lunes, 4 de marzo de 2013

Mycobacterial Lineages Causing Pulmonary and Extrapulmonary Tuberculosis, Ethiopia - Vol. 19 No. 3 - March 2013 - Emerging Infectious Disease journal - CDC

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Mycobacterial Lineages Causing Pulmonary and Extrapulmonary Tuberculosis, Ethiopia - Vol. 19 No. 3 - March 2013 - Emerging Infectious Disease journal - CDC
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Table of Contents
Volume 19, Number 3– March 2013


Volume 19, Number 3—March 2013



Dispatch



Mycobacterial Lineages Causing Pulmonary and Extrapulmonary Tuberculosis, Ethiopia




Rebuma Firdessa12, Stefan Berg1, Elena Hailu1, Esther Schelling, Balako Gumi, Girume Erenso, Endalamaw Gadisa, Teklu Kiros, Meseret Habtamu, Jemal Hussein, Jakob Zinsstag, Brian D. Robertson, Gobena Ameni, Amanda J. Lohan, Brendan Loftus, Iñaki Comas, Sebastien Gagneux, Rea Tschopp, Lawrence Yamuah, Glyn Hewinson, Stephen V. Gordon, Douglas B. Young, and Abraham AseffaComments to Author 


Author affiliations: Author affiliations: Armauer Hansen Research Institute, Addis Ababa, Ethiopia (R. Firdessa, E. Hailu, B. Gumi, G. Erenso, E. Gadisa, T. Kiros, M. Habtamu, J. Hussein, R. Tschopp, L. Yamuah, A. Aseffa); Animal Health and Veterinary Laboratories Agency, Weybridge, UK (S. Berg, G. Hewinson); Swiss Tropical and Public Health Institute, Basel, Switzerland (E. Schelling, J. Zinsstag, S. Gagneux, R. Tschopp); University of Basel, Basel (E. Schelling, J. Zinsstag, S. Gagneux); Imperial College, London, London, UK (B.D. Robertson, D.B. Young); Addis Ababa University, Addis Ababa (G. Ameni); University College Dublin Conway Institute, Dublin, Ireland (A.J. Lohan, B. Loftus, S.V. Gordon); National Institute for Medical Research, London (I. Comas, D.B. Young); Centre for Public Health Research, Valencia, Spain (I. Comas); Centro de Investigación y Educación en Red en Epidemiología Biomédica Pública, Madrid, Spain (I. Comas)

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Abstract


Molecular typing of 964 specimens from patients in Ethiopia with lymph node or pulmonary tuberculosis showed a similar distribution of Mycobacterium tuberculosis strains between the 2 disease manifestations and a minimal role for M. bovis. We report a novel phylogenetic lineage of M. tuberculosis strongly associated with the Horn of Africa.

Ethiopia is among the countries with the highest incidence of tuberculosis (TB) and has a yearly incidence of 261 cases/100,000 population. TB lymphadenitis in cervical lymph nodes (TBLN) accounts for ≈33% of all new cases in this country, which is greater than the global average of ≈15% (1). Ethiopia has the largest livestock population in Africa (≈51 million cattle), and recent studies have shown that bovine TB is endemic in this country (estimated prevalence 1%–10%) (2).
To explore the public health risk for bovine TB in Ethiopia, we have used molecular typing to characterize mycobacterial isolates from persons with TBLN and pulmonary TB who were visiting hospitals throughout the country. Our aim was to define the role of Mycobacterium bovis in human TB and to define the overall structure of the M. tuberculosis complex in Ethiopia.


The Study



Patients with suspected TBLN or pulmonary TB who came to hospitals or health centers in study sites and provided voluntary consent were recruited into the study during 2006–2010. Fine needle–aspirate samples and sputum samples were collected from 2,151 patients attending hospitals in Gondar, Woldiya, Ghimbi, Butajira, and Negelle, Ethiopia. In addition, sputum samples were collected from patients at hospitals in Fiche, Jinka, and Filtu and at health centers at 3 suburban sites in Addis Ababa (Holeta, Sululta, and Chancho). Samples were cultured on Löwenstein-Jensen medium supplemented with glycerol or pyruvate and on modified Middlebrook 7H11 medium optimized for culture of M. bovis.
We characterized isolates belonging to the M. tuberculosis complex by using multiplex PCR for large sequence polymorphisms (3,4), spoligotyping (5), and lineage-specific single-nucleotide polymorphism analysis (4,6). Isolates of selected spoligotypes were characterized by 24-loci mycobacterial interspersed repetitive unit–variable number tandem repeat (MIRU-VNTR) analysis (7). Four M. tuberculosis isolates from a group of 36 with unusual spoligotype patterns were further characterized by genome sequencing (Illumina Inc., San Diego, CA, USA). Sequencing reads were mapped to the inferred most recent common ancestor of the M. tuberculosis complex (6). A final alignment of 13,199 single-nucleotide polymorphism positions was generated and analyzed by using the neighbor-joining method with a Tamura-Nei evolutionary model (www.megasoftware.net/mega_papers.php). Nontuberculous mycobacteria were characterized by sequencing of the 16S rDNA gene.
Characteristics of 964 cultures positive for acid-fast bacilli are summarized in Table 1. Most of these isolates had an intact RD9 region, which identified them as M. tuberculosis. Only 4 (0.4%) of 964 isolates had undergone RD9 and RD4 deletions characteristic of M. bovis (3). The 4 M. bovis isolates were obtained from cases of pulmonary TB, 3 of which were from patients living in pastoralist communities in southern Ethiopia. The 10 nontuberculous mycobacterial isolates were identified as M. intracellulare, M. flavescens, and M. simiae; 2 of the isolates were from patients co-infected with M. tuberculosis.

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