Clinical usefulness of the nested polymerase chain reaction in the diagnosis of extrapulmonary tuberculosis.

OBJECTIVE: To evaluate the effectiveness of nested polymerase chain reaction (PCR) for diagnosis of extrapulmonary tuberculosis (ETB), as well as the impact of PCR results on clinical management. MATERIALS AND METHODS: We conducted a study of nested PCR tests in 45 patients and a review of patient hospital files, calculating sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). RESULTS: PCR was positive in 51% of cases; PCR sensitivity for diagnosing TB was 86%, specificity was 79%, PPV was 76%, and NPV was 88%. When solely analyzing urine samples, sensitivity and NPV increased to 100%. PCR exerted an influence on management in 27% of patients. CONCLUSIONS: PCR for rapid diagnosis of extrapulmonary TB has an adequate effect, which improves when performed on urine. The results of PCR exerted an acceptable impact on the clinical management of these patients.

Polymorphisms in tumor necrosis factor and lymphotoxin A in tuberculosis without and with response to treatment.

This study compared the frequency of the genetic polymorphisms of tumor necrosis factor (TNF) in pulmonary tuberculosis without and with response to treatment. We carried out an observational, prospective, comparative study. Three groups were studied: healthy subjects, responders, and non-responders to directly observed treatment short-course. We took a peripheral blood sample for identification of polymorphic genotypes TNF -308G/A and lymphotoxin A (LTA) +252G/A by polymerase chain reaction, and their later digestion with the Nco1 restriction enzyme. We studied a total of 138 subjects: 42 (non-responders) and 48 in each of the remaining groups. Healthy subjects had significantly high frequency of the LTA +252A allele compared to groups of patients and could be related with protection from the disease. Patients had higher frequency of the non-polymorphic allele LTA +252G than healthy subjects. With regard to LTA +252G/A genotype, we did find a significant difference with a greater frequency in the group of patients. The LTA +252G/A genotype was associated with impaired response to treatment.

Clinical usefulness of the nested polymerase chain reaction in the diagnosis of extrapulmonary tuberculosis / Utilidad clínica de la reacción en cadena de la polimerasa anidada para el diagnóstico de tuberculosis extrapulmonar

OBJECTIVE:To evaluate the effectiveness of nested polymerase chain reaction (PCR) for diagnosis of extrapulmonary tuberculosis (ETB), as well as the impact of PCR results on clinical management. MATERIALS AND METHODS:We conducted a study of nested PCR tests in 45 patients and a review of patient hospital files, calculating sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). RESULTS:PCR was positive in 51% of cases; PCR sensitivity for diagnosing TB was 86%, specificity was 79%, PPV was 76%, and NPV was 88%. When solely analyzing urine samples, sensitivity and NPV increased to 100%. PCR exerted an influence on management in 27% of patients. CONCLUSIONS:PCR for rapid diagnosis of extrapulmonary TB has an adequate effect, which improves when performed on urine. The results of PCR exerted an acceptable impact on the clinical management of these patients.

OBJETIVO:Evaluar la eficacia de la reacción en cadena de la polimerasa (PCR) anidada para el diagnóstico de tuberculosis extrapulmonar, así como el impacto de sus resultados en el manejo clínico. MATERIAL Y MÉTODOS: Se realizó PCR anidada en 45 pacientes y se llevó a cabo la revisión de expedientes. Se calculó sensibilidad, especificidad, valor predictivo positivo (VPP) y valor predictivo negativo (VPN). RESULTADOS:La PCR fue positiva en 51% de los casos, la sensibilidad fue de 86%, la especificidad de 79%, el VPP de 76% y el VPN de 88%. Al analizar solamente las muestras de orina, la sensibilidad y VPN se incrementaron a 100%. La PCR influyó en el manejo de 27% de los pacientes. CONCLUSIONES:La PCR para el diagnóstico rápido de TB extrapulmonar tiene una eficacia adecuada, la cual mejora cuando se realiza en orina. El resultado de la PCR tuvo un impacto aceptable en el manejo clínico de estos pacientes.