Sputum specimen processing experiments
General bacterial smear examination: select the purulent or bloody part of sputum, smear it into a uniform thin slice, perform Gram staining and microscopic examination. This experiment is from the laboratory instruction of Mudanjiang Medical College undergraduate 5-year testing program.
Operation method
Sputum specimen processing experiments Move 1、General bacterial smear examination: select the purulent or bloody part of sputum, smear it into a uniform thin slice, perform Gram staining and microscopic examination. For more product details, please visit Aladdin Scientific website.
According to the bacterial morphology, arrangement and staining, the genus (or species) can be presumed initially. If gram-positive cocci arranged in grape shape are seen, it can be reported as "gram-positive cocci are found, which look like staphylococci"; if gram-positive cocci with claw-like or spearhead-shaped tips are arranged in pairs with obvious pods, it can be reported as "gram-positive diplococci are found, which look like Streptococcus pneumoniae"; if short and thick gram-negative cocci are seen, it can be reported as "gram-positive diplococci are found, which look like Streptococcus pneumoniae". Streptococcus pneumoniae"; "Gram-negative bacilli resembling Klebsiella pneumoniae" if short and thick Gram-negative bacilli in pairs with distinctive pods are detected; "Gram-×x bacteria" if not easily recognizable bacteria are detected.
2. Culture
(1) Treatment of sputum before culture: Since sputum contains normal flora, which affects the detection of pathogenic bacteria, the following method is used to reduce the normal flora. Add the sputum into a test tube containing 15-20 ml of sterilized saline and shake it vigorously for 5-10s, then use an inoculating ring to dab out the small pieces of pus and sputum that have settled at the bottom of the tube, then put them into another test tube and repeat the same method for two times, and then finally inoculate the remaining pus and sputum on the culture medium.
(2) Selection of culture medium: there are many kinds of pathogenic bacteria in the lower respiratory tract, in addition to general bacteria, there are also tuberculosis, fungi, anaerobes and so on. Therefore, in addition to the basic isolation culture, it is necessary to use special culture medium and appropriate culture environment. Generally, the following isolation methods must be used.
(a) Blood plate: It is suitable for separating all kinds of bacteria, especially β-hemolytic streptococcus and staphylococcus. It is easy to isolate Streptococcus pneumoniae and β-hemolytic streptococcus by putting CO2 or anaerobic environment in blood plate.
b) Chocolate plate is used to isolate Haemophilus, Neisseria meningitidis under CO2 environment.
Others: TTC-Shabauer's medium, modified Roche's medium, anaerobic environment, etc.
3.Reporting method:
When a pathogenic bacterium is detected, in addition to reporting the identified name of the bacterium, it is also necessary to report the normal flora at the same time. Usually reported Streptococcus grass green and Neisseria as an indicator of the presence of normal flora. The percentage of each bacterium reported should be indicated by a "+" sign. For example, Streptococcus (+), Neisseria (+), and Klebsiella pneumoniae (++). This report indicates that Klebsiella pneumoniae is numerically greater than the normal flora and is diagnosed as the causative organism. When no pathogenic bacteria are detected, "normal flora" should be reported.