Sequencing of the rpoB gene in Legionella pneumophila and characterization of mutations associated with rifampin resistance in the Legionellaceae.
نویسندگان
چکیده
Rifampin in combination with erythromycin is a recommended treatment for severe cases of legionellosis. Mutations in the rpoB gene are known to cause rifampin resistance in Escherichia coli and Mycobacterium tuberculosis, and the purpose of the present study was to investigate a possible similar resistance mechanism within the members of the family Legionellaceae. Since the RNA polymerase genes of this genus have never been characterized, the DNA sequence of the Legionella pneumophila rpoB gene was determined by the Vectorette technique for genome walking. A 4,647-bp DNA sequence that contained the open reading frame (ORF) of the rpoB gene (4,104 bp) and an ORF of 384 bp representing part of the rpoC gene was obtained. A 316-bp DNA fragment in the center of the L. pneumophila rpoB gene, corresponding to a previously described site for mutations leading to rifampin resistance in M. tuberculosis, was sequenced from 18 rifampin-resistant Legionella isolates representing four species (L. bozemanii, L. longbeachae, L. micdadei, and L. pneumophila), and the sequences were compared to the sequences of the fragments from the parent (rifampin-sensitive) strains. Six single-base mutations which led to amino acid substitutions at five different positions were identified. A single strain did not contain any mutations in the 316-bp fragment. This study represents the characterization of a hitherto undescribed resistance mechanism within the family Legionellaceae.
منابع مشابه
Characterization of Mutations in the Rpob and Katg Gene of Mycobacterium Tuberculosis Isolates From Pasteur Institute of Tehran
Objective: The Rifampicin resistance and susceptibility of Mycobacterium tuberculosis are caused by mutations in the 81-base pair region of the rpoB gene encoding the b-subunit of RNA polymerase. Methods: Isoniazid resistance of M. tuberculosis is related to mutations in inha , oxyR and ahpC genes which 30 to 90 percent of Isoniazid resistance is occurred in 3015 codons of kat...
متن کاملCharacterization of Mutations in the Rpob and Katg Gene of Mycobacterium Tuberculosis Isolates From Pasteur Institute of Tehran
Objective: The Rifampicin resistance and susceptibility of Mycobacterium tuberculosis are caused by mutations in the 81-base pair region of the rpoB gene encoding the b-subunit of RNA polymerase. Methods: Isoniazid resistance of M. tuberculosis is related to mutations in inha , oxyR and ahpC genes which 30 to 90 percent of Isoniazid resistance is occurred in 3015 codons of kat...
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Background and Objectives: The incidence of rifampin-resistant strains of Mycobacterium tuberculosis has attracted more attention than the tuberculosis infection due to laborious treatment and control. Recognizing the Mycobacterium tuberculosis genotypes involving in drug resistance via multiplex PCR, a simple and rapid genotyping method, is an emergency for better tre...
متن کاملUpdate on rifampin resistance in the Legionellaceae.
A recent article described rpoB mutations in 18 rifampinresistant variants of Legionella spp. (4). One of these 18 strains, isolate 8749, an in vitro-generated high-level rifampin-resistant (MIC $ 256 mg/ml) variant of K26, a susceptible clinical Legionella bozemanii isolate, was shown to harbor no codon exchange in the cluster I rpoB 69-bp hot spot, the DNA region investigated. Besides codon e...
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ورودعنوان ژورنال:
- Antimicrobial agents and chemotherapy
دوره 44 10 شماره
صفحات -
تاریخ انتشار 2000