Blood culture

[سلطان حكمي]

When the test is order ?

Blood cultures are collected from patients with suspected sepsis or bacteremia.

Virtually any organism may cause bacteremia. Thus, the isolation of all organisms from a blood culture must be considered significant and correlated with the clinical picture.


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what is the sample type?

blood , sterial fluide , CSF , Bone Marrow



طبعاً العينة هنا سواء كانت دم أو نخاع العظم ... إلخ توضع في القوارير Vial التالية :





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How it's work?

The sample to be tested is inoculated into one or more vials which are inserted into the BACTEC fluorescent series instrument for incubation and periodic reading. Each vial contains a chemical sensor which can detect increases in CO2 produced by the growth of microorganisms. The sensor is monitored by the instrument every ten minutes for an increase in its fluorescence, which is proportional to the amount of CO2 present. A positive reading indicates the presumptive presence of viable microorganisms in the vial. Detection is limited to microorganisms that will grow in a particular type of medium.




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what is the component of the media in the vials ?








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Blood Culture Systems

Routine Blood Culture BacT/* blood culture bottles.

A blood culture set is - One aerobe bottle (adequate for most yeast also) and one anaerobe bottle.


Blood culture bottle set (aerobic and anaerobic)





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Blood culture, neonate

Neonate Blood Bottle (PEDS Plus) for aerobic organisms. (A separate adult anaerobic may be sent if clinically indicated.)



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Incubate Blood culture bottles in the BacT/* System

بعد مرحلة السحب و دخول الدم في الـ vials تدخل في هذا الجهاز ..





In the laboratory, blood culture bottles are placed in a blood culture machine set at 370C. Here the barcode is “read” in order to enter details of the bottle into the computer of the blood culture machine. After 12-48 hours bolic products from a growing population of bacteria trigger a sensor, and the machine *s that bottle as being “positive”.




(يوجد ملف AUTOMATED BLOOD CULTURE BACTEC آخر الموضوع حول عمل الجهاز بجميع التفاصيل )


فترة الـ incubation تختلف باختلاف العينات




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Interpretation of BacT/* Blood Culture Bottles


The BacT/* System will continuously rock the blood culture bottles at 70 cycles per minute and scan all bottles (every 10 minutes) for evidence of growth. The machine will automatically flag any positive blood cultures.


Negative Cultures


i) Routine, Bone marrow (for sterility testing), sterile fluids, and general fungus/yeast/candida/cryptococcus blood cultures:
Discard all negative bottles after 5 days incubation and issue a negative report.

ii) Bone bank blood cultures:
Discard all negative bottles after 7 days incubation and issue a negative report.

iii) SBE/IE and PUO/FUO, Brucella:
After 21 days incubation, discard all negative bottles and issue a negative report.



Positive Cultures


When the bottle has been flagged positive by the BacT/* or is macroscopically positive (i.e. bulging septum, obvious discoloration or lemon-yellow sensor disc) process ONLY the suspected positive bottle (do not sub-culture the matching bottle unless it is also macroscopically positive or flagged positive). If only one bottle has been flagged positive, leave the companion bottle in the BacT/* until completion of its incubation time, then discard if negative. Process all suspected positive bottles as follows:


i) Gram stain




ii) Sub-culture onto the following (whole) plates*:

Media Incubation

Blood Agar (BA) CO2 35°C x 48 hours
Chocolate Agar (CHOC) CO2 35°C x 48 hours
MacConkey Agar (MAC) CO2 35°C x 48 hours
Fastidious Anaerobic Agar (BRUC) AnO2 35°C x 48 hours





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