A comparison of nontreponemal tests in cerebrospinal fluid for neurosyphilis diagnosis: equivalent detection of specific antibodies / Uma comparação de testes não treponêmicos no líquido cefalorraquidiano para diagnóstico de neurossífilis: detecção equivalente de anticorpos específicos

ABSTRACT Syphilis is a re-emerging sexually-transmitted infection, caused by the spirochete Treponema pallidum, that may penetrate early into the central nervous system. The venereal disease research laboratory test (VDRL) on the cerebrospinal fluid (CSF) is the most widely used for neurosyphilis diagnosis. We evaluated the performance of two other nontreponemal tests (rapid plasma reagin [RPR] and unheated serum reagin [USR] tests) in comparison with the VDRL in CSF. Methods: We analyzed CSF samples from 120 individuals based on VDRL reactivity in the CSF and the clinical picture of neurosyphilis. Results: High inter-rater reliability was found among all three tests, with equivalent sensitivity and specificity. Intraclass correlation coefficient for absolute agreement was 1 for VDRL versus USR, 0.99 for VDRL versus RPR, and 0.99 for RPR versus USR. Conclusions: Rapid plasma reagin and unheated serum reagin tests were identified as excellent alternatives for neurosyphilis diagnosis.

RESUMO A sífilis é uma infecção reemergente sexualmente transmissível pelo espiroqueta Treponema pallidum, que pode penetrar precocemente no sistema nervoso central. O teste venereal disease research laboratory test (VDRL) no líquido cefalorraquidiano (LCR) é o mais amplamente utilizado para diagnóstico de neurossífilis. Avalia-se o desempenho de dois outros testes não treponêmicos (rapid plasma reagin - RPR and unheated serum reagin - USR tests) em comparação ao VDRL no LCR. Métodos: Foram analisadas amostras de LCR de 120 indivíduos com base no quadro clínico compatível com neurossifilis e reatividade no VDRL no LCR. Resultados: Os testes apresentaram elevada concordância. O coeficiente de correlação intraclasse para concordância absoluta foi de 1 para VDRL versus USR, 0,99 para VDRL versus RPR e 0,99 para RPR versus USR. Conclusões: Os testes rapid plasma reagin e unheated serum reagin foram identificados como excelentes alternativas para o diagnóstico de neurossífilis.

Evaluation of Lionex TB kits and mycobacterial antigens for IgG and IgA detection in cerebrospinal fluid from tuberculosis meningitis patients

To evaluate commercial Lionex TB together with four antigens of Mycobacterium tuberculosis (MPT-64, MT10.3, 16 kDa and 38 kDa) for IgG and IgA cerebrospinal fluid (CSF) detection in the diagnosis of tuberculosis meningitis (TBM) with CSF negative acid-fast bacilli staining, 19 cases of TBM, 64 cases of other infectious meningoencephalitis and 73 cases of other neurological disorders were tested by enzyme linked immunosorbent assay. IgA-MPT-64 and IgG Lionex showed the highest sensitivities, specificities, positive predictive value and negative predictive value (63.2 percent, 47.4 percent; 95 percent, 93.7 percent; 40 percent, 98 percent and 28.4 percent, 97.1 percent, respectively). However, while grey zone was 12.7 percent and 6 percent, respectively, lowering sensitivity but maintains high specificity (> 95 percent). High protein concentration in CSF was associated with antibody positivity CSF/HIV+ which did not influence the sensitivity of both tests. To our knowledge, this is the first description of IgA-MPT-64 and IgG Lionex antibodies in CSF-TBM and, although there is good specificity, adjustments are needed based on antigen composition to enhance sensitivity.