title: Sequence analysis for detection of drug resistance in Mycobacterium tuberculosis complex isolates from the Central Region of Cameroon.
abstract: BACKGROUND
  The potential of genetic testing to rapidly diagnose drug resistance has lead to the development of new diagnostic assays. However, prior to implementation in a given setting, the association of specific mutations with specific drug resistance phenotypes should be evaluated. The purpose of this study was to evaluate molecular markers in predicting drug resistance in the Central Region of Cameroon.
  
  
  RESULTS
  From April 2010 and March 2011, 725 smear positive pulmonary tuberculosis patients were enrolled and all positive cultures were tested for drug susceptibility. A total of 63 drug resistant and 100 drug sensitive Mycobacterium tuberculosis complex clinical isolates were screened for genetic mutations in katG, inhA, ahpC, rpoB, rpsL, rrs, gidB and embCAB loci using DNA sequencing. Of the 44 isoniazid resistant (INHR) isolates (24 high level, 1 μg/ml and 20 low level, 0.2 μg/ml), 73% (32/44) carried the katG315 and/or the -15 inhA promoter mutations. Of the 24 high level INHR, 17 (70.8%) harbored katG315 mutation, 1 a point mutation (-15C → T) in the inhA promoter and 6 were (25.0%) wild types. Thus, for INHR high level detection, katG315 mutation had a specificity and a sensitivity of 100% and 70.8% respectively. Of the 20 low level INHR, 10 (50.0%) had a -15C → T mutation in the inhA promoter region, and 1 (2.2%) a -32G → A mutation in the ahpC promoter region. All of the 7 rifampicin resistant (RIFR) isolates carried mutations in the rpoB gene (at codons Ser531Leu (71.4%), His526Asp (14.3%), and Asp516Val (14.3%)). Of the 27 streptomycin resistant (SMR) isolates, 7 carried mutations at the rpsL and the gidB genes. 1 of the 2 ethambutol resistant (EMBR) isolates displayed a mutation in embB gene.
  
  
  CONCLUSIONS
  This study provided the first molecular investigation assessing the correlation of phenotypic to genotypic characteristics on MTB isolates from the Central Region of Cameroon using DNA sequencing. Mutations on rpoB, katG315 and -15 point mutations in inhA promoter loci could be used as markers for RIF and INH -resistance detection respectively.
authors.forename: Emmanuel Mouafo
authors.initials: EM
authors.lastname: Tekwu
authors.forename: Larissa Kamgue
authors.initials: LK
authors.lastname: Sidze
authors.forename: Jean-Paul Assam
authors.initials: JP
authors.lastname: Assam
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Tedom
authors.forename: Serges
authors.initials: S
authors.lastname: Tchatchouang
authors.forename: Gaëlle Guiewi
authors.initials: GG
authors.lastname: Makafe
authors.forename: Anne-Laure Tchokote
authors.initials: AL
authors.lastname: Wetewale
authors.forename: Christopher
authors.initials: C
authors.lastname: Kuaban
authors.forename: Sara
authors.initials: S
authors.lastname: Eyangoh
authors.forename: Francine
authors.initials: F
authors.lastname: Ntoumi
authors.affiliation: Laboratory for Tuberculosis Research (LTR), Biotechnology Centre (BTC)-Nkolbison, University of Yaoundé I, Yaoundé, Cameroon. v.penlap@yahoo.fr.
authors.forename: Véronique N Penlap
authors.initials: VN
authors.lastname: Beng
authors.forename: Matthias
authors.initials: M
authors.lastname: Frank
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D002163:Cameroon; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D003625:Data Collection; D024881:Drug Resistance, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA; D014376:Tuberculosis / Q000382:microbiology*
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial