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Serial measurement of M. tuberculosis in blood from critically-ill patients with HIV-associated tuberculosis.

Barr, David A, Schutz, Charlotte, Balfour, Avuyonke, Shey, Muki, Kamariza, Mireille, Bertozzi, Carolyn R, de Wet, Timothy J, Dinkele, Ryan, Ward, Amy, Haigh, Kathryn A, Kanyik, Jean-Paul, Mizrahi, Valerie, Nicol, Mark P, Wilkinson, Robert J, Lalloo, David ORCID:, Warner, Digby F, Meintjes, Graeme and Davies, Gerry (2022) 'Serial measurement of M. tuberculosis in blood from critically-ill patients with HIV-associated tuberculosis.'. EBioMedicine, Vol 78, p. 103949.

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Despite being highly prevalent in hospitalised patients with severe HIV-associated tuberculosis (TB) and sepsis, little is known about the mycobacteriology of Mycobacterium tuberculosis bloodstream infection (MTBBSI). We developed methods to serially measure bacillary load in blood and used these to characterise MTBBSI response to anti-TB therapy (ATT) and relationship with mortality.

We established a microscopy method for direct visualisation of M. tuberculosis bacilli in blood using a novel lysis-concentration protocol and the fluorescent probe, 4-N,N-dimethylaminonaphthalimide-trehalose (DMN-Tre). We tested blood using GeneXpert® MTB/RIF-Ultra (Xpert-ultra) and Myco/F lytic culture after processing blood through lysis-wash steps to remove PCR inhibitors and anti-microbial drug carry-over. HIV-positive patients predicted to have MTBBSI gave blood samples 0, 4, 24, 48 and 72 h after ATT initiation. Bacillary loads were quantified using microscopy, Xpert-ultra cycle threshold, and culture time-to-positivity. Pharmacodynamics were modelled using these measures combined on an ordinal scale, including association with 12-week mortality.

M. tuberculosis was detected in 27 of 28 recruited participants; 25 (89%) by blood Xpert-ultra, 22 (79%) by DMN-Tre microscopy, and 21 (75%) by Myco/F lytic blood culture. Eight (29%) participants died by 12-week follow-up. In a combined pharmacodynamic model, predicted probabilities of negative DMN-Tre microscopy, blood Xpert-ultra, or blood culture after 72 h treatment were 0·64, 0·27, and 0·94, respectively, in those who survived, compared with 0·23, 0·06, and 0·71 in those who died (posterior probability of slower clearance of MTBBSI in those that died >0·99). DMN-Tre microscopy of blood demonstrated heterogenous bacillary morphologies, including microcolonies and clumps. Bacillary cell-length varied significantly with ATT exposure (mean cell-length increase 0·13 log-µm/day; 95%CrI 0·10–0·16).

Pharmacodynamics of MTBBSI treatment can be captured using DMN-Tre microscopy, blood Xpert-ultra and culture. This could facilitate interventional trials in severe HIV-associated TB.

Item Type: Article
Subjects: QV Pharmacology > Anti-Inflammatory Agents. Anti-Infective Agents. Antineoplastic Agents > QV 268 Antitubercular agents. Antitubercular antibiotics
QY Clinical Pathology > Blood. Blood Chemistry > QY 450 Blood chemistry
WC Communicable Diseases > Infection. Bacterial Infections > Bacterial Infections > WC 240 Bacteremia. Sepsis. Toxemias
WC Communicable Diseases > Virus Diseases > Acquired Immunodeficiency Syndrome. HIV Infections > WC 503 Acquired immunodeficiency syndrome. HIV infections
WF Respiratory System > Tuberculosis > WF 200 Tuberculosis (General)
WF Respiratory System > Tuberculosis > WF 220 Diagnosis. Prognosis
Faculty: Department: Clinical Sciences & International Health > Clinical Sciences Department
Digital Object Identifer (DOI):
SWORD Depositor: JISC Pubrouter
Depositing User: JISC Pubrouter
Date Deposited: 21 Jul 2022 12:59
Last Modified: 15 Jun 2023 13:22


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