Evaluation of four molecular methods for the diagnosis of tuberculosis in pulmonary and blood samples from immunocompromised patients

Abstract

The present study analysed the concordance among four different molecular diagnostic methods for tuberculosis (TB) in pulmonary and blood samples from immunocompromised patients. A total of 165 blood and 194 sputum samples were collected from 181 human immunodeficiency virus (HIV)-infected patients with upper respiratory complaints, regardless of suspicious for TB. The samples were submitted for smear microscopy, culture and molecular tests: a laboratory-developed conventional polymerase chain reaction (PCR) and real-time quantitative PCR (qPCR) and the Gen-Probe and Detect-TB Ampligenix kits. The samples were handled blindly by all the technicians involved, from sample processing to results analysis. For sputum, the sensitivity and specificity were 100% and 96.7% for qPCR, 81.8% and 94.5% for Gen-Probe and 100% and 66.3% for Detect-TB, respectively. qPCR presented the best concordance with sputum culture [kappa (k) = 0.864)], followed by Gen-Probe (k = 0.682). For blood samples, qPCR showed 100% sensitivity and 92.3% specificity, with a substantial correlation with sputum culture (k = 0.754) and with the qPCR results obtained from sputum of the corresponding patient (k = 0.630). Conventional PCR demonstrated the worst results for sputa and blood, with a sensitivity of 100% vs. 88.9% and a specificity of 46.3% vs. 32%, respectively. Commercial or laboratory-developed molecular assays can overcome the difficulties in the diagnosis of TB in paucibacillary patients using conventional methods available in most laboratories.

Diagnostic accuracy of in-house real-time PCR assay for Mycobacterium tuberculosis: a systematic review and meta-analysis

“… Liquid and solid sp – 1451/0 1347 4 4 96 Inoue 2011 [ 25 ] Cross-sectional Singapore 414 414 55/128 IS6110 ? MGIT sp csf,pf,ti 104/66 43 3 8 116 Lee 2011 [ 26 ] Case-control Korea 370 129 53/76 senX3-regX3 ZN 3% Ogawa ti ti 53/76 47 1 16 65 Lira, LA 2012 [ 27 ] Case-control Brazil 165 165 66/99 IS6110 ZN LJ sp – 165/0 58 2 8 97 Lyra 2014 [ 28 ] Cross-sectional Brazil 181 194 11/91 IS6110 ZN LJ sp – 102/0 11 3 0 88 Miller 2011 [ 29 ] Cross-sectional America 90 112 89/23 IS6110 ? MGIT, LJ,7H11 sp,ba,bal.,ti In,ab,pf,ti 89/23 30 4 7 71 Rao 2016 [ 30 ...…”

Diagnóstico de tuberculosis pulmonar en lavado broncoalveolar: desempeño de la PCR en comparación con las pruebas microbiológicas de rutina

“…En extendidos de muestras respiratorias coloreados con Ziehl Neelsen, positivas para Mycobacterium tuberculosis, la sensibilidad y especificidad de los métodos moleculares son del 95% y el 98% respectivamente; en extendidos de muestras negativas, la sensibilidad es alrededor del 75% al 95% [34,35]. De esta manera, una prueba molecular positiva en un paciente con sospecha clínica soporta el diagnóstico de tuberculosis, al igual que un resultado de extendido coloreado con Ziehl Neelsen positivo con una prueba molecular positiva [36]; aunque una prueba molecular negativa no excluye la enfermedad en un paciente con sospecha clínica [37,38].…”