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Laboratory: Clinical Microbiology
Test Name:
Test Code: SFCS
Clinical Information:
Test Indications:
To establish the etiologic agent of bacterial infections within the central nervous system (CNS) in patient showing signs and symptoms of:
-  Meningitis
-  Focal infections of brain parenchyma, i.e.:
   1. Contiguous spread (otitis media, sinusitis, mastoiditis or dental infection); trauma; neurosurgical complication
   2. Hematogenous spread from distant site, e.g. skin, pulmonary, pelvic, intraabdominal, esophageal, endocarditis
-  CNS shunt infections, ventriculitis, subdural empyema or epidural abscess.
In patients with encephalitis, an etiology is not identified in the majority of cases and it is usually viral.
Agents of acute bacterial meningitis vary according to age and underlying comorbidities: S. pneumoniae and N. meningitidis in adults; E. coli and group B Streptococcus (S. agalactiae) in neonates; L. monocytogenes affecting both neonates and the elderly.
Patients with head trauma or who have undergone neurosurgical procedures or present with a shunt infection/ventriculitis are at-risk for infections by S. aureus, coagulase-negative staphylococci, and aerobic Gram-negative bacilli.  Anaerobic cultures may be considered in these scenarios but is not recommended for community-acquired meningitis.
M. tuberculosis, Nocardia spp, and fungi are associated with chronic bacterial meningitis, which manifests with an indolent onset of symptoms (≥4 weeks).  C. neoformans is the most common causes of fungal meningitis and occurs in the context of immunosuppression (e.g., AIDS patients).

1. CSF specimens are routinely evaluated by microscopy (STAT) and bacterial culture (aerobic).
2. Obtain sample prior to initiation of antimicrobial therapy. If not possible, indicate antimicrobial and/or antifungal therapy on the ordering requisition.
3. If Mycobacteria, Yeast or Moulds/Systemic mycoses are suspected, these must be specifically requested on the microbiology requisition.
4. Culture of CSF for anaerobic bacteria is only recommended in the context of trauma or the presence of a device, e.g., shunt. If requesting anaerobic culture, indicate justification on the requisition.
5. Investigations for neurosyphilis, Lyme disease, and viral etiologies of meningitis are referred to the Cadham Provincial Laboratory.
6. Blood cultures should also be obtained if bacterial meningitis is suspected.
7. Indicate on requisition if unusual pathogens (e.g., Brucella) are suspected.
8. A minimum of 1 mL of CSF should be sent to the microbiology laboratory in a sterile container for bacterial testing. Larger volumes (5–10 mL) increase the sensitivity and are required for optimal recovery of mycobacteria and fungi.
9. When the specimen volume is less than required for multiple test requests, prioritization of testing must be provided to the laboratory.
10. Samples and requisitions must be labeled/completed in accordance with the Shared Health Specimen Acceptance Policy.
11. Accurate patient identification must be made prior to sample collection. Patient identification should be done in accordance with the site policy.

Patient Preparation Instructions:
1. Samples MUST be acquired using aseptic technique.
2. Multiple tubes of CSF are collected via lumbar puncture or spinal tap.
3. Follow protocols outlined by your health care facility for this sample type.
4. Submit the SECOND (Tube #2) or THIRD (Tube #3) tube collected for microbiologic examination.
5. The first tube (Tube #1) is sub-optimal, with a greater chance of being contaminated with skin flora.
Collection Devices:
The second or third tube should be submitted to microbiology.
Specimen Required:

Bacteria:  ≥1.0 mL  (minimum volume)
Fungi: ≥2.0 mL  (5-10 mL optimum)
AFB: ≥2.0 mL  (5-10 mL optimum)
Pediatric: Sample volume collected at discretion of physician.
Larger volumes increase the sensitivity of testing.  Obtain prior to initiation of antimicrobial therapy.
Reference Values:
Microscopy:  No Bacteria Seen.
Bacterial culture:  No organism isolated after 5 days incubation.
Fungal culture:  No fungi isolated after 4 weeks.
Mycobacterial culture:  No acid-fast bacilli isolated after 7 weeks.
For positive samples, a descriptive report will be provided.
See Also:
More Information:
Specimen Handling:
Local: Transport to the laboratory AS SOON AS POSSIBLE (≤15 minutes). Hold at room temperature.  Do NOT refrigerate.
Courier/Local Storage: ≤24 hrs at room temperature.
Ensure samples that are being sent to the referral laboratory are packaged in accordance with Transport of Dangerous Goods recommendations for diagnostic samples.