Detection of hemolytic streptococcus in disposable medical masks

Detection of hemolytic streptococcus in disposable medical masks

1.1 operation steps

Add 5 ml of sampling solution to 50 ml of grape juice, and incubate for 24 h at 35 ℃ ± 2'c

The culture was inoculated on blood agar plate and cultured at 35 ℃ for 24 h. On the blood plate, Streptococcus haemolyticus is gray white, translucent or opaque, with needle like protrusion, smooth surface, neat edge and colorless and transparent hemolytic circle around.

The typical colonies were selected for smear and Gram staining microscopy. It should be gram positive and chain arranged cocci. The following tests shall be carried out if the microscopic examination meets the above conditions:

Streptokinase test: 0.2 ml of potassium oxalate plasma (0.01 g potassium oxalate plus 5 ml rabbit plasma was mixed, centrifuged and precipitated, and the supernatant was drawn). 0.8 ml sterile normal saline was added, and then 0.5 ml broth culture of bacteria to be tested and 0.25% calcium chloride 0.25 ml were added, Mix well, put it in 3510 ± 2 ℃ water bath, observe once every 2 minutes (generally it can be coagulated within 10 minutes). After plasma coagulation, continue to observe and record the melting time. If it does not dissolve within 2 hours, continue to place it for 24 hours for observation. If the clot is completely dissolved, it will be negative if it still does not dissolve within 24 hours.

Bacterial skin sensitivity test: apply the bacterial liquid to the blood plate, take each piece of paper containing 0.04 unit of bacilli skin with sterilization tweezers and put it on the surface of the plate. At the same time, with known positive strains as the control, they are placed at 35 ℃ and 2 ℃ for 18-24 h, and those with antibacterial band are considered as positive.

1.2 result report

Microscopic examination showed gram positive chain arrangement sphere m, hemolytic circle appeared on blood plate, streptokinase and M1 limb test were positive, and hemolytic streptococcus was detected in the tested samples.