Abstract
ObjectivesCross-reactivity with nontuberculous mycobacteria (NTM) species might limit the use of urine lipoarabinomannan (LAM) test to diagnose tuberculosis (TB) in people living with HIV (PLWH). This study aimed to investigate the utility of the LAM test among hospitalized HIV-positive patients. MethodsThis prospective study enrolled HIV-positive inpatients with any TB symptom or seriously ill patients with advanced immunodeficiency. Urine samples were tested using the Alere Determine LAM Ag, and participants were categorized as confirmed TB, confirmed NTM infection, unclassified mycobacteria infection, and no mycobacteria infection based on microbiologic reference standards. ResultsA total of 382 participants were included. The prevalence of confirmed TB and NTM infection was 5.24% (20 of 382) and 4.45% (17 of 382), respectively. The sensitivity and specificity of the urine LAM for TB diagnosis were 65.00% (95% confidence interval [CI] 40.78-84.61) and 89.36% (95% CI 85.68-92.36), respectively. The LAM test for NTM yielded a sensitivity of 58.82% (95% CI 32.92-81.56) and specificity of 88.61% (95% CI 84.87-91.70). Notably, the negative predictive values of the urine LAM for TB and NTM were 97.85% (95% CI 95.63-99.13) and 97.85% (95% CI 95.63-99.13), respectively. ConclusionsCross-reactivity with NTM cause high false-positive LAM for TB diagnosis in PLWH. The correct identification of mycobacteria species is crucial for deciding treatment strategies.
Highlights
People living with HIV (PLWH) who are co-infected with nontuberculous mycobacteria (NTM) or Mycobacterium tuberculosis (MTB) may have similar clinical presentation
LAM has a comparable sensitivity in diagnosing TB and non-tuberculous mycobacteria (NTM) diseases but could not distinguish TB from NTM diseases
The high negative predictive value (NPV) of LF-LAM suggests its application in excluding mycobacterial infection in hospitalized people living with HIV (PLWH)
Summary
People living with HIV (PLWH) who are co-infected with nontuberculous mycobacteria (NTM) or Mycobacterium tuberculosis (MTB) may have similar clinical presentation. Tuberculosis (TB) remains to be the leading cause of morbidity and mortality among PLWH (Organization, 2020), emerging evidence suggests that the prevalence of NTM diseases is increasing (Brode et al, 2014, Rachow et al, 2011). This may be attributed to the grossly underestimated prevalence in the past since both MTB and NTMs show positivity to the conventional smear acid-fast staining method (Liu et al, 2018, Tran et al, 2019). Incorrect diagnosis of NTM diseases as TB may lead to unfavorable outcomes and unnecessary quarantine
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