Predictors for MTB culture-positivity among HIV-infected smear-negative presumptive tuberculosis patients in Uganda: Application of new tuberculosis diagnostic technology

Lydia Nakiyingi, Bareng A.S. Nonyane, Willy Ssengooba, Bruce J. Kirenga, Damalie Nakanjako, Gloria Lubega, Pauline Byakika-Kibwika, Moses L. Joloba, Jerry J. Ellner, Susan E. Dorman, Harriet Mayanja-Kizza, Yukari C. Manabe

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Background The existing World Health Organization diagnostic algorithms for smear-negative TB perform poorly in HIV-infected individuals. New TB diagnostics such as urine TB lipoarabinomannan (LAM) could improve the accuracy and reduce delays in TB diagnosis in HIVinfected smear-negative presumptive TB. We sought to determine predictors for MTB culture- positivity among these patients. Methods This study was nested into a prospective evaluation of HIV-infected outpatients and inpatients clinically suspected to have TB who were screened by smear-microscopy on two spot sputum samples. Data on socio-demographics, clinical symptoms, antiretroviral therapy. CXR, CD4 count, mycobacterial sputum and blood cultures and TB-LAM were collected. Logistic regression and conditional inference tree analysis were used to determine the most predictive indicators for MTB culture-positivity. Results Of the 418 smear-negative participants [female, 64%; median age (IQR) 32 (28-39) years, median CD4 106 (IQR 22 - 298) cells/mm3], 96/418 (23%) were sputum and/ or blood culture- positive for Mycobacterium tuberculosis (MTB) complex. Abnormal CXR (aOR 3.68, 95% CI 1.76- 7.71, p=0.001) and positive urine TB-LAM (aOR 6.21, 95% CI 3.14-12.27, p< 0.001) were significantly associated with MTB culture-positivity. Previous TB treatment (aOR 0.41, 95% CI 0.17-0.99, p=0.049) reduced the likelihood of a positive MTB culture. A conditional inference tree analysis showed that positive urine TB-LAM and abnormal CXR were the most predictive indicators of MTB culture-positivity. A combination of urine TBLAM test and CXR had sensitivity and specificity of 50% and 86.1%respectively overall, and 70.8% and 84.1%respectively among those with CD4<100 cells/mm3. Conclusions A positive urine TB-LAM test and an abnormal CXR significantly predict MTB culture-positivity among smear-negative HIV-infected presumptive TB patients while previous TB treatment reduces the likelihood of a positive MTB culture. Validation studies to assess the performance of diagnostic algorithms that include urine TB-LAM in the diagnosis of smearnegative TB in HIV-infected individuals are warranted.

Original languageEnglish (US)
Article numbere0133756
JournalPloS one
Issue number7
StatePublished - Jul 29 2015

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General


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