Sputum Mycobacterium tuberculosis mRNA as a Marker of Bacteriologic Clearance in Response to Antituberculosis Therapy

• Published in: Journal of Clinical Microbiology 2010-01, Vol.48 (1), p.46-51
• Main Authors: Li, L, Mahan, C.S, Palaci, M, Horter, L, Loeffelholz, L, Johnson, J.L, Dietze, R, Debanne, S.M, Joloba, M.L, Okwera, A, Boom, W.H, Eisenach, K.D
• Format: Article
• Language: English
• Subjects: Antitubercular Agents - therapeutic use; Bacteria; Bacteriology; Biological and medical sciences; Colony Count, Microbial; Drug Monitoring - methods; Fundamental and applied biological sciences. Psychology; Humans; Microbial Viability; Microbiology; Miscellaneous; Mycobacteriology and Aerobic Actinomycetes; Mycobacterium tuberculosis; Mycobacterium tuberculosis - genetics; Mycobacterium tuberculosis - growth & development; Mycobacterium tuberculosis - isolation & purification; Reverse Transcriptase Polymerase Chain Reaction - methods; RNA, Bacterial - genetics; RNA, Bacterial - isolation & purification; RNA, Messenger - genetics; RNA, Messenger - isolation & purification; Sputum - microbiology; Statistics as Topic; Tuberculosis, Pulmonary - diagnosis; Tuberculosis, Pulmonary - drug therapy; Young Adult
• ISSN: 0095-1137; 1098-660X
• DOI: 10.1128/JCM.01526-09

mRNA is a marker of cell viability. Quantifying Mycobacterium tuberculosis mRNA in sputum is a promising tool for monitoring response to antituberculosis therapy and evaluating the efficacy of individual drugs. mRNA levels were measured in sputum specimens from patients with tuberculosis (TB) receiving monotherapy in an early bactericidal activity study of fluoroquinolones and in those receiving a standard rifampin-based regimen in an interleukin-2 (IL-2) trial. In the early bactericidal activity study, sputum for quantitative culture and mRNA analysis was collected for 2 days before and daily during 7 days of study drug administration. In the IL-2 trial, sputum was collected for quantitative culture, Bactec 460 liquid culture, and mRNA analysis throughout the intensive treatment phase. RNA was isolated from digested sputum and tested in quantitative reverse transcription-PCR assays for several gene targets. mRNA for the glyoxylate cycle enzyme isocitrate lyase declined at similar rates in patients receiving isoniazid, gatifloxicin, levofloxacin, and moxifloxacin monotherapy. Isocitrate lyase mRNA correlated highly with CFU in sputum prior to therapy and during 7 days of monotherapy in all treatment arms. Isocitrate lyase mRNA was detectable in sputum of culture-positive TB patients receiving a rifampin-based regimen for 1 month. At 2 months, sputum for isocitrate mRNA correlated more closely with growth in liquid culture than did growth on solid culture medium. Data suggest that isocitrate lyase mRNA is a reliable marker of M. tuberculosis viability.