Fungal meningitis Flashcards
what is the definition of fungal meningitis?
Meningitis is an inflammatory disease of the leptomeninges. All major fungal pathogens have the capacity to cause meningitis. The incidence of fungal meningitis is increasing worldwide due to the increasing number of patients immunosuppressed by pharmacological agents and HIV infection
what is the epidemiology of fungal meningitis?
Strains vary geographically
More common amongst HIV positive patients
what is the aetiology of fungal meningitis?
Cryptococcus neoformans and Cryptococcus gattii are environmental saprophytes, found as budding yeasts in clinical specimens. C neoformans is found worldwide and has been isolated from soil contaminated by birds, especially pigeon excreta. C neoformans (serotypes A and D) usually causes infection in immunocompromised individuals. In contrast, C gattii (serotypes B and C) predominantly causes infection in apparently immunocompetent individuals, and is found primarily in tropical and subtropical regions, notably Australia and Papua New Guinea. C gattii has been found in association with several species of eucalyptus trees
what are the risk factors for fungal meningitis?
HIV infection Corticosteroid use Underlying chronic disease Exposure to disturned soil Imoaired cell mediated immunity Filipinos and african americans Neutropenia Neurosurgery Infants and neonates
what is the pathophysiology of fungal meningitis?
With the notable exception of Candida species, many fungal pathogens are thought to be acquired through inhalation. Meningeal involvement, either isolated or associated with widely disseminated infection, results from haematogenous dissemination from the lungs. This may occur either following primary infection, or after a period of controlled, latent infection, when host immunity is compromised. Protection from Cryptococcus neoformans and the endemic mycoses is associated with an active granulomatous inflammatory response, and depends on intact cell-mediated immunity involving both CD4 and CD8 T cells (Th1 pattern of cytokine release)
what are the key presentations of fungal meningitis?
Risk factors Progressive headache Severe headache Meningismus Symptoms of hydrocephalus Behavioural changes Reduced visual acuity and papilloedema
what are the first line and gold standard investigations for fungal meningitis?
CT or MRI head scan - normal or demonstrating enhancement, parenchymal lesions, hydrocephalus
Fungal blood cultures (3 sets) - positive or negative
Serum cryptococcal antigen test - positive in cases of cryptococcal meningitis
Serum and urine histoplasma antigen - positive in majority of cases of progressive disseminated histoplasmosis
Immunodiffusion tests and comolicant fixation test for coccidioidomycosis - typically positive in cases of coccidioidal meningitis
CSF opening pressure - elevated
CSF WBC - elevated
CSF protein - elevated
CSF glucose - low
CSF fluid india ink stain - positive in cryptococcal meningitis
CSF culture - pos or neg
CSF cryptococcal polysaccharide antigen test - positive in cryptococcal meningitis
CSF fluid histoplasma antigen and antibodies - positive in histoplasmal meningitis
CSF coccidioidal IgG antibodies - positive in coccidioidal meningitis
CSF galactomannan antigen test - positive in aspergillus meningitis
what are the differential diagnoses for fungal meningitis?
other meningitis
how is fungal meningitis managed?
Cryptococcal:
amphotericin B deoxycholate: 0.7 to 1 mg/kg/day intravenously for 2 weeks and flucytosine: 100 mg/kg/day orally given in divided doses every 6 hours for 2 weeks, antiretroviral therapy for HIV patients, therapeutic drainage of CSF
Histoplasmal:
amphotericin B liposomal: 5 mg/kg/day intravenously for 4-6 weeks and itraconazole: 200 mg orally twice to three times daily
Coccidioidal:
fluconazole: 400-1200 mg orally once daily, amphotericin B deoxycholate: see consultant for guidance on intrathecal dose, ventricular shunt replacement
Candidal:
amphotericin B deoxycholate: 0.7 to 1 mg/kg/day intravenously for 2-6 weeks and flucytosine: 50-100 mg/kg/day orally given in divided doses every 6 hours for 2-6 weeks, removal of prosthesis, fluconazole: 800 mg orally once daily
how is fungal meningitis monitored?
Cryptococcal meningitis:
Patients who have recovered from cryptococcal meningitis require careful follow-up for recurrence of symptoms.
Histoplasmal meningitis:
Cerebrospinal fluid (CSF) analysis should be repeated after 1 month, when amphotericin-B is replaced by an azole antifungal, and at 1 year, and if failure or relapse is suspected.
Coccidioidal meningitis:
CSF analysis is repeated monthly initially.
Candidal meningitis:
Due to the high rates of relapse in candidal meningitis, antifungal therapy must be given for a minimum of 4 weeks after resolution of all signs and symptoms
what are the complications of fungal meningitis?
amphotericin-B therapy side effects - anaemia, electrolytes disturbance and nephrotoxicity
Histoplasmosis
IRIS
what is the prognosis of fungal meningitis?
Mortality high, depending on strain, immunosuppressed (HIV) patients fair worse
