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Original ArticleOpen Access
Serum Cryptococcal Antigen : Diagnostic Value in the Diagnosis of AIDS-Related Cryptococcal Meningitis
Asawavichienjinda T 
,
SitthiAmorn C ,
Tanyanont V
,
SitthiAmorn C ,
Tanyanont V Rationale: The incidences of HIV-AIDS patients with opportumstic infections of the
central nervous system are increasing. Of these, cryptococcal meningitis is the most important
and serious. A simple method for the diagnosis of cryptococcal meningitis is needed despite its
variable clinical features and the lack of a capacity in most health facilities in Thailand to exclude
it from other diseases especially mass lesions in the brain.
Objective: To identify the capability and cut off point of serum cryptococcal antigen for
diagnosis and screening of cryptococcal meningitis in HIV-AIDS patients.
Method: One hundred consecutive cases of HIV-AIDS patients suspected of having
central nervous system infections were prospectively recruited for the study. The serum of all
patients were examined for cryptococcal antigen by latex agglutination test, the Pastorex
Cryptococcus manufactured by Sanofi Diagnostic Pasteur, France. If a test was positive, the serum
dilution was carried out using 10-fold serial dilution. Every patient went through pre-defined
standard investigations to derive at a definite diagnosis. The gold standard for diagnosis of
cryptococcal meningitis was the presence of encapsulated yeast forms in the cerebrospinal fluid
or a positive culture for cryptococcal neoformans from the cerebrospinal fluid.
Result: Of 100 patients enrolled in this study, 58 patients had cryptococcal meningitis
and serum cryptococcal antigen was detectable in 60 patients. If the cut-off point for a positive
test was when the serum cryptococcal antigen titer was more than zero, then, the sensitivity of the
test was 91.4 per cent, the specificity was 83.3 per cent, likelihood ratio if test positive (LR+) was
5.47, likelihood ratio if test negative (LR-) was 0.1, false positive was 16.7 per cent, false negative
was 8.6 per cent.
Conclusion: We conclude that serum cryptococcal antigen is a simple and rapid screening
method for diagnosis of cryptococcal meningitis.
Key word : Cryptococcal Meningitis - AIDS-Related - Opportunistic Infection - Diagnosis - Serum Cryptococcal Antigen
central nervous system are increasing. Of these, cryptococcal meningitis is the most important
and serious. A simple method for the diagnosis of cryptococcal meningitis is needed despite its
variable clinical features and the lack of a capacity in most health facilities in Thailand to exclude
it from other diseases especially mass lesions in the brain.
Objective: To identify the capability and cut off point of serum cryptococcal antigen for
diagnosis and screening of cryptococcal meningitis in HIV-AIDS patients.
Method: One hundred consecutive cases of HIV-AIDS patients suspected of having
central nervous system infections were prospectively recruited for the study. The serum of all
patients were examined for cryptococcal antigen by latex agglutination test, the Pastorex
Cryptococcus manufactured by Sanofi Diagnostic Pasteur, France. If a test was positive, the serum
dilution was carried out using 10-fold serial dilution. Every patient went through pre-defined
standard investigations to derive at a definite diagnosis. The gold standard for diagnosis of
cryptococcal meningitis was the presence of encapsulated yeast forms in the cerebrospinal fluid
or a positive culture for cryptococcal neoformans from the cerebrospinal fluid.
Result: Of 100 patients enrolled in this study, 58 patients had cryptococcal meningitis
and serum cryptococcal antigen was detectable in 60 patients. If the cut-off point for a positive
test was when the serum cryptococcal antigen titer was more than zero, then, the sensitivity of the
test was 91.4 per cent, the specificity was 83.3 per cent, likelihood ratio if test positive (LR+) was
5.47, likelihood ratio if test negative (LR-) was 0.1, false positive was 16.7 per cent, false negative
was 8.6 per cent.
Conclusion: We conclude that serum cryptococcal antigen is a simple and rapid screening
method for diagnosis of cryptococcal meningitis.
Key word : Cryptococcal Meningitis - AIDS-Related - Opportunistic Infection - Diagnosis - Serum Cryptococcal Antigen
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