RESUMO
Having reported that pretreatment of serum samples with EDTA at 100 degrees C improved the sensitivity for the detection of Histoplasma antigenemia, we have evaluated this method for the detection of Coccidioides antigenemia. Urine and serum samples from patients with coccidioidomycosis were tested using the MVista Coccidioides enzyme immunoassay, and serum samples with and without EDTA-heat treatment were tested. Antigenemia was detected in 28.6% of patients whose samples were not EDTA-heat treated and in 73.1% of those whose samples were treated. Antigenuria was detected in 50% of patients. Specificity of 100% was obtained in healthy subjects, but cross-reactions were seen in 22.2% of patients with histoplasmosis or blastomycosis. EDTA-heat treatment improves the sensitivity for the detection of Coccidioides antigenemia.
Assuntos
Antígenos de Fungos/sangue , Coccidioides/imunologia , Coccidioidomicose/diagnóstico , Coccidioidomicose/imunologia , Infecções Oportunistas Relacionadas com a AIDS/diagnóstico , Infecções Oportunistas Relacionadas com a AIDS/imunologia , Infecções Oportunistas Relacionadas com a AIDS/microbiologia , Complexo Antígeno-Anticorpo/sangue , Blastomicose/diagnóstico , Blastomicose/imunologia , Estudos de Casos e Controles , Coccidioidomicose/complicações , Coccidioidomicose/microbiologia , Reações Cruzadas , Ácido Edético , Histoplasmose/diagnóstico , Histoplasmose/imunologia , Temperatura Alta , Humanos , Técnicas Imunoenzimáticas/métodos , Técnicas Imunoenzimáticas/estatística & dados numéricos , Sensibilidade e EspecificidadeRESUMO
The potential for cross-reaction between Cryptococcus neoformans and Histoplasma capsulatum in antigen assays was evaluated. We tested patient samples, spleens from infected mice, and purified polysaccharides in the MVista Histoplasma antigen enzyme immunoassay and cryptococcal antigen latex agglutination system for cross-reactivity, and none was observed.
Assuntos
Antígenos de Fungos/imunologia , Criptococose/diagnóstico , Cryptococcus neoformans/imunologia , Glucanos/imunologia , Histoplasma/imunologia , Histoplasmose/diagnóstico , Técnicas Imunoenzimáticas/métodos , Animais , Reações Cruzadas , Cryptococcus neoformans/isolamento & purificação , Histoplasma/isolamento & purificação , Humanos , Camundongos , Sensibilidade e EspecificidadeRESUMO
The second-generation Histoplasma antigen immunoassay is semiquantitative, expressing results as a comparison to a negative control, which requires repeat testing of the prior specimen with the current specimen to accurately determine a change in antigen. Reporting results in this manner often is confusing to the ordering physician and laboratory. Development of a quantitative assay could improve accuracy, reduce interassay variability, and eliminate the need to test the prior sample with the current sample in the same assay. Calibrators with known concentrations of Histoplasma antigen were used to quantitate antigen in specimens from patients with histoplasmosis and from controls. Samples from cases of disseminated histoplasmosis or other mycoses and controls were tested to evaluate the performance characteristics of the quantitative assay. Paired specimens were evaluated to determine if quantitation eliminated the need to test the current and prior specimens in the same assay to assess a change in antigen. The sensitivity in samples from patients with AIDS and disseminated histoplasmosis was 100% in urine and 92.3% in serum. Cross-reactions occurred in 70% of other endemic mycoses, but not in aspergillosis. Specificity was 99% in controls with community-acquired pneumonia, medical conditions in which histoplasmosis was excluded, or healthy subjects. A change in antigen level categorized as an increase, no change, or decrease based on antigen units determined in the same assay agreed closely with the category of change in nanograms/milliliter determined from testing current and prior specimens in different assays. Sensitivity, specificity, and interassay precision are excellent in the new third-generation quantitative Histoplasma antigen immunoassay.
Assuntos
Antígenos de Fungos/análise , Histoplasma/imunologia , Histoplasmose/diagnóstico , Técnicas Imunoenzimáticas/métodos , Antígenos de Fungos/sangue , Antígenos de Fungos/urina , Estudos de Casos e Controles , Reações Cruzadas , Histoplasmose/etiologia , Humanos , Técnicas Imunoenzimáticas/normas , Modelos Lineares , Curva ROC , Sensibilidade e EspecificidadeRESUMO
Given the recent report of a false-positive result in the Platelia Aspergillus enzyme immunoassay in a patient with cryptococcosis and in yeast extracts and purified galactoxylomannan of Cryptococcus neoformans, we evaluated culture extracts, purified polysaccharides, clinical specimens, and specimens from animals following experimental infection. Our results revealed no cross-reactions.
Assuntos
Aspergillus fumigatus/imunologia , Reações Cruzadas , Cryptococcus neoformans/imunologia , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/imunologia , Animais , Sequência de Carboidratos , Técnicas Imunoenzimáticas , Camundongos , Camundongos Endogâmicos BALB C , Polissacarídeos , CoelhosRESUMO
We observed false-positive results in the Platelia Aspergillus enzyme-linked immunoassay (EIA) for specimens from patients with histoplasmosis and mice with experimental infection. Platelia Aspergillus EIA-positive specimens were negative in the second-generation Histoplasma antigen EIA. Care must be taken to exclude histoplasmosis for patients with positive Platelia Aspergillus EIA results.