title: Molecular characterization of Mycobacterium tuberculosis isolated from pulmonary tuberculosis patients in Felege Hiwot Referral Hospital, northwest Ethiopia.
abstract: BACKGROUND
  Tuberculosis (TB), caused by the Mycobacterium tuberculosis complex (MTBC), is a serious infection in humans and animals. Ethiopia is one of the countries in Sub-Saharan Africa with the highest burden of TB. However, limited information is available on the genotypic characteristics of M. tuberculosis strains infecting humans. The objective of the present study was to characterize the mycobacterial species isolated from pulmonary TB patients using molecular typing.
  
  
  METHODS
  A cross-sectional study was conducted on 123 patients with smear-positive pulmonary TB, using Ziehl Neelsen staining and bacteriological culturing. Molecular characterizations of the mycobacterial isolates were performed using region of difference 9 (RD9) deletion typing and spoligotyping methods.
  
  
  RESULTS
  The proportion of culture positivity was 95.9% (118/123). All the 118 isolates were confirmed to be M. tuberculosis by polymerase chain reaction-based RD9 deletion typing. Further characterization of all isolates using spoligotyping resulted in the identification of 36 different spoligotype patterns. Out of these, 32 (88.9%) patterns have already been reported in the SpolDB database, whereas the remaining four (11.1%) patterns were new and not registered in the database. The isolates were further grouped into 17 clustered (99 isolates) and 19 nonclustered patterns. The most predominant spoligotypes were SIT25 and SIT53, consisting of 22 isolates and 14 isolates, respectively. Classification of the spoligotype patterns using TB-insight RUN SPOTCLUST showed that the dominant lineages identified in the present study were Euro-American and Central Asian genotypes consisting of 64 isolates and 37 isolates, respectively.
  
  
  CONCLUSIONS
  This study confirmed the presence of known M. tuberculosis strains and revealed new strains circulating in northwest Ethiopia and the distribution of the major phylogenetic families. It thus contributes to a better understanding of the genotypic profile of M. tuberculosis strains circulating in Ethiopia.
authors.affiliation: Department of Microbiology, Immunology, and Parasitology, College of Medicine and Health Sciences, Bahir Dar University, Bahir Dar, Ethiopia. Electronic address: teddyrozg@yahoo.com.
authors.forename: Tewodros
authors.initials: T
authors.lastname: Debebe
authors.affiliation: Amhara National Regional State Health Bureau, Bahir Dar, Ethiopia.
authors.forename: Aschalew
authors.initials: A
authors.lastname: Admassu
authors.affiliation: Department of Biomedical Sciences, Faculty of Veterinary Medicine, Addis Ababa University, Addis Ababa, Ethiopia.
authors.forename: Gezahegne
authors.initials: G
authors.lastname: Mamo
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
authors.forename: Gobena
authors.initials: G
authors.lastname: Ameni
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D005002:Ethiopia / Q000453:epidemiology; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D058889:Molecular Typing; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D062486:Public Health Surveillance; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology* / Q000382:microbiology*; D055815:Young Adult
keywords: Mycobacterium tuberculosis complex (MTBC); SpolDB database; Spoligotyping; Tuberculosis (TB)