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. 2023 Feb 13;24(4):3715.
doi: 10.3390/ijms24043715.

Performance of Tuberculosis Molecular Bacterial Load Assay Compared to Alere TB-LAM in Urine of Pulmonary Tuberculosis Patients with HIV Co-Infections

Daniel Adon Mapamba  1   2 , Elingarami Sauli  2 , Julieth Lalashowi  1 , Joram Buza  2 , Joseph John  1 , Zawadi Mwaisango  1 , Peter Tarmo  1 , Issa Sabi  1 , Andrea Rachow  3   4 , Nyanda Elias Ntinginya  1 , Bariki Mtafya  1
Affiliations

Performance of Tuberculosis Molecular Bacterial Load Assay Compared to Alere TB-LAM in Urine of Pulmonary Tuberculosis Patients with HIV Co-Infections

Daniel Adon Mapamba et al. Int J Mol Sci. .

Abstract

Alternative tools are needed to improve the detection of M. tuberculosis (M. tb) in HIV co-infections. We evaluated the utility of Tuberculosis Molecular Bacterial Load Assay (TB-MBLA) compared to lipoarabinomannan (LAM) to detect M. tb in urine. Sputum Xpert MTB/RIF-positive patients were consented to provide urine at baseline, weeks 2, 8, 16, and 24 of treatment for TB-MBLA, culture, and LAM. Results were compared with sputum cultures and microscopy. Initial M. tb. H37Rv spiking experiments were performed to validate the tests. A total of 63 urine samples from 47 patients were analyzed. The median age (IQR) was 38 (30-41) years; 25 (53.2%) were male, 3 (6.5%) had urine for all visits, 45 (95.7%) were HIV positive, of whom 18 (40%) had CD4 cell counts below 200 cells/µL, and 33 (73.3%) were on ART at enrollment. Overall urine LAM positivity was 14.3% compared to 4.8% with TB-MBLA. Culture and microscopy of their sputum counterparts were positive in 20.6% and 12.7% of patients, respectively. Of the three patients with urine and sputum at baseline, one (33.33%) had urine TB-MBLA and LAM positive compared to 100% with sputum MGIT culture positive. Spearman's rank correction coefficient (r) between TB-MBLA and MGIT was -0.85 and 0.89 with a solid culture, p > 0.05. TB-MBLA has the promising potential to improve M. tb detection in urine of HIV-co-infected patients and complement current TB diagnostics.

Keywords: HIV; TB-LAM; TB-MBLA; TB-lipoarabinomannan; human immunodeficiency virus; tuberculosis-molecular bacterial load assay; urine.

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Conflict of interest statement

The authors have no conflict of interest to declare.

Figures

Figure 1
Figure 1
Flow of M. tb., H37Rv spiking experiment, and real patient samples: A 0.5 MacFarland of M. tb, H37Rv culture was serially diluted in urine up to 10 × 101 CFU/mL and processed for MGIT, solid culture in 7H11, and TB-MBLA. For real patient urine, 1 mL of fresh urine was treated with guanidine thiocyanate (GTC) for TB-MBLA, 0.06 mL used for TB-LAM, and 2–5 mL decontaminated with the NALC-NaOH method for culture in MGIT and LJ. Three technical replicates were performed for each of the M. tb H37Rv spiking experiments.
Figure 2
Figure 2
In vitro M. tb H3Rv urine spiking experiments. TB-MBLA correlated strongly with 7H11 media in (A) and with time to positivity (TTP) in MGIT in (B). The correlation between MGIT-TTP and 7H11 media was pronounced in (C). Each dot represents average data from three technical replicates of experiments presented with a standard deviation (SD).
Figure 3
Figure 3
M. tb positivity in three patients with all visit samples. The probability of urine TB-MBLA andLAM positivity was low compared to their sputum counterparts at baseline and throughout week 24 of treatment (n = 3). The relation of sputum positivity between each test (smear, MGIT, or LJ) was not different at each time point in treatment, p > 0.05.
See this image and copyright information in PMC

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