Detection of Pulmonary Tuberculosis in HIV Patients: A Comparison of LJ Culture and TrueNat Methods

Abstract

ntroduction:Mycobacterium tuberculosis (MTB) is the airborne pathogen responsible for tuberculosis (TB), a disease that primarily affects the lungs. The prevalence of active tuberculosis is significantly higher—15 to 22 times—among individuals living with HIV. Although culture on Löwenstein-Jensen (LJ) medium remains the gold standard for TB diagnosis, it is time-consuming and requires meticulous techniques to yield positive results. In contrast, the more straightforward and rapid Nucleic Acid Amplification Technique (TrueNat) not only facilitates early diagnosis of tuberculosis but also has the capability to detect drug-resistant strains, making it particularly beneficial for HIV-infected patients due to its enhanced speed and sensitivity.

Aim and Objective: present study aims to conduct a comparative analysis of LJ culture and TrueNat for the detection of pulmonary TB in sputum samples, particularly in the context of co-infection with HIV patients.

Materials and Methods: This prospective study was conducted over a 12-month period from March 2023 to March 2024 in the Department of Microbiology. A total of 100 sputum samples from individuals with suspected pulmonary tuberculosis were screened. Each sample was tested for HIV using a rapid test card, and both LJ culture and the TrueNat test were performed. Additionally, five milliliters of blood were drawn from TB patients confirmed positive and processed according to the guidelines of the National AIDS Control Organization (NACO).

Results: In this study, TrueNat detected TB in 60 (60%) of the 100 sputum samples, whereas LJ culture identified 53 (53%). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of LJ culture were 86%, 98%, 98%, and 82%, respectively. TrueNat identified 10 patients as having multidrug-resistant TB (MDR-TB), with sensitivity, specificity, PPV, and NPV of 94%, 79%, 83%, and 93%, respectively. Among the positive pulmonary TB cases, six patients were HIV-positive.

Conclusion:While LJ culture remains a reliable and cost-effective diagnostic method, TrueNat offers superior sensitivity and rapid results for early tuberculosis diagnosis and rifampicin resistance detection, especially in HIV co-infected patients. Thus, TrueNat should be prioritized in clinical settings for its enhanced diagnostic capabilities.