Comparación de adenosina deaminasa y detección de anticuerpos anti-antígeno A60 para el diagnóstico de meningitis tuberculosa / A comparative study for adenosine deaminase and anti-antigen A-60 antibodies detection for the diagnosis of tuberculous meningitis

Background: Diagnosis of tuberculous meningitis (TBM) is hampered by the lack of rapid and accurate diagnostic tools. We evaluated the immunological response to Mycobacterium tuberculosis anti-A60 antibodies in cerebrospinal fluid (CSF) in comparison to adenosine deaminase (ADA) determination, for the diagnosis of TBM. Methods: A total of 63 CSF samples were analyzed by indirect ELISA for the detection of anti- A60 IgG, IgM and IgA. These include samples from 17 patients with confirmed TBM and 46 control patients with other infections. Results: The mean individual anti-A60 IgM, IgG and IgA CSF antibody titers were significantly higher in TBM in comparison with control groups (p < 0.01). The best discriminatory CSF antibody for confirming TBM diagnosis was IgM, with an area under the receiver operating characteristic curve of 0.928 (95%CI 0.834-0.978), compared to 0.863 (95% CI: 0.752-0.936) for ADA testing (p = NS). The sensitivity of anti- A60 IgM CSF antibody titers (cutoff > 0.06 U/ml) was 94.1% compared to 88.2% for ADA (cutoff > 6.2 U/ml), p = NS. Both anti A60 IgM and ADA showed the same moderate specificity (80.4%). Two cases of TBM were correctly identified by anti-A60 IgM but missed by ADA. Conclusion: The ELISA test for anti-antigen A60 antibodies (IgM) is a rapid and sensitive tool for the rapid diagnosis of TBM that can be a complement to ALDA determination. The specificity of both tests is still a limitation in TBM diagnosis.

Antecedentes: El diagnóstico de meningitis tuberculosa (MTBC) se ve limitado por la ausencia de técnicas diagnósticas rápidas y precisas en líquido cefalorraquídeo (LCR). En este estudio evaluamos la respuesta inmunoló-gica de anticuerpos anti-antígeno A60 de Mycobacterium tuberculosis en LCR en comparación a la determinación de adenosina deaminasa (ADA). Métodos: Un total de 63 muestras de LCR fueron estudiadas mediante ELISA indirecto para detección de IgG, IgM e IgA anti-A60. Estas muestras incluyeron 17 casos de MTBC confirmada y 46 controles con otras infecciones. Resultados: Los títulos de IgG, IgM e IgA anti A-60 resultaron significativamente superiores en casos de MTBC versus controles (p > 0,01). El anticuerpo con mej or poder discriminatorio resultó IgM, con un área bajo la curva ROC de 0,928 (95%IC 0,8340,978), comparado a 0,863 (95% IC: 0,752-0,936) para ADA (p = NS). La sensibilidad de IgM anti-A60 (nivel de corte > 0,06 U/ml) fue de 94,1% versus 88,2% para ADA (nivel de corte > 6,2 U/ml), p = NS. Ambos IgM anti-A60 y ADA presentaron la misma especificidad baja-moderada (80,4%). Dos casos de MMTBC fueron correctamente identificados por IgM anti-A60 pero no por ALDA. Conclusión: La detección de anticuerpos anti-A60 (IgM) puede ser de ayuda en el diagnostico de MTBC en forma complementaria a la determinación de ALDA. La baja especificidad de ambos tests constituye su principal limitante.

[A comparative study for adenosine deaminase and anti-antigen A-60 antibodies detection for the diagnosis of tuberculous meningitis]. / Comparación de adenosina deaminasa y detección de anticuerpos anti-antígeno A60 para el diagnóstico de meningitis tuberculosa.

BACKGROUND: Diagnosis of tuberculous meningitis (TBM) is hampered by the lack of rapid and accurate diagnostic tools. We evaluated the immunological response to Mycobacterium tuberculosis anti-A60 antibodies in cerebrospinal fluid (CSF) in comparison to adenosine deaminase (ADA) determination, for the diagnosis of TBM. METHODS: A total of 63 CSF samples were analyzed by indirect ELISA for the detection of anti- A60 IgG, IgM and IgA. These include samples from 17 patients with confirmed TBM and 46 control patients with other infections. RESULTS: The mean individual anti-A60 IgM, IgG and IgA CSF antibody titers were significantly higher in TBM in comparison with control groups (p < 0.01). The best discriminatory CSF antibody for confirming TBM diagnosis was IgM, with an area under the receiver operating characteristic curve of 0.928 (95%CI 0.834-0.978), compared to 0.863 (95% CI: 0.752-0.936) for ADA testing (p = NS). The sensitivity of anti- A60 IgM CSF antibody titers (cutoff > 0.06 U/ml) was 94.1% compared to 88.2% for ADA (cutoff > 6.2 U/ml), p = NS. Both anti A60 IgM and ADA showed the same moderate specificity (80.4%). Two cases of TBM were correctly identified by anti-A60 IgM but missed by ADA. CONCLUSION: The ELISA test for anti-antigen A60 antibodies (IgM) is a rapid and sensitive tool for the rapid diagnosis of TBM that can be a complement to ALDA determination. The specificity of both tests is still a limitation in TBM diagnosis.

[Inflammatory reconstitution immune syndrome associated to antiretroviral therapy and meningeal cryptococcosis]. / Síndrome de restauración inmune asociado a tratamiento antirretroviral y criptococosis meníngea. Caso clínico.

The objective of high activity antiretroviral therapy (HAART) in patients with AIDS, is to obtain immune restoration. This means a reduction of the viral load and restitution of the CD4 cell count. A decreased rate of HIV replication improves both the number and function of CD4 cells. Nevertheless, this treatment sometimes results in the reappearance of previous symptoms from treated conditions due to opportunistic infections (ie: tuberculosis, criptococcosis, hepatitis, Pneumocystis jirovesi, toxoplasmosis, etc) or non infectious condition such as sarcoidosis, Graves disease or Kaposi sarcoma. This is known as Inflammatory Reconstitution Immune Syndrome (IRIS). We report a 37 year-old woman in stage C3-AIDS with a previous criptococcal meningitis. She was treated, achieving a marked improvement with treatment and subsequent suppressive therapy with fluconazole 200 mg/day. IRIS appeared after 8 months of ongoing antiretroviral therapy with immune restoration with the development of aseptic meningitis and intracranial hypertension. The opportunistic agent could not be identified by cultures. Additional laboratory tests excluded toxoplasmosis, tuberculosis, bacterial cerebral abscesses, syphilitic cerebral gummas, and lymphoma. Brain CT and magnetic resonance studies were compatible with brain vasculitis and leptomeningitis. The patient condition improved with general measures, such as a repeated lumbar punctures and non steroidal anti-inflammatory drugs. We conclude that this patient had an IRIS due to a Cryptococcus neoformans antigen.

Terapia antiretroviral en pacientes con VIH: una respuesta inesperada / Antiretroviral therapy in HIV infected patients: an unexpected response

En relación al uso de terapia antiretroviral (TAR) en pacientes con VIH, se ha descrito un síndrome clínico tras el inicio o cambio de la terapia, denominado Síndrome de Reconstitución Inmune (SRI). Se trata de un cuadro caracterizado por el deterioro inesperado en el estado clínico de los pacientes, producto de una respuesta inflamatoria exagerada en contra de patógenos oportunistas, tumores o antígenos propios del paciente. El manejo del SRI, incluye uso de antimicrobianos específicos y/o terapia antiinflamatoria, sin ser necesaria la descontinuación de la TAR. Es prioritario en la investigación del SRI, el desarrollo de estrategias de prevención, métodos de pesquisa de factores de riesgo y criterios diagnósticos.

Related to the antiretroviral therapy in HIV infected persons, it has been described a clinical syndrome called the Immune Restoration Disease (IRD). It appears after the initiation or switching of the therapy and is characterized by an exaggerated inflammatory response after the improvement of the immune system, which leads to an unexpected worsening of the clinical condition of the patient. This inflammatory response is presented against opportunist pathogens, tumors or the patient’s own antigens. The management of IRD often requires the use of anti-microbial and/or anti-inflammatory therapy, without interruption of the antiretroviral therapy. It is a priority for future research, to develop strategies to prevent IRD, risk assessment methods and diagnostic criteria.