High Genotypic Discordance of Concurrent Mycobacterium tuberculosis Isolates from Sputum and Blood of HIV-Infected Individuals

Abstract

BackgroundAmong HIV-infected individuals with CD4 less than 200 cells/mm3, tuberculosis often has an atypical presentation, is more likely to be disseminated and is diagnostically challenging. We sought to understand the genotypic discordance of concurrent sputum and blood M. tuberculosis (MTB) isolates from HIV-infected individuals.MethodsFrom a prospective diagnostic accuracy study with 182 HIV-infected culture-positive TB adults, isolates were obtained from 51 of 66 participants who were MTB culture-positive by both sputum and blood. Isolates were subjected to susceptibility testing to 1st line drugs, spoligotyping and 24 locus- MIRU-VNTR.ResultsThe median age of the participants was 31 (IQR; 27–38) years and 51% were male. The median CD4 count was 29 (IQR; 10–84) cells/mm3 with 20% taking ART; 8.0% were previously treated for TB, and 63% were AFB smear-negative. The isolates belonged to two of the main global MTB-lineages; East-African-Indian (L3) 17 (16.7%) and Euro-American (L4) 85 (83.3%). We identified 26 (51.0%) participants with discordant MTB-genotypes between sputum and blood, including two patients with evidence of mixed infection in either compartment. Having discordant MTB-genotypes was not predicted by the MTB-lineage in either blood or sputum, CD4 cell count, or any other clinical characteristic.ConclusionsThere is a high genotypic discordance among M. tuberculosis concurrently isolated from sputum and blood of HIV-infected individuals. These findings suggest that infection with more than one strain of M. tuberculosis occurs in at least half of patients with advanced HIV infection.

Whole genome sequencing reveals mycobacterial microevolution among concurrent isolates from sputum and blood in HIV infected TB patients

“…From a previous study of 51 HIV-infected TB patients who had concurrent blood and sputum M. tuberculosis isolates at enrolment, we selected patients found to have identical genotypes from our previous study [ 22 ] using both spoligotyping [ 5 ] and MIRU-VNTR 24 loci methods [ 3 ]. In this strain selection process, we considered pairs ( n = 25) with maximum one spacer and/or locus difference to be identical MTB-genotypes.…”

Determine TB –LAM Lateral Flow Assay, Does M. tuberculosis lineage influence its performance?

“…Briefly, from a prospective cohort of HIV-positive adult aged 18 years and above from outpatients' department of the Infectious Diseases Institute [IDI] and inpatients of Mulago National Referral Hospital medial wards, both in Kampala, Uganda. Participants were tested for both pulmonary and extra pulmonary tuberculosis using laboratory culture methods as described in the previous study [13]. A total of 68 HIV-positive patients with either pulmonary tuberculosis and/or TB bacteremia were considered in the current study.…”

“…The same sample was also inoculated on Lowenstein Jensen (LJ) media and incubated at 37oc for up to eight weeks following standard protocol whereas blood samples were cultured in an automated machine (BACTEC 9120), incubated up to six weeks and reported as previously described [12]. The M. tuberculosis isolates were tested for susceptibility to anti-TB drugs also as previously described [13]. Only three 5 participants with isolate pairs from sputum and blood showed resistance to ethambutaol in MGIT 960 at 5.0 µg/mL, all others were susceptible to first-line TB drugs.…”

“…Isolates were typed for M. tuberculosis lineages using Mycobacterial Interspersed Repetitive Units Variable Number of Tandem Repeats (MIRU-VNTR) 24 loci, and/or spoligotyping (spacer oligonucleotide typing) performed on bacterial lysates as described in our previous study [13]. For lineage assignment, we considered either method and where there was disagreement, MIRU-VNTR-24 loci was used as final results if available.…”

“…Data from animal models suggest that the structure, internal heterogeneity and abundance of LAM vary between M. tuberculosis strains exhibiting distinct degrees of virulence [6][7][8]. In Uganda, the most We retrospectively reviewed LF-LAM results from our previous study [12] and M. tuberculosis lineage data from our previous studies [12,13]…”