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Updated: Apr 4, 2026
Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
Published on: September 25, 2014
Pitfalls in Serological Diagnosis of Cryptococcus gattii Infections
Kathrin Tintelnot1, Ferry Hagen2, Chang Ok Han3
1Division of Mycology, Robert Koch Institute, Berlin, Germany tintelnotk@rki.de.
Insights
Certain latex agglutination tests (LATs) show insufficient sensitivity for detecting Cryptococcus gattii infections. Broader specificity assays are recommended for accurate cryptococcal antigen screening to prevent delayed diagnosis.
Area of Science:
- Medical Mycology
- Infectious Diseases
- Diagnostic Immunology
Background:
- Cryptococcal antigen detection is crucial for diagnosing Cryptococcus infections.
- Cryptococcus gattii is expanding geographically, posing new diagnostic challenges.
- Existing latex agglutination tests (LATs) may lack sensitivity for certain Cryptococcus species.
Purpose of the Study:
- To evaluate the sensitivity of commercially available latex agglutination tests (LATs) and a lateral flow assay (LFA) for detecting Cryptococcus gattii antigen.
- To assess the diagnostic performance of these assays in patients with C. gattii or hybrid Cryptococcus infections.
- To highlight the implications of assay sensitivity on the diagnosis of cryptococcosis.
Main Methods:
- Cerebrospinal fluid and/or serum samples from 10 patients with C. gattii or hybrid Cryptococcus infections were tested.
- Three LATs (IMMY Latex-Crypto, Pastorex Crypto Plus, Remel Cryptococcus Antigen Test Kit) and one LFA (Immuno-Mycologics) were utilized.
- Assay performance was evaluated based on antigen detection sensitivity.
Main Results:
- Monoclonal antibody-based LATs demonstrated insufficient sensitivity, failing to detect four out of 10 C. gattii infections.
- One hybrid C. gattii and C. neoformans infection was also missed by these sensitive LATs.
- This highlights a significant risk of delayed diagnosis due to inadequate assay sensitivity.
Conclusions:
- Current LATs, particularly those using monoclonal antibodies, exhibit limited sensitivity for C. gattii and its hybrids.
- The geographical spread of C. gattii necessitates the use of diagnostic assays with broad specificity and sensitivity.
- Preliminary screening for cryptococcal antigen should employ methods capable of detecting both C. neoformans and C. gattii, including hybrids, to ensure timely and accurate diagnosis.
Abstract:
The detection of cryptococcal antigen by latex agglutination tests (LATs), enzyme-linked immunoassays (ELISA), or lateral flow assay (LFA) is an important tool for diagnosis of a Cryptococcus infection. Cerebrospinal fluid and/or serum samples of 10 patients with cryptococcosis due to Cryptococcus gattii or a hybrid of Cryptococcus neoformans and C. gattii were examined by three LATs (the IMMY Latex-Crypto(®) test, the Pastorex(TM) Crypto Plus, and the Remel Cryptococcus Antigen Test Kit) and the LFA made by Immuno-Mycologics. LATs based on monoclonal antibodies (mAbs) like the Pastorex(TM) Crypto Plus or the Remel Cryptococcus Antigen Test Kit turned out to have an insufficient sensitivity to detect four out of 10 C. gattii infections, including one infection by a hybrid between C. gattii and C. neoformans. Reflecting the ongoing expansion of C. gattii in geographical zones outside of tropical and subtropical areas like Mediterranean countries, Vancouver Island (British Columbia, Canada) and the Pacific Northwest region (USA), these findings are alarming because of the risk of delayed diagnosis of infections caused by C. gattii. Therefore, the preliminary serological screening for cryptococcal antigen in the case of a suspected Cryptococcus infection should be performed by using an assay with a broad range specificity and sensitivity for C. neoformans and C. gattii, including their hybrids.
