title: Analysis of mutations in streptomycin-resistant strains reveals a simple and reliable genetic marker for identification of the Mycobacterium tuberculosis Beijing genotype.
abstract: The Mycobacterium tuberculosis pandemic is a major health problem, further complicated by an increasing incidence of drug-resistant isolates and the existence of highly transmissible strains, such as those in the Beijing family. Streptomycin (STR)-resistant M. tuberculosis clinical isolates have been analyzed to look for mutations in the rpsL, rrs, and gidB genes. In addition, the Rv1258c gene, which encodes Tap, an efflux pump that transports STR, has been sequenced. Mutations affecting codons 43 and 88 of the rpsL gene were found in 44.4% of the strains, and 16.7% of the strains carried mutations in the rrs gene, both of which probably contribute to STR resistance. Many strains presented with mutations in the gidB gene, but the implication of those mutations in STR resistance remains unclear. Interestingly, a cytosine nucleotide insertion between positions 580 and 581 (denominated Tap(580)) in the Rv1258c gene has been found in all Beijing isolates included in this study, suggesting that it might be a novel polymorphism specific to the Beijing family of M. tuberculosis. A simple and fast restriction fragment length polymorphism (RFLP)-PCR method for detecting the Tap(580) insertion has been developed and used to screen a collection of 220 DNA samples obtained from cultures of M. tuberculosis isolates and 30 respiratory specimens. In all cases, the Beijing and non-Beijing representative samples were identified correctly. Tap(580) is a novel polymorphism specific to the highly transmissible Beijing family, which allows for fast detection of these strains even at the very early stages of infection.
authors.affiliation: Departamento de Microbiología, Medicina Preventiva y Salud Pública, Facultad de Medicina, Universidad de Zaragoza, Zaragoza, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Villellas
authors.forename: Liselotte
authors.initials: L
authors.lastname: Aristimuño
authors.forename: María-Asunción
authors.initials: MA
authors.lastname: Vitoria
authors.forename: Cristina
authors.initials: C
authors.lastname: Prat
authors.forename: Silvia
authors.initials: S
authors.lastname: Blanco
authors.forename: Darío
authors.initials: D
authors.lastname: García de Viedma
authors.forename: José
authors.initials: J
authors.lastname: Domínguez
authors.forename: Sofía
authors.initials: S
authors.lastname: Samper
authors.forename: José A
authors.initials: JA
authors.lastname: Aínsa
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005819:Genetic Markers; D005838:Genotype; D006801:Humans; D058889:Molecular Typing / Q000379:methods*; D016254:Mutagenesis, Insertional; D009169:Mycobacterium tuberculosis / Q000145:classification* / Q000187:drug effects / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D012680:Sensitivity and Specificity; D013307:Streptomycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D005819:Genetic Markers; D013307:Streptomycin