typhimurium lacks the enzyme, and fermented glucose produces only acid and does not produce gas. People who need to be examined are suspected of having Escherichia coli, or a bacterial infection such as Salmonella typhimurium. Precautions Inappropriate crowd: No. Before taboos: Maintain healthy eating habits and skin hygiene. Requirements for inspection: Actively cooperate with the doctor. The sugar used in the fermentation test is of high purity. The bacteria inoculated into the fermentation tube should be pure. If mixed with bacteria, the result will be affected. Since Neisseria gonorrhoeae does not grow well in common nutrient agar, animal proteins such as serum should be added to the medium for gonococcal fermentation. When cystine trypsin agar (CTA) is used as the sugar fermentation test, the bacteria can be used to seed the upper third of the culture tube with the inoculation needle. If the amount of agar is increased from 1% to 1.5% and the sugar content is increased from 1% to 2%, the time of the sugar fermentation test can be shortened to 4h. If the sugar fermentation tube is placed in a 37°C water bath, the time of the result is observed. Can be shorter. Inspection process 1, number The name of the fermentation medium and the name of the inoculated bacteria were indicated on each tube with a marker. 2. Vaccination Four tubes containing glucose fermentation medium were taken, Escherichia coli was inoculated according to the number 1 branch, and Proteus vulgaris was inoculated in the other, and the third tube was not inoculated as a control. Take the inspection site culture solution and connect to the fourth branch. Another tube of lactose fermentation medium was taken, and the same one was inoculated with Escherichia coli, one was inoculated with common Proteus, and the third was not inoculated as a control. Take the inspection site culture solution and connect to the fourth branch. 3. The above-mentioned inoculated glucose and lactose fermentation tubes and control tubes were cultured in a greenhouse at 37 ° C for 24 hours. 4. Observe the results and draw conclusions. Not suitable for the crowd No. Adverse reactions and risks no.