Mechanisms of infection by the human fungal pathogen Cryptococcus neoformans.

Brain infection by the fungus Cryptococcus neoformans results in inflammation of the meninges and brain parenchyma, a condition known as meningoencephalitis. One million people are estimated to suffer cryptococcal meningitis globally and >60% of these cases die within 3 months of diagnosis. Humans are believed to contract infection by inhalation of spores or dried yeast cells, which subsequently colonize the lung tissue. In the lungs, cryptococci may be cleared by the lung phagocytes, stay latent, cause pulmonary infection and/or disseminate to other body parts, preferentially the brain, culminating in cryptococcal meningoencephalitis. In this review, we discuss the pathogenesis of C. neoformans from the environment to the brain, the current understanding of the mechanisms of cryptococcal transmission into the brain and cryptococcal meningitis. We also give an insight into future cryptococcosis research and the development of novel therapies.

[Cryptococcus neoformans meningoencephalitis in immunocompetent schoolchildren]. / Meningoencefalitis por Criptococcus neoformans en escolares inmunocompetentes.

Cryptococcus neoformans meningoencephalitis is the most common fungal central nervous system infection, in people affected by the human immunodeficiency virus. It is rare in inmunocompetent children and it is often fatal. It predominates in males at a ratio of 3 to 1. We describe the cases of two school children, one male and one female, with history of contact with pigeons (Columba livea), whose clinical symptoms were fever, headache, photophobia, diplopia, ataxia and meningeal signs, with unilateral involvement of cranial nerve VI. The diagnosis was established by the isolation of Cryptococcus neoformans in culture, staining with India ink and evidence of latex antigen agglutination in the cerebrospinal fluid. The determination of antibodies to human immunodeficiency virus and quantification of CD4, CD8 and T lymphocyte cells, were normal. In the first case, a chest X-ray showed a round mass, circumscribed in the bottom half of the left lung. A brain MRI revealed an image compatible with a nodular cryptococcoma in the parietal region. A pattern of intracranial hypertension was established, with papilledema and bilateral amaurosis, that evolved unsatisfactorily, with the subsequent death of the patient. Both were treated with amphotericin B (1 mg/Kg/day) or fluconazole (6 mg/Kg/day). The second case had a favorable evolution. The Crypotococcus neoformans is not a common fungus in inmunocompetent children. Early detection of the disease and appropriate treatment is essential to achieve a better prognosis ot the disease.

Zoonotic transmission of Cryptococcus neoformans from a magpie to an immunocompetent patient.

We report a case of cryptococcal meningitis in an immunocompetent female patient with exposure to a pet magpie (Pica pica). Genetically indistinguishable isolates were cultured from the cerebrospinal fluid of the patient and excreta of the bird. Our data strongly suggest zoonotic transmission of Cryptococcus neoformans var. grubii from a magpie to this patient.

Mother-to-child transmission of cryptococcus neoformans.

Cryptococcal meningitis was diagnosed in a 92-day-old boy who was not HIV-1-infected and who survived after treatment, although with hydrocephalus. The mother was HIV-1-infected, delivered prematurely, had peripartum cryptococcal meningitis and died 14 days postpartum. There was no other possible source for cryptococcal infection in this infant. This is believed to be a case of mother-to-child transmission of cryptococcosis.

Cryptococcal meningitis in renal transplant patients associated with environmental exposure.

Fungal infections in renal transplant recipients are less common than bacterial infections; however, the morbidity from fungal infections is high. There is limited information in the literature concerning post-transplantation cryptococcal infection due to environmental exposure of patients living in high-risk areas. We report three patients who were diagnosed with cryptococcal meningitis after kidney transplantation. Cryptococcal titers prior to transplant surgery were negative in all three patients. These patients all lived in rural areas and demonstrated evidence of environmental exposure leading to subsequent cryptococcal meningitis. All patients had exposure to pigeon and chicken excreta and, after treatment, two patients are alive and well with excellent allograft function. The third patient has marginal renal function but is currently not on dialysis. Early diagnosis is essential for salvage from these potentially lethal infections. Intense headache was a prominent feature in the clinical presentation of our patients, and should signal the need for early sampling and culture of spinal fluid. Meningismus was not present in any of our patients, even when other systemic symptoms were identified. We recommend a high index of suspicion post-transplantation for all patients who may have environmental or occupational exposure to cryptococcus. If infection is detected quickly and treatment instituted promptly, patient recovery and allograft survival are possible. Long-term therapy with fluconazole, a non-nephrotoxic agent, should permit eradication of the infection with preservation of kidney function.

First environmental isolation of Cryptococcus neoformans var. neoformans and var. gatti from the Gharbia Governorate, Egypt.

Flowers from two Eucalyptus camaldulensis trees in the Qutur area and one tree from the Tanta area yielded three isolates of Cryptococcus neoformans var. gattii. Pigeon and sparrow droppings were also investigated for the occurrence of C. neoformans within the study area. Ninety five isolates of the neoformans variety of C. neoformans were recovered from 550 samples of avian droppings.

Cryptococcal ventricular-peritoneal shunt infection: clinical and epidemiological evaluation of two closely associated cases.

OBJECTIVE: To determine the cause of meningitis associated with Cryptococcus neoformans in two patients with recent ventricular-peritoneal (VP) shunt placement. DESIGN: A retrospective review of materials, records, and concurrent cases of VP shunt procedures. Isolates of C neoformans from each patient were submitted for analysis by colony morphology, biochemical testing, and karyotyping by pulsed-field electrophoresis. SETTING: Two 400-bed community hospitals. PATIENTS: Two immunocompetent patients presented with symptoms of progressive hydrocephalus in August 1991. Each received a VP shunt on the same day by the same surgeon using materials from a common vendor and hospital. RESULTS: Both patients presented within six to eight weeks with symptoms of fever, headache, rash, and cultures of cerebrospinal fluid (CSF) that yielded C neoformans. Each patient recovered after therapy with amphotericin B and flucytosine followed by several months of fluconazole, although one required replacement of the VP shunt for cure. Review of each patient's history and CSF characteristics at the time of shunt placement suggested reactivation of a preexisting infection. Isolates of C neoformans from each patient were submitted for analysis by colony morphology, biochemical testing, and karyotyping by pulsed-field electrophoresis. Each isolate was found to be unique by chromosomal karyotyping. CONCLUSIONS: Our data and previous reports suggest that cryptococcal VP shunt infections appear to be a complication of shunts placed in previously infected persons rather than nosocomial transmission of cryptococcus during placement.