Rapid detection of fluoroquinolone resistance in Mycobacterium tuberculosis using a novel multienzyme isothermal rapid assay.

Simple, rapid, and accurate detection of Fluoroquinolone (FQ) resistance is essential for early initiation of appropriate anti-tuberculosis treatment regimen among rifampicin-resistant tuberculosis (RR-TB). In this study, we developed a new assay, which combines multienzyme isothermal rapid amplification and a lateral flow strip (MIRA-LF), to identify the mutations on codons 90 and 94 of gyrA for detecting levofloxacin (LFX) resistance. Compared to conventional phenotypic drug susceptibility testing, the new assay detected fluoroquinolone resistance with a sensitivity, specificity, and accuracy of 92.4%, 98.5%, and 96.5%, respectively. Thus, these characteristics of the newly developed MIRA-LF assay make it particularly useful and accurate for detecting FQ resistance in Mycobacterium tuberculosis in resource-limited condition.

[Main Infection Control Measures for Respiratory Infectious Diseases in Medical Institutions and Public Places in China].

Respiratory infectious diseases (RID) are the major public health problems threatening the people's lives and health.Infection control (IC) is one of the effective tools to contain the occurrence and spread of RID.We collected the articles and data on IC published since January 1,2018 and summarized the achievements,problems,and challenges of IC from administrative control,management control,environment and engineering control,and personal protection in the medical institutions and public places in China.The efforts for IC vary in different regions and medical institutions of different levels.There are still links to be improved for IC from administrative control,management control,environment and engineering control,and personal protection,especially in community-level medical institutions and public areas.It is urgent to strengthen the implementation of IC policies and conduct IC precisely according to local situations.We proposed the following suggestions.First,the existing IC products and tools should be applied to precisely implement the IC measures;second,modern high technology should be employed to develop efficient and convenient IC products and tools;finally,a digital or intelligent IC platform should be built for monitoring infections,so as to contain the occurrence and spread of RID.

rpoB Mutations are Associated with Variable Levels of Rifampin and Rifabutin Resistance in Mycobacterium tuberculosis.

Objective: To assess the relationship between the variant rpoB mutations and the degree of rifampin (RIF)/rifabutin (RFB) resistance in Mycobacterium tuberculosis (M. tuberculosis). Methods: We analyzed the whole rpoB gene in 177 M. tuberculosis clinical isolates and quantified their minimum inhibitory concentrations (MICs) using microplate-based assays. Results: The results revealed that of the 177 isolates, 116 were resistant to both RIF and RFB. There were 38 mutated patterns within the sequenced whole rpoB gene of the 120 isolates. Statistical analysis indicated that mutations, S450L, H445D, H445Y, and H445R, were associated with RIF and RFB resistance. Of these mutations, S450L, H445D, and H445Y were associated with high-level RIF and RFB MIC. H445R was associated with high-level RIF MIC, but not high-level RFB MIC. D435V and L452P were associated with only RIF, but not RFB resistance. Q432K and Q432L were associated with high-level RFB MIC. Several single mutations without statistical association with rifamycin resistance, such as V170F, occurred exclusively in low-level RIF but high-level RFB resistant isolates. Additionally, although cross-resistance to RIF and RFB is common, 21 RIF-resistant/RFB-susceptible isolates were identified. Conclusion: This study highlighted the complexity of rifamycin resistance. Identification of the rpoB polymorphism will be helpful to diagnose the RIF-resistant tuberculosis that has the potential to benefit from a treatment regimen including RFB.

rpoB Mutations and Effects on Rifampin Resistance in Mycobacterium tuberculosis.

OBJECTIVE: To investigate the mutations within the whole rpoB gene of Mycobacterium tuberculosis and analyze their effects on rifampin (RIF) resistance based on crystal structure. METHODS: We sequenced the entire rpoB gene in 175 tuberculosis isolates and quantified their minimum inhibitory concentrations using microplate-based assays. Additionally, the structural interactions between wild-type/mutant RpoB and RIF were also analyzed. RESULTS: Results revealed that a total of 34 mutations distributed across 17 different sites within the whole rpoB gene were identified. Of the 34 mutations, 25 could alter the structural interaction between RpoB and RIF and contribute to RIF resistance. Statistical analysis showed that S450L, H445D, H445Y and H445R mutations were associated with high-level RIF resistance, while D435V was associated with moderate-level RIF resistance. CONCLUSION: Some mutations within the rpoB gene could affect the interaction between RpoB and RIF and thus are associated with RIF resistance. These findings could be helpful to design new antibiotics and develop novel diagnostic tools for drug resistance in TB.

Immunogenicity of Whole Mycobacterium intracellulare Proteins and Fingding on the Cross-Reactive Proteins between M. intracellulare and M. tuberculosis.

OBJECTIVES: To evaluate the immunogenicity of Mycobacterium intracellulare proteins and determine the cross-reactive proteins between M. intracellulare and M. tuberculosis. METHODS: Protein extracts from M. intracellulare were used to immunize BALB/c mice. The antigens were evaluated using cellular and humoral immunoassays. The common genes between M. intracellular and M. tuberculosis were identified using genome-wide comparative analysis, and cross-reactive proteins were screened using immunoproteome microarrays. RESULTS: Immunization with M. intracellulare proteins induced significantly higher levels of the cytokines interferon-γ (IFN-γ), interleukin-2 (IL-2), interleukin-12 (IL-12), interleukin-6 (IL-6) and immunoglobulins IgG, IgG1, IgM, and IgG2a in mouse serum. Bone marrow-derived macrophages isolated from mice immunized with M. intracellulare antigens displayed significantly lower bacillary loads than those isolated from mice immunized with adjuvants. Whole-genome sequence analysis revealed 396 common genes between M. intracellulare and M. tuberculosis. Microchip hybridization with M. tuberculosis proteins revealed the presence of 478 proteins in the serum of mice immunized with M. intracellulare protein extracts. Sixty common antigens were found using both microchip and genomic comparative analyses. CONCLUSION: This is the advanced study to investigate the immunogenicity of M. intracellulare proteins and the cross-reactive proteins between M. intracellulare and M. tuberculosis. The results revealed the presence of a number of cross-reactive proteins between M. intracellulare and M. tuberculosis. Therefore, this study provides a new way of identifying immunogenic proteins for use in tuberculosis vaccines against both M. intracellulare and M. tuberculosis in future.

[A comparative study of cerebellar development between appropriate-for-gestational age infants and small-for-gestational-age infants].

OBJECTIVE: To investigate whether there is a difference in cerebellar development between appropriate -for-gestational-age (AGA) infants and small-for-gestational-age (SGA) infants. METHODS: A total of 165 AGA infants and 105 SGA infants, with a gestational age of 26-40+6 weeks, were enrolled in this study. Within 24-48 hours after birth, ultrasound examination was performed to measure the transverse diameter of the cerebellum, the height of the vermis, the area of the vermis, the perimeter of the vermis, and the area and perimeter of the cerebellum on transverse section. A Pearson correlation analysis was used to investigate the correlation between cerebellar measurements and gestational age. RESULTS: In both AGA and SGA infants, all cerebellar measurements were positively correlated with gestational age (r=0.50-0.81, P<0.05). In AGA and SGA infants, there were no significant differences in the measurements between the 25-27+6 weeks, 28-30+6 weeks, and 31-33+6 weeks of gestational age subgroups (P>0.05), while in the 34-36+6 weeks and 37-40+6 weeks subgroups, the SGA infants had significantly lower measurements than the AGA infants (P<0.05). CONCLUSIONS: The SGA infants with a gestational age of <34 weeks have intrauterine cerebellar development similar to AGA infants, but those with a gestational age of ≥34 weeks have poorer intrauterine cerebellar development than AGA infants.

Detecting Ethambutol Resistance in Mycobacterium tuberculosis Isolates in China: A Comparison Between Phenotypic Drug Susceptibility Testing Methods and DNA Sequencing of embAB.

With the increasing incidence of drug-resistant tuberculosis (DR-TB), determining a rapid and accurate drug susceptibility testing (DST) method to identify ethambutol (EMB) resistance in Mycobacterium tuberculosis has become essential for patient management in China. Herein, we evaluated the correlation between three phenotypic DST methods, namely, proportion method (PM), MGIT 960 system, and microplate alamar Blue assay (MABA), and DNA sequencing of embAB in 118 M. tuberculosis isolates from China. When the results of the phenotypic DST methods were compared with those of DNA sequencing, the overall agreement and kappa values of the PM, MGIT 960 system, and MABA were 81.4% and 0.61, 77.1% and 0.55, and 84.7% and 0.67, respectively. The agreement for EMB resistance between MABA and PM was significantly higher than that between the MGIT 960 system and PM (P = 0.02). Moreover, among the isolates with detectable embAB mutations, 97.2% (70/72 isolates) harbored mutations in embB. The analysis of embB mutations predicted EMB resistance with 81.3% sensitivity, 86.8% specificity, and 83.1% accuracy. Thus, MABA may be a better phenotypic DST method for detecting EMB resistance. DNA sequencing of embB may be useful for the early identification of EMB resistance and the consequent optimization of the treatment regimen.

Accuracy of a reverse dot blot hybridization assay for simultaneous detection of the resistance of four anti-tuberculosis drugs in Mycobacterium tuberculosis isolated from China.

BACKGROUND: Drug resistant tuberculosis poses a great challenge for tuberculosis control worldwide. Timely determination of drug resistance and effective individual treatment are essential for blocking the transmission of drug resistant Mycobacterium tuberculosis. We aimed to establish and evaluate the accuracy of a reverse dot blot hybridization (RDBH) assay to simultaneously detect the resistance of four anti-tuberculosis drugs in M. tuberculosis isolated in China. METHODS: In this study, we applied a RDBH assay to simultaneously detect the resistance of rifampicin (RIF), isoniazid (INH), streptomycin (SM) and ethambutol (EMB) in 320 clinical M. tuberculosis isolates and compared the results to that from phenotypic drug susceptibility testing (DST) and sequencing. The RDBH assay was designed to test up to 42 samples at a time. Pearson's chi-square test was used to compute the statistical measures of the RDBH assay using the phenotypic DST or sequencing as the gold standard method, and Kappa identity test was used to determine the consistency between the RDBH assay and the phenotypic DST or sequencing. RESULTS: The results showed that the concordances between phenotypic DST and RDBH assay were 95% for RIF, 92.8% for INH, 84.7% for SM, 77.2% for EMB and the concordances between sequencing and RDBH assay were 97.8% for RIF, 98.8% for INH, 99.1% for SM, 93.4% for EMB. Compared to the phenotypic DST results, the sensitivity and specificity of the RDBH assay for resistance detection were 92.4 and 98.5% for RIF, 90.3 and 97.3% for INH, 77.4 and 91.5% for SM, 61.4 and 85.7% for EMB, respectively; compared to sequencing, the sensitivity and specificity of the RDBH assay were 97.7 and 97.9% for RIF, 97.9 and 100.0% for INH, 97.8 and 100.0% for SM, 82.6 and 99.1% for EMB, respectively. The turnaround time of the RDBH assay was 7 h for testing 42 samples. CONCLUSIONS: Our data suggested that the RDBH assay could serve as a rapid and efficient method for testing the resistance of M. tuberculosis against RIF, INH, SM and EMB, enabling early administration of appropriate treatment regimens to the affected drug resistant tuberculosis patients.

Beijing genotype of Mycobacterium tuberculosis is less associated with drug resistance in south China.

Mycobacterium tuberculosis Beijing genotype strains are widespread globally. However, there has been no systematic study on the association between Beijing genotype and the characteristics of drug resistance. In this study, 359 M. tuberculosis isolates from south China were collected and their background information, genotype diversity and drug resistance was investigated. The results revealed that 66.0% of strains (237/359) were categorised as Beijing genotype. There was no statistical difference between Beijing and non-Beijing genotype strains in terms of patient sex, age, place of residence and treatment history. Drug resistance testing showed that 34.8% (125/359) of isolates were resistant to at least one of the seven drugs tested. The proportions of multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis were 17.0% and 1.4%, respectively. Previously treated patients presented a significantly higher risk of developing drug resistance than new cases. Although the prevalence of drug resistance was higher in Beijing genotype than in non-Beijing genotype strains, there was no significant difference between these two genotypes in the multivariate analysis. Even in re-treated patients, the association of Beijing genotype with drug resistance was not significant. This study provides an insight into genotype diversity and demonstrates the characteristics of drug resistance in Beijing genotype strains, which will be useful in generating efficient tuberculosis prevention and control strategies in China.

Immunological Evaluation of a Novel Mycobacterium tuberculosis Antigen Rv0674.

OBJECTIVE: This study aimed to characterize the diagnostic and vaccine potential of a novel Mycobacterium tuberculosis antigen Rv0674. METHODS: To evaluate the diagnostic potential and antigenicity of Rv0674, IgG was evaluated using ELISA and interferon (IFN)-γ was done by using ELISpot assay among TB patients and healthy donors. For immunogenicity evaluation, BALB/c mice were immunized with Rv0674. Cytokine production was determined by cytokine release assay using an ELISA kit, and the antibodies were tested using ELISA. RESULTS: The results of serum Elisa tests showed that Rv0674 specific immunoglobulin G (IgG) response was higher in TB patients than negative controls. And Rv0674 had good performance in serological test with sensitivity and specificity of 77.1% and 81.1%, respectively. While it shows poor sensitivity and specificity of 26.23% and 79.69% for IFN-γ tests. In BALB/c mice, Rv0674 adjuvant by DDA/Poly I:C could also induce a high level of IFN-γ, interleukin-2 and interleukin-6 as well as a high IgG titer in both high- and low-dose groups indicating that Rv0674 is essential in humoral and cellular immunity. Moreover, the cytokine profile and IgG isotype characterized Rv0674 as a Th1/Th2-mixed-type protective immunity with the predominance of Th1 cytokines. CONCLUSION: Rv0674 may be a good potential candidate for the development of TB serological diagnosis and a new TB vaccine.

Preliminary Study on Drug Susceptibility Profile and Resistance Mechanisms to Macrolides of Clinical Isolates of Non-tuberculous Mycobacteria from China.

OBJECTIVE: Macrolide susceptibility and drug resistance mechanisms of clinical non-tuberculous mycobacteria (NTM) isolates were preliminarily investigated for more accurate diagnosis and treatment of the infection in China. METHODS: Four macrolides, including clarithromycin (CLAR), azithromycin (AZM), roxithromycin (ROX), and erythromycin (ERY), were used to test the drug susceptibility of 310 clinical NTM isolates from six provinces of China with the broth microdilution method. Two resistance mechanisms, 23S rRNA and erm, were analyzed with nucleotide sequence analysis. RESULTS: Varied effectiveness of macrolides and species-specific resistance patterns were observed. Most Mycobacterium abscessus subsp. massiliense were susceptible and all M. fortuitum were highly resistant to macrolides. All the drugs, except for erythromycin, exhibited excellent activities against slow-growing mycobacteria, and drug resistance rates were below 22.2%. Only four highly resistant strains harbored 2,058/2,059 substitutions on rrl and none of other mutations were related to macrolide resistance. G2191A and T2221C on rrl were specific for the M. abscessus complex (MABC). Seven sites, G2140A, G2210C, C2217G, T2238C, T2322C, T2404C, and A2406G, were specifically carried by M. avium and M. intracellulare. Three sites, A2192G, T2358G, and A2636G, were observed only in M. fortuitum and one site G2152A was specific for M. gordonae. The genes erm(39) and erm(41) were detected in M. fortuitum and M. abscessus and inducible resistance was observed in relevant sequevar. CONCLUSION: The susceptibility profile of macrolides against NTM was demonstrated. The well-known macrolide resistance mechanisms, 23S rRNA and erm, failed to account for all resistant NTM isolates, and further studies are warranted to investigate macrolide resistance mechanisms in various NTM species.

First Report in China on the Identification and Drug Sensitivity of Mycobacterium elephantis Isolated from the Milk of a Cow with Mastitis.

OBJECTIVE: In this study, milk from a cow with mastitis was analyzed to determine the presence of mycobacterial infection. Milk quality and security problems pertaining to the safe consumption of dairy products were also discussed in this study. METHODS: Milk was preprocessed with 4% NaOH. Then, mycobacteria were isolated from the milk sample on L-J medium. The isolate was identified using multiple loci Polymerase Chain Reaction (PCR) and multi-locus sequence analysis with 16S rRNA, sodA, hsp65, and ITS genes. The drug sensitivity of the isolate to 27 antibiotics was tested through alamar blue assay. RESULTS: Smooth, moist, pale yellow colonies appeared on the L-J medium within a week after inoculation. Based on the results of multiple loci PCR analysis, the isolate was preliminarily identified as non-tuberculous mycobacteria. The 16S rRNA, SodA, hsp65, and ITS gene sequences of the isolate exhibited 99%, 99%, 99%, and 100% similarities, respectively, with those of the published reference strains of Mycobacterium elephantis (M. elephantis). The drug sensitivity results showed that the strain is resistant to isoniazid, p-aminosalicylic acid, and trimesulf but is sensitive to ofloxacin, rifampicin, amikacin, capreomycin, moxifloxacin, kanamycin, levofloxacin, cycloserine, ethambutol, streptomycin, tobramycin, rifabutin, ciprofloxacin, linezolid, cefoxitin, clarithromycin, and minocycline. CONCLUSION: To the best of our knowledge, this study is initially to report the isolation of M. elephantis from the milk of a cow with mastitis in China.

Mutations in lysX as the new and reliable markers for tuberculosis Beijing and modern Beijing strains.

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.

Identification of mutations conferring streptomycin resistance in multidrug-resistant tuberculosis of China.

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.

Analysis of embCAB mutations associated with ethambutol resistance in multidrug-resistant mycobacterium tuberculosis isolates from China.

Ethambutol (EMB) plays a pivotal role in the chemotherapy of drug-resistant tuberculosis (TB), including multidrug-resistant tuberculosis (MDR-TB). Resistance to EMB is considered to be caused by mutations in the embCAB operon (embC, embA, and embB). In this study, we analyzed the embCAB mutations among 139 MDR-TB isolates from China and found a possible association between embCAB operon mutation and EMB resistance. Our data indicate that 56.8% of MDR-TB isolates are resistant to EMB, and 82.2% of EMB-resistant isolates belong to the Beijing family. Overall, 110 (79.1%) MDR-TB isolates had at least one mutation in the embCAB operon. The majority of mutations were present in the embB gene and the embA upstream region, which also displayed significant correlations with EMB resistance. The most common mutations occurred at codon 306 in embB (embB306), followed by embB406, embA(-16), and embB497. Mutations at embB306 were associated with EMB resistance. DNA sequencing of embB306-497 was the best strategy for detecting EMB resistance, with 89.9% sensitivity, 58.3% specificity, and 76.3% accuracy. Additionally, embB306 had limited value as a candidate predictor for EMB resistance among MDR-TB infections in China.

Rapid detection of rifampin-resistant clinical isolates of Mycobacterium tuberculosis by reverse dot blot hybridization.

OBJECTIVE: A PCR-reverse dot blot hybridization (RDBH) assay was developed for rapid detection of rpoB gene mutations in 'hot mutation region' of Mycobacterium tuberculosis (M. tuberculosis). METHODS: 12 oligonucleotide probes based on the wild-type and mutant genotype rpoB sequences of M. tuberculosis were designed to screen the most frequent wild-type and mutant genotypes for diagnosing RIF resistance. 300 M. tuberculosis clinical isolates were detected by RDBH, conventional drug-susceptibility testing (DST) and DNA sequencing to evaluate the RDBH assay. RESULTS: The sensitivity and specificity of the RDBH assay were 91.2% (165/181) and 98.3% (117/119), respectively, as compared to DST. When compared with DNA sequencing, the accuracy, positive predictive value (PPV) and negative predictive value (NPV) of the RDBH assay were 97.7% (293/300), 98.2% (164/167), and 97.0% (129/133), respectively. Furthermore, the results indicated that the most common mutations were in codons 531 (48.6%), 526 (25.4%), 516 (8.8%), and 511 (6.6%), and the combinative mutation rate was 15 (8.3%). One and two strains of insertion and deletion were found among all strains, respectively. CONCLUSION: Our findings demonstrate that the RDBH assay is a rapid, simple and sensitive method for diagnosing RIF-resistant tuberculosis.

Molecular characterisation of extensively drug-resistant Mycobacterium tuberculosis isolates in China.

The emergence of extensively drug-resistant tuberculosis (XDR-TB) in China is a great threat to TB control. To determine the molecular characterisation of XDR-TB isolates from China and the correlations between specific drug resistance-associated mutations and different genotype strains, 58 XDR-TB isolates were sequenced in eight drug loci, including katG, inhA, oxyR-ahpC intergenic region, rpoB, eis, rrs, gyrA and gyrB, and were genotyped using spoligotyping and analysis of the noise transfer function region. Compared with the phenotypic data, the sensitivities and specificities for DNA sequencing were 87.9% and 100.0% for isoniazid (INH), 91.4% and 98.3% for rifampicin (RIF), 60.4% and 100.0% for kanamycin (KAN) and 81.0% and 100.0% for ofloxacin (OFX), respectively. A combination of eight drug loci predicted XDR-TB phenotypes with 53.4% sensitivity (31/58 isolates) and 100.0% specificity. The most frequent mutations among these XDR-TB isolates were katG315 and inhA-15 (for INH), 531, 526 and 516 in rpoB (for RIF), rrs1401 and eis-10 (for KAN) and 94, 90 and 91 in gyrA (for OFX). Also, among these XDR-TB isolates, 44 (75.9%) were identified as Beijing genotype strain, of which 31 (70.5%) belonged to the modern Beijing sublineage. inhA-8, rpoB526 and rpoB531 mutations demonstrated significant statistical associations with ancient and modern Beijing family sublineage (P<0.05). However, Beijing and non-Beijing genotypes showed no association with specific resistance-conferring mutations. These results will be helpful in designing new molecular biology-based techniques to diagnose XDR-TB in China.

Prevalence and molecular characteristics of drug-resistant Mycobacterium tuberculosis in Hunan, China.

To determine the prevalence and molecular characteristics of drug-resistant tuberculosis in Hunan province, drug susceptibility testing and spoligotyping methods were performed among 171 M. tuberculosis isolates. In addition, the mutated characteristics of 12 loci, including katG, inhA, rpoB, rpsL, nucleotides 388 to 1084 of the rrs gene [rrs(388-1084)], embB, pncA, tlyA, eis, nucleotides 1158 to 1674 of the rrs gene [rrs(1158-1674)], gyrA, and gyrB, among drug-resistant isolates were also analyzed by DNA sequencing. Our results indicated that the prevalences of isoniazid (INH), rifampin (RIF), streptomycin (SM), ethambutol (EMB), pyrazinamide (PZA), capreomycin (CAP), kanamycin (KAN), amikacin (AKM), and ofloxacin (OFX) resistance in Hunan province were 35.7%, 26.9%, 20.5%, 9.9% 15.2%, 2.3%, 1.8%, 1.2%, and 10.5%, respectively. The previously treated patients presented significantly increased risks for developing drug resistance. The majority of M. tuberculosis isolates belonged to the Beijing family. Almost all the drug resistance results demonstrated no association with genotype. The most frequent mutations of drug-resistant isolates were katG codon 315 (katG315), inhA15, rpoB531, rpoB526, rpoB516, rpsL43, rrs514, embB306, pncA96, rrs1401, gyrA94, and gyrA90. These results contribute to the knowledge of the prevalence of drug resistance in Hunan province and also expand the molecular characteristics of drug resistance in China.

Crystallographic determination of solid-state structural transformations in a dynamic metal-organic framework.

Various solid-state transformations in a metal-organic framework were determined by X-ray crystallography.

Molecular characterization of multidrug-resistant Mycobacterium tuberculosis isolates from China.

To investigate the molecular characterization of multidrug-resistant tuberculosis (MDR-TB) isolates from China and the association of specific mutations conferring drug resistance with strains of different genotypes, we performed spoligotyping and sequenced nine loci (katG, inhA, the oxyR-ahpC intergenic region, rpoB, tlyA, eis, rrs, gyrA, and gyrB) for 128 MDR-TB isolates. Our results showed that 108 isolates (84.4%) were Beijing family strains, 64 (59.3%) of which were identified as modern Beijing strains. Compared with the phenotypic data, the sensitivity and specificity of DNA sequencing were 89.1% and 100.0%, respectively, for isoniazid (INH) resistance, 93.8% and 100.0% for rifampin (RIF) resistance, 60.0% and 99.4% for capreomycin (CAP) resistance, 84.6% and 99.4% for kanamycin (KAN) resistance, and 90.0% and 100.0% for ofloxacin (OFX) resistance. The most prevalent mutations among the MDR-TB isolates were katG315, inhA15, rpoB531, -526, and -516, rrs1401, eis-10, and gyrA94, -90, and -91. Furthermore, there was no association between specific resistance-conferring mutations and the strain genotype. These findings will be helpful for the establishment of rapid molecular diagnostic methods to be implemented in China.