title: Antigen detection as a point-of-care test for TB: the case of lipoarabinomannan.
abstract: The limitations of sputum smear microscopy, routine chest radiology for HIV-associated TB and culture-based diagnosis are well recognized, especially in resource-limited settings. The diagnostic accuracy of a new point-of-care lateral-flow urine strip test for lipoarabinomannan (Determine(®) TB-LAM; Alere, MA, USA), which costs US$3.50 per test strip and provides results within 30 min, was evaluated in a cohort of South African patients for HIV-associated TB before starting anti-retroviral therapy in South Africa. Prevalence of culture-positive TB cases was 17.4%, among which 28.2% had sputum smear positivity. Determine(®) TB-LAM (Alere, MA, USA) had highest sensitivity at low CD4 cell counts: 66.7, 51.7 and 39.0% at <50 cells, <100 cells and <200 cells per µl, respectively; specificity was greater than 98% for all strata. There was an incremental sensitivity when Determine TB-LAM was combined with smear microscopy, which did not differ statistically from the sensitivities obtained by testing a single sputum sample with the Xpert(®) MTB/RIF (Cepheid; CA, USA) assay. Determine TB-LAM is a simple, low-cost alternative to existing diagnostic assays for TB screening in HIV-infected patients with very low CD4(+) cell counts.
authors.affiliation: National Institute for Research in Tuberculosis, Chetpet, Chennai, India. doctorsoumya@yahoo.com
authors.forename: Soumya
authors.initials: S
authors.lastname: Swaminathan
authors.forename: V V Banu
authors.initials: VV
authors.lastname: Rekha
mesh_terms: D000942:Antigens, Bacterial / Q000652:urine*; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D008070:Lipopolysaccharides / Q000652:urine*; D008297:Male; D019095:Point-of-Care Systems; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*
chemical_list: D000942:Antigens, Bacterial; D008070:Lipopolysaccharides