I. Collection method
1. Culture bottle disinfection procedure: sterilize the rubber stopper of the culture bottle and leave it to dry.
2. Skin disinfection procedure: use disinfectant to draw a circle from the puncture point outward to disinfect, until the diameter of the disinfected area reaches 5cm or more, and wait for the disinfectant to evaporate and dry before blood collection.
3. Venipuncture and culture bottle inoculation procedure: after aseptic puncture with a 10 ml syringe to obtain blood, exhaust the air in the needle, do not change the needle (if a second puncture or scalp needle to obtain blood, the needle should be changed), after blood collection, directly injected into the blood culture bottle, first injected 5 ml in the anaerobic culture bottle, and pay attention to avoid the injection of air, and then injected into the other culture bottles, gently mixed to prevent blood coagulation or strictly in accordance with the manufacturer's recommended methods of blood collection.
II. Note
1. Blood specimens should be sent for examination immediately after collection, and those who cannot be sent for examination in time should be stored at room temperature, not in the refrigerator. The test form should indicate the use of antimicrobial drugs (especially sulfonamide, penicillin), the collection time and location (such as the left arm, etc.), the suspected diagnosis.
2. Blood collection site: usually the elbow vein, suspected bacterial endocarditis to the elbow artery or femoral artery blood collection is appropriate, do not drip antibacterial drugs in the vein of blood collection. In adult patients, blood specimens should be collected from two separate sites each time a fever develops to help distinguish between pathogenic and contaminating bacteria. Blood should be taken from different sites and the same organism isolated 2 times to be sure it is pathogenic. Blood should not be obtained from indwelling venous or arterial catheters, which are susceptible to contamination with intrinsic flora.
3. Timing of blood collection: the sooner the better during the patient's fever, preferably before antimicrobial therapy, half an hour before the chills and fever are developing or 24 hours after stopping antibiotics.
4. The number and interval of blood collection: the need for immediate antibacterial treatment of acute febrile diseases (such as meningitis, bacterial pneumonia) or need for emergency surgery, such as (acute osteomyelitis, septic arthritis, etc.), should be immediately taken from the two arms of the two specimens. For patients with infective endocarditis, blood should be taken 3 times within 24h, each time at an interval of not less than 30min; if necessary, blood cultures should be done twice on the following day. For patients with unknown cause of fever, blood was taken twice at an interval of 60min; if necessary, blood was taken twice more after 24~48 hours. Because one blood culture is not enough to explain the problem, and will miss the positive results. Overseas statistics can detect 80% of bacteremia in one blood culture, 90% in two, and 99% in three. Domestic statistics 17 hospitals 1 time blood culture positive rate of 10.8%, 18 hospitals more than 2 times blood culture positive rate of 14.8%
5. blood collection: adults with bacteremia or sepsis blood contains less bacteria, the average of 1 ~ 3 ml of blood only 1 bacteria. Therefore, the amount of blood collected must be sufficient. The ratio of culture medium to blood is 10:1 to dilute the antibiotics, antibodies and other bactericidal substances in the blood. Collecting too little blood will significantly reduce the positive rate. Adults collect 5 ml of blood per culture bottle (with 50 ml of medium), infants and children collect 2 ml of blood per culture bottle (with 20 ml of medium)
6. There is no need to change the needle before injecting blood into the medium, use a sterile dry cotton ball to press the stopper, and as far as possible, to avoid the results of the residual disinfectant on the rubber stopper of the blood culture bottle affecting the results.
7. Blood was collected at least twice a day in each case, at intervals of 0.5 to 1 h.
III. Judgment of results
1. Healthy human blood is sterile.
2. Usually bacteria or fungi isolated by blood culture can be considered as blood infection. Pathogens.
3. Most bacteremia is intermittent and often needs to be confirmed with multiple positive blood cultures. In the case of Staphylococcus epidermidis, Corynebacterium diphtheriae-like and other skin resident bacteria, two consecutive cultures of the same species are required to confirm.
4. Common bacteria in the blood are Staphylococcus aureus, Staphylococcus epidermidis, group A, group B streptococcus, Streptococcus pneumoniae, enterococci, Klebsiella pneumoniae, Pseudomonas aeruginosa, and so on.
IV. Clinical microbiology specimens sent to the attention of the examination
1. All specimens should be sent to the laboratory immediately after collection, preferably within 2 hours. If it is not possible to send the test in time, put it in a room temperature environment.
2. The specimen should be sent to the source, the purpose of the test and sampling time, so that the laboratory can correctly select the appropriate medium and appropriate culture environment.
3. Anaerobic culture specimens need to maintain anaerobic state transportation: the use of special transport medium or syringe to extract the specimen after exhausting the air, in the needle on the sterile rubber plug after transportation.
4. The optimal delivery of clinical specimens, including anaerobic culture specimens, depends first on the amount of specimen obtained. Low volume specimens should be sent within 15-30 minutes of collection.
5. Safety precautions should be taken during delivery:
①The container in which the specimen is placed must be leak-proof, and it is prohibited to send the leaking specimen to the laboratory.
② It is strictly prohibited to send syringes with exposed needles to the laboratory.