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Genotyping results and DNA sequencing analysis of 235 Mycobacterium tuberculosis (M. tuberculosis) isolates from China indicated that mutations at codon 995 (Pro CCG to Pro CCA) and 701 (Ile ATT to Thr ACT) in lysX gene (Rv1640c), are specific markers for Beijing and modern Beijing strains, respectively. This observation was also confirmed by 24 genomes of M. tuberculosis strains from other countries. Moreover, a simple and fast multiplex allele-specific PCR (MAS-PCR) method for detecting mutations at codon 995 and 701 in lysX has been established and used to screen 235 DNA samples obtained from M. tuberculosis isolates. In all cases, Beijing and modern Beijing strains were identified correctly., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

We investigated the spectrum and frequency of mutations in rpsL, rrs, and gidB among 140 multidrug-resistant tuberculosis (MDR-TB) clinical isolates from China. The association between mutations and different genotypes was also analyzed. Our data revealed that 65.7% of MDR-TB were resistant to streptomycin (STR), and 90.2% of STR-resistant isolates were Beijing strains. STR resistance was correlated with Beijing family (P=0.00). Compared with phenotypic data, detection of mutations for the combination of these 3 genes exhibited 94.6% sensitivity, 91.7% specificity, and 93.6% accuracy. The most common mutations in STR-resistant isolates were rpsL128, 262, and rrs514, of which rpsL128 showed association with Beijing lineage (P=0.00). A combination of these 3 mutations can serve as the reliable predictors for STR resistance, showing the sensitivity, specificity, and accuracy of 85.9%, 97.9%, and 90.0%, respectively. Furthermore, gidBA276C, not A615G, was Beijing lineage specific. These findings are useful to develop rapid molecular diagnostic methods for STR resistance in China., (Copyright © 2015 Elsevier Inc. All rights reserved.)

However, the number of high-level RFB isolates with low-level RIF MIC was only six, among which four isolates had RIF MICs of 64 µg/mL, very close to the MIC definition of high-level RIF MIC (128 µg/mL). Results MIC Results Of the 177 tested isolates, 106 (59.9%) were resistant to RIF and RFB, 21 (11.9%) were RIF-resistant and RFB-susceptible, and 50 (28.2%) were susceptible to RIF and RFB. Mutations D435V and L452P were significantly associated with only RIF resistance, but not RFB resistance, consistent with the prior data.[17],[32] Cases carrying the isolates with these two mutations may be RFB-susceptible and benefit from the RFB-containing treatment regimen. [Extracted from the article]

Tuberculosis (TB) from a tertiary care TB hospital in China. The emergence of drug-resistant TB, especially multidrug-resistant TB (MDR-TB) Drug resistant-TB can occur when appropriate anti-TB medications are used TB requires more expensive anti-TB drugs and longer ther- (6/18) of patients with MDR-TB were pre-XDR TB, pla-. [Extracted from the article]