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.