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  1. Willy Ssengooba1,
  2. Lydia Nakiyingi2,
  3. Joloba Moses1
  1. 1Department of Medical Microbiology, College of Health Sciences Makerere University Kampala, Uganda
  2. 2Infectious Diseases Institute, College of Health Sciences Makerere University, Kampala, Uganda


Background Among HIV-positive individuals with CD4 ≤100 cells/mm3, M. tuberculosis (Mtb) bacteraemia is associated with a positive tuberculosis urine lipoarabinomannan (LAM) test. We conducted a retrospective study, to determine the effect of Mtb lineage on the performance of the Determine TB LAM lateral flow (LF-LAM) assay.

Methods This was nested in a prospective TB diagnostics accuracy study among HIV-positive presumptive TB patients from Mulago National Referral Hospital, Kampala, Uganda, including both inpatients and outpatients. We considered data of 51 HIV-positive individuals with both pulmonary and Mtb bacteraemia. We also evaluated the effect of having mixed Mtb strains using both spoligotyping and MIRU-VNTR 24 loci methods.

Results LF-LAM was; negative among 4 (7.8%; 95% CI, 2.17% to 18.8%), positive among 39 (76.5%; 95% CI, 62.5% to 87.2%) and indeterminate among 8 (15.7%; 95% CI, 7.0% to 28.5%) participants. Mtb lineages from blood samples were: Central Asian Strain (CAS; L3) 10/51 (19.6%) and Euro-American lineage (L4) 41/51 (80.4%). Mtb lineages from sputum samples were 7/51 (13.7%) L3 and 44/51 (86.3%) were L4. Among participants with L3 in blood, LFLAM was positive in 9 (90%; 95% CI, 55.4%–99.7%) whereas those with L4, LF-LAM was positive among 30 (73.2% 95% CI, 57.0% to 85.7%). For those with L3 in sputum, LF-LAM was positive among 7 (100%) and those with L4 was 32 (72.7%; 95% CI 57.2% to 85.0%). Two participants had mixed Mtb strains (all L4) and all LF-LAM positive (2+ and 4+).

Conclusion Our study shows that M. tuberculosis lineage 3 may have more sensitivity to LF-LAM assay than lineage 4. The high number of indeterminate results with L4 requires more investigations. Our findings suggest that LF-LAM performance may differ by geographical regions depending on the dominant M. tuberculosis lineage.

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