Special Precautions/Comments:

N.B. Must be received in lab as soon as possible after collection. WBCs & RBCs may lyse after 2 hrs.

QEH: Do not send through tube system, must be hand delivered to pathology.

SRH & STDH: Please contact the laboratory to arrange transport if necessary.

Interferences:  Antibiotics may affect growth of certain bacteria.

Clotted samples or blood- stained samples will interfere with the cell count.

Method:  The examination of cerebrospinal fluid (CSF) within Microbiology includes total cell count, differential leucocyte count, examination of gram stained smear and culture for pathogens. CSF Meningitis/Encephalitis (ME) Panel PCR is also available if clinically appropriate. Any organisms isolated are identified using Maldi-Tof and relevant antimicrobial susceptibility testing is performed on all isolates. Significant isolates will be sent to a referral laboratory for sequencing/typing.  Calibration: Centrifuges and the ThermoShandon Cytospin are calibrated to UKAS standard. EQA scheme: UKNEQAS General Bacteriology scheme (culture and identification). BMS MICRO EQA (sterile fluid). IQC: In-house preparations (gram stains).

Interpretation: The laboratory will communicate out any positive results at the earliest opportunity. All positive results will be reviewed by the Consultant Microbiologist and appropriate clinical comment will be provided. The Consultant Microbiologist will be alerted to any positive gram stain results by the laboratory and a CSF Meningitis/Encephalitis (ME) Panel PCR test will be performed.

Due to interference, total cell count will not be performed on clotted samples. Additionally, differential leucocyte count will not be performed on heavily blood stained samples.

 

Additional Information:

Background information:  Meningitis is inflammation of the meninges. This process may be acute or chronic, infective or non-infective. Many infective agents may cause meningitis including, bacteria, viruses, fungi and parasites. Acute bacterial meningitis is a medical emergency, whereas viral meningitis tends to be less severe; however exceptions do exist.

The species of the infecting organisms tend to be characteristically, but not exclusively, associated with the age or predisposing status of the patient (Ref UKHSA SMI B27):

• From neonates and babies up to two months of age: Lancefield group B streptococci, Escherichia coli, Listeria monocytogenes, Herpes simplex virus and Neisseria meningitidis. Premature neonates requiring intensive care are at risk of Candida meningitis as a result of candidaemia.
• From children older than two months to young adults: N. meningitidis, S. pneumoniae, viruses and Haemophilus influenzae type b.
• From adults: S. pneumoniae, N. meningitidis, viruses and occasionally non-group b H. influenzae. Patients older than 60 years may also develop Listeria monocytogenes infection.
•  Patients who are immunosuppressed are additionally susceptible to meningitis caused by organisms such as Listeria monocytogenes, Cryptococcus neoformans, Norcardia and Toxoplasma gondii.

For further information please refer to: Public Health England. (2017). Investigation of Cerebrospinal Fluid. UK Standards for Microbiology Investigations. B 27 Issue 6.1. https://www.gov.uk/uk-standards-for-microbiology-investigations-smi-quality-and-consistency-in-clinical-laboratories