Meningococcemia laboratory findings: Difference between revisions
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* Skin [[biopsy]] and [[gram stain]] | * Skin [[biopsy]] and [[gram stain]] | ||
* [[Urinalysis]] | * [[Urinalysis]] | ||
*Invasive meningococcal disease is typically diagnosed by isolation of N. meningitidis from a normally sterile site. However, sensitivity of bacterial culture may be low, particularly when performed after initiation of antibiotic therapy. A Gram stain of cerebrospinal fluid showing gram-negative diplococci strongly suggests meningococcal meningitis. | |||
*Kits to detect polysaccharide antigen in cerebrospinal fluid are rapid and specific, but false-negative results are common, particularly in serogroup B disease. Antigen tests of urine or serum are unreliable. | |||
*Serologic testing (e.g., enzyme immunoassay) for antibodies to polysaccharide may be used as part of the evaluation if meningococcal disease is suspected but should not be used to establish the diagnosis. | |||
=== Electrolyte and Biomarker Studies === | === Electrolyte and Biomarker Studies === | ||
Revision as of 17:13, 19 November 2014
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]
Laboratory Findings
Blood tests will be done to rule out other infections and help confirm meningococcemia. Such tests may include:
- Blood culture
- Complete blood count with differential
- Clotting studies (PT, PTT)
Other tests that may be done include:
- Lumbar puncture to obtain spinal fluid sample for CSF culture
- Skin biopsy and gram stain
- Urinalysis
- Invasive meningococcal disease is typically diagnosed by isolation of N. meningitidis from a normally sterile site. However, sensitivity of bacterial culture may be low, particularly when performed after initiation of antibiotic therapy. A Gram stain of cerebrospinal fluid showing gram-negative diplococci strongly suggests meningococcal meningitis.
- Kits to detect polysaccharide antigen in cerebrospinal fluid are rapid and specific, but false-negative results are common, particularly in serogroup B disease. Antigen tests of urine or serum are unreliable.
- Serologic testing (e.g., enzyme immunoassay) for antibodies to polysaccharide may be used as part of the evaluation if meningococcal disease is suspected but should not be used to establish the diagnosis.
Electrolyte and Biomarker Studies
- Blood cultures were positive in 41.4% of 400 cultures in one series of patients with meningococcal disease.
- Cerebrospinal fluid (CSF) culture and gram stain were positive in 94% of patients in the same series.
- The ability to culture the meningococcus from CSF will not be substantially reduced if the cultures are obtained within one hour of antibiotic administration.
- One series revealed a median leukocyte count of approximately 1200 in CSF (range 10 to 65,000/mm). Approximately 75% had a CSF glucose level less than 40 mg/100 mL. CSF protein ranged from 25 to over 800 mg/100 mL with a median value of 150 mg/100 mL.
- Polymerase chain reaction (PCR) has been shown in a study with 54 samples to be 91% sensitive and specific, particularly useful when cultures may be negative due to prior antibiotic administration.
- Latex agglutination can detect A, B, C, Y, and W-135 though the sensitivity of detecting serogroup B is low.
HUSSEIN AND SHAFRAN CANADIAN REVIEW OF BACTERIAL MENINGITIS
| Cloudy CSF | 78% |
| CSF >= 1000 WBC/mm3 | 56% |
| CSF >= 10,000 WBC/mm3 | 14% |
| CSF Neutrophil predominance | 90% |
| CSF Glucose =< 50 mg/deL | 70% |
| CSF Protein > 200 mg/dL | 66% |
| Gram Stain without bacteria | 53% |
| Gram Stain Neg --> Culture Pos | 47% |