title: Time to culture positivity and sputum smear microscopy during tuberculosis therapy.
abstract: Sputum smear microscopy is widely used for tuberculosis diagnosis and treatment monitoring. We evaluated the correlation between smear microscopy and time to liquid culture positivity during early tuberculosis treatment. The study included patients with smear-positive pulmonary tuberculosis hospitalized at a tuberculosis reference centre in Germany between 01/2012 and 05/2013. Patient records were reviewed and clinical, radiological and microbiological data were analysed. Sputum samples were collected before treatment initiation and weekly thereafter. A number of 310 sputum samples from 30 patients were analysed. Time to liquid culture positivity inversely correlated with smear grade (Spearman's rho -0.439, p<0.001). There was a better correlation within the first two months vs. after two months of therapy (-0.519 vs. -0.416) with a trend to a more rapid increase in time to positivity between baseline and week 2 in patients who culture-converted within the first two months (5.9 days vs. 9.4 days, p = 0.3). In conclusion, the numbers of acid-fast bacilli in sputum smears of patients with pulmonary tuberculosis and time to culture positivity for M. tuberculosis cultures from sputum are correlated before and during tuberculosis treatment. A considerable proportion of patients with culture conversion after two months of therapy continued to have detectable acid-fast bacilli on sputum smears.
authors.affiliation: Division of Clinical Infectious Diseases, Research Center Borstel, Borstel, Germany; German Center for Infection Research (DZIF), Research Center Borstel, Borstel, Germany.
authors.forename: Ioana D
authors.initials: ID
authors.lastname: Olaru
authors.affiliation: Division of Clinical Infectious Diseases, Research Center Borstel, Borstel, Germany; German Center for Infection Research (DZIF), Research Center Borstel, Borstel, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Heyckendorf
authors.affiliation: Division of Clinical Infectious Diseases, Research Center Borstel, Borstel, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Grossmann
authors.affiliation: Division of Clinical Infectious Diseases, Research Center Borstel, Borstel, Germany; German Center for Infection Research (DZIF), Research Center Borstel, Borstel, Germany; International Health/Infectious Diseases, University of Lübeck, Lübeck, Germany; Department of Medicine, University of Namibia School of Medicine, Windhoek, Namibia.
authors.forename: Christoph
authors.initials: C
authors.lastname: Lange
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000627:therapeutic use*; D001431:Bacteriological Techniques / Q000379:methods; D005260:Female; D054884:Host-Pathogen Interactions / Q000187:drug effects; D006801:Humans; D008297:Male; D008853:Microscopy / Q000379:methods; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000502:physiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013183:Sputum / Q000187:drug effects* / Q000382:microbiology; D013997:Time Factors; D016896:Treatment Outcome; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000188:drug therapy* / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents