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

Abstract

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.Key words: tuberculosis; extrapulmonary tuberculosis; polymerase chain reaction; nested polymerase chain reaction ResumenObjetivo. 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.Palabras clave: tuberculosis; tuberculosis extrapulmonar; reacción en cadena de la polimerasa; reacción en cadena de la polimerasa anidada (

Diagnosis of extrapulmonary tuberculosis by PCR

“…To confirm genitourinary TB (both in men and women) in urine samples, PCR targeting MPT-64 protein gene has earlier been demonstrated to be the most sensitive indicator as compared to intravenous urography, bladder biopsy or urine culture (Hemal et al, 2000). High sensitivity up to 100% has been claimed by nested PCR based on MTP-40 protein gene of M. tuberculosis (Garcia-Elorriaga et al, 2009). High sensitivity up to 100% has been claimed by nested PCR based on MTP-40 protein gene of M. tuberculosis (Garcia-Elorriaga et al, 2009).…”

Detection of 123 bp fragment of insertion element IS6110 Mycobacterium tuberculosis for diagnosis of extrapulmonary tuberculosis

“…Earlier studies reported [16][17][18][19] the increased positivity by PCR targeting the IS6110 element in specimens of EPTB and 63%, 51%, 77% and 62% as positivity among EPTB specimens. In comparison, we found 72.6% positivity by PCR targeting the IS6110 element in specimens of EPTB.…”

“…Less sensitivity may arise when specimens contain very few mycobacteria. García et al, [17] Kolk et al, [21] Haron et al, [22] Pietrzak et al, [23] Singh et al [24] and Shukla et al [25] showed the detection of M. tuberculosis by PCR results as summarized in Table 2. Reported studies showed data of the positivity of the M. tuberculosis complex by IS6110 PCR on 50 to 250 sample size of EPTB case.…”

Super-paramagnetic iron oxide nanoparticles for use in extrapulmonary tuberculosis diagnosis

“…Extrapulmonary TB (ETB) is an even greater diagnostic challenge than primary TB (PTB), as it occurs less frequently and with little liberation of bacilli. Thus, the combination of small numbers of bacilli and inaccessible sites makes bacteriological confirmation of extrapulmonary TB more difficult [7]. Also in ETB, fewer bacilli cause much greater damage secondary to bacterial invasion of solid organs, which induces severe immunological reactions.…”

“…Also in ETB, fewer bacilli cause much greater damage secondary to bacterial invasion of solid organs, which induces severe immunological reactions. Thus, the combination of small numbers of bacilli and inaccessible sites makes bacteriological confirmation of extrapulmonary TB more difficult [7].…”