Urine-Based Nested PCR for the Diagnosis of Mycobacterium tuberculosis: A Comparative Study Between HIV-Positive and HIV-Negative Patients

Background: While tuberculosis (TB) can be diagnosed by microscopy and culture, the sensitivity of Ziehl-Neelsen staining is variable and culture results require 4-8 weeks to be determined. Polymerase chain reaction (PCR) and its modifications, including nested PCR, might be promising methods for the rapid diagnosis of TB. Objectives: This study aimed to evaluate the performance of nested PCR on urine samples of human immunodeficiency virus (HIV)positive and -negative patients with different manifestations of clinical TB. Methods: In a prospective study, three early-morning urine samples from 100 patients with pulmonary TB (PTB) or extrapulmonary TB (EPTB) were evaluated using a molecular target with insertion element IS6110, specific to the Mycobacterium tuberculosis genome, and nested PCR was performed. The results were analyzed with SPSS version 22. Results: A total of 100 patients, including 74 (74%) with PTB and 26 (26%) with EPTB, were enrolled. Positive smears were seen in 38 patients (38%). Lymph nodes were the most commonly involved organ in 14 of the 26 (53.8%) EPTB patients (13.5%). Seven (23.1%) of the EPTB patients were HIV-positive. Urine PCR was positive in only 28 patients (28%). Seven HIV-positive patients with PTB showed positive urine PCR results. Moreover, PCR results were positive in only one of the seven HIV-positive subjects with EPTB. Positive PCR results were found in 20 of the 73 HIV-negative patients (27.4%) and in 8 of the 27 HIV-positive patients (29.6%). Therefore, there was no significant difference between the HIV-negative and HIV-positive patients for urine PCR (sensitivity 29.6%, specificity 72.6%; positive and negative predictive values 28% and 72%, respectively; P = 0.138). Conclusions: Nested PCR showed the same sensitivity in HIV-positive and HIV-negative patients. It can be applied as a rapid technique for the diagnosis of TB.