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Stem Cell Sterility Check (Bacteriology)

Stem cells samples are submitted from two clinical teams:

  • Cellular Therapeutics Ltd, Grafton Street Unit (Manchester University) Dr Ryan Guest (Purple top & Pink Top Bottle)
  • Stem Cell Unit, Haematology Department MFT, Wendy Ogden (Single Pink Top Bottle)

General information

Collection container (including preservatives): Collect specimens in BD Bactec bottle using aseptic technique. Bactec bottles should be stored at room temperature before use.

Specimen type:

Bactec 1 Bactec 2

Collection: Culture bottles are prepared during stem cell processing and stem cell product manufacture to ensure the stem cells have not been contaminated with bacteria.

Specimen transport: Samples should not be refrigerated. Inoculated bottles should be incubated as soon as possible, and within a maximum of four hours.

The four hour turnaround time from collection to incubation for blood culture samples reflects their clinical significance.

Type and volume of sample: A Paediatric (pink top) blood culture bottle requires 1-3ml of stem cell product.

An Anaerobic (purple top) blood culture bottle requires 5-8ml of stem cell product.

Do not exceed the manufacturer's recommended maximum volume for each bottle as shown on label.

Special precautions: Use aseptic technique.Inspect the blood culture bottles for damage.

Ensure that the blood culture bottles have not exceeded their expiry date.

Do not re-sheathe needles.

Laboratory information

Measurement units: Growth detected or not detected

Biological reference units: Not applicable

Turnaround time for provisional result (working days): Negative result 3 days

Turnaround time to final result (working days): 10 days

Clinical information

Clinical decision points: Not applicable

Factors known to significantly affect the results: Any recent antimicrobial therapy can have a significant effect on blood culture results by decreasing the sensitivity of the test. 

Limitations: It is estimated that 2-5% of positives samples may be missed if bottles are pre-incubated, these organisms may fail to trip the threshold algorithm of the continuous monitoring blood culture machine.

This may occur with Abiotrophia species (nutritionally variant streptococci), S. pneumoniae which have undergone a degree of autolysis, and fastidious organisms which are unable to grow on routine solid culture media. 
Organisms may include:

  • Campylobacter species.
  • Helicobacter species.
  • Capnophilic organisms.
  • Slow-growing anaerobes


(Last reviewed October 24th 2017)