Sequence analysis for detection of drug resistance in Mycobacterium tuberculosis complex isolates from the Central Region of CameroonReport as inadecuate

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BMC Microbiology

, 14:113

Clinical microbiology and vaccines


BackgroundThe 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.

ResultsFrom 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 INH 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 INH, 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 INH high level detection, katG315 mutation had a specificity and a sensitivity of 100% and 70.8% respectively. Of the 20 low level INH, 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 RIF isolates carried mutations in the rpoB gene at codons Ser531Leu 71.4%, His526Asp 14.3%, and Asp516Val 14.3%. Of the 27 streptomycin resistant SM isolates, 7 carried mutations at the rpsL and the gidB genes. 1 of the 2 ethambutol resistant EMB isolates displayed a mutation in embB gene.

ConclusionThis 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.

KeywordsPhenotype Mutation Drug resistance Mycobacterium tuberculosis Cameroon AbbreviationsTBTuberculosis

MDRMulti-drug resistance

SLDSecond-line drug

DOTSDirectly observed treatment short course

HIVHuman immunodeficiency virus

ATCCAmerican type culture collection





ASTAntimicrobial susceptibility testing

MICMinimal inhibitory concentration

DNADésoxyribonucleic acid

CANTAMCentral Africa Network on Tuberculosis, AIDS-HIV and Malaria

RRDRRifampicin resistant determining region.

Emmanuel Mouafo Tekwu, Larissa Kamgue Sidze contributed equally to this work.

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Author: Emmanuel Mouafo Tekwu - Larissa Kamgue Sidze - Jean-Paul Assam Assam - Jean-Claude Tedom - Serges Tchatchouang - Gaëlle 


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