Disrupting Mycobacterium smegmatis biofilm using enzyme-immobilized rifampicin loaded silk fibroin nanoparticles for dual anti-bacterial and anti-biofilm action.

Biofilm formation is a major challenge in the treatment of tuberculosis, leading to poor treatment outcomes and latent infections. The complex and dense extracellular polymeric substances (EPS) of the biofilm provides safe harbour for bacterium enabling persistence against anti-TB antibiotics. In this study, we demonstrated that rifampicin-encapsulated silk fibroin nanoparticles immobilized with antibiofilm enzymes can disrupt the Mycobacterium smegmatis biofilm and facilitate the anti-bacterial action of Rifampicin (RIF). The EPS of M.smegmatis biofilm predominantly comprised of lipids (48.8 ± 1.32 %) and carbohydrates (34.8 ± 4.70 %), similar to tuberculosis biofilms. Pre-formed biofilm eradication screening revealed that hydrolytic enzymes such as ß-Glucosidase, Glucose oxidase, ɑ-Amylase, Acylase, and Phytase can exhibit biofilm eradication of M.smegmatis biofilms. The enzyme-mediated biofilm disruption was associated with a decrease in hydrophobicity of biofilm surfaces. Treatment with ß-glucosidase and Phytase demonstrated a putative biofilm eradication by reducing the total carbohydrates and lipid composition without causing any significant bactericidal activity. Further, Phytase (250 µg/ml) and ß-Glucosidase (112.5 ± 17.6 µg/ml) conjugated rifampicin-loaded silk fibroin nanoparticles (R-SFNs) exhibited an enhanced anti-bacterial activity against pre-formed M.smegmatis biofilms, compared to free rifampicin (32.5±7 µg/ml). Notably, treatment with ß-glucosidase, Phytase and ɑ-amylase immobilized SFNs decreased the biofilm thickness by ∼98.84 % at 6h, compared to control. Thus, the study highlights that coupling anti-mycobacterial drugs with biofilm-eradicating enzymes such as amylase, phytase or ß-glucosidase can be a potential strategy to improve the TB therapeutic outcomes.

Impact of isoniazid monoresistance on overall and vulnerable patient populations in Taiwan.

Isoniazid is an early bactericidal anti-tuberculosis (TB) agent and isoniazid mono-resistance TB is the most prevalent drug-resistant TB worldwide. Concerns exist regarding whether resistance to isoniazid would lead to delayed culture conversion and worst outcomes. From January 2008 to November 2017, adult culture-positive pulmonary TB patients receiving isoniazid, rifampicin, pyrazinamide, and ethambutol were identified through Taiwan Center for Disease Control database and were followed until the end of 2017. Primary outcomes included time to sputum culture conversion (SCC) within two months. Secondary outcomes included death and unfavourable outcomes at the end of 2nd month. A total of 37,193 drug-susceptible and 2,832 isoniazid monoresistant pulmonary TB patients were identified. Compared with no resistance, isoniazid monoresistance was not associated with a delayed SCC (HR: 0.99, 95% CI: 0.94─1.05, p = 0.8145), a higher risk of 2-month mortality (HR: 1.19, 95% CI: 0.92─1.53, p = 0.1884), and unfavourable outcomes at 2nd month (OR: 1.05, 95% CI: 0.97─1.14, p = 0.2427). Isoniazid monoresistance was associated with delayed SCC (HR: 0.90, 95% CI: 0.83─0.98, p = 0.0099) and a higher risk of unfavourable outcomes (OR:1.18, 95% CI: 1.05─1.32, p = 0.0053) in patients aged between 20 and 65, and delayed SCC in patients without underlying comorbidities (HR: 0.90, 95% CI: 0.81─0.98, p = 0.0237). Isoniazid mono-resistant TB had a comparable outcome with drug-susceptible TB at the end of the intensive phase. Healthy, and non-elderly patients were more likely to had culture persistence, raising concerns about disease transmission in these subgroups and warranting early molecular testing for isoniazid resistance.

A novel dual probe-based method for mutation detection using isothermal amplification.

Cost efficient and rapid detection tools to detect mutations especially those linked to drug-resistance are important to address concerns of the rising multi-drug resistance infections. Here we integrated dual probes, namely a calibrator probe and an indicator probe, into isothermal amplification detection system. These two probes are designed to bind distinct regions on the same amplicon to determine the presence or absence of mutation. The calibrator probe signal is used as an internal signal calibrator for indicator probe which detects the presence or absence of the mutation. As an illustrative example, we evaluated the applicability of this dual probe method for detecting mutations associated with rifampicin (RIF) drug resistance at codons 516, 526 and 531 of the rpoB gene in Mycobacterium tuberculosis. In this assessment, we examined 127 artificial samples comprising wild types and mutants with single or multiple mutations. Our results demonstrated 100% accuracy for both wild types and mutants for mutations at codons 526 and 531. As regards to mutations at codon 516, the wild type was identified with 100% accuracy, while the mutants were identified with 95% accuracy. Moreover, when we extended our evaluation to include clinical MTB strains and the Zeptometrix MTB Verification panel, our method achieved 100% accuracy (5 out of 5) in identifying wild-type strains. Additionally, we successfully detected a RIF-resistant strain with mutations at codon 531 of the rpoB gene in Zeptometrix verification panel. Our isothermal mutation detection system, relying on dual probes exhibits a versatile approach. With the capability to identify mutations without prior knowledge of their specific mutation direction, our dual-probe method shows significant promise for applications in drug resistance nucleic acid testing, particularly in resource-limited settings.

Predictors of early and interim culture un-conversion in multidrug-resistant/rifampicin-resistant tuberculosis: a retrospective multi-center cohort study in China.

BACKGROUND: We aimed to evaluate the predictors for early and interim culture conversion within 2 months and 6 months of treatment in multidrug-resistant/rifampicin-resistant tuberculosis (MDR/RR-TB) patients in China. METHODS: This study included adult MDR/RR-TB patients with a positive baseline sputum culture from 8 institutions located in different cities in China from May 2018 to January 2022. We mainly used logistic regression model to derive possible predictors of early and interim culture conversion. RESULTS: A total of 813 patients were enrolled and 28.5% of them received multidrug-resistant treatment regimens containing bedaquiline. Of these, 362 (44.5%) patients experienced culture conversion within 2 months of treatment, and 649 (79.8%) within 6 months. The results of the multivariable logistic regression analysis revealed that acid-fast bacilli smear positive (adjusted odds ratio [aOR] = 1.637, 95% confidence interval [CI] = 1.197-2.238), cavities (aOR = 1.539, 95% CI = 1.132-2.092), bilateral disease (aOR = 1.638, 95% CI = 1.183-2.269), and viral hepatitis (aOR = 2.585, 95% CI = 1.189-5.622) were identified as risk factors for early culture un-conversion within 2 months of treatment. Additionally, smoking history (aOR = 2.197, 95% CI = 1.475-3.273), previous treatment for tuberculosis (aOR = 1.909, 95% CI = 1.282-2.844), bilateral disease (aOR = 2.201, 95% CI = 1.369-3.537), viral hepatitis (aOR = 2.329, 95% CI = 1.094-4.962) were identified as risk factors for interim culture un-conversion within 6 months of treatment, while patients with regimen containing bedaquiline (aOR = 0.310, 95% CI = 0.191-0.502) was a protective factor. CONCLUSIONS: A history of smoking, a baseline sputum AFB smear positive, lung cavities, bilateral disease, previous anti-tuberculosis treatment, or a comorbidity of viral hepatitis can be used as the predictors for early and interim culture un-conversion in MDR/RR-TB patients, while bedaquiline was a protective factor .

Drug-resistance characteristics, genetic diversity, and transmission dynamics of multidrug-resistant or rifampicin-resistant Mycobacterium tuberculosis from 2019 to 2021 in Sichuan, China.

BACKGROUND: Multidrug- or rifampicin-resistant tuberculosis (TB; MDR/RR-TB) is a significant public health threat. However, the mechanisms involved in its transmission in Sichuan, China are unclear. To provide a scientific basis for MDR/RR-TB control and prevention, we investigated the drug-resistance characteristics, genetic diversity, and transmission dynamics and analyzed the demographic and clinical characteristics of patients to identify risk factors for the acquisition of MDR/RR-TB in Sichuan, Western China. METHODS: Whole-genome sequencing was performed using a sample comprised of all MDR/RR-TB strains isolated from patients with pulmonary TB (≥ 15 years) at the 22 surveillance sites in Sichuan province between January 2019 and December 2021, to analyze genotypic drug resistance and genetic diversity. Moreover, we performed statistical analyses of the epidemiological characteristics and risk factors associated with the transmission dynamics of MDR/RR-TB. RESULTS: The final analysis included 278 MDR/RR TB strains. Lineage 2.2, the major sub-lineage, accounted for 82.01% (228/278) of isolates, followed by lineage 4.5 (9.72%, 27/278), lineage 4.4 (6.83%, 19/278), and lineage 4.2 (1.44%, 4/278). The drug resistance rates, ranging from high to low, were as follows: isoniazid (229 [82.37%]), streptomycin (177 [63.67%]), ethambutol (144 [51.80%]), pyrazinamide (PZA, 119 [42.81%]), fluoroquinolones (FQs, 93 [33.45%]). Further, the clofazimine, bedaquiline, and delamanid resistance rates were 2.88, 2.88, and 1.04%, respectively. The gene composition cluster rate was 32.37% (90/278). In addition, 83.81% (233/278) of MDR/RR-TB cases were determined to be likely caused by transmission. Finally, patients infected with lineage two strains and strains with the KatG S315T amino acid substitution presented a higher risk of MDR/RR-TB transmission. CONCLUSION: Transmission plays a significant role in the MDR/RR-TB burden in Sichuan province, and lineage 2 strains and strains harboring KatG S315T have a high probability of transmission. Further, high levels of FQ and PZA drug resistance suggest an urgent need for drug susceptibility testing prior to designing therapeutic regimens. New anti-TB drugs need to be used standardly and TB strains should be regularly monitored for resistance to these drugs.

Increased coproporphyrin serum levels in healthy volunteers treated with the cholesterol uptake inhibitor ezetimibe.

Ezetimibe undergoes glucuronidation that results in the active metabolite ezetimibe phenoxy-glucuronide (ezetimibe-glucuronide). This phase-II metabolite was shown to interact with the clinically relevant hepatic transporter organic anion transporting polypeptide (OATP) 1B1. In recent years, coproporphyrin I (CPI) was established as a Tier 1 biomarker for OATP1B-mediated interactions among other endogenous substrates like CPIII. To evaluate whether levels of the biomarker are affected by ezetimibe treatment, we assessed the impact of ezetimibe and ezetimibe-glucuronide on OATP1B1-mediated transport of CPs in vitro. Then, we quantified CP levels in serum samples of healthy volunteers treated with a single oral dose of ezetimibe (20 mg) alone or in combination with rifampin (600 mg). Results from our in vitro experiments showed a significant reduction in cellular CPI accumulation in the presence of ezetimibe-glucuronide with an IC50 of 1.97 µM [95% CI: 1.04 to 3.96], while CPIII accumulation was impacted by 10 µM and above. In the in vivo study, we observed peak CP concentrations 1.33 h after dosing, which is closest to the tmax of the ezetimibe metabolite. Co-administration of ezetimibe with rifampin resulted in even higher serum CP levels. The AUC0-24h of CPI and CPIII increased two- and threefold, respectively, after concomitant dosing compared to ezetimibe alone. Moreover, we quantified CP levels in cumulative urine from both study phases where the renally excreted amount (Ae) of CPI and CPIII increased after ezetimibe and rifampin co-administration compared to ezetimibe alone. In conclusion, our findings indicate that rifampin co-administration results in additional inhibition of OATP1B1 in vivo.

Bedaquiline versus injectable containing regimens for rifampicin-resistant and multidrug-resistant tuberculosis in a reference center in Brazil - a real-world evidence study using a retrospective design.

BACKGROUND: Drug resistance (DR) is one of the several challenges to global tuberculosis (TB) control. The implementation of bedaquiline (BED) for DR-TB after more than 40 years was expected to improve treatment outcomes as well as microbiologic conversion and adverse events (AE) occurrence. METHODS: Retrospective cohort study based on secondary data of patients with rifampicin-resistant (RR) or multidrug-resistant (MDR) TB reported to the Outpatient Clinic of Mycobacterial Diseases of the Thorax Diseases Institute - Federal University of Rio de Janeiro - Brazil, between 2016 and 2023. We aimed to evaluate microbiologic conversion, AE and TB treatment outcomes and compare them according to the treatment regimen used for RR/MDR-TB patients under routine conditions [Injectable Containing Regimens (ICR) versus BED Containing Regimens (BCR)]. Logistic regression and survival analysis using Cox regression and Kaplan Meier curve were used for statistical analysis. RESULTS: Of the 463 DR-TB patients notified during the study period, 297 (64.1%) were included for analysis (ICR = 197 and BCR = 100). Overall AEs were more frequent (83.7 vs. 16.3%, p < 0.001) and occurred earlier in the ICR group (15 days vs. 65 days, p = 0.003). There were no cases of cardiotoxicity requiring interruption of BED treatment. None of the regimens of treatment tested were associated with smear or culture conversion on Cox regression analysis (p = 0.60 and 0.88, respectively). BED-containing regimens were also associated with favorable outcomes in multivariable logistic regression [adjusted odds ratio (aOR) = 2.63, 95% confidence interval (CI)1.36-5.07, p = 0.004], as higher years of schooling, primary drug resistance, and no previous TB treatment. In the survival analysis, BCR was inversely associated with the occurrence of AE during treatment follow-up (aHR 0.24, 95% CI 0.14-0.41, p < 0.001). In addition, TB treatment regimens with BED were also associated with favorable outcomes (aHR 2.41, 95% CI 1.62-3.57, p < 0.001), along with no illicit drug use and primary drug resistance. CONCLUSIONS: The implementation of a fully oral treatment for RR/MDR-TB in a reference center in Brazil was safe and associated with favorable outcomes under routine conditions, despite social, demographic, and behavioral factors that may influence TB treatment completion.

Mycobacterial HelD connects RNA polymerase recycling with transcription initiation.

Mycobacterial HelD is a transcription factor that recycles stalled RNAP by dissociating it from nucleic acids and, if present, from the antibiotic rifampicin. The rescued RNAP, however, must disengage from HelD to participate in subsequent rounds of transcription. The mechanism of release is unknown. We show that HelD from Mycobacterium smegmatis forms a complex with RNAP associated with the primary sigma factor σA and transcription factor RbpA but not CarD. We solve several structures of RNAP-σA-RbpA-HelD without and with promoter DNA. These snapshots capture HelD during transcription initiation, describing mechanistic aspects of HelD release from RNAP and its protective effect against rifampicin. Biochemical evidence supports these findings, defines the role of ATP binding and hydrolysis by HelD in the process, and confirms the rifampicin-protective effect of HelD. Collectively, these results show that when HelD is present during transcription initiation, the process is protected from rifampicin until the last possible moment.

Exploring gene mutations and multidrug resistance in Mycobacterium tuberculosis: a study from the Lung Hospital in Vietnam.

BACKGROUND: Drug-resistant tuberculosis not only diminishes treatment efficacy but also heightens the risk of transmission and mortality. Investigating Mycobacterium tuberculosis resistance to first-line antituberculosis drugs is essential to tackle a major global health challenge. METHODS AND RESULTS: Using Sanger sequencing, this study investigates gene mutations associated with multidrug resistance in drug-resistant M. tuberculosis strains. Among 30 samples, mutations were found in genes linked to first-line anti-tuberculosis drug resistance. Rifampicin resistance was observed in 46.67% of the samples, with the most frequent mutation in the rpoB gene at codon 450 (S450L) occurring in 23.33% of cases. Similarly, isoniazid resistance was found in 86.67% of samples, with 33.33% of cases indicating the katG gene mutation at codon 315 (S315T). Additionally, streptomycin resistance was present in 76.67% of samples, and 30% of these cases were mainly linked to the rpsL gene mutation at codon 43 (K43R). CONCLUSION: These findings illuminate the genetic mechanisms behind drug resistance in M. tuberculosis. By identifying specific genetic markers, this research enhances our ability to diagnose and treat drug-resistant Tuberculosis more accurately and efficiently.

Toward a Clinical Decision Support System for Monitoring Therapeutic Antituberculosis Medical Drugs in Tanzania (Project TuberXpert): Protocol for an Algorithm' Development and Implementation.

BACKGROUND: The end tuberculosis (TB) strategy requires a novel patient treatment approach contrary to the one-size-fits-all model. It is well known that each patient's physiology is different and leads to various rates of drug elimination. Therapeutic drug monitoring (TDM) offers a way to manage drug dosage adaptation but requires trained pharmacologists, which is scarce in resource-limited settings. OBJECTIVE: We will develop an automated clinical decision support system (CDSS) to help practitioners with the dosage adaptation of rifampicin, one of the essential medical drugs targeting TB, that is known for large pharmacokinetic variability and frequent suboptimal blood exposure. Such an advanced system will encourage the spread of a dosage-individualization culture, including among practitioners not specialized in pharmacology. Thus, the objectives of this project are to (1) develop the appropriate population pharmacokinetic (popPK) model for rifampicin for Tanzanian patients, (2) optimize the reporting of relevant information to practitioners for drug dosage adjustment, (3) automate the delivery of the report in line with the measurement of drug concentration, and (4) validate and implement the final system in the field. METHODS: A total of 3 teams will combine their efforts to deliver the first automated TDM CDSS for TB. A cross-sectional study will be conducted to define the best way to display information to clinicians. In parallel, a rifampicin popPK model will be developed taking advantage of the published literature, complemented with data provided by existing literature data from the Pan-African Consortium for the Evaluation of Antituberculosis Antibiotics (panACEA), and samples collected within this project. A decision tree will be designed and implemented as a CDSS, and an automated report generation will be developed and validated through selected case studies. Expert pharmacologists will validate the CDSS, and finally, field implementation in Tanzania will occur, coupled with a prospective study to assess clinicians' adherence to the CDSS recommendations. RESULTS: The TuberXpert project started in November 2022. In July 2024, the clinical study in Tanzania was completed with the enrollment of 50 patients to gather the required data to build a popPK model for rifampicin, together with a qualitative study defining the report design, as well as the CDSS general architecture definition. CONCLUSIONS: At the end of the TuberXpert project, Tanzania will possess a new tool to help the practitioners with the adaptation of drug dosage targeting complicated TB cases (TB or HIV, TB or diabetes mellitus, and TB or malnutrition). This automated system will be validated and used in the field and will be proposed to other countries affected by endemic TB. In addition, this approach will serve as proof of concept regarding the feasibility and suitability of CDSS-assisted TDM for further anti-TB drugs in TB-burdened areas deprived of TDM experts, including second-line treatments considered important to monitor. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/58720.

Efficacy and safety of shorter multidrug-resistant or rifampicin-resistant tuberculosis regimens: a network meta-analysis.

BACKGROUND: Drug-resistant tuberculosis (DR-TB) remains a threat to public health. Shorter regimens have been proposed as potentially valuable treatments for multidrug or rifampicin resistant tuberculosis (MDR/RR-TB). We undertook a systematic review and network meta-analysis to evaluate the efficacy and safety of shorter MDR/RR-TB regimens. METHODS: We searched PubMed/MEDLINE, Cochrane Center for Clinical Trials (CENTRAL), Scopus, ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, US Food and Drug Administration, and Chinese Clinical Trial Registry for primary articles published from 2013 to July 2023. Favorable (cured and treatment completed) and unfavorable (treatment failure, death, loss to follow-up, and culture conversion) outcomes were assessed as the main efficacy outcomes, while adverse events were assessed as the safety outcomes. The network meta-analysis was performed using R Studio version 4.3.1 and the Netmeta package. The study protocol adhered to the PRISMA-NMA guidelines and was registered in PROSPERO (CRD42023434050). RESULT: We included 11 eligible studies (4 randomized control trials and 7 cohorts) that enrolled 3,548 patients with MDR/RR-TB. Treatment with a 6-month combination of BdqLzdLfxZTrd/Eto/H had two times more favorable outcomes [RR 2.2 (95% CI 1.22, 4.13), P = 0.0094], followed by a 9-11 month combination of km/CmMfx/LfxPtoCfzZEHh [RR1.67 (95% CI 1.45, 1.92), P < 0.001] and a 6-month BdqPaLzdMfx [RR 1.64 (95% CI 1.24, 2.16), P < 0.0005] compared to the standard longer regimens. Treatment with 6 months of BdqPaLzdMfx [RR 0.33 (95% CI 0.2, 0.55), P < 0.0001] had a low risk of severe adverse events, followed by 6 months of BdqPaLzd [RR 0.36 (95% CI 0.22, 0.59), P ≤ 0.001] and BdqPaLzdCfz [RR 0.54 (95% CI 0.37, 0.80), P < 0.0001] than standard of care. CONCLUSION: Treatment of patients with RR/MDR-TB using shorter regimens of 6 months BdqLzdLfxZTrd/Eto/H, 9-11 months km/CmMfx/LfxPtoCfzZEHh, and 6 months BdqPaLzdMfx provides significantly higher cure and treatment completion rates compared to the standard longer MDR/RR-TB. However, 6BdqPaLzdMfx, 6BdqPaLzd, and 6BdqPaLzdCfz short regimens are significantly associated with decreased severity of adverse events. The findings are in support of the current WHO-recommended 6-month shorter regimens.

Silicosis predicts drug resistance and retreatment among tuberculosis patients in India: a secondary data analysis from Khambhat, Gujarat (2006-2022).

BACKGROUND: India, with the highest global burden of tuberculosis (TB) and drug-resistant TB, aims to eliminate TB by 2025. Yet, limited evidence exists on drug resistance patterns and retreatment among patients with silico-tuberculosis. This study explores these patterns and assesses the impact of silicosis on TB retreatment in India. METHODS: This secondary data analysis stems from a larger retrospective cohort study conducted in Khambhat, Gujarat, between January 2006 and February 2022. It included 138 patients with silico-tuberculosis and 2,610 TB patients without silicosis. Data from the Nikshay TB information portal were linked with silicosis diagnosis reports from the Pneumoconiosis Board using the unique Nikshay ID as the linking variable. Drug-resistant TB was defined as resistance to any anti-TB drug recorded in Nikshay. Retreatment refers to TB patients who have previously undergone anti-TB treatment for one month or more and need further treatment. Recurrent TB denotes patients who were previously declared cured or had completed treatment but later tested positive for microbiologically confirmed TB. Multivariable logistic regression was used to determine the impact of co-prevalent silicosis on drug resistance and retreatment. RESULTS: Patients with silico-tuberculosis showed a higher proportion of retreatment compared to those without silicosis (55% vs. 23%, p < 0.001). Notably, 28% of patients with silico-tuberculosis were recurrent TB cases, compared to 11% among those without silicosis. Regarding drug resistance, the silico-tuberculosis group exhibited a higher rate (6% vs. 3%), largely due to rifampicin resistance (5% vs. 2%, p = 0.022). Co-prevalent silicosis was associated with a 2.5 times greater risk of drug-resistant TB (adjusted OR 2.5, 95% CI, 1.1-5.3; p = 0.021). Additionally, patients with silico-tuberculosis had a fourfold increased risk of retreatment for TB (adjusted OR 4, 95% CI, 3-6; p < 0.001). CONCLUSIONS: Co-prevalent silicosis significantly elevates the risk of drug resistance, recurrence, and retreatment among TB patients in India. This study indicates a need for improved treatment protocols and suggests that future research should focus on randomized controlled trials to evaluate appropriate anti-TB regimen and duration of therapy for this high-risk group. Given India's goal to eliminate TB by 2025, addressing the challenges posed by silico-tuberculosis is critical.

Development of a Method for the Determination of Rifaximin and Rifampicin Residues in Foods of Animal Origin.

Rifaximin and rifampicin are good broad-spectrum antimicrobials. The irrational use of antimicrobial drugs in veterinary clinics could threaten public health and food safety. It is necessary to develop a reliable detection method of the residue for enhancing the rational supervision of the use of such drugs, reducing and slowing down the generation of bacterial resistance, and promoting animal food safety and human health. So, this study developed an LC-MS/MS method for the detection of rifaximin and rifampicin residues in animal-origin foods. The residual rifaximin and rifampicin of homogenized test materials were extracted with acetonitrile-dichloromethane solution or acetonitrile in the presence of anhydrous sodium sulfate and vitamin C, purified by dispersible solid phase extraction, determined by LC-MS/MS, and quantified by the internal standard method. The specificity, sensitivity, matrix effect, accuracy, and precision of the method were investigated in the edible tissues of cattle, swine, or chicken. In addition, the stability of the standard stock solution and the standard working solution was also investigated. The method was suitable for the muscle, liver, kidney, fat, milk, and eggs of cattle, swine, or chicken, as well as fish and shrimp. The specificity of the method was good, and the detection of the analytes was not affected by different matrices. Both the LOD and LOQ of the two analytes were 5 µg/kg and 10 µg/kg, respectively. The results of matrix effects in each tissue were in the range of 80-120%; there were no significant matrix effects. The average accuracy of rifaximin and rifampicin in different foodstuffs of animal origin was between 80% and 120%, and the method precision was below 20% (RSD). The proposed method showed good performance for determination, which could be employed for the extraction, purification, and detection of residual rifaximin and rifampicin in edible animal tissues. The pretreatment procedure of tissue samples was simple and feasible. The method was highly specific, stable, reliable, and with high sensitivity, accuracy, and precision, which met the requirements of quantitative detection of veterinary drug residues.

Early Prediction and Impact Assessment of CYP3A4-Related Drug-Drug Interactions for Small-Molecule Anticancer Drugs Using Human-CYP3A4-Transgenic Mouse Models.

Early detection of drug-drug interactions (DDIs) can facilitate timely drug development decisions, prevent unnecessary restrictions on patient enrollment, resulting in clinical study populations that are not representative of the indicated study population, and allow for appropriate dose adjustments to ensure safety in clinical trials. All of these factors contribute to a streamlined drug approval process and enhanced patient safety. Here we describe a new approach for early prediction of the magnitude of change in exposure for cytochrome P450 (P450) CYP3A4-related DDIs of small-molecule anticancer drugs based on the model-based extrapolation of human-CYP3A4-transgenic mice pharmacokinetics to humans. Victim drugs brigatinib and lorlatinib were evaluated with the new approach in combination with the perpetrator drugs itraconazole and rifampicin. Predictions of the magnitude of change in exposure deviated at most 0.99- to 1.31-fold from clinical trial results for inhibition with itraconazole, whereas exposure predictions for the induction with rifampicin were less accurate, with deviations of 0.22- to 0.48-fold. Results for the early prediction of DDIs and their clinical impact appear promising for CYP3A4 inhibition, but validation with more victim and perpetrator drugs is essential to evaluate the performance of the new method. SIGNIFICANCE STATEMENT: The described method offers an alternative for the early detection and assessment of potential clinical impact of CYP3A4-related drug-drug interactions. The model was able to adequately describe the inhibition of CYP3A4 metabolism and the subsequent magnitude of change in exposure. However, it was unable to accurately predict the magnitude of change in exposure of victim drugs in combination with an inducer.

Negative outcome in cutaneous Mycobacterium marinum infection treated with surgical intervention: Two-case report.

RATIONALE: Mycobacterium marinum (M marinum), a slow-growing nontuberculous mycobacterium (NTM), is widely distributed in aquatic environments. It is a well-known cutaneous pathogen, which causes sporotrichosis-like lesions. PATIENT CONCERNS: In this report, we describe 2 cases of subcutaneous M marinum infection. Both patients underwent several surgical procedures at local hospitals, and despite optimal surgical site healing, new lesions appeared in adjacent sites. DIAGNOSES: Based on NTM culture, identification by gene sequencing, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry, the diagnosis of subcutaneous NTM infection was confirmed. INTERVENTIONS: The patients were treated with oral rifampicin 0.45 g/day and clarithromycin 1 g/day and oral doxycycline hydrochloride capsules (200 mg/day), respectively. OUTCOMES: Both patients were treated for 8 and 5 weeks, respectively, and the lesions healed. LESSONS: Surgical debridement cannot compete with or impede NTM lymphatic spread; antimicrobial therapy is the first choice for the treatment of M marinum infections.

Intestinal obstruction following antituberculosis therapy in a patient with pancreatic carcinoma and pulmonary tuberculosis: a case report.

INTRODUCTION: Intestinal obstruction is a common complication in patients with advanced malignancies, often attributed to the disease itself or as a side effect of opioid analgesics used for pain management. However, the occurrence of intestinal obstruction following antituberculosis therapy is rare. CASE PRESENTATION: We report a unique case of a 58-year-old Asian male diagnosed with stage IV pancreatic carcinoma and pulmonary tuberculosis. The patient was initiated on a regimen of ethambutol hydrochloride, pyrazinamide, rifampicin, and isoniazid tablets (II) for tuberculosis, alongside morphine for the management of severe cancer-related pain. Subsequently, he developed symptoms indicative of intestinal obstruction. Despite discontinuation of morphine, the patient's symptoms persisted until he autonomously ceased all medications, leading to a rapid improvement in his condition. This unexpected resolution highlighted the antituberculosis drugs as the probable cause of his intestinal obstruction. CONCLUSIONS: This case underscores the importance of considering antituberculosis drugs as a potential cause of intestinal obstruction, especially in patients who do not respond to conventional management strategies for drug-induced gastrointestinal side effects. It also emphasizes the need for heightened vigilance and monitoring when prescribing these medications to patients with advanced malignancies, to promptly identify and address rare but significant side effects.

Unraveling energy transfer and fluorescence quenching dynamics in biomolecular complexes: a comprehensive study of imiquimod-rifampicin interaction.

In nature, numerous biomolecules are implicated in charge transfer (CT) and energy transfer (ET) mechanisms crucial for fundamental processes such as photosynthesis. Unveiling these mechanisms is pertinent to multiple disciplines including chemistry, engineering and biochemistry. This article presents a detailed study involving two molecules forming a model system with efficient ET properties. Specifically, their complex exhibits dark quenching phenomena arising from fluorescence resonance energy transfer (FRET) from the donor (imiquimod) to the acceptor (rifampicin). In addition, the energy transfer properties were also elucidated by considering the two forms of rifampicin (RIF), non-ionic and zwitter-ionic in the solution. Supplemented by spectroscopic findings, molecular dynamics simulations and time dependent density functional theory (TD-DFT) calculations conclusively validate the ET properties from imiquimod (IMQ) to RIF forms. Interestingly, these ET processes were found to be associated with pi-pi and hydrogen bond interactions. Their contribution was observed to depend upon the non-ionic and zwitter-ionic form of RIF.

Distribution of lineages and type II toxin-antitoxin systems among rifampin-resistant Mycobacterium Tuberculosis Isolates.

Type II toxin-antitoxin systems such as mazEF3, vapBC3, and relJK play a role in antibiotic resistance and tolerance. Among the different known TA systems, mazEF3, vapBC3, and relJK, which are type II systems, have specific roles in drug resistance. Therefore, the aim of this study was to investigate the mutations in these genes in sensitive and resistant isolates of Mycobacterium tuberculosis. Thirty-two rifampin-resistant and 121 rifampin-sensitive M. tuberculosis isolates were collected from various regions of Iran. Lineage typing was performed using the ASO-PCR method. Mutations in the rpoB gene were analyzed in all isolates by MAS-PCR. Furthermore, mutations in the mazEF3, relJK, and vapBC3 genes of the type II toxin system were assessed through PCR sequencing. These sequences were analyzed using COBALT and SnapGene 2017, and submitted to the GenBank database. Among the 153 M. tuberculosis samples, lineages 4, 3 and 2 were the most common. Lineage 2 had the highest rate of rifampin resistance. Mutations in rpoB531 were the most frequent in resistant isolates. Examination of the toxin-antitoxin system showed that rifampin-resistant isolates belonging to lineage 3 had mutations in either the toxin or antitoxin parts of all three TA systems. A mutation in nucleotide 195 (codon 65) of mazF3 leading to an amino acid change from threonine to isoleucine was detected in all rifampin-resistant isolates. M. tuberculosis isolates belonging to lineage 2 exhibited the highest rifampin resistance in our study. Identifying the mutation in mazF3 in all rifampin-resistant isolates can highlight the significance of this mutation in the development of drug resistance in M. tuberculosis. Expanding the sample size in future studies can help develop a new method for identifying resistant isolates.

Prevalence of rifampicin and isoniazid mono-resistance among cases of pulmonary tuberculosis from Western Uttar Pradesh, North India.

BACKGROUND: Mono-resistance to rifampicin/isoniazid increases poor treatment outcomes and the risk of multi-drug resistance (MDR) in tuberculosis (TB) patients. Limited information exists about mono-resistance status of TB patients in Uttar Pradesh, North India. This study aimed to estimate the burden of rifampicin and isoniazid mono-resistance in Western Uttar Pradesh. METHODS AND RESULTS: 153 sputum samples of suspected pulmonary tuberculosis patients were processed to isolate Mycobacterium tuberculosis using the Lowenstein-Jensen (L-J) culture medium. The isolates were identified using an immuno-chromatographic test and IS6110 PCR. The confirmed Mycobacterium tuberculosis isolates were tested for drug susceptibility testing against rifampicin and isoniazid anti-tuberculosis drugs. The results of the drug susceptibility testing were compared with demographic information and analyzed statistically. Out of 153 sputum samples, 83 (54.24%) samples were positive for growth on L-J medium, including 82 (98.79%) Mycobacterium tuberculosis isolates. Of the 82 Mycobacterium tuberculosis isolates, 16 (19.51%), 7 (8.54%), and 5 (6.10%) isolates were MDR, mono-resistant to rifampicin and isoniazid, respectively. The occurrence of RIF/INH mono-resistant-TB was higher in patients of male gender, age above 45 years, living in rural conditions, history of weight loss, and previous anti-TB treatment, but the effect was not statistically significant. CONCLUSIONS: The study reported the status of rifampicin and isoniazid mono-resistance among TB patients and highlighted the need for continuous monitoring and improved intervention for the initial detection of mono-drug-resistant cases. This will improve clinical treatment outcomes and decrease the rate of drug-resistant TB in Uttar Pradesh, North India.