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

David A Barr; Charlotte Schutz; Avuyonke Balfour; Muki Shey; Mireille Kamariza; Carolyn R Bertozzi; Timothy J de Wet; Ryan Dinkele; Amy Ward; Kathryn A Haigh; Jean-Paul Kanyik; Valerie Mizrahi; Mark P Nicol; Robert J Wilkinson; David G Lalloo; Digby F Warner; Graeme Meintjes; Gerry Davies

doi:10.1016/j.ebiom.2022.103949

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

EBioMedicine. 2022 Apr:78:103949. doi: 10.1016/j.ebiom.2022.103949. Epub 2022 Mar 21.

Authors

David A Barr¹, Charlotte Schutz², Avuyonke Balfour³, Muki Shey², Mireille Kamariza⁴, Carolyn R Bertozzi⁵, Timothy J de Wet⁶, Ryan Dinkele⁶, Amy Ward², Kathryn A Haigh⁷, Jean-Paul Kanyik⁸, Valerie Mizrahi⁹, Mark P Nicol¹⁰, Robert J Wilkinson¹¹, David G Lalloo¹², Digby F Warner⁹, Graeme Meintjes², Gerry Davies⁷

Affiliations

¹ Wellcome Centre for Infectious Diseases Research in Africa (CIDRI-Africa), Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Observatory 7925, South Africa; Institute of Infection and Global Health, University of Liverpool, Liverpool L7 3EA, UK. Electronic address: david.barr@liverpool.ac.uk.
² Wellcome Centre for Infectious Diseases Research in Africa (CIDRI-Africa), Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Observatory 7925, South Africa; Department of Medicine, University of Cape Town, Observatory 7925, South Africa.
³ Wellcome Centre for Infectious Diseases Research in Africa (CIDRI-Africa), Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Observatory 7925, South Africa.
⁴ Department of Biology, Stanford University, Stanford, CA 94305, USA.
⁵ Department of Chemistry, Stanford University, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
⁶ SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, Institute of Infectious Disease and Molecular Medicine and Department of Pathology, University of Cape Town, Observatory 7925, South Africa.
⁷ Institute of Infection and Global Health, University of Liverpool, Liverpool L7 3EA, UK.
⁸ Wellcome Centre for Infectious Diseases Research in Africa (CIDRI-Africa), Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Observatory 7925, South Africa; Khayelitsha Hospital, Department of Medicine, Cape Town, South Africa.
⁹ Wellcome Centre for Infectious Diseases Research in Africa (CIDRI-Africa), Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Observatory 7925, South Africa; SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, Institute of Infectious Disease and Molecular Medicine and Department of Pathology, University of Cape Town, Observatory 7925, South Africa.
¹⁰ Division of Infection and Immunity School of Biomedical Sciences, University of Western Australia, Perth, Australia,; Division of Medical Microbiology, University of Cape Town, Cape Town, South Africa.
¹¹ Wellcome Centre for Infectious Diseases Research in Africa (CIDRI-Africa), Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Observatory 7925, South Africa; Department of Medicine, University of Cape Town, Observatory 7925, South Africa; The Francis Crick Institute, London NW1 1AT, UK; Department of Infectious Disease, Imperial College, London W12 0NN, United Kingdom.
¹² Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK.

Abstract

Background: 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.

Methods: 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.

Findings: 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).

Interpretation: 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.

Funding: Wellcome Trust, NIH Fogarty International Center, South African MRC, NIHR(UK), National Research Foundation of South Africa.

Keywords: Blood stream infection; Critical-illness; HIV-associated tuberculosis; Pharmacodynamics; Sepsis.

MeSH terms

Critical Illness
HIV Infections* / complications
HIV Infections* / drug therapy
Humans
Mycobacterium tuberculosis*
Sensitivity and Specificity
Sputum / microbiology
Tuberculosis* / complications
Tuberculosis* / diagnosis
Tuberculosis* / drug therapy
Tuberculosis, Pulmonary* / microbiology

Abstract

MeSH terms

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