High-Valence Metals Accelerate the Reaction Kinetics for Boosting Water Oxidation.

The transition metal with high valence state in oxyhydroxides can accelerate the reaction kinetics, enabling highly intrinsic OER activity. However, the formation of high-valence transition-metal ions is thermodynamically unfavorable in most cases. Here, a novel strategy is proposed to realize the purpose and reveal the mechanism by constructing amorphous phase and incorporating of elements with the characteristic of Lewis acid or variable charge state. A model catalyst, CeO2-NiFeOxHy, is presented to achieve the modulation of valence state of active site (Ni2+→Ni3+→Ni4+) for improved OER, leading to dominant active sites with high valence state. The CeO2-NiFeOxHy electrode exhibits superior OER performance with overpotential of 214 and 659 mV at 10 and 500 mA cm-2, respectively (without IR correction), and high stability, which are much better than those of NiOxHy, NiFeOxHy and CeO2-NiOxHy. These findings provide an effective strategy to achieve the active metals with high-valence state for highly efficient OER.

Electrolyte-Assisted Structure Reconstruction Optimization of Sn-Zn Hybrid Oxide Boosts the Electrochemical CO2-to-HCOO- Conversion.

Electrolyte plays crucial roles in electrochemical CO2 reduction reaction (e-CO2RR), yet how it affects the e-CO2RR performance still being unclarified. In this work, it is reported that Sn-Zn hybrid oxide enables excellent CO2-to-HCOO- conversion in KHCO3 with a HCOO- Faraday efficiency ≈89%, a yield rate ≈0.58 mmol cm-2 h-1 and a stability up to ≈60 h at -0.93 V, which are higher than those in NaHCO3 and K2SO4. Systematical characterizations unveil that the surface reconstruction on Sn-Zn greatly depends on the electrolyte using: the Sn-SnO2/ZnO, the ZnO encapsulated Sn-SnO2/ZnO and the Sn-SnO2/Zn-ZnO are reconstructed on the surface by KHCO3, NaHCO3 and K2SO4, respectively. The improved CO2-to-HCOO- performance in KHCO3 is highly attributed to the reconstructed Sn-SnO2/ZnO, which can enhance the charge transportation, promote the CO2 adsorption and optimize the adsorption configuration, accumulate the protons by enhancing water adsorption/cleavage and limit the hydrogen evolution. The findings may provide insightful understanding on the relationship between electrolyte and surface reconstruction in e-CO2RR and guide the design of novel electrocatalyst for effective CO2 reduction.

Transmission dynamics of tuberculosis in a high-burden area of China: An 8-year population-based study using whole genome sequencing.

OBJECTIVES: This study investigated the transmission patterns of tuberculosis (TB) and its associated risk factors in Hunan province to inform the development of prevention and control strategies in the region. METHODS: An 8-year retrospective population-based genomic epidemiological study was conducted. Genomic clusters were defined using distance thresholds of 12-single-nucletide-polymorphisms. Risk factors associated with TB transmission were analyzed using logistic regression model. Kernel Density analysis was used to locate hotspots where transmission occurred. RESULTS: Among 2649 TB cases included in this study, 275 clusters were identified, with an overall clustering rate of 24.7% (654/2649). Nearly 95% (620/654) of clustered strains were isolated from the same county. Of the 275 clusters, 23 (8.4%, 23/275) had differences in drug-resistant profiles, with FQs resistance mutations occurring most frequently (52.2%, 12/23). Multivariate analysis identified male TB patients, those aged 30-60 years, ethnic minorities, nonfarmers, retreated TB patients, and individuals infected with MDR/RR-TB as independent risk factors for TB transmission (P < 0.05). Kernel density analysis showed that among the 5 drug-resistant surveillance sites, Leiyang had the highest clustering rate, followed by Yongshun, Qidong, Hecheng, and Taojiang. CONCLUSION: Recent transmission in the region is predominantly occurring within counties. The risk factors related to TB transmission and the hotspots where transmission occurs can provide a scientific basis for the formulation of targeted TB prevention and control strategies.

Industrial-Si-based photoanode for highly efficient and stable water splitting.

Photoelectrochemical (PEC) water splitting is an effective and sustainable method for solar energy harvesting. However, the technology is still far away from practical application because of the high cost and low efficiency. Here, we report a low-cost, stable and high-performing industrial-Si-based photoanode (n-Indus-Si/Co-2mA-xs) that is fabricated by simple electrodeposition. Systematic characterizations such as scanning electron microscopy, X-ray photoelectron spectroscopy have been employed to characterize and understand the working mechanisms of this photoanode. The uniform and adherent dispersion of co-catalyst particles result in high built-in electric field, reduced charge transfer resistance, and abundant active sites. The core-shell structure of co-catalyst particles is formed after the activation process. The reconstructed morphology and modified chemical states of the surface co-catalyst particles improve the separation and transfer of charges, and the reaction kinetics for water oxidation greatly. Our work demonstrates that large-scale PEC water splitting can be achieved by engineering the industrial-Si-based photoelectrode, which shall guide the development of solar energy conversion in the industry.

The Recent Transmission and Associated Risk Factor of Mycobacterium tuberculosis in Golmud City, China.

Background: Tuberculosis (TB) remains a severe public health problem globally, and it is essential to comprehend the transmission pattern to control tuberculosis. Herein, we evaluated the drug-resistant characteristics, recent transmission, and associated risk factors of TB in Golmud, Qinghai, China. Methods: In this study, we performed a population-based study of patients diagnosed with TB in Golmud from 2013 to 2018. Drug-susceptibility testing and whole-genome sequencing were performed on 133 Mycobacterium tuberculosis strains. The genomic clustering rate was calculated to evaluate the level of recent transmission. Risk factors were identified by logistic regression analysis. Results: Our results showed that 46.97% (62/132) of strains were phylogenetically clustered and formed into 23 transmission clusters, suggesting a high recent transmission of TB in the area. 12.78% (17/133) strains were multidrug-resistant/rifampicin tuberculosis (MDR/RR-TB), with a high drug-resistant burden. Based on drug resistance gene analysis, we found 23 strains belonging to genotype MDR/RR-TB, where some strains may have borderline mutations. Among these strains, 65.2% (15/23) were found within putative transmission clusters. Additionally, risk factor analysis showed that recent transmission of TB happened more in patients with Tibetan nationality or older age. Conclusion: Overall our study indicates that the recent transmissions of MTB strains, especially genotypic MDR/RR strains, drive the tuberculosis epidemic in Golmud, which could contribute to developing effective TB prevention and control strategies.

Triggering efficient reconstructions of Co/Fe dual-metal incorporated Ni hydroxide by phosphate additives for electrochemical hydrogen and oxygen evolutions.

Alkaline electrochemical water splitting has been considered as an efficient way for the green hydrogen production in industry, where the electrocatalysts play the critical role for the electricity-to-fuel conversion efficiency. Phosphate salts are widely used as additives in the fabrication of electrocatalysts with improved activity, but their roles on the electrocatalytic performance have not been fully understood. Herein, we fabricate Co, Fe dual-metal incorporated Ni hydroxide on Ni foam using NaH2PO4 ((Co, Fe)NiOxHy-pi) and NaH2PO2 ((Co, Fe)NiOxHy-hp) as additive, respectively. We find that (Co, Fe)NiOxHy-hp with NaH2PO2 in the fabrication shows high activity and stability for both HER and OER (a overpotential of -0.629 V and 0.65 V at 400 mA cm-2 for HER and OER, respectively). Further experiment reveals that the reconstructed structures of electrocatalyst by using NaH2PO2 (hp) endow high electrocatalytic performances: (1) in-situ generated active metal improves the accumulation, transportation and activity of hydrogen species in the HER process; and (2) in-situ generated poor-crystalline hydroxide endows superior charge/mass transportation and kinetics improvements in the OER process. Our study may provide an insightful understanding on the catalytic performance of non-precious metal electrocatalysts by controlling additives and guidance for the design and synthesis of novel electrocatalysts.

Association of lineage 4.2.2 of Mycobacterium tuberculosis with the 63-bp deletion variant of the mpt64 gene.

IMPORTANCE: To date, rapid diagnostic methods based on the MPT64 antigen assay are increasingly utilized to differentiate between non-tuberculous mycobacteria and TB disease in clinical settings. Furthermore, numerous novel techniques based on the MPT64 release assay are continuously being developed and applied for the identification of both pulmonary and extrapulmonary TB. However, the diagnostic accuracy of the MPT64 antigen assay is influenced by the presence of 63 bp deletion variants within the mpt64 gene. To our knowledge, this is the first report on the association between the 63 bp deletion variant in mpt64 and Mycobacterium tuberculosis L4.2.2 globally, which highlights the need for the cautious utilization of MPT64-based testing in regions where L4.2.2 isolates are prevalent, such as China and Vietnam, and MPT64 negative results should be confirmed with another assay. In addition, further studies on vaccine development and immunology based on MPT64 should consider these isolates with 63 bp deletion variant.

Insight into the drug-resistant characteristics and genetic diversity of multidrug-resistant Mycobacterium tuberculosis in China.

Multidrug-resistant tuberculosis (MDR-TB) has a severe impact on public health. To investigate the drug-resistant profile, compensatory mutations and genetic variations among MDR-TB isolates, a total of 546 MDR-TB isolates from China underwent drug-susceptibility testing and whole genome sequencing for further analysis. The results showed that our isolates have a high rate of fluoroquinolone resistance (45.60%, 249/546) and a low proportion of conferring resistance to bedaquiline, clofazimine, linezolid, and delamanid. The majority of MDR-TB isolates (77.66%, 424/546) belong to Lineage 2.2.1, followed by Lineage 4.5 (6.41%, 35/546), and the Lineage 2 isolates have a strong association with pre-XDR/XDR-TB (P < 0.05) in our study. Epidemic success analysis using time-scaled haplotypic density (THD) showed that clustered isolates outperformed non-clustered isolates. Compensatory mutations happened in rpoA, rpoC, and non-RRDR of rpoB genes, which were found more frequently in clusters and were associated with the increase of THD index, suggesting that increased bacterial fitness was associated with MDR-TB transmission. In addition, the variants in resistance associated genes in MDR isolates are mainly focused on single nucleotide polymorphism mutations, and only a few genes have indel variants, such as katG, ethA. We also found some genes underwent indel variation correlated with the lineage and sub-lineage of isolates, suggesting the selective evolution of different lineage isolates. Thus, this analysis of the characterization and genetic diversity of MDR isolates would be helpful in developing effective strategies for treatment regimens and tailoring public interventions. IMPORTANCE Multidrug-resistant tuberculosis (MDR-TB) is a serious obstacle to tuberculosis prevention and control in China. This study provides insight into the drug-resistant characteristics of MDR combined with phenotypic drug-susceptibility testing and whole genome sequencing. The compensatory mutations and epidemic success analysis were analyzed by time-scaled haplotypic density (THD) method, suggesting clustered isolates and compensatory mutations are associated with MDR-TB transmission. In addition, the insertion and deletion variants happened in some genes, which are associated with the lineage and sub-lineage of isolates, such as the mpt64 gene. This study offered a valuable reference and increased understanding of MDR-TB in China, which could be crucial for achieving the objective of precision medicine in the prevention and treatment of MDR-TB.

Facile formation of Zn-incorporated NiFe layered double hydroxide as highly-efficient oxygen evolution catalyst.

Electrochemical water splitting is the primary method to produce green hydrogen, which is considered an efficient alternative to fossil fuels for achieving carbon neutrality. For meeting the increasing market demand for green hydrogen, high-efficiency, low-cost, and large-scale electrocatalysts are crucial. In this study, we report a simple spontaneous corrosion and cyclic voltammetry (CV) activation method to fabricate Zn-incorporated NiFe layered double hydroxide (LDH) on commercial NiFe foam, which shows excellent oxygen evolution reaction (OER) performance. The electrocatalyst achieves an overpotential of 565 mV and outstanding stability of up to 112 h at 400 mA cm-2. The active layer for OER is shown to be ß-NiFeOOH according to the results of in-situ Raman. Our findings suggest that the NiFe foam treated by simple spontaneous corrosion has promising industrial applications as a highly efficient OER catalyst.

Endogenous relapse and exogenous reinfection in recurrent pulmonary tuberculosis: A retrospective study revealed by whole genome sequencing.

Background: Tuberculosis may reoccur due to reinfection or relapse after initially successful treatment. Distinguishing the cause of TB recurrence is crucial to guide TB control and treatment. This study aimed to investigate the source of TB recurrence and risk factors related to relapse in Hunan province, a high TB burden region in southern China. Methods: A population-based retrospective study was conducted on all culture-positive TB cases in Hunan province, China from 2013 to 2020. Phenotypic drug susceptibility testing and whole-genome sequencing were used to detect drug resistance and distinguish between relapse and reinfection. Pearson chi-square test and Fisher exact test were applied to compare differences in categorical variables between relapse and reinfection. The Kaplan-Meier curve was generated in R studio (4.0.4) to describe and compare the time to recurrence between different groups. p < 0.05 was considered statistically significant. Results: Of 36 recurrent events, 27 (75.0%, 27/36) paired isolates were caused by relapse, and reinfection accounted for 25.0% (9/36) of recurrent cases. No significant difference in characteristics was observed between relapse and reinfection (all p > 0.05). In addition, TB relapse occurs earlier in patients of Tu ethnicity compared to patients of Han ethnicity (p < 0.0001), whereas no significant differences in the time interval to relapse were noted in other groups. Moreover, 83.3% (30/36) of TB recurrence occurred within 3 years. Overall, these recurrent TB isolates were predominantly pan-susceptible strains (71.0%, 49/69), followed by DR-TB (17.4%, 12/69) and MDR-TB (11.6%, 8/69), with mutations mainly in codon 450 of the rpoB gene and codon 315 of the katG gene. 11.1% (3/27) of relapse cases had acquired new resistance during treatment, with fluoroquinolone resistance occurring most frequently (7.4%, 2/27), both with mutations in codon 94 of gyrA. Conclusion: Endogenous relapse is the main mechanism leading to TB recurrences in Hunan province. Given that TB recurrences can occur more than 4 years after treatment completion, it is necessary to extend the post-treatment follow-up period to achieve better management of TB patients. Moreover, the relatively high frequency of fluoroquinolone resistance in the second episode of relapse suggests that fluoroquinolones should be used with caution when treating TB cases with relapse, preferably guided by DST results.

High diversity of clinical Mycobacterium intracellulare in China revealed by whole genome sequencing.

Mycobacterium intracellulare is the most common cause of nontuberculous mycobacterial lung disease, with a rapidly growing prevalence worldwide. In this study, we performed comparative genomic analysis and antimicrobial susceptibility characteristics analysis of 117 clinical M. intracellulare strains in China. Phylogenetic analysis showed that clinical M. intracellulare strains had high genetic diversity and were not related to the geographical area. Notably, most strains (76.07%, 89/117) belonged to Mycobacterium paraintracellulare (MP) and Mycobacterium indicus pranii (MIP) in the genome, and we named them MP-MIP strains. These MP-MIP strains may be regarded as a causative agent of chronic lung disease. Furthermore, our data demonstrated that clarithromycin, amikacin, and rifabutin showed strong antimicrobial activity against both M. intracellulare and MP-MIP strains in vitro. Our findings also showed that there was no clear correlation between the rrs, rrl, and DNA gyrase genes (gyrA and gyrB) and the aminoglycosides, macrolides, and moxifloxacin resistance, respectively. In conclusion, this study highlights the high diversity of M. intracellulare in the clinical setting and suggests paying great attention to the lung disease caused by MP-MIP.

Transmission and Drug Resistance Genotype of Multidrug-Resistant or Rifampicin-Resistant Mycobacterium tuberculosis in Chongqing, China.

Multidrug-resistant or rifampicin-resistant tuberculosis (MDR/RR-TB) is a global barrier for the Stop TB plan. To identify risk factors for treatment outcome and cluster transmission of MDR/RR-TB, whole-genome sequencing (WGS) data of isolates from patients of the Chongqing Tuberculosis Control Institute were used for phylogenetic classifications, resistance predictions, and cluster analysis. A total of 223 MDR/RR-TB cases were recorded between 1 January 2018 and 31 December 2020. Elderly patients and those with lung cavitation are at increased risk of death due to MDR/RR-TB. A total of 187 MDR/RR strains were obtained from WGS data; 152 were classified as lineage 2 strains. Eighty (42.8%) strains differing by a distance of 12 or fewer single nucleotide polymorphisms were classified as 20 genomic clusters, indicating recent transmission. Patients infected with lineage 2 strains or those with occupations listed as "other" are significantly associated with a transmission cluster of MDR/RR-TB. Analysis of resistant mutations against first-line tuberculosis drugs found that 76 (95.0%) of all 80 strains had the same mutations within each cluster. A total of 55.0% (44 of 80) of the MDR/RR-TB strains accumulated additional drug resistance mutations along the transmission chain, especially against fluoroquinolones (63.6% [28 of 44]). Recent transmission of MDR/RR strains is driving the MDR/RR-TB epidemics, leading to the accumulation of more serious resistance along the transmission chains. IMPORTANCE The drug resistance molecular characteristics of MDR/RR-TB were elucidated by genome-wide analysis, and risk factors for death by MDR/RR-TB were identified in combination with patient information. Cluster characteristics of MDR/RR-TB in the region were analyzed by genome-wide analysis, and risk factors for cluster transmission (recent transmission) were analyzed. These analyses provide reference for the prevention and treatment of MDR/RR-TB in Chongqing.

Genomic analysis of diversity, biogeography, and drug resistance in Mycobacterium bovis.

Mycobacterium bovis is the cause of bovine tuberculosis, and it can also cause disease in humans, with symptoms similar to those caused by M. tuberculosis. However, our understanding of its genomic diversity, biogeography, and drug resistance remains incomplete. We performed a comparative and phylogenetic analysis of 3228 M. bovis genomes from 24 countries. Following drug susceptibility testing, we applied a bacterial genome-wide association study to capture associations between genomic variation and drug resistance in 74 newly isolated strains from China. The data show that the cattle-adapted M. bovis were divided into six lineages with a strong phylogeographical population structure. Lineages 1 and 6 are the most widespread globally, while others show a strong geographical restriction. Note that 17.39% of M. bovis isolates were resistant to at least one drug in China. Furthermore, we identify genomic variations associated with an increased risk of resistance acquisition. This study furthers our knowledge of M. bovis diversity, biogeography, and drug resistance and will facilitate more deeply informed genomic tracking and surveillance to minimize its threat to human health, as a cause of zoonotic tuberculosis.

Identification and drug susceptibility testing of the subspecies of Mycobacterium avium complex clinical isolates in mainland China.

OBJECTIVES: The Mycobacterium avium complex (MAC), comprising a series of subspecies, has a worldwide distribution, with differences in drug susceptibility among subspecies. This study aimed to assess the composition of MAC and susceptibility differences among subspecies in mainland China. METHODS: A total of 287 MAC clinical strains were included in the study. Multitarget sequences were applied to accurately identify subspecies, and a microdilution method was used to evaluate minimum inhibitory concentrations (MICs) among subspecies using Sensititre SLOMYCO plates. RESULTS: Mycobacterium intracellular (N = 169), Mycobacterium avium (N = 52), Mycobacterium chimaera (N = 22), Mycobacterium marseillense (N = 25), Mycobacterium colombiense (N = 14), Mycobacterium yongonense (N = 4), Mycobacterium vulneris (N = 3) and Mycobacterium timonense (N = 2) were isolated from MAC. Clarithromycin, amikacin and rifabutin showed lower MIC50 and MIC90 values than other drugs, and the resistance rates of clarithromycin, amikacin, linezolid and moxifloxacin were 6.3%, 10.5%, 51.9% and 46.3%, respectively. The resistance rates of clarithromycin and moxifloxacin in the initial treatment group were significantly lower than those in the retreatment group (4.09% vs. 12.94%; 30.41% vs. 75.29%; P < 0.05). Drug susceptibility differences were observed in clarithromycin and moxifloxacin among the five major subspecies (P < 0.05); however, those statistically significant differences disappeared when MACs were divided into two groups according to previous anti-tuberculosis (anti-TB) treatment history. CONCLUSION: This study revealed that MAC, primarily comprising M. intracellulare, was susceptible to clarithromycin, amikacin and rifabutin. Drug susceptibility among subspecies did not exhibit intrinsic differences in our study. Previous anti-TB treatment patients are more resistant to drugs; thus, attention should be given to those patients in the clinic.

Diagnosis of pulmonary tuberculosis via identification of core genes and pathways utilizing blood transcriptional signatures: a multicohort analysis.

BACKGROUND: Blood transcriptomics can be used for confirmation of tuberculosis diagnosis or sputumless triage, and a comparison of their practical diagnostic accuracy is needed to assess their usefulness. In this study, we investigated potential biomarkers to improve our understanding of the pathogenesis of active pulmonary tuberculosis (PTB) using bioinformatics methods. METHODS: Differentially expressed genes (DEGs) were analyzed between PTB and healthy controls (HCs) based on two microarray datasets. Pathways and functional annotation of DEGs were identified and ten hub genes were selected. They were further analyzed and selected, then verified with an independent sample set. Finally, their diagnostic power was further evaluated between PTB and HCs or other diseases. RESULTS: 62 DEGs mostly related to type I IFN pathway, IFN-γ-mediated pathway, etc. in GO term and immune process, and especially RIG-I-like receptor pathway were acquired. Among them, OAS1, IFIT1 and IFIT3 were upregulated and were the main risk factors for predicting PTB, with adjusted risk ratios of 1.36, 3.10, and 1.32, respectively. These results further verified that peripheral blood mRNA expression levels of OAS1, IFIT1 and IFIT3 were significantly higher in PTB patients than HCs (all P < 0.01). The performance of a combination of these three genes (three-gene set) had exceeded that of all pairwise combinations of them in discriminating TB from HCs, with mean AUC reaching as high as 0.975 with a sensitivity of 94.4% and a specificity of 100%. The good discernibility capacity was evaluated d via 7 independent datasets with an AUC of 0.902, as well as mean sensitivity of 87.9% and mean specificity of 90.2%. In regards to discriminating PTB from other diseases (i.e., initially considered to be possible TB, but rejected in differential diagnosis), the three-gene set equally exhibited an overall strong ability to separate PTB from other diseases with an AUC of 0.999 (sensitivity: 99.0%; specificity: 100%) in the training set, and 0.974 with a sensitivity of 96.4% and a specificity of 98.6% in the test set. CONCLUSION: The described commonalities and unique signatures in the blood profiles of PTB and the other control samples have considerable implications for PTB biosignature design and future diagnosis, and provide insights into the biological processes underlying PTB.

Diversity of glpK Gene and Its Effect on Drug Sensitivity in Mycobacterium bovis.

Background: Glycerol kinase (glpK) is essential for the first step of glycerol catabolism in Mycobacterium tuberculosis. However, Mycobacterium bovis has been known to grow poorly in glycerol media because of a base insertion in the glpK gene. Methods: We analyzed the glpK gene sequences of 60 clinical M. bovis isolates, and determined the minimum inhibitory concentration of 14 drugs by microdilution method to evaluate the effect of frameshift mutations on drug sensitivity. The effect of M. bovis growth rate on its drug sensitivity was investigated using bacteria grown on glycerol or pyruvate. Results: A total of 44 (73.33%) clinical M. bovis isolates have frameshift mutations in a homopolymeric tract of 7 cytosines in the glpK gene. 15.00% M. bovis isolates showed phenotypic drug resistance. Glycerol metabolism-deficient M. bovis showed reduced susceptibility to 9 out of 14 tested drugs. Mutations in the glpK gene can lead to impaired growth in glycerol-based media, while the minimal inhibitory concentration values of slow-growing M. bovis were higher. Conclusion: Mutations in the glpK gene can lead to slowed growth and reduced susceptibility to drugs in M. bovis, which may contribute to the emergence of drug-resistant M. bovis and pose a threat to human health owing to the zoonotic capacity of M. bovis.

Drug-Resistant Characteristics, Genetic Diversity, and Transmission Dynamics of Rifampicin-Resistant Mycobacterium tuberculosis in Hunan, China, Revealed by Whole-Genome Sequencing.

To gain a deep insight into the additional drug-resistant profiles, genetic diversity, and transmission dynamics of rifampicin-resistant tuberculosis (RR-TB) circulating in Hunan province, drug susceptibility testing and whole-genome-sequencing were performed among RR-TB strains collected from Jan. 2013 to Jun. 2018 in Hunan province. A total of 124 RR-TB strains were recovered successfully and included into the final analysis. Lineage 2.2.1 was the dominant sublineage, accounting for 72.6% (90/124), followed by lineage 4.5 (11.3%, 14/124), lineage 4.4 (8.1%, 10/124), lineage 4.2 (6.5%, 8/124) and lineage 2.2.2 (1.6%, 2/124). Overall, 83.1% (103/124) and 3.2% (4/124) of RR-TB were MDR-TB and XDR-TB, respectively. Nearly 30% of RR-TB isolates were resistant to fluoroquinolones, and 26.6% (33/124) were pre-XDR-TB. Moreover, 30.6% (38/124) of RR-TB strains were identified as phenotypically resistance to pyrazinamide. Totally, 17 clusters containing 48 (38.7%, 48/124) RR-TB strains were identified, ranging in size from 2 to 10 isolates. No significant difference was detected in clustering rate between lineage 2 and lineage 4 (χ2 = 0.027, P = 0.870). Our study revealed the complexity of RR-TB strains circulating in Hunan province with complex additional drug-resistant profile and relatively higher clustering rates. Comprehensive information based on WGS should be used to guide the design of treatment regimens and tailor public interventions. IMPORTANCE Comprehensive information such as genetic background and drug-resistant profile of MTB strains could help to tailor public interventions. However, these data are limited in Hunan province, one of the provinces with high-TB burden in China. So, this study aimed to provide us with deep insight into the molecular epidemiology of RR-TB isolates circulating in Hunan province by combining phenotypic drug susceptibility testing and whole-genome sequencing. To our knowledge, this is the first study to use whole-genome sequencing data of RR-TB strains spanning more than 5 years for molecular epidemiology analysis in Hunan province, which allows us to identify genetic background information and clustered strains more accurately. Our study revealed the complexity of RR-TB strains circulating in Hunan province with complex additional drug-resistant profile and relatively higher clustering rates. Comprehensive information based on WGS should be used to guide the design of treatment regimens and tailor public interventions.

Whole-genome sequencing for surveillance of tuberculosis drug resistance and determination of resistance level in China.

OBJECTIVES: Phenotypic drug susceptibility testing for prediction of tuberculosis (TB) drug resistance is slow and unreliable, limiting individualized therapy and monitoring of national TB data. Our study evaluated whole-genome sequencing (WGS) for its predictive accuracy, use in TB drug-resistance surveillance and ability to quantify the effects of resistance-associated mutations on MICs of anti-TB drugs. METHODS: We used WGS to measure the susceptibility of 4880 isolates to ten anti-TB drugs; for pyrazinamide, we used BACTEC MGIT 960. We determined the accuracy of WGS by comparing the prevalence of drug resistance, measured by WGS, with the true prevalence, determined by phenotypic susceptibility testing. We used the Student-Newman-Keuls test to confirm MIC differences of mutations. RESULTS: Resistance to isoniazid, rifampin and ethambutol was highly accurately predicted with at least 92.92% (95% confidence interval [CI], 88.19-97.65) sensitivity, resistance to pyrazinamide with 50.52% (95% CI, 40.57-60.47) sensitivity, and resistance to six second-line drugs with 85.05% (95% CI, 80.27-89.83) to 96.01% (95% CI, 93.89-98.13) sensitivity. The rpoB S450L, katG S315T and gyrA D94G mutations always confer high-level resistance, while rpoB L430P, rpoB L452P, fabG1 C-15T and embB G406S often confer low-level resistance or sub-epidemiological cutoff (ECOFF) MIC elevation. CONCLUSION: WGS can predict phenotypic susceptibility with high accuracy and could be a valuable tool for drug-resistance surveillance and allow the detection of drug-resistance level; It can be an important approach in TB drug-resistance surveillance and for determining therapeutic schemes.

Tuberculosis Outbreak in an Educational Institution in Henan Province, China.

On June 17, 2018, a case of pulmonary tuberculosis (TB) was reported among students at a senior high school in Luoning, China. The outbreak encompassed a total of 23 cases along with TB screening in the whole school by means of PPD and chest X-ray. By the end of September 2018, the entire 9 cases cultured positive had epidemiological association. All of the 9 Mycobacterium tuberculosis (Mtb) isolates available were sensitive to all drugs tested and had similar spoligotyping and 15 loci mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) profile. Whole-genome sequencing (WGS) of the Mtb isolates revealed 20 variable nucleotide positions within 8 cases, indicating a clonal outbreak. The index case, which was first identified and diagnosed, is separated from the cluster by a minimum number of 95 distinct SNPs. Minimum distance spanning tree (MST) indicted that the 8 cases were indeed part of a single transmission chain. It was concluded that this is an epidemic situation of TB outbreak exposed by the aggrieved index case at school, which was caused by the veiled infectious case wherein a student was suffering from TB and attending school simultaneously.

Prevalence of Mycobacterium tuberculosis resistant to bedaquiline and delamanid in China.

OBJECTIVES: The new antituberculous drugs delamanid and bedaquiline form the last line of defence against drug-resistant tuberculosis (TB). Understanding the background prevalence of resistance to new drugs can help predict the lifetime of these drugs' effectiveness and inform regimen design. METHODS: Mycobacterium tuberculosis without prior exposure to novel anti-TB drugs were analysed retrospectively. Drug susceptibility testing for bedaquiline, delamanid, linezolid, clofazimine and widely used first- and second-line anti-TB drugs was performed. All TB isolates with resistance to new or repurposed drugs were subjected to whole-genome sequencing to explore the molecular characteristics of resistance and to perform phylogenetic analysis. RESULTS: Overall, resistance to delamanid, bedaquiline, linezolid and clofazimine was observed in 0.7% (11/1603), 0.4% (6/1603), 0.4% (7/1603) and 0.4% (6/1603) of TB isolates, respectively. Moreover, 1.0% (1/102), 2.9% (3/102), 3.9% (4/102) and 1.0% (1/102) of multidrug-resistant TB (MDR-TB) were resistant to bedaquiline, delamanid, linezolid and clofazimine, respectively. Whereas 22.2% (2/9) of extensively-drug resistant tuberculosis (XDR-TB) isolates were resistant to both delamanid and linezolid, and none was resistant to bedaquiline or clofazimine. Phylogenetic analysis showed that recent transmission occurred in two XDR-TB with additional resistance to delamanid and linezolid. None known gene mutation associated with delamanid resistance was detected. All four isolates with cross-resistance to bedaquiline and clofazimine had a detected gene mutation in Rv0678. Three of five strains with linezolid resistance had a detected gene mutation in rplC. CONCLUSION: Detection of resistance to new anti-TB drugs emphasises the pressing need for intensive surveillance for such resistance before their wide usage.