Strictly aseptic technique, 3-5 ml of venous blood should be injected into the blood culture bottle and immediately sent to the laboratory, incubated at 35℃ for 7 days, and should not be stored in the refrigerator before sending to the laboratory. When injecting blood into an anaerobic bottle, be careful not to inject air from the syringe into the bottle, otherwise the anaerobic state of the bottle will be destroyed. When the laboratory receives the blood culture bottles sent for testing, handle them as follows. This experiment is derived from the laboratory instruction of Mudanjiang Medical College undergraduate 5-year testing program.

Operation method

Bacterial inoculation tests on blood and bone marrow specimens

Principle

Strictly aseptic technique, 3-5 ml of venous blood should be injected into the blood culture bottle and immediately sent to the laboratory, incubated at 35℃ for 7 days, and should not be stored in the refrigerator before sending to the laboratory. When injecting blood into an anaerobic bottle, be careful not to inject air from the syringe into the bottle, otherwise the anaerobic state of the bottle will be destroyed. When the laboratory receives the blood culture bottles for testing, they should be handled as follows.

Move

experimental step

1. Incubate the blood culture flasks at 35℃ for 12-18 h, and then blindly pass the seed on the blood plate or chocolate plate once. This method allows early detection of positive specimens.

2、After blind seeding, incubate the bottles until the 7th day, take out the bottles every morning to check whether there is any growth, and shake the culture solution well to continue incubation. The following conditions are indicative of bacterial growth.

(1) Uniform turbidity, fermented glucose produces bubbles.

(2) Slightly turbid with a green color change.

(3) Granular or flocculent precipitate growth above the hemocoel layer, or severe hemolysis from the bottom up.

(4) Turbidity with jelly-like coagulation and granular adherence to the walls of the bottle.

(5) Bacterial film on the surface, with ring-like growth of bacteria, and turbidity underneath.

3、Bacterial growth is seen by the naked eye, do the following:

(l) Take a smear of the growth and do Gram stain.

(2) Take the growth material for drug sensitivity test (direct test).

(3) Take the growth material and do the corresponding biochemical identification.

(4) Take the growth material and transfer it to blood plate, chocolate and Chinese orchid/McConkey/Imelan plate. The results seen based on Gram staining should be promptly reported to the clinician.

According to the results of Gram staining, the culture fluid in the culture flask is used as the bacterial fluid to do the direct method of drug susceptibility determination, and strive to produce preliminary results in a relatively short period of time for clinicians as a reference for treatment. After the specimen is separated and purely cultured by plate, standardized drug sensitivity test is done and formally reported to the clinician.

If the smear result confirms the growth of one type of bacteria, then the identification test can be done directly with the bacteria-enhancing solution. If there are two or more types of bacteria growing at the same time, it must be isolated and cultured to obtain pure bacteria for identification.

4, no bacterial growth performance of culture bottles, in the observation of 7 days, at least 2 times should be blind seeding. 7 days still do not see growth, report negative. Such as suspected Brucella can be cultured for 28 days, suspected legionella can be cultured for 10 days.

5, aerobic bacteria culture can be transferred to blood plate or chocolate plate. With blood plate, bacterial hemolysis can be observed, but may lose hemophilus. If we use chocolate plate, not only hemophilus can grow, but also Neisseria meningitidis can grow. Transfection of chocolate plates requires a CO2 environment.

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