Pyrazinamide (PZA) is one of the most important drugs for the treatment of Mycobacterium tuberculosis infection. However, the increasing frequency of PZA-resistant strains limits its effectiveness. In Korea, most PZA-resistant strains also exhibit both isoniazid and rifampin resistance making it essential to identify these resistant strains accurately and rapidly for effective treatment of mycobacterial infection. In this study, the characteristics and frequency of mutations of the pncA gene encoding pyrazinamidase were investigated in PZA-resistant clinical isolates from Korea. Automated DNA sequencing was used to evaluate the usefulness of DNA-based detection of PZA resistance. Among 95 PZA-resistant clinical isolates, 92 (97%) exhibited mutations potentially affecting either the production or the activity of the enzyme. Mutations were found throughout the pncA gene including the upstream region. Single nucleotide replacement appeared to be the major mutational event (69/92), although multiple substitutions as well as insertion and deletion of nucleotides were also identified. The high frequency of pncA mutations observed in this study supports the usefulness of DNA-based detection of PZA-resistant M. tuberculosis. Having verified the scattered and diverse mutational characteristics of the pncA gene, automated DNA sequencing seems to be the best strategy for rapid detection of PZA-resistant M. tuberculosis.
Amidohydrolases/*genetics ; Antitubercular Agents/*pharmacology ; Drug Resistance, Bacterial ; *Mutation ; Mycobacterium tuberculosis/*drug effects/genetics ; Pyrazinamide/*pharmacology

Antitubercular Agents ; pharmacology ; Drug Resistance, Bacterial ; genetics ; Genotype ; Mycobacterium tuberculosis ; classification ; drug effects ; genetics

NO Abstract Available
Antitubercular Agents/*pharmacology ; Chromosome Mapping ; Drug Resistance, Bacterial ; Ethambutol/*pharmacology ; Korea ; *Mutation ; Mycobacterium tuberculosis/drug effects/*genetics ; Pentosyltransferases/*genetics

Antitubercular Agents ; pharmacology ; Drug Resistance, Multiple, Bacterial ; genetics ; Humans ; Microbial Sensitivity Tests ; methods ; Mycobacterium tuberculosis ; drug effects ; genetics

OBJECTIVETo explore the correlation between Beijing genotype (Beijing family) strains of Mycobacterium tuberculosis (MTB) and drug resistance.

METHODSA computer retrieval of Medline, Embase, SCI, EBSCO, CNKI, Weipu and Wanfang databases from 1990 to 2010 was conducted. A total of 525 articles exploring the relationship of Beijing genotype of MTB and drug resistance were found through literature search. Following the inclusion and exclusion criteria, a Meta-subgroup analysis was conducted in Beijing genotype of MTB and drug resistance.

RESULTSA total of 38 articles were selected, including 22 articles on isoniazid resistance, 24 articles on rifampin resistance, 19 articles on ethambutol resistance, 18 articles on ethambutol resistance, 26 articles on multi-drug resistance (MDR). Meta-subgroup analysis showed that in China, there was an association between Beijing genotype and resistance to rifampin, ethambutol and MDR: rifampin (OR = 1.62, 95%CI: 1.13 - 2.31), ethambutol (OR = 1.67, 95%CI: 1.16 - 2.40), MDR (OR = 1.79, 95%CI: 1.20 - 2.68); in Russia, there was an association between Beijing genotype and resistance to isoniazid, rifampin, ethambutol and MDR: isoniazid (OR = 4.82, 95%CI: 3.19 - 7.29), rifampin (OR = 4.84, 95%CI: 3.84 - 6.10), ethambutol (OR = 3.32, 95%CI: 2.51 - 4.40), MDR (OR = 5.42, 95%CI: 3.36 - 8.74); in Vietnam, there was an association between Beijing genotype and resistance to isoniazid, rifampin, ethambutol and MDR: isoniazid (OR = 2.12, 95%CI: 1.55 - 2.91), rifampin (OR = 4.71, 95%CI: 3.01 - 7.36), ethambutol (OR = 3.78, 95%CI: 1.63 - 8.77), MDR (OR = 4.21, 95%CI: 1.58 - 11.18); in other countries, there was an association between Beijing genotype and resistance to isoniazid, rifampin, ethambutol and MDR: isoniazid (OR = 1.69, 95%CI: 1.19 - 2.42), rifampin (OR = 2.48, 95%CI: 1.92 - 3.19), ethambutol (OR = 3.04, 95%CI: 2.13 - 4.33), MDR (OR = 2.36, 95%CI: 1.52 - 3.68).

CONCLUSIONBeijing genotype of MTB was positively associated with three kinds of first-line anti-tuberculosis drugs (isoniazid, rifampin, ethambutol) and MDR, and the relationship intensity was different in different countries.

Antitubercular Agents ; pharmacology ; China ; DNA, Bacterial ; Drug Resistance, Multiple, Bacterial ; Genotype ; Humans ; Mycobacterium tuberculosis ; drug effects ; genetics ; isolation & purification ; Russia ; Tuberculosis, Multidrug-Resistant ; genetics ; microbiology ; Vietnam

OBJECTIVETo understand the characteristics of pncA gene in multidrug-resistant Mycobacterium tuberculosis isolates and its correlation with drug resistance to pyrazinamide.

METHODSA total of 127 clinical isolates of multidrug-resistant mycobacterium tuberculosis were collected from Shenzhen from year 2007 to 2009. PZA susceptibility was determined by the BACTEC MGIT 960 PZA method. Pyrazinamidase (PZase) activity testing and pncA gene sequencing were performed in all the isolates. The type and frequency of mutations in pncA were determined. Correlation analysis among PZA susceptibility and PZase activity, pncA mutation was performed.

RESULTSAmong the 127 isolates, 62 isolates (48.8%) were found resistance to PZA. Among the 62 PZA resistant isolates, 45 isolates which had various pncA mutations were negative for PZase. Mutation rate was 77.4% (48/62) in total PZA resistance isolates. Different types of 48 resistant isolates were identified in the pncA gene, including base substitution (33 isolates), frame shift mutation (12 isolates) and codon mutation (3 isolates). No mutations except one isolate (N11D) existed in all PZA-susceptibility isolates which were positive for PZase. A total of 5 mutations which have not been described previously were found as follows: H57P, P62Q, G108R, D110Y and G162V. The correlation among the PZA susceptibility and the PZase activity (r = 0.895, P < 0.05), the pncA mutation (r = 0.779, P < 0.05) were significant in 127 multidrug-resistant isolates.

CONCLUSIONA high diversity of pncA gene mutation was found among PZA resistant strains of MTB. This study revealed five new mutations of the pncA gene that were not previously described, which scattered in the hot-spot regions located in the metal coordination site and active site of the enzyme. Mutations had a high correlation with the PZA resistance.

Antitubercular Agents ; pharmacology ; DNA, Bacterial ; genetics ; Humans ; Mutation ; Mycobacterium tuberculosis ; drug effects ; genetics ; isolation & purification ; Pyrazinamide ; pharmacology ; Tuberculosis, Multidrug-Resistant ; genetics ; microbiology

OBJECTIVETo understand the characteristics of embB gene mutation of Mycobacterium tuberculosis (MTB) isolates from tuberculosis patients in Chongqing, and the value of embB306 as a molecular marker used to diagnose ethambutol (EMB)-resistant MTB strains.

METHODSDirect sequencing was used to analyze the polymorphism of embB mutation in 51 EMB-resistant MTB strains and 50 EMB-sensitive MTB strains. And diagnostic testing was used to evaluate the value of embB306 as a molecular marker of EMB -resistant MTB strains as compared with the traditional sensitivity test.

RESULTSAll 34 of 51 EMB-resistant strains (66.7%) and 3 of 51 EMB-sensitive strains (6%) had had embB306 mutation. The embB306 mutation rate in EMB-resistant strains coming from previously treated case was 87.5%, showing significantly higher than that from new cases (48.1%, P < 0.01); embB306 mutation rate was increased with the number of the resistant drugs; embB306 mutation serving as a marker to diagnose EMB-resistant MTB strains comparing with the traditional sensitivity test, had the rate of sensitivity = 66.7%, specificity = 94.0%, accuracy = 80.2% and Youden index = 60.7%.

CONCLUSIONembB306 mutation should be the main mechanism of MTB resistance to EMB in Chongqing, showing an association with the history of the treated and numbers of the resistant drugs. embB306 mutation should be a good marker to diagnose EMB-resistant MTB strains.

China ; DNA Mutational Analysis ; DNA, Bacterial ; genetics ; Genes, Bacterial ; Humans ; Mutation ; Mycobacterium tuberculosis ; drug effects ; genetics ; isolation & purification ; Pentosyltransferases ; genetics ; Tuberculosis, Multidrug-Resistant ; microbiology

OBJECTIVEWe determined the genetic diversity of Mycobacterium tuberculosis (MTB) in a remote mountainous area of southwest China and evaluated the resolving ability of single nucleotide polymorphism (SNP) genotyping combined with variable number tandem repeat (VNTR) genotyping for Beijing family strains in association with drug resistance status.

METHODSThree hundred thirty-one MTB strains were isolated from patients living in mountainous regions of southwest China, and 8-loci SNP, VNTR-15 genotyping assays, and drug susceptibility testing of 9 drugs were performed.

RESULTSA total of 183 [55.29% (183/331)] strains were classified into the Beijing family. Of the 183 strains, 111 (60.66%) were defined as modern Beijing strains. The most predominant modern Beijing sub-lineage and ancient Beijing sub-lineage were Bmyc10 [39.34% (72/183)] and Bmyc25 [20.77% (38/183)], respectively. Of the isolates, 19.64% (65/331) were resistant to at least 1 of the 9 anti-TB drugs and 17 [4.98% (17/331)] MTB isolates were multi-drug resistant tuberculosis (MDR-TB). Two hundred sixty-one isolates showed a clustering rate of 14.18% (37/261) and a discriminatory index of 0.9990. The Beijing lineage exhibited a significantly higher prevalence of MDR-TB, as well as resistance to isoniazid (INH), rifampin (RIF), and para-aminosalicylic acid (PAS) when analyzed independently (P = 0.005, P = 0.017, P = 0.014, and P = 0.006 respectively). The Beijing lineage was not associated with genetic clustering or resistance to any drug. In addition, genetic clustering was not associated with drug resistance.

CONCLUSIONMTB strains demonstrate high genetic diversity in remote mountainous areas of southwest China. Beijing strains, especially modern Beijing strains, are predominant in remote mountainous area of China. The combination of 8-loci SNPs and VNTR-15 genotyping is a useful tool to study the molecular epidemiology of MTB strains in this area.

Antitubercular Agents ; pharmacology ; China ; epidemiology ; Cluster Analysis ; Drug Resistance, Bacterial ; Genotype ; Humans ; Mycobacterium tuberculosis ; drug effects ; genetics ; Phylogeny ; Polymorphism, Single Nucleotide ; Tuberculosis ; epidemiology ; microbiology

OBJECTIVETo detect the mutations of rpoB gene in Mycobacterium tuberculosis by pyrosequencing and to evaluate the values on detection of rifampin resistance in clinical isolates.

METHODSUsing the new technology of pyrosequencing, the mutations in the rifampin resistance determining region (RRDR) of rpoB gene were analyzed. The results were compared with those obtained from methods of the absolute concentration and the minimum inhibitory concentration (MIC).

RESULTSAmong the 150 Mycobacterium tuberculosis clinical isolates, 84 were susceptible and 66 resistant to RIF. 54 of the 66 resistant isolates were multidrug-resistant (MDR) strains. Ser531Leu and His526Asp or Tyr, including twelve different genotypes and six codons, were the most common mutations. In the drug susceptibility testing, the accordance rates of the pyrosequencing and the absolute concentration method as well as MIC were 92.7% and 97.8% respectively.

CONCLUSIONNot only is the pyrosequencing technology a fast, sensitive and high throughput method in detecting rifampin resistance in Mycobacterium tuberculosis, but also a useful tool in the research of rifampin resistance mechanism.

Bacterial Proteins ; genetics ; DNA-Directed RNA Polymerases ; Drug Resistance, Bacterial ; genetics ; Humans ; Microbial Sensitivity Tests ; Mutation ; Mycobacterium tuberculosis ; drug effects ; genetics ; Phosphoric Acids ; Polymerase Chain Reaction ; Rifampin ; pharmacology

OBJECTIVETo induce Mycobacterium tuberculosis (MTB) resistance with ofloxacin (Ofx) of stepwise increasing concentration in vitro, investigate stability to fluoroquinolone (FQs) antibiotic of MTB, and analyze the molecular mechanism and mutation specialty of drug resistance preliminarily.

METHODSMTB Standard strain H37RV and 24 clinical isolates susceptible to Ofx were selected and experimentally serially subcultured in liquid culture medium containing increasing concentration of Ofx and induced the drug resistance to Ofx. Variety of Minimal Inhibitory Concentrations (MICs) to FQs drugs were detected by microwell-MIC-test method. Mutations of quinolone resistance determining region (QRDR) of gyrA gene were sequenced and identified. Relationship of different mutation sites and drug resistant degree were analyzed. A total of 6 MTB clinical isolates resistant to Ofx and induced drug resistant isolates in vitro were serially subcultured in liquid culture medium without drug. Variety of drug resistant stability, including MIC and mutation of gyrA gene were detected.

RESULTSMIC values of 21 Ofx susceptible isolates after induction were eight times higher than before, which were induced to drug resistant strains successfully and also resistant to Lfx and Mfx. Hot mutations of QRDR of gyrA gene were detected by sequencing, except one strain. Mutation of codon 94 occurred in 60% (12/20) of the strains with mutations and corresponding value of 50% Minimal Inhibitory Concentrations(MIC50) was ≥ 8 µg/ml. In all, 4 of 6 MTB clinical isolates resistant to Ofx harbored mutation of codon 90 (67%) , but the corresponding value of MIC50 was 2 µg/ml. After 21 serially subcultured in liquid culture medium without drug, MIC values of 6 clinical isolates resistant to Ofx were not changed obviously and mutations were also not changed. After 11 times serially subcultured in culture medium without drug, MIC values of induced drug resistant strains were also not changed obviously, but new mutations were detected in QRDR of 3 isolates.

CONCLUSIONMTB strains resistant to three kinds of FQs antibiotic were obtained by induction in vitro with Ofx. Codons 88, 94 mutations of QRDR of gyrA gene were related to the high level FQs drug resistance of MTB. Drug resistant stability of MTB to FQs was strong, and it is difficult for MTB to resume susceptibility.

Antitubercular Agents ; pharmacology ; DNA Gyrase ; genetics ; Drug Resistance, Bacterial ; genetics ; Microbial Sensitivity Tests ; Mycobacterium tuberculosis ; drug effects ; genetics ; isolation & purification ; Ofloxacin ; pharmacology