Epidemiology and antimicrobial resistance of Mycobacterium spp. in the United Arab Emirates: a retrospective analysis of 12 years of national antimicrobial resistance surveillance data.

Introduction: The Eastern Mediterranean Regional Office (EMRO) region accounts for almost 8% of all global Mycobacterium tuberculosis (TB) cases, with TB incidence rates ranging from 1 per 100,000 per year in the United Arab Emirates (UAE) to 204 per 100,000 in Djibouti. The national surveillance data from the Middle East and North Africa (MENA) region on the epidemiology and antimicrobial resistance trends of TB, including MDR-TB remains scarce. Methods: A retrospective 12-year analysis of N = 8,086 non-duplicate diagnostic Mycobacterium tuberculosis complex (MTB complex) isolates from the UAE was conducted. Data were generated through routine patient care during the 2010-2021 years, collected by trained personnel and reported by participating surveillance sites to the UAE National Antimicrobial Resistance (AMR) Surveillance program. Data analysis was conducted with WHONET, a windows-based microbiology laboratory database management software developed by the World Health Organization Collaborating Center for Surveillance of Antimicrobial Resistance, Boston, United States (https://whonet.org/). Results: A total of 8,086 MTB-complex isolates were analyzed. MTB-complex was primarily isolated from respiratory samples (sputum 80.1%, broncho-alveolar lavage 4.6%, pleural fluid 4.1%). Inpatients accounted for 63.2%, including 1.3% from ICU. Nationality was known for 84.3% of patients, including 3.8% Emiratis. Of UAE non-nationals, 80.5% were from 110 countries, most of which were Asian countries. India accounted for 20.8%, Pakistan 13.6%, Philippines 12.7%, and Bangladesh 7.8%. Rifampicin-resistant MTB-complex isolates (RR-TB) were found in 2.8% of the isolates, resistance to isoniazid, streptomycin, pyrazinamide, and ethambutol, was 8.9, 6.9, 3.4 and 0.4%, respectively. A slightly increasing trend of resistance among MTB-complex was observed for rifampicin from 2.5% (2010) to 2.8% (2021). Conclusion: Infections due to MTB-complex are relatively uncommon in the United Arab Emirates compared to other countries in the MENA region. Most TB patients in the UAE are of Asian origin, mainly from countries with a high prevalence of TB. Resistance to first line anti-tuberculous drugs is generally low, however increasing trends for MDR-TB mainly rifampicin linked resistance is a major concern. MDR-TB was not associated with a higher mortality, admission to ICU, or increased length of hospitalization as compared to non-MDR-TB.

Bedaquiline: An Insight Into its Clinical Use in Multidrug-Resistant Pulmonary Tuberculosis.

Every year, the World Health Organization reports 500,000 new cases of drug-resistant tuberculosis (TB), which poses a serious global danger. The increased number of XDR-TB and MDR-TB cases reported worldwide necessitates the use of new therapeutic approaches. The main issues with the antitubercular medications now in use for the treatment of multidrug-resistant tuberculosis are their poor side effect profile, reduced efficacy, and antimicrobial resistance. One possible remedy for these problems is bedaquiline. The need for better treatment strategies is highlighted by the strong minimum inhibitory concentrations that bedaquiline (BDQ), a novel anti-TB medicine, exhibits against both drug-resistant and drug-susceptible TB. Bedaquiline may be able to help with these problems. Bedaquiline is a medication that is first in its class and has a distinct and particular mode of action. Bedaquiline is an ATP synthase inhibitor that is specifically directed against Mycobacterium tuberculosis and some nontuberculous mycobacteria. It is metabolized by CYP3A4. Bedaquiline preclinical investigations revealed intralesional drug biodistribution. The precise intralesional and multi-compartment pharmacokinetics of bedaquiline were obtained using PET bioimaging and high-resolution autoradiography investigations. Reduced CFU counts were observed in another investigation after a 12-week course of therapy. Meta-analyses and systematic reviews of phase II trials on bedaquiline's efficacy in treating drug-resistant tuberculosis in patients reported higher rates of cure, better culture conversion, and lower death rates when taken in conjunction with a background regimen. Here is a thorough medication profile for bedaquiline to aid medical professionals in treating individuals with tuberculosis.

Rapid Gene Silencing Followed by Antimicrobial Susceptibility Testing for Target Validation in Antibiotic Discovery.

Mycobacterium tuberculosis is the main causative agent of tuberculosis (TB)-an ancient yet widespread global infectious disease to which 1.6 million people lost their lives in 2021. Antimicrobial resistance (AMR) has been an ongoing crisis for decades; 4.95 million deaths were associated with antibiotic resistance in 2019. While AMR is a multi-faceted problem, drug discovery is an urgent part of the solution and is at the forefront of modern research.The landscape of drug discovery for TB has undoubtedly been transformed by the development of high-throughput gene-silencing techniques that enable interrogation of every gene in the genome, and their relative contribution to fitness, virulence, and AMR. A recent advance in this area is CRISPR interference (CRISPRi). The application of this technique to antimicrobial susceptibility testing (AST) is the subject of ongoing research in basic science.CRISPRi technology can be used in conjunction with the high-throughput SPOT-culture growth inhibition assay (HT-SPOTi) to rapidly evaluate and assess gene essentiality including non-essential, conditionally essential (by using appropriate culture conditions), and essential genes. In addition, the HT-SPOTi method can develop drug susceptibility and drug resistance profiles.This technology is further useful for drug discovery groups who have designed target-based inhibitors rationally and wish to validate the primary mechanisms of their novel compounds' antibiotic action against the proposed target.

A Microtiter Plate Assay at Acidic pH to Identify Potentiators that Enhance Pyrazinamide Activity Against Mycobacterium tuberculosis.

Pyrazinamide (PZA) is a key component of chemotherapy for the treatment of drug-susceptible tuberculosis (TB) and is likely to continue to be included in new drug combinations. Potentiation of PZA could be used to reduce the emergence of resistance, shorten treatment times, and lead to a reduction in the quantity of PZA consumed by patients, thereby reducing the toxic effects. Acidified medium is required for the activity of PZA against Mycobacterium tuberculosis. In vitro assessments of pyrazinamide activity are often avoided because of the lack of standardization, which has led to a lack of effective in vitro tools for assessing and/or enhancing PZA activity.We have developed and optimized a novel, robust, and reproducible, microtiter plate assay, that centers around acidity levels that are low enough for PZA activity. The assay can be applied to the evaluation of novel compounds for the identification of potentiators that enhance PZA activity. In this assay, potentiation of PZA is demonstrated to be statistically significant with the addition of rifampicin (RIF), which can, therefore, be used as a positive control. Conversely, norfloxacin demonstrates no potentiating activity with PZA and can be used as a negative control. The method, and the associated considerations, described here, can be adapted in the search for potentiators of other antimicrobials.

Improved Diagnosis and Treatment Monitoring of Tuberculosis Using Stool and the Tuberculosis Bacterial Load Assay (TB-MBLA).

The diagnosis and monitoring of tuberculosis treatment is difficult as many patients are unable to produce sputum. This means that many patients are treated on the basis of clinical findings and consequently some will be exposed to anti-tuberculosis drugs unnecessarily. Moreover, for those appropriately on treatment and unable to produce a sputum sample, it will be impossible to monitor the response to treatment. We have shown that stool is a potential alternative sample type for diagnosis of tuberculosis. Currently, available protocols like the Xpert MTB/RIF use DNA as a target to detect Mycobacterium tuberculosis in stool but DNA survives long after the organism is dead so it is not certain whether a positive test is from an old or a partially treated infection. The TB MBLA only detects live organisms and thus, can be used to follow the response to treatment. In this chapter, we describe a protocol for TB-MBLA, an RNA-based assay, and apply it to quantify TB bacteria in stool.

Use of Whole Genome Sequencing for Mycobacterium tuberculosis Complex Antimicrobial Susceptibility Testing: From Sequence Data to Resistance Profiles.

Whole genome sequencing of Mycobacterium tuberculosis complex (MTBC) isolates has been shown to provide accurate predictions for resistance and susceptibility for many first- and second-line anti-tuberculosis drugs. However, bioinformatic pipelines and mutation catalogs to predict antimicrobial resistances in MTBC isolates are often customized and detailed protocols are difficult to access. Here, we provide a step-by-step workflow for the processing and interpretation of short-read sequencing data and give an overview of available analysis pipelines.

Use of Whole Genome Sequencing for Mycobacterium tuberculosis Complex Antimicrobial Susceptibility Testing.

Whole genome sequencing (WGS) is becoming an important diagnostic tool for antimicrobial susceptibility testing of Mycobacterium tuberculosis complex (MTBC) isolates in many countries. WGS protocols usually start with the preparation of a DNA-library: the critical first step in the process. A DNA-library represents the genomic content of a DNA sample and consists of unique short DNA fragments. Although available DNA-library protocols come with manufacturer instructions, details of the entire process, including quality controls, instrument parameters, and run evaluations, often need to be developed and customized by each laboratory to implement WGS technology effectively. Here, we provide a detailed workflow for a DNA-library preparation based on an adapted Illumina protocol optimized for the reduction of reagent costs.

Diagnostic accuracy of the Xpert® MTB/XDR assay for detection of Isoniazid and second-line antituberculosis drugs resistance at central TB reference laboratory in Tanzania.

INTRODUCTION: Early diagnosis of tuberculosis (TB) and universal access to drug-susceptibility testing (DST) are critical elements of the WHO End TB Strategy. Current rapid tests (e.g., Xpert® MTB/RIF and Ultra-assays) can detect rifampicin resistance-conferring mutations, but cannot detect resistance to Isoniazid and second-line anti-TB agents. Although Line Probe Assay is capable of detecting resistance to second-line anti-TB agents, it requires sophisticated laboratory infrastructure and advanced skills which are often not readily available in settings replete with TB. A rapid test capable of detecting Isoniazid and second-line anti-TB drug resistance is highly needed. METHODS: We conducted a diagnostic accuracy study to evaluate a new automated Xpert MTB/XDR 10-colour assay for rapid detection of Isoniazid and second-line drugs, including ethionamide, fluoroquinolones, and injectable drugs (Amikacin, Kanamycin, and Capreomycin). Positive Xpert MTB/RIF respiratory specimens were prospectively collected through routine diagnosis and surveillance of drug resistance at the Central TB Reference Laboratory in Tanzania. Specimens were tested by both Xpert XDR assay and LPA against culture-based phenotypic DST as the reference standard. FINDINGS: We analysed specimens from 151 TB patients with a mean age (SD) of 36.2 (12.7) years. The majority (n = 109, 72.2%) were males. The sensitivity for Xpert MTB/XDR was 93.5% (95% CI, 87.4-96.7); for Isoniazid, 96.6 (95% CI, 92.1-98.6); for Fluoroquinolone, 98.7% (95% Cl 94.8-99.7); for Amikacin, 96.6%; and (95% CI 92.1-98.6) for Ethionamide. Ethionamide had the lowest specificity of 50% and the highest was 100% for Fluoroquinolone. The diagnostic performance was generally comparable to that of LPA with slight variations between the two assays. The non-determinate rate (i.e., invalid M. tuberculosis complex detection) of Xpert MTB/XDR was 2·96%. CONCLUSION: The Xpert MTB/XDR demonstrated high sensitivity and specificity for detecting resistance to Isoniazid, Fluoroquinolones, and injectable agents. This assay can be used in clinical settings to facilitate rapid diagnosis of mono-isoniazid and extensively drug-resistant TB.

Inhibition of M. tuberculosis and human ATP synthase by BDQ and TBAJ-587.

Bedaquiline (BDQ), a first-in-class diarylquinoline anti-tuberculosis drug, and its analogue, TBAJ-587, prevent the growth and proliferation of Mycobacterium tuberculosis by inhibiting ATP synthase1,2. However, BDQ also inhibits human ATP synthase3. At present, how these compounds interact with either M. tuberculosis ATP synthase or human ATP synthase is unclear. Here we present cryogenic electron microscopy structures of M. tuberculosis ATP synthase with and without BDQ and TBAJ-587 bound, and human ATP synthase bound to BDQ. The two inhibitors interact with subunit a and the c-ring at the leading site, c-only sites and lagging site in M. tuberculosis ATP synthase, showing that BDQ and TBAJ-587 have similar modes of action. The quinolinyl and dimethylamino units of the compounds make extensive contacts with the protein. The structure of human ATP synthase in complex with BDQ reveals that the BDQ-binding site is similar to that observed for the leading site in M. tuberculosis ATP synthase, and that the quinolinyl unit also interacts extensively with the human enzyme. This study will improve researchers' understanding of the similarities and differences between human ATP synthase and M. tuberculosis ATP synthase in terms of the mode of BDQ binding, and will allow the rational design of novel diarylquinolines as anti-tuberculosis drugs.

[A New Method for Determination of Rifampicin and Isoniazid Resistance in Mycobacterium tuberculosis complex Isolates: Capillary Tube Method]. / Mycobacterium tuberculosis Kompleks Izolatlarinda Rifampisin ve Izoniyazid Direncinin Belirlenmesi için Yeni Bir Yöntem: Kapiller Tüp Yöntemi.

Tuberculosis continues to be an important public health problem worldwide. Culture methods are still considered the gold standard in the diagnosis of tuberculosis and the determination of drug resistance. The most important limitation of these methods is their long turnaround time. Commercial culture systems developed to shorten the duration are emerging as an economic problem, especially for developing countries. Therefore, cheap, fast, easy to apply and objectively evaluable tests are needed. In this study, in addition to culture-based methods for determining RIF and INH resistance in Mycobacterium tuberculosis complex isolates, it was aimed to develop the capillary tube method to accelerate the evaluation process. The study included 27 RIF-resistant, 36 RIF -sensitive, 30 INH-resistant, and 33 INH-sensitive isolates obtained from the mycobacteriology laboratory culture collection, for which susceptibility testing to firstline drugs were previously performed using the BACTEC MGIT 960 system (BD, USA) and were stored. H37Rv standard strain and an external quality control strain (IDT3) with known RIF and INH resistance were used as quality control isolates in the study. As a new testing method, the capillary tube method for detecting rifampicin and isoniazid resistance was compared to the standard BACTEC MGIT 960 system. In the determination of RIF and INH resistance, the sensitivity of the capillary tube method compared to the reference method was determined as 85% and 80%, respectively; however, the specificity values (25% and 45.5%, respectively) for both drugs were found to be low in the studies. The time to detect resistance with the capillary tube method varied between 4-9 days. Capillary tube method, which was developed especially for the rapid identification and treatment of multidrug-resistant isolates, is promising in that it detects resistant strains in a short time with a relatively high sensitivity, although its specificity is very low. It is thought that it would be beneficial to continue the study with a larger number of samples and even improve the method with studies conducted directly from clinical samples.

Potential of Pan-Tuberculosis Treatment to Drive Emergence of Novel Resistance.

New tuberculosis (TB) drugs with little existing antimicrobial resistance enable a pan-TB treatment regimen, intended for universal use without prior drug-susceptibility testing. However, widespread use of such a regimen could contribute to an increasing prevalence of antimicrobial resistance, potentially rendering the pan-TB regimen ineffective or driving clinically problematic patterns of resistance. We developed a model of multiple sequential TB patient cohorts to compare treatment outcomes between continued use of current standards of care (guided by rifampin-susceptibility testing) and a hypothetical pan-TB approach. A pan-TB regimen that met current target profiles was likely to initially outperform the standard of care; however, a rising prevalence of transmitted resistance to component drugs could make underperformance likely among subsequent cohorts. Although the pan-TB approach led to an increased prevalence of resistance to novel drugs, it was unlikely to cause accumulation of concurrent resistance to novel drugs and current first-line drugs.

Analysis on epidemiological and drug resistance characteristics of lymph node tuberculosis from Hunan province, China.

Objectives: To investigate the clinical epidemiological and drug resistance (DR) characteristics of lymph node tuberculosis (LNTB) in Hunan Province which locates in South-central China, and to provide scientific clues for effective prevention and treatment of LNTB. Methods: We retrospectively collected LNTB patients with Mycobacterium tuberculosis culture positive at Hunan Chest Hospital, the biggest TB reference hospital in South-central China, from January 2013 to December 2021. The multiple demographic, clinical and drug susceptibility data of patients were collected from the hospital's electronic patient records. Descriptive statistical methods, Chi-square test and logistic regression analysis were employed as statistical methods. Results: Of the 577 LNTB cases, 373 (64.64%) were males, 352 (61.01%) were farmers; majority (161, 33.10%) aged at 20-29 years old; 147 (25.48%) had simple LNTB, 350 (60.66%) had LNTB combined with pulmonary TB (PTB) (defined as LNTB-PTB), and 80 (13.86%) had LNTB combined with other extrapulmonary TB (EPTB) (defined as LNTB-EPTB). A total of 345 (59.79%, 345/577) LNTB patients had cervical node infection, and the simple LNTB patients (81.63%, 120/147) had higher proportion of this infection than LNTB-PTB (51.71%, 181/350) and LNTB-EPTB (55.00%, 44/80) (both p values <0.017), respectively. LNTB-EPTB was more inclined to have abdominal tuberculous LNs (20%, 16/80) and at least four tuberculous lesions (22.50%, 18/80) than simple LNTB and LNTB-PTB. Seventy-seven (13.34%) and 119 (20.62%) were resistant to rifampicin (RIF) and isoniazid (INH), respectively; 72 (12.48%) were multi-drug resistant (MDR), and a total of 150 (26.00%) were DR (resistant to at least one of RIF, INH, ethambutol and streptomycin). LNTB patients aged 30-34 and 50-54 years old (compared to those aged <30 years) were independent predictors of RIF resistance (RR) (ORs were 3.47 and 2.83, respectively; 95% CIs were 1.64-7.35 and 1.08-7.46, respectively). Conclusion: Our study disclosed the epidemiological and DR characteristics of LNTB in Hunan Province, China. High LNTB prevalence was found in younger people while high RR LNTB prevalence was found in older ones, suggesting that we should conduct further studies to clarify the occurrence of RR in LNTB, meanwhile, strengthen the diagnoses and treatments of LNTB to prevent the emergence of RR.

Recent efforts in the development of glycoconjugate vaccine and available treatment for tuberculosis.

Tuberculosis (TB) continues to pose a grave threat to global health, despite relentless eradication efforts. In 1882, Robert Koch discovered that Mycobacterium tuberculosis (Mtb) is the bacterium responsible for causing tuberculosis. It is a fact that tuberculosis has claimed the lives of more than one billion people in the last few decades. It is imperative that we must take immediate and effective action to increase resources for TB research and treatment. Effective TB treatments demand an extensive investment of both time and finances, often requiring 6-9 months of rigorous antibiotic therapy. The most efficient way to control tuberculosis is by receiving a childhood Bacillus Calmette-Guérin (BCG) vaccination. Despite years of research on vaccine development, we still do not have any new approved vaccine for tuberculosis, except BCG, which is partially effective in young children. This review discusses briefly the available treatment for tuberculosis and remarkable advancements in glycoconjugate-based TB vaccine developments in recent years (2013-2024) and offers valuable direction for future research priorities.

The T120P or M172V mutation on rv2172c confers high level para-aminosalicylic acid resistance in Mycobacterium tuberculosis.

Although para-aminosalicylic acid (PAS) has been used to treat tuberculosis for decades, mechanisms of resistance to this drug in Mycobacterium tuberculosis (M. tuberculosis) clinical isolates have not been thoroughly investigated. Previously, we found that decreased methylenetetrahydrofolate reductase (MTHFR) activity of Rv2172c led to increased sensitivity to antifolates in M. tuberculosis. In this study, we collected the genome-sequencing data of 173 PAS-resistant and 803 PAS-sensitive clinical isolates and analyzed rv2172c mutations in those 976 isolates. The results showed that two mutations (T120P and M172V) on rv2172c could be identified in a certain proportion (6.36%) of PAS-resistant isolates. The results of AlphaFold2 prediction indicated that the T120P or M172V mutation might affect the enzymatic activity of Rv2172c by influencing nicotinamide adenine dinucleotide (NADH) binding, and this was verified by subsequent biochemical analysis, demonstrating the role of residues Thr120 and Met172 on NADH binding and enzymatic activity of Rv2172c. In addition, the effect of rv2172c T120P or M172V mutation on methionine production and PAS resistance was determined in M. tuberculosis. The results showed that both T120P and M172V mutations caused increased intracellular methionine concentrations and high level PAS resistance. In summary, we discovered new molecular markers and also a novel mechanism of PAS resistance in M. tuberculosis clinical isolates and broadened the understanding of the NADH-dependent MTHFR catalytic mechanism of Rv2172c in M. tuberculosis, which will facilitate the molecular diagnosis of PAS resistance and also the development of new drugs targeting Rv2172c.

Missed rifampicin and isoniazid resistance by commercial molecular assays.

Drug-resistant tuberculosis (TB) has poor outcomes unless resistance is detected early, ideally by commercially available molecular tests. We present a case of occult multidrug-resistant TB where both rifampicin and isoniazid resistance were missed by molecular testing and were only identified by phenotypic testing.

Apramycin has high in vitro activity against Mycobacterium tuberculosis.

Introduction. Aminoglycoside antibiotics such as amikacin and kanamycin are important components in the treatment of Mycobacterium tuberculosis (Mtb) infection. However, more and more clinical strains are found to be aminoglycoside antibiotic-resistant. Apramycin is another kind of aminoglycoside antibiotic that is commonly used to treat infections in animals.Hypothesis. Apramycin may have in vitro activity against Mtb.Aim. This study aims to evaluate the efficacy of apramycin against Mtb in vitro and determine its epidemiological cut-off (ECOFF) value.Methodology. One hundred Mtb isolates, including 17 pansusceptible and 83 drug-resistant tuberculosis (DR-TB) strains, were analysed for apramycin resistance using the MIC assay.Results. Apramycin exhibited significant inhibitory activity against Mtb clinical isolates, with an MIC50 of 0.5 µg ml-1 and an MIC90 of 1 µg ml-1. We determined the tentative ECOFF value as 1 µg ml-1 for apramycin. The resistant rates of multidrug-resistant tuberculosis (MDR-TB), pre-extensively drug-resistant (pre-XDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) strains were 12.12 % (4/33), 20.69 % (6/29) and 66.67 % (14/21), respectively. The rrs gene A1401G is associated with apramycin resistance, as well as the cross-resistance between apramycin and other aminoglycosides.Conclusion. Apramycin shows high in vitro activity against the Mtb clinical isolates, especially the MDR-TB clinical isolates. This encouraging discovery calls for more research on the functions of apramycin in vivo and as a possible antibiotic for the treatment of drug-resistant TB.

The Nitrofuran-Warhead-Equipped Spirocyclic Azetidines Show Excellent Activity against Mycobacterium tuberculosis.

A series of 21 new 7'H-spiro[azetidine-3,5'-furo [3,4-d]pyrimidine]s substituted at the pyrimidine ring second position were synthesized. The compounds showed high antibacterial in vitro activity against M. tuberculosis. Two compounds had lower minimum inhibitory concentrations against Mtb (H37Rv strain) compared with isoniazid. The novel spirocyclic scaffold shows excellent properties for anti-tuberculosis drug development.

Imidazoquinoline Derivatives as Potential Inhibitors of InhA Enzyme and Mycobacterium tuberculosis.

Tuberculosis is a serious public health problem worldwide. The search for new antibiotics has become a priority, especially with the emergence of resistant strains. A new family of imidazoquinoline derivatives, structurally analogous to triazolophthalazines, which had previously shown good antituberculosis activity, were designed to inhibit InhA, an essential enzyme for Mycobacterium tuberculosis survival. Over twenty molecules were synthesized and the results showed modest inhibitory efficacy against the protein. Docking experiments were carried out to show how these molecules could interact with the protein's substrate binding site. Disappointingly, unlike triazolophthlazines, these imidazoquinoline derivatives showed an absence of inhibition on mycobacterial growth.