Part 2: Unit 2 CSF

What is done for collection of CSF?

• insert needle into subarachnoid space

  • avoid skin contamination

• collect 3-5 tubes of CSF

Describe Tube 1 for CSF collection.

• chemistry

  • total proteins

  • chemistry

  • immunoglobulin testing

Describe Tube 2 for CSF collection.

• Microbiology

  • gram stain

  • culture

  • cryptococcal antigen testing

  • fungal culture

Describe Tube 3 for CSF collection.

• AFB culture and stains

  • if NEEDED

Describe Tube 4 for CSF collection.

• Hematology

  • cell count

  • cytology

  • flow cytometry

Describe Tube 5 for CSF collection.

• Special requests

  • viral PCR

  • west nile virus

  • protozoa

  • CJ disease

  • HSV PCR

  • enterovirus PCR

What is the correct transport procedure for CSF?

• hand deliver IMMEDIATELY to lab

• Gram stains are STAT

• do NOT refrigerate

Describe proper processing for CSF.

• must be immediate

  • use biology safety cabinet and wear gloves

  • if processing is delayed, store sample at room temperature

  • do NOT refrigerate

    • except CSF for viral studies can be refrigerated or stored at 70 C

  • clear fluids : centrifuge/filtration

  • purulent materia: inoculate media

  • clotted specimen: homogenize to release trapped bacterial cells

What is India Ink used for?

• visualize capsule of Cryptococcus neoformans

  • only about 50% sensitivity, should perform antigen testing

How is gram stain done for CNS specimen?

• Cytocentrifuge specimen

• alternative method - acridine orange stain

• communicate/ teliphone results IMMEDIATELY

• used to guide therapy.

What culture media and conditions are needed for CNS specimen?

• SBA and Choc agar plat

• incubate plates 72 hrs at 35 C in 5% CO2

• Thioglycollate broth - incubate at 35 C for 7 days

  • traumatic injury, shunt, metal cranial plates

• even 1 colony is significant

What do gram stain results mean?

• if anaerobes suggested → add anaerobic blood agar plate

• if GNC seen → inoculate MacConkey plate

• if yeast or mycobacteria

  • use appropriate media

  • fungus: 2 tubes at 30 and 35 C

• no organisms → viral etiology

When should a wet mount or direct trichrome stain be used?

• amoebas

When should AFB stain be used?

• ONLY if patient history of TB exposure

• positive PPD

• immunocompromised

What media are used for CSF culture?

• Sheep blood agar

• chocolate agar

• 'thioglycollate broth

• anaerobic blood agar

• MacConkey agar

• fungal media

• mycobacterial media

What is the quelling reaction?

• perform on lancet-shaped gram positive cocci only

• Polyvalent antisera against 84 serotypes

Name the microorganism and structure responsible for a positive quellung reaction.

• Streptococcus pneumoniae

• Structure: polysaccharide capsule

What Nonculture methods can be used for CNS?

• direct antigen tests

• Serology

• Molecular methodology

Describe Direct Antigen tests.

• direct bacterial antigen testing is NOT recommended

• cryptococcal antigen (CRAG) is diagnostic

  • 98% sensitivity from CSF

• be cautious of prozone effect

Evaluate non-culture detection methods in terms of identification and time to final report.

• CSF examination: minutes

• gram stain: minutes

• CSF culture: days

• India ink stain: minutes

• rapid latex agglutination: minutes

• traditional targeted PCR: hours

• end-out for test results: days

What is used to test for Neurosyphilis?

• general CSF lab tests: VDRL

  • antibodies to Treponema pallidum in CSF

  • be cautious of false positives

What are causes of biological false positives of the VDRL tests?

• Autoimmune conditions.

• Certain viral infections.

• Some other acute or chronic infections.

• Pregnancy.

• Older age.

• Some other inflammatory or systemic conditions.

What type of infection is this:

Leukocytes: 2-2,000 (mean 80)

main cell type: mononuclear

protein: 50-100 mg/dL

glucose: normal

• Viral infection

What type of infection is this:

Leukocytes: 5-20,000 (mean 800)

main cell type: PMN “left shift”

protein: > 100 mg/dL

glucose: low < 45 mg/dL

• bacterial infection

What type of infection is this:

Leukocytes: 5-2000 (mean 100)

main cell type: mononuclear

protein: >100 mg/dL

glucose: normal or low (< 45 mg/dL)

• Tuberculosis and fungi

What are the sources of infection that can cause a brain abscess?

• sinus / ear infection

• hematogenous spread

• skull trauma - Staphylococcus aureus

• predisposing factors

  • diabetes mellitus

  • corticosteroid therapy

  • AIDS

  • malignancy

What organisms are commonly associated with brain abscesses?

• Streptococci

• Bacteroides

• Gram negative aerobes

• Staphylococci

• Neonates

  • Citrobacter koseri

• Fungi

  • Aspergillus spp.

  • Zygomyces

  • systemic fungi: Histoplasma, Blastomyces