Masan National Tuberculosis Hospital

SETTING: This was a nationwide cohort study.OBJECTIVE: To assess the treatment outcomes in patients with multidrug-resistant TB (MDR-TB) who underwent treatment guided by a national TB expert review committee in South Korea.DESIGN: We enrolled all patients with MDR-TB submitted for approval for the use of new TB drugs, including bedaquiline and delamanid, from 2016 to 2019. Patients were classified into two groups: those on new TB drugs and those not on new TB drugs. We compared the final treatment outcomes between the groups and analysed the prognostic factors.RESULTS: Of a total of 785 patients, respectively 754 (96.1%) and 31 (3.9%) were classified into the "new TB drugs" group and "no new TB drugs" group. The new TB drugs group had a higher acid-fast bacilli smear positivity rate and higher resistance rate to second-line injectable drugs or fluoroquinolones. Of all the patients, 97.8% achieved culture conversion (97.7% vs. 100%), and 80.4% achieved treatment success (80.2% vs. 86.7%); there was no difference between the two groups.CONCLUSIONS: New drugs are currently recommended for use in all MDR-TB treatment regimens, and the use of new drugs, as determined by an expert committee, in mainly quinolone-susceptible MDR-TB, did not compromise the treatment success rate.

The ability of Mycobacterium tuberculosis (Mtb) to persist in its host may enable an evolutionary advantage for drug resistant variants to emerge. A potential strategy to prevent persistence and gain drug efficacy is to directly target the activity of enzymes that are crucial for persistence. We present a method for expedited discovery and structure-based design of lead compounds by targeting the hypoxia-associated enzyme L-alanine dehydrogenase (AlaDH). Biochemical and structural analyses of AlaDH confirmed binding of nucleoside derivatives and showed a site adjacent to the nucleoside binding pocket that can confer specificity to putative inhibitors. Using a combination of dye-ligand affinity chromatography, enzyme kinetics and protein crystallographic studies, we show the development and validation of drug prototypes. Crystal structures of AlaDH-inhibitor complexes with variations at the N6 position of the adenyl-moiety of the inhibitor provide insight into the molecular basis for the specificity of these compounds. We describe a drug-designing pipeline that aims to block Mtb to proliferate upon re-oxygenation by specifically blocking NAD accessibility to AlaDH. The collective approach to drug discovery was further evaluated through in silico analyses providing additional insight into an efficient drug development strategy that can be further assessed with the incorporation of in vivo studies.

Tuberculosis (TB) is a severe public health challenge in Korea. Of all Mycobacterium tuberculosis (M. tb) strains, the Beijing genotype strain reportedly correlates with hypervirulence and drug resistance. Hence, an early identification of the Beijing genotype strain of M. tb plays a significant role in initial TB treatment. Kogenebiotech® (KoRT-polymerase chain reaction [PCR]) has developed a real-time PCR 17 18 kit to determine the Beijing genotype strain classified as M. tb. To determine the feasibility of the commercially produced KoRT-PCR kit in identifying the M. tb strain. We used 100 clinical isolates of M. tb and 100 non-M. tb samples for the assessment. We evaluated the overall concordance between the KoRT-PCR kit and the mycobacterial interspersed repetitive unite variable number tandem repeat typing kit (GenoScreen, Lille, France). Moreover, we measured the detection limits based on the chromosomal DNA copies for the KoRT-PCR kit. In addition, we determined the reproducibility among individual technicians using the KoRT-PCR. The KoRT-PCR kit successfully discriminated all M. tb (confidence interval [CI]: 96.38%-100.00% for both sensitivity and specificity) and Beijing genotype strain (CI: 95.70%-100.00% for sensitivity and 96.87%-100.00% for specificity). We confirmed no significant deviation in the reproducibility between the technicians. The KoRT-PCR kit displayed sufficient capability of discriminating the Beijing genotype strain, which enabled the rapid identification of the Beijing genotype strain from the M. tb clinical isolates.

Tuberculosis (TB) remains a serious public health burden in Korea. Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeat (MIRU-VNTR) is preferred for epidemiological TB investigation. Until recently, the difficulty lies in epidemiological TB investigation due to the absence of commercialized MIRU-VNTR in Korea. Here, we have evaluated the newly designed MIRU-VNTR kit by Kogenebiotech, Korea. A total of 200 samples, where 100 are Mycobacrerium tuberculosis (M. tuberculosis), and the other 100 are non-M. tuberculosis, were used. Initially, the Kogenebiotech MIRU-VNTR typing kit (KoMIRU) was compared with Multilocus Variable Number Tandem Repeat Genotyping of M. tuberculosis typing kit (MVNTR) by Philip Supply for validation purpose. Then, Limit of Detection for DNA copies was optimized. Finally, KoMIRU and Genoscreen MIRU-VNTR typing kit (GeMIRU) were tested and comparatively analyzed for its specificity and sensitivity. The study showed that the KoMIRU has slightly higher discriminatory power over MVNTR, 100% versus 97.5%. In comparative analysis, the KoMIRU has shown comparable capability as GeMIRU, showing 100% for sensitivity and specificity with a 95% CI value of 96.38 to 100.00%. Also, no discrepancies were observed on discriminated lineage strains between KoMIRU and GeMIRU. Out of 100, 84 were identified as Beijing strains, and remains were identified as NEW-1 (n = 8), Uganda (n = 6), East African Indian (EAI) (n = 6), Turkey (n = 2), and Haarlem (n = 1). In this study, KoMIRU has shown a comparable capability to GeMIRU. Furthermore, previous researches had suggested an association between lineage strains and drug resistance; hence, the implementation of KoMIRU can help in TB control and prevention.

Mycobacterium abscessus (M. abscessus) causes chronic pulmonary infections and is the most difficult non-tuberculous mycobacteria (NTM) to treat due to its resistance to current antimicrobial drugs, with a treatment success rate of 45.6%. Thus, novel treatment drugs are needed, of which we identified the drug clomiphene citrate (CC), known to treat infertility in women, to exhibit inhibitory activity against M. abscessus. To assess the potential of CC as a treatment for M. abscessus pulmonary diseases, we measured its efficacy in vitro and established the intracellular activity of CC against M. abscessus in human macrophages. CC significantly inhibited the growth of not only wild-type M. abscessus strains but also clinical isolate strains and clarithromycin (CLR)-resistant strains of M. abscessus. CC’s drug efficacy did not have cytotoxicity in the infected macrophages. Furthermore, CC worked in anaerobic non-replicating conditions as well as in the presence of biofilm. The results of this in vitro study on M. abscessus activity suggest the possibility of using CC to develop new drug hypotheses for the treatment of M. abscessus infections.

Face masks will be used to prevent pandemic recurrence and outbreaks of mutant SARS-CoV-2 strains until mass immunity is confirmed. The polypropylene (PP) filter is a representative disposable mask material that traps virus-containing bioaerosols, preventing secondary transmission. In this study, a copper thin film (20 nm) was deposited via vacuum coating on a spunbond PP filter surrounding a KF94 face mask to provide additional protection and lower the risk of secondary transmission. Film adhesion was improved using oxygen ion beam pretreatment, resulting in cuprous oxide formation on the PP fiber without structural deformation. The copper-coated mask exhibited filtration efficiencies of 95.1 ± 1.32% and 91.6 ± 0.83% for NaCl and paraffin oil particles, respectively. SARS-CoV-2 inactivation was evaluated by transferring virus-containing media onto the copper-coated PP filters and subsequently adding Vero cells. Infection was verified using real-time polymerase chain reaction and immunochemical staining. Vero cells added after contact with the copper-coated mask did not express the RNA-dependent RNA polymerase and envelope genes of SARS-CoV-2. The SARS-CoV-2 nucleocapsid immunofluorescence results indicated a reduction in the amount of virus of more than 75%. Therefore, copper-coated antiviral PP filters could be key materials in personal protective equipment, as well as in air-conditioning systems.