title: Utility of propidium monoazide viability assay as a biomarker for a tuberculosis disease.
abstract: Reliable laboratory diagnosis of tuberculosis (TB), including laboratory biomarkers of cure, remains a challenge. In our study we evaluated the performance of a Propidium Monoazide (PMA) assay for the detection of viable TB bacilli in sputum specimens during anti-TB chemotherapy and its potential use as a TB biomarker. The study was conducted at three centres on 1937 sputum specimens from 310 adult bacteriologically confirmed pulmonary TB patients obtained before commencing anti-TB treatment and at regular intervals afterwards. Performance of the PMA assay was assessed using various readout assays with bacteriology culture results and time to positivity on liquid media used as reference standards. Treatment of sputum with N-acetyl-cysteine was found to be fully compatible with the PMA assay. Good sensitivity and specificity (97.5% and 70.7-80.0%) for detection of live TB bacilli was achieved using the Xpert(®) MTB/RIF test as a readout assay. Tentative Ct and ΔCt thresholds for the Xpert(®) MTB/RIF system were proposed. Good correlation (r = 0.61) between Ct values and time to positivity of TB cultures on liquid media was demonstrated. The PMA method has potential in monitoring bacterial load in sputum specimens and so may have a role as a biomarker of cure in TB treatment.
authors.affiliation: Infection and Immunity Department, Medical School, Imperial College London, United Kingdom; Blizard Institute of Cell and Molecular Science, Queen Mary University of London, United Kingdom. Electronic address: v.nikolayevskyy@imperial.ac.uk.
authors.forename: Vladyslav
authors.initials: V
authors.lastname: Nikolayevskyy
authors.affiliation: Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Miotto
authors.affiliation: Infectious Diseases and Tuberculosis Hospital, Affiliate of Vilnius University Hospital Santariskiu Klinikos, Vilnius, Lithuania.
authors.forename: Edita
authors.initials: E
authors.lastname: Pimkina
authors.affiliation: Infection and Immunity Department, Medical School, Imperial College London, United Kingdom; Blizard Institute of Cell and Molecular Science, Queen Mary University of London, United Kingdom; Department for Infectious Diseases Epidemiology, Robert Koch Institute, Berlin, Germany.
authors.forename: Yanina
authors.initials: Y
authors.lastname: Balabanova
authors.affiliation: Samara TB Regional Service, Samara, Russian Federation.
authors.forename: Irina
authors.initials: I
authors.lastname: Kontsevaya
authors.affiliation: Samara TB Regional Service, Samara, Russian Federation.
authors.forename: Olga
authors.initials: O
authors.lastname: Ignatyeva
authors.affiliation: Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ambrosi
authors.affiliation: Tuberculosis and Lung Diseases Centre, Riga East University Hospital, Riga, Latvia.
authors.forename: Girts
authors.initials: G
authors.lastname: Skenders
authors.affiliation: Vilnius University, Vilnius, Lithuania.
authors.forename: Arvydas
authors.initials: A
authors.lastname: Ambrozaitis
authors.affiliation: Samara TB Regional Service, Samara, Russian Federation.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kovalyov
authors.affiliation: Samara TB Regional Service, Samara, Russian Federation.
authors.forename: Anna
authors.initials: A
authors.lastname: Sadykhova
authors.affiliation: Samara TB Regional Service, Samara, Russian Federation.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Simak
authors.affiliation: Samara TB Regional Service, Samara, Russian Federation.
authors.forename: Andrey
authors.initials: A
authors.lastname: Kritsky
authors.affiliation: Samara TB Regional Service, Samara, Russian Federation.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Mironova
authors.affiliation: Samara TB Regional Service, Samara, Russian Federation.
authors.forename: Olesya
authors.initials: O
authors.lastname: Tikhonova
authors.affiliation: Samara TB Regional Service, Samara, Russian Federation.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Dubrovskaya
authors.affiliation: Samara TB Regional Service, Samara, Russian Federation.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Rodionova
authors.affiliation: Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Cirillo
authors.affiliation: Infection and Immunity Department, Medical School, Imperial College London, United Kingdom; Blizard Institute of Cell and Molecular Science, Queen Mary University of London, United Kingdom.
authors.forename: Francis
authors.initials: F
authors.lastname: Drobniewski
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000494:pharmacology / Q000627:therapeutic use; D001386:Azides; D058491:Bacterial Load; D016903:Drug Monitoring / Q000379:methods; D006801:Humans; D050296:Microbial Viability / Q000187:drug effects*; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000302:isolation & purification; D011419:Propidium / Q000031:analogs & derivatives*; D013048:Specimen Handling / Q000379:methods; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000188:drug therapy; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents; D001386:Azides; C533957:propidium monoazide; D011419:Propidium
keywords: Biomarkers; Laboratory diagnosis; Tuberculosis; Viability assays