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Related Experiment Videos

Microscopy and latex antigen negative cryptococcal meningitis

I F Laurenson1, J D Ross, L J Milne

  • 1Department of Medical Microbiology, University of Edinburgh Medical School, UK.

The Journal of Infection
|November 20, 1998
PubMed
Summary
This summary is machine-generated.

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Cryptococcal meningitis can be missed by standard tests like latex antigen and microscopy, even in HIV patients. Culture is crucial for diagnosis, as yeast may appear acapsular initially but can form capsules later.

Area of Science:

  • Infectious Diseases
  • Mycology
  • Immunology

Background:

  • Cryptococcal meningitis is a serious opportunistic infection, particularly in individuals with advanced HIV.
  • Diagnosis often relies on cerebrospinal fluid (CSF) analysis, including latex antigen testing and direct microscopy.
  • Standard diagnostic methods may not always detect Cryptococcus neoformans, especially in certain clinical scenarios.

Observation:

  • An HIV-positive patient with cryptococcal meningitis initially tested negative via CSF latex antigen and direct microscopy.
  • Diagnosis was confirmed by CSF and urine cultures, revealing an apparently acapsular Cryptococcus neoformans strain.
  • A relapse occurred after 19 months, with capsulated yeasts detected by CSF microscopy and a positive latex antigen test.

Findings:

Related Experiment Videos

  • Subsequent cultures during relapse also yielded apparently acapsular isolates.
  • Retrospective cultures of all isolates in sterile CSF induced capsule formation.
  • In vitro studies showed that neutrophil-cryptococcus attachment required normal, non-heat-inactivated serum, suggesting a role for capsule expression.

    • Implications:

    • Negative results from latex antigen and direct microscopy do not definitively exclude cryptococcal meningitis.
    • The expression of Cryptococcus neoformans capsules can be variable and influenced by host or environmental factors.
    • Culture-based methods remain essential for accurate diagnosis and understanding the pathogenesis of cryptococcosis.