CSF (cerebrospinal fluid)
| About This Test |
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Department: Microbiology, Virology and Molecular Microbiology Requirement: For routine cell count & culture; ideally a minimum volume of 1 mL in sterile leak proof containers. Special instructions PCR testing - For suspected of community-acquired eningitis/encephalitis where PCR testing is required, please send separate bottle to reduce the risk of a false-positive result due to contamination with DNA or RNA, Please send a minimum of 200 µL for molecular (PCR) tests. Mycobacteria species culture (TB), 6mL CSF is required where possible CSF is normally collected sequentially into three or more separate containers which should be numbered consecutively. Contact laboratory for urgent samples NB DO NOT send samples from suspected variant CJD or CJD unless laboratory notified in advance.
Turnaround Time: 30 mins to 1 hour for microscopy if urgent, 1-3 days for culture. Rapid PCR may be performed in some circumstances |
Tests included :Cell count and culture, Gram stain and white cell differential if count is raised
For demyelination and other non-infective neurological conditions, cell count only will performed
For all microbiology requests, relevant clinical data and details of recent or current antimicrobial treatment should be provided
Other Comments:
Specimen transport: If processing is delayed, refrigeration is preferable to storage at ambient temperature. Delays of over 48hr are undesirable. Do not freeze.
PCR testing PCR testing should be performed using a container of CSF that is not opened prior to arrival in the Molecular Laboratory. Microbiology requires a CSF in sterile container specifically for molecular (PCR) tests, in addition to a CSF container for Gram stain, cell count, and culture. A separate sample is required for Biochemistry glucose and protein concentrations.
If a patient has suspected community-acquired meningitis/encephalitis and a separate CSF bottle for molecular tests has not been obtained from the patient, PCR testing may be performed on a CSF sample that has been opened for other tests. A laboratory comment will be added with the following disclaimer:
“PCR tests have been performed on a CSF from a container that was opened for other tests prior to arrival in the molecular laboratory, raising the risk of DNA/RNA contamination and a false-positive result. Hence any positive PCR result reported on this specimen should be viewed with suspicion and ideally confirmed on a CSF from a container that has not been opened prior to arrival in the molecular laboratory.”