Thanks Maria for presenting a great case. This case was a young woman presenting with acute-subacute onset headache, nausea/vomiting, nuchal rigidity with CSF studies most consistent with aseptic meningitis.
- CSF analysis can be broken down into 4 groups depending on WBC (100s vs 1000s) and Glucose (normal vs low).
- WBC 1000s & glucose low: MCC acute bacterial
- WBC 100s & glucose low: MCC granulomatous
- WBC 1000s & glucose normal: MCC aseptic meningitis
- Aseptic meningitis can be thought of as infectious (viral, fungal, bacterial, parasitic) vs noninfectious (autoimmune, meds, neoplastic).
- Empiric coverage for bacterial meningitis includes vancomycin (for pen-resistent S pneumo) and ceftriaxone. Ceftriaxone is dosed at 2g IV q12 for CNS penetration and S pneumo, N meningitidis, H flu.
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More common ddx for aseptic meningitis:
- Viral – enterovirus, HSV2 (which can also cause a Mollaret's meningitis/ recurrent benign lymphocytic), HIV, coxsackie, arbovirus
- Bacterial – partially treated bacterial, mycobacteria, lyme, syphilis, leptospirosis, parameningeal infection, atypicals
- Fungal – crypto, endemic mycosis
- Parasitic - toxoplasma, strongy
- Autoimmune – SLE, sarcoid
- Medications – NSAIDs, TMP-SMX, immunosupp (IVIG, azathioprine)
- Neoplasm – leukemia, lymphoma, metastatic cancer
Rabies virus invades the peripheral nerves and moves through retrograde transport into the CNS. Rabies encephalitis can be diagnosed with a nuchal skin biopsy -> IHC and PCR. Sensitivity is about 60% in early encephalitis and 100% in the terminal stage of disease. For more info: here is a link to the CDC website and a JAMA dermatology article on this subject.
Antibiotic choice for meningitis
Empiric coverage includes vancomycin and ceftriaxone. Ampicillin for age > 50 (and consider for pregnancy and IC state). For patients with penicillin allergies, can substitute aztreonam for ceftriaxone and TMP-SMX for ampicillin. Here are IDSA guidelines for suspected bacterial meningitis. Note Figure 2 which has a nice algorithm for adults and Table 4 noting empiric antibiotics.
Ddx elevated protein in an LP sample
cocci, crypto, TB, epidural abscess