title: Detection of embB codon 306 mutations in ethambutol resistant Mycobacterium tuberculosis directly from sputum samples: a low-cost, rapid approach.
abstract: Substitutions of codon 306 in the gene embB are the most common mutations found in ethambutol resistant Mycobacterium tuberculosis. The characterization of these mutations has been hampered by the need for prior cultivation of the mycobacteria, or the need for DNA sequencing, or both. Here, we describe a simple and culture-independent technique to detect embB codon 306 mutations directly from sputum samples, requiring little more than a PCR machine and a simple agarose minigel. There is no need for labelled probes or DNA sequencing. In a preliminary test of feasibility, interpretable results were obtained from 21 of 24 selected sputum samples, 12 of which were determined to contain ethambutol resistant M. tuberculosis after culture. All of six samples with embB codon 306 mutations were correctly identified. Although an exact validation of this technique is beyond the scope of this technical report, we conclude from well-known embB codon 306 mutation prevalence figures that approximately one half of EMB resistant cases could already be predicted within 2 working days, with little equipment or hands-on time needed, instead of weeks required for conventional resistance testing.
authors.affiliation: Department of Infectious Diseases and Tropical Medicine, University of Munich, Leopoldstr.5, 80202 Munich, Germany. rinder@lrz.uni-muenchen.de
authors.forename: H
authors.initials: H
authors.lastname: Rinder
authors.forename: K T
authors.initials: KT
authors.lastname: Mieskes
authors.forename: E
authors.initials: E
authors.lastname: Tortoli
authors.forename: E
authors.initials: E
authors.lastname: Richter
authors.forename: M
authors.initials: M
authors.lastname: Casal
authors.forename: M
authors.initials: M
authors.lastname: Vaquero
authors.forename: E
authors.initials: E
authors.lastname: Cambau
authors.forename: K
authors.initials: K
authors.lastname: Feldmann
authors.forename: T
authors.initials: T
authors.lastname: Löscher
mesh_terms: D002624:Chemistry, Clinical / Q000191:economics / Q000379:methods*; D003001:Cloning, Molecular; D003062:Codon; D004351:Drug Resistance; D004587:Electrophoresis, Agar Gel; D004977:Ethambutol / Q000494:pharmacology*; D006801:Humans; D008957:Models, Genetic; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000378:metabolism; D010430:Pentosyltransferases / Q000235:genetics*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA; D013183:Sputum / Q000378:metabolism*
chemical_list: D003062:Codon; D004977:Ethambutol; D010430:Pentosyltransferases; C101967:arabinosyltransferase