Menu

Mycoplasma Screening Service

Bioresearch Support Core

Overview

Mycoplasma contamination in cell cultures can significantly alter both cellular behavior and genetic content, compromising the reliability of phenotypic and genotypic experimental results. Recognizing its impact, the Bioresearch Support Core has been offering weekly mycoplasma PCR detection services to research laboratories in the Faculty of Medicine since 2018. Given that mycoplasma is highly transmissible and difficult to eliminate, regular screening and proper handling of contaminated cultures are strongly recommended to maintain experimental integrity.

Sample Submission and Preparation Guide

Sample Submission and Preparation Guide
Researchers may submit samples in various forms, as outlined in the guide below. Please follow the preparation instructions carefully to ensure accurate and efficient processing.

⚠️ Strictly Prohibited:

Submission of pathogen-containing samples, pathogen-infected materials, or any samples classified as Biosafety Level 3 (BSL-3) is strictly prohibited.

A. Cell Culture Medium

A1. Culture sample cells in antibiotic-free medium for at least 3 days (Over 1 week is preferred). Do not change the medium during the last 3 days prior to sample collection.

A2. Collect 3 mL of culture medium and aliquot it into two 2-mL microcentrifuge tubes (i.e. 1.5 mL/ tube; samples submitted in cryo-tube will NOT be accepted).
The recommended micro-centrifuge tubes (Axygen MCT-200-C) can be purchased through the Bioreagent Core’s Online Ordering System for routine sample preparation.

A3. Store the sample tubes at 4oC until submission.

B. Extracted DNA

B1. Aliquot at least 100ul of extracted DNA in one 1.5-mL micro-centrifuge tube. The concentration of the host DNA is not concerned.

B2. Store the sample tubes at -20oC until submission.

C. Surface Swab

C1. Swab can be used to check the presence of mycoplasma on working surfaces (e.g. incubator, BSC).

C2. Swab the surface against the area of interest and put the swab back into the sample tube with 3mL PBS.

C3. Store the samples at 4oC and aliquot to 2-mL microcentrifuge tubes prior to submission.

  1. Label your sample tubes clearly with “Initial of your name – sample number” on the tubes. PLEASE ensure that both tubes for the same sample are labeled with the exact same sample name.
    Example:
    If CHAN, Tai Man submits 3 samples, they should be labeled as:
    CTM-1, CTM-2, CTM-3 — each in duplicate (i.e., two tubes per sample), resulting in a total of 6 tubes.
  2. Submit your screening order on the PPMS system in accordance with the Mycoplasma Screening Service User Standard Operation Protocol.
  3. Place your sample tubes in a sealed zipper bag along with a paper note clearly stating:
    1. User Name
    2. Principal Investigator (PI) Name
    3. Order Number
  4. Submit the sealed bag to the sample submission icebox located at L6-01, Laboratory Block.
  5. Log your submission properly into the logbook provided at the site.
    ⚠️ Important:

    Samples without a properly labelled note in the sample submission bag will NOT be processed.

  6. A confirmation email will be sent to your PPMS registered mailbox upon the acceptance of your sample submission by CPOS staff.

Sample Submission Schedule

Samples may be submitted to the icebox near L6-01, Laboratory Block between 10:00 AM and 5:00 PM every Tuesday.

⚠️ Please Note:

No testing will be conducted during weeks that include a public holiday on Tuesday, Wednesday, or Thursday.

Detailed schedule can be reviewed from the calendar at:
Mycoplasma Screening Service Schedule

Assay References: Mycoplasma Screening References

Decontamination

If a cell culture is confirmed to be contaminated with mycoplasma, it is strongly recommended to discard or autoclave all associated cultures and stocks to prevent further spread.

In exceptional cases where the contaminated cell line is irreplaceable, antibiotic treatment may be considered.

⚠️ Important Considerations:

  • Decontamination success is not guaranteed due to potential antibiotic resistance in some mycoplasma strains.
  • Cytotoxic effects of antibiotics may lead to loss of the culture.

Unless absolutely essential, infected cultures should be discarded. If decontamination is pursued:

  • Treated cultures should be resubmitted for screening:
    • Immediately after antibiotic treatment
    • In subsequent months to confirm sustained clearance

A limited supply of Plasmocin® (InvivoGen) is available from the Core upon request.

To request this reagent:

  1. Complete the Decontamination Reagent Request Form
  2. Submit it to bioresearch.cpos@hku.hk or L6-01, Laboratory Block

For any enquiries, please contact bioresearch.cpos@hku.hk or 3917 7555.