L Portillo-Gómez1, M V Murillo-Neri, J Gaitan-Mesa, E G Sosa-Iglesias. 1. Laboratorio de Microbiología y Parasitología, Departamento de Microbiología y Patología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico. lpgegsi@prodigy.net.mx
Abstract
SETTING: Cervical tuberculous lymphadenitis (CTBL) diagnosis is a critical problem due to the difficulty in culturing Mycobacterium tuberculosis. OBJECTIVE: To evaluate a nested polymerase chain reaction (nPCR) for the diagnosis of CTBL. DESIGN: Thirty-eight children initially diagnosed on the basis of clinical and laboratory criteria as suffering from chronic cervical lymphadenitis were included in the study. Forty-one cervical lymph node specimens were analysed by bacterial staining, culture, cytology or histopathology. The IS6110 DNA sequence of M. tuberculosis complex was amplified by nPCR. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and efficiency were determined for the assay. RESULTS: The sensitivity of nPCR was 96%, the specificity 93%, PPV 96%, NPV 93% and efficiency 95%. Among 25 patients with CTBL, six presented a 'definite' diagnosis (24%) according to established criteria; 10 were classified as 'highly probable' cases (40%) and nine presented a 'possible' diagnosis (36%). The sensitivity of nPCR was higher than the sensitivity of staining (15%), culture (26%) and cytology or histopathology (62.5%) (95%CI P < 0.05, chi(2) P < 0.001). CONCLUSION: The nPCR used is a highly sensitive, specific and efficient method for the diagnosis of CTBL among children.
SETTING:Cervical tuberculous lymphadenitis (CTBL) diagnosis is a critical problem due to the difficulty in culturing Mycobacterium tuberculosis. OBJECTIVE: To evaluate a nested polymerase chain reaction (nPCR) for the diagnosis of CTBL. DESIGN: Thirty-eight children initially diagnosed on the basis of clinical and laboratory criteria as suffering from chronic cervical lymphadenitis were included in the study. Forty-one cervical lymph node specimens were analysed by bacterial staining, culture, cytology or histopathology. The IS6110 DNA sequence of M. tuberculosis complex was amplified by nPCR. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and efficiency were determined for the assay. RESULTS: The sensitivity of nPCR was 96%, the specificity 93%, PPV 96%, NPV 93% and efficiency 95%. Among 25 patients with CTBL, six presented a 'definite' diagnosis (24%) according to established criteria; 10 were classified as 'highly probable' cases (40%) and nine presented a 'possible' diagnosis (36%). The sensitivity of nPCR was higher than the sensitivity of staining (15%), culture (26%) and cytology or histopathology (62.5%) (95%CI P < 0.05, chi(2) P < 0.001). CONCLUSION: The nPCR used is a highly sensitive, specific and efficient method for the diagnosis of CTBL among children.