Emergence Of Resistance Research Articles

Metabolic Reprogramming of Immune Cells in the Tumor Microenvironment

Metabolic reprogramming of immune cells within the tumor microenvironment (TME) plays a pivotal role in shaping tumor progression and responses to therapy. The intricate interplay between tumor cells and immune cells within this ecosystem influences their metabolic landscapes, thereby modulating the immune evasion tactics employed by tumors and the efficacy of immunotherapeutic interventions. This review delves into the metabolic reprogramming that occurs in tumor cells and a spectrum of immune cells, including T cells, macrophages, dendritic cells, and myeloid-derived suppressor cells (MDSCs), within the TME. The metabolic shifts in these cell types span alterations in glucose, lipid, and amino acid metabolism. Such metabolic reconfigurations can profoundly influence immune cell function and the mechanisms by which tumors evade immune surveillance. Gaining a comprehensive understanding of the metabolic reprogramming of immune cells in the TME is essential for devising novel cancer therapeutic strategies. By targeting the metabolic states of immune cells, it is possible to augment their anti-tumor activities, presenting new opportunities for immunotherapeutic approaches. These strategies hold promise for enhancing treatment outcomes and circumventing the emergence of drug resistance.

Inhibition mechanism of potential antituberculosis compound lansoprazole sulfide

Tuberculosis is one of the most common causes of death worldwide, with a rapid emergence of multi-drug-resistant strains underscoring the need for new antituberculosis drugs. Recent studies indicate that lansoprazole—a known gastric proton pump inhibitor and its intracellular metabolite, lansoprazole sulfide (LPZS)—are potential antituberculosis compounds. Yet, their inhibitory mechanism and site of action still remain unknown. Here, we combine biochemical, computational, and structural approaches to probe the interaction of LPZS with the respiratory chain supercomplex III 2 IV 2 of Mycobacterium smegmatis , a close homolog of Mycobacterium tuberculosis supercomplex. We show that LPZS binds to the Q o cavity of the mycobacterial supercomplex, inhibiting the quinol substrate oxidation process and the activity of the enzyme. We solve high-resolution (2.6 Å) cryo-electron microscopy (cryo-EM) structures of the supercomplex with bound LPZS that together with microsecond molecular dynamics simulations, directed mutagenesis, and functional assays reveal key interactions that stabilize the inhibitor, but also how mutations can lead to the emergence of drug resistance. Our combined findings reveal an inhibitory mechanism of LPZS and provide a structural basis for drug development against tuberculosis.

Emergence of multiple resistance to EPSPS and ALS herbicides in smooth pigweed (Amaranthus hybridus): a growing concern in Brazil

Abstract Recently, farmers in Brazil have observed a decline in efficacy of glyphosate, chlorimuron, and imazethapyr control of smooth pigweed (Amaranthus hybridus L.). The objectives of this study were to quantify the resistance of Amaranthus in Brazil to glyphosate and acetolactate synthase (ALS)-inhibiting herbicides, elucidate the mechanism of resistance, and assess the frequency of sensitivity shifts to glyphosate and chlorimuron in Brazil. Dose–response assays were conducted in a greenhouse with glyphosate, chlorimuron, and imazethapyr. This was followed by sequencing of the EPSPS and ALS genes. Additionally , 740 Amaranthus populations across several Brazilian states were monitored over 4 yr, subjected to a single discriminatory dose of glyphosate and chlorimuron. The populations BR18Asp051 and BR21Asp205 were resistant to glyphosate, chlorimuron, and imazethapyr. The elevated resistance level to glyphosate in these populations is attributed to multiple amino acid substitutions (TAP-IVS) in the EPSPS gene; and cross-resistance to sulfonylureas and imidazolinones is conferred by the Trp-574-Leu substitution in the ALS gene in both populations. Overall, resistance distribution indicated that 88% of the sampled populations were considered sensitive to glyphosate, while 66% were sensitive to chlorimuron. Furthermore, 10% of the samples demonstrated multiple resistance to both active ingredients. A shift in glyphosate sensitivity was observed in four states in Brazil; however, sensitivity shifts to chlorimuron were more widely dispersed in Brazilian agricultural regions.

EXTH-46. TESTING PRECISION GENOMICS-GUIDED THERAPY IN A MODEL OF ANAPLASTIC PLEOMORPHIC XANTHOASTROCYTOMA: DUAL INHIBITION OF CDK4/6 AND MEK

Abstract Typical survival for pediatric high-grade gliomas remains less than 18 months despite recent improved understanding of the molecular drivers of these tumors. Hyperactivating MAPK and CDK4/6 pathway mutations are common and targetable alterations implicated in tumorigenesis and malignant transformation in pediatric glioma. We have established and characterized a novel patient-derived xenograft (PDX) model, RHT128, from a pediatric patient diagnosed with the high-grade glioma anaplastic pleomorphic xanthoastrocytoma (APXA). The molecular landscape of PDX RHT128 exhibits molecular fidelity to the patient’s tumor. Clinical precision genomics analysis of the tumor revealed a novel BRAF chromosomal rearrangement and CDKN2A/B deletion. Based on this molecular signature, the patient was treated with MEK inhibitor trametinib as a monotherapy and, following progression of disease, with CDK4/6 inhibitor ribociclib. However, the tumor continued to progress. In this study our objective is to simultaneously target the CDK4/6 and MAPK pathways in RHT128 and determine to what extent this combination therapy minimizes emergence of therapeutic resistance. Single-agent efficacy assessments in a subcutaneous RHT128 model, showing significant dose-dependent reduction in tumor volume after treatment with abemaciclib (p<0.05), palbociclib (p<0.01), and the blood-brain barrier-permeable MEK inhibitor mirdametinib (p<0.0001). Analysis of the global kinome in CDK4/6 inhibitor-treated PDX tissues compared to vehicle treatment using multiplexed-inhibitor bead chromatography–mass spectrometry demonstrated effective inhibition of CDK4/6. Moreover, this analysis revealed dose-dependent alterations in the MAPK and PI3K pathways and modulation of critical neurotransmitter pathways in treated tissues. Future studies will explore efficacy of these MEK and CDK4/6 inhibitors in combination and in our BRAF wild-type and BRAF V600E variant APXA models to gain further mechanistic insights. The pervasiveness of alterations to the MAPK and CDK4/6 pathways in pediatric gliomas make this approach promising for further study in a broader range of these deadly tumors.

In-Vitro Antimicrobial Activities of Grape Seed, Green Tea, and Rosemary Phenolic Extracts Against Liver Abscess Causing Bacterial Pathogens in Cattle

Liver abscesses, which occur in finishing cattle, are of significant economic concern to the feedlot industry. The causative agents include both Fusobacterium necrophorum subspecies (F. necrophorum and F. funduliforme), Trueperella pyogenes (T. pyogenes), and Salmonella enterica serotype Lubbock (S. Lubbock). Tylosin, a macrolide antibiotic, is supplemented in the feed to reduce liver abscesses. However, due to the concern with emergence of antimicrobial resistance, the antimicrobial activities of the plant-based phenolic compounds could be an antibiotic alternative to control liver abscesses. We investigated the inhibitory activities of phenolic compounds extracted from grape seed, green tea, and rosemary on liver-abscess-causing bacterial pathogens. Total phenolic content was determined spectrophotometrically. Anaerobic Brain–Heart Infusion broth (for Fusobacterium) and Muller–Hinton broth (for S. enterica and T. pyogenes) with phenolic extracts at 0, 0.1, 1, and 2 mg/mL were prepared. Growth was measured at 0, 12, 24 and 48 h by determining bacterial concentrations. A micro-broth dilution method was used to quantify the inhibition. Grape seed and green tea phenolics inhibited growth of both Fusobacterium subspecies, T. pyogenes and S. enterica. Green tea at 1 mg/mL concentration was more effective in inhibiting the growth of Fusobacterium when compared to grape seed and rosemary. Green tea at 2 mg/mL was more effective than at 1 mg/mL against Salmonella. The inhibitory effect was dose-dependent, which was consistent across all strains within the same bacterial species. The phenolic extracts were inhibitory against T. pyogenes with minimum inhibitory concentration ranging from 6.25 to 12.5 µg/mL. Among the phenolic extracts tested, green tea showed the most potent activity, suggesting its strong potential as a natural alternative to conventional antibiotics. Plant-based phenolic compounds supplemented in the feed may have the potential to control liver abscesses.

In vitro monitoring of drug resistance emergence during stepwise induction of bedaquiline and clofazimine, alone and in combination: a phenotypic and genotypic analysis

Abstract Objectives The co-resistance between bedaquiline and clofazimine raises significant concerns, as they are commonly co-administered as core drugs in drug-resistant TB regimens. The present study aimed to monitor drug resistance-associated gene mutations and the phenotypic change in Mycobacterium tuberculosis (Mtb) under a stepwise drug resistance induction in vitro using bedaquiline, clofazimine or combined drugs. Methods Drug-resistant Mtb strains were gradually induced in vitro on a drug-containing solid medium with a 2-fold increasing concentration of bedaquiline, clofazimine and their combination. The MIC of the induced drug-resistant Mtb strains was determined. The drug resistance-associated genes, including Rv0678, Rv1979c, atpE and pepQ, were sequenced and analysed. Results Unlike exposure to bedaquiline alone or the combination of these two drugs, clofazimine alone resulted in drug resistance gene mutations occurring later, specifically in the fourth round of induction as opposed to the second round of induction. Besides, nucleotide deletion or insertion in Rv0678 was the main mutation type for induction under the two-drug combination, while single-nucleotide polymorphisms (SNPs) in Rv0678 were the major mutation types when induced by bedaquiline or clofazimine alone. Rv0678 mutation happened at a relatively lower bedaquiline concentration exposure alone, while atpE mutation occurred at a higher bedaquiline concentration. Regardless of the drug exposure manner, a strong correlation between bedaquiline MICs and clofazimine MICs was observed in all drug resistance strains. Conclusions Combined exposure to bedaquiline and clofazimine developed Rv0678 mutation as early as exposure to bedaquiline alone. However, rather than SNPs, deletion and insertion were the dominant mutation types in dual-drug exposure strain.

A possible alternative to antibacterial therapy in the treatment of acute rhinosinusitis

High incidence of acute rhinosinusitis in a population remains one of the topical issues in practical otolaryngology. Statistical data show an increasing trend towards transition of acute rhinosinusitis in patients into chronic rhinosinusitis. According to literary sources, the emergence of bacterial resistance to antibiotics is as a rule the major reason of protracted course of the disease. Unreasonable antibiotics prescription, irrational use and uncontrolled intake result in the rapid development of antibiotic resistance. In this context, the use of herbal medicines having not only antibacterial, but also mucolytic, fungicidal, antioxidant effects in the complex therapy is a modern solution for disease management. Respero Myrtol, a standardized myrtol-based medicine, has taken its rightful place in the therapy. This article is aimed to investigate the possibilities of the effective use of medicine containing standardized myrtol as its main ingredient in the treatment of acute rhinosinusitis (based on the review of literature). Research materials included scientific articles on aspects of acute rhinosinusitis in otorhinolaryngology practice that were published in domestic specialized periodicals of eLIBRARY and scientific databases Scopus, Web of Science, Medline from 2014 to 2024. The published literature was analysed using the cause-and-effect technique. A clinical example was dis-cussed. With regard to the analysis of scientific literature, a brief overview of the epidemiology, etiology, predisposing factors for the development, diagnosis and treatment of acute rhinosinusitis was provided. The article addresses relevant socio-economic issues related to acute rhinosinusitis, the problem of antibiotic resistance. The issues of improving acute rhinosinusitis treatments using a standardized myrtol medicine in complex therapy as an alternative to antibiotic therapy were brought to attention. As a result, the authors concluded that the use of Respero Myrtol contributes to the rapid relief of clinical symptoms of acute rhinosinusitis, improves the patient’s quality of life, and can be advised as an alternative to antibiotic therapy in uncomplicated course of the disease.

Murine colon cancer derived cells exhibit heterogeneous resistance profiles against an oncolytic virus

Oncolytic virotherapy has shown efficacy in various animal models and a few human cancers. However, there are still significant limitations for the implementation of these therapies. One such limitation is the emergence of cellular resistances, which may appear rapidly considering the high genetic heterogeneity of most tumors. We previously showed that cellular resistance to an oncolytic virus can be mediated by the chronic activation of innate immunity. Here, we explored the existence of additional resistance mechanisms in murine colon cancer-derived cells. For this purpose, we isolated two cellular clones that were resistant to the oncolytic virus VSV-D51. While one of the clones showed a strong resistance profile associated with increased cytokine-mediated antiviral responses, the other clone showed a lower level of resistance that involves cytoskeletal reorganization, signaling by small GTPases, and cell structural changes. These results demonstrate the capacity of tumor cells to deploy heterogeneous mechanisms of resistance to oncolytic viruses.

Audit project on the appropriateness of teicoplanin prescribing in Milton Keynes University Hospital (MKUH)

Abstract Introduction Teicoplanin is the Trust’s preferred glycopeptide antibiotic compared to vancomycin due to the once-daily dosing, less toxic side effects and monitoring requirements1. Teicoplanin dosing regimen is weight-dependent, including loading and maintenance doses adjusted according to creatinine clearance (CrCl) from Day 52. As antimicrobial resistance emergence continues to be a public health concern, appropriate teicoplanin use is vital to avoid treatment failure in line with antimicrobial stewardship3. Aim and Standards To assess teicoplanin prescribing compliance with the Trust guideline. 100% compliance was expected for the following standards: 1. Teicoplanin is prescribed for an approved indication according to Trust guideline or by a Consultant Microbiologist. 2. Loading dose of teicoplanin is prescribed for treatment initiation. 3. Appropriate teicoplanin loading dose is prescribed based on actual body weight (ABW) and indication. 4. Appropriate teicoplanin maintenance dose is prescribed until Day 4 based on ABW and indication. 5. Appropriate teicoplanin maintenance dose is prescribed from Day 5 onwards based on CrCl, ABW and indication. Method This study did not require ethics approval. To assess audit feasibility, a pilot was done looking at teicoplanin prescriptions and clinical notes against the audit standards. CrCl was calculated where appropriate. Retrospective data of 18 teicoplanin prescriptions between 08/11/2022-14/11/2022 were extracted from the Electronic Prescribing and Medicines Administration (EPMA) system onto an Excel data collection spreadsheet. No changes were made to the data collection tool. One month’s data between 11/10/2022-07/11/2022 were further extracted and process was repeated. Paediatric patients and indications for surgical prophylaxis and Clostridioides difficile infection were excluded. Results 88 patients were included in the study. 90% (n=79) of teicoplanin prescriptions were prescribed for an indication approved on the Trust’s antimicrobial guideline or by a Consultant Microbiologist. Teicoplanin loading dose was prescribed for 82% (n=71) of patients. 1 patient was excluded as loading dose was administered in another hospital. 46% (n=40) of patients were prescribed the appropriate teicoplanin loading dose. 60% (n=34) of the 57 patients who continued teicoplanin up until Day 4 were prescribed the appropriate teicoplanin maintenance dose. 56% (n=22) of the 39 patients treated with teicoplanin past Day 4 were prescribed the appropriate teicoplanin maintenance dose. None of the 5 standards were met. Conclusion The results indicate inappropriate teicoplanin prescribing against the current Trust guideline which need improvement. Training with prescribers on utilising the EPMA’s pre-populated teicoplanin dose prescription function alongside encouraging pledges to be an Antibiotic Guardian are recommended during their induction. This would help avoid prescription errors and reduce antimicrobial resistance development. The data collected did not subdivide patients under specific specialities, which could highlight areas where training should be focused on. This limitation should be addressed when the re-audit due in 1 years’ time is carried out, to evaluate the changes implemented.

Evaluating Treatment and Management Strategies for Diarrhea and Typhoid Fever in Uganda

Diarrhea and typhoid fever remain significant public health challenges in Uganda, contributing to high morbidity and mortality, particularly among vulnerable populations. This review evaluates current treatment and management strategies for these diseases, focusing on standard protocols, rehydration therapy, and the escalating issue of antibiotic resistance. Diarrhea, primarily caused by infectious agents, accounts for a substantial portion of childhood morbidity and mortality, while typhoid fever, caused by Salmonella enterica serotype Typhi, poses severe health risks, particularly in urban areas with poor sanitation. Effective management relies on timely interventions, including rehydration therapy, which significantly reduces the risk of dehydration-related complications. However, the emergence of antibiotic resistance complicates treatment efficacy, necessitating ongoing evaluation and adaptation of management strategies. This review highlights the importance of integrated public health approaches that combine treatment, prevention, and community education to address the interplay of these diseases in Uganda. Key recommendations include the exploration of novel treatment modalities, robust surveillance of resistance patterns, and understanding the impact of climate change on disease incidence. Keywords: Diarrhea, Typhoid fever, Uganda, Public health, Rehydration therapy, Antibiotic resistance.

Carry-over effects of Bacillus thuringiensis on tolerant Aedes albopictus mosquitoes

BackgroundThe biological larvicide Bacillus thuringiensis subsp. israelensis (Bti) represents a safe and effective alternative to chemical insecticides for mosquito control. Efficient control of mosquitoes implicates continuous and extensive application of Bti. This massive use of Bti imposes strong selective pressure, but the complex mode of action of the numerous synergistic Bti endotoxins lower the risk of the emergence of resistance. Although resistance to Bti has not been identified at the population level in nature, some larvae can survive Bti exposure, suggesting tolerance mechanisms. Here we investigated whether Bti-tolerant Aedes albopictus larvae experience any fitness costs. We also studied how this tolerance affects different aspects of the phenotype of the emerging adults that could be relevant for arboviral transmission.MethodsWe exposed Ae. albopictus larvae to lethal concentration of Bti and studied the fitness and gut microbiota of tolerant larvae and their adult counterparts. We further compared the transcript abundance of nine key immunity genes in the gut of Bti-tolerant larvae and their emerging adults versus those not exposed to Bti.ResultsOur results showed that Bti exposure has multifaceted impacts on Ae. albopictus mosquitoes during both larval and adult stages. The carry-over effect of Bti exposure on tolerant larvae manifested in reduced adult emergence rate, shorter lifespan, and decreased fecundity. Bti also alters the gut microbiota of both larvae and adults. We observed higher microbial diversity in Bti-tolerant larvae and changes in the richness of core microbiota. Bti infection and the altered microbiota triggered immune responses in the larval and adult guts.ConclusionsThe observed reduction in mosquito fitness and changes in the composition of the microbiota of adults emerging from tolerant larvae could negatively influence mosquito vectorial capacity. Understanding these impacts is crucial for evaluating the broader implications of Bti-based insecticides in mosquito control programs.Graphical

Data-Driven Approaches in Antimicrobial Resistance: Machine Learning Solutions

Background/Objectives: The emergence of antimicrobial resistance (AMR) due to the misuse and overuse of antibiotics has become a critical threat to global public health. There is a dire need to forecast AMR to understand the underlying mechanisms of resistance for the development of effective interventions. This paper explores the capability of machine learning (ML) methods, particularly unsupervised learning methods, to enhance the understanding and prediction of AMR. It aims to determine the patterns from AMR gene data that are clinically relevant and, in public health, capable of informing strategies. Methods: We analyzed AMR gene data in the PanRes dataset by applying unsupervised learning techniques, namely K-means clustering and Principal Component Analysis (PCA). These techniques were applied to identify clusters based on gene length and distribution according to resistance class, offering insights into the resistance genes’ structural and functional properties. Data preprocessing, such as filtering and normalization, was conducted prior to applying machine learning methods to ensure consistency and accuracy. Our methodology included the preprocessing of data and reduction of dimensionality to ensure that our models were both accurate and interpretable. Results: The unsupervised learning models highlighted distinct clusters of AMR genes, with significant patterns in gene length, including their associated resistance classes. Further dimensionality reduction by PCA allows for clearer visualizations of relationships among gene groupings. These patterns provide novel insights into the potential mechanisms of resistance, particularly the role of gene length in different resistance pathways. Conclusions: This study demonstrates the potential of ML, specifically unsupervised approaches, to enhance the understanding of AMR. The identified patterns in resistance genes could support clinical decision-making and inform public health interventions. However, challenges remain, particularly in integrating genomic data and ensuring model interpretability. Further research is needed to advance ML applications in AMR prediction and management.

In vivo emergence of resistance to ceftazidime/avibactam through modification of chromosomal AmpC β-lactamase in Klebsiella aerogenes.

We describe the in vivo emergence of resistance to ceftazidime/avibactam via modification of AmpC in a clinical Klebsiella aerogenes isolate during therapy with this combination. Paired ceftazidime/avibactam-susceptible/resistant isolates were obtained before and during ceftazidime/avibactam treatment. Whole genome sequencing revealed a differential mutation in AmpC (R148W) in the ceftazidime/avibactam-resistant isolate. Molecular cloning and structural studies confirmed the impact of this substitution, which affects the architecture of the H10 helix, on the evolved resistant phenotype.

Superior target genes and pathways for RNAi-mediated pest control revealed by genome-wide analysis in the beetle Tribolium castaneum.

An increasing human population, the emergence of resistances against pesticides and their potential impact on the environment call for the development of new eco-friendly pest control strategies. RNA interference (RNAi)-based pesticides have emerged as a new option with the first products entering the market. Essentially, double-stranded RNAs targeting essential genes of pests are either expressed in the plants or sprayed on their surface. Upon feeding, pests mount an RNAi response and die. However, it has remained unclear whether RNAi-based insecticides should target the same pathways as classic pesticides or whether the different mode-of-action would favor other processes. Moreover, there is no consensus on the best genes to be targeted. We performed a genome-wide screen in the red flour beetle to identify 905 RNAi target genes. Based on a validation screen and clustering, we identified the 192 most effective target genes in that species. The transfer to oral application in other beetle pests revealed a list of 34 superior target genes, which are an excellent starting point for application in other pests. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analyses of our genome-wide dataset revealed that genes with high efficacy belonged mainly to basic cellular processes such as gene expression and protein homeostasis - processes not targeted by classic insecticides. Our work revealed the best target genes and target processes for RNAi-based pest control and we propose a procedure to transfer our short list of superior target genes to other pests. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Evaluating the Genetic Landscape of (Plasmodium falciparum) PfKelch13 Gene Polymorphisms in Côte d'Ivoire Following a Decade of Artemisinin-based Combination Therapy

Introduction: Artemisinin-based combination therapies (ACTs) are the mainstay of malaria treatment globally. However, their effectiveness is threatened by the emergence of resistance in Plasmodium falciparum (P.f), particularly in Southeast Asia (SEA). Specific mutations within the pfKelch13 gene, such as Cys-580-Tyr, Arg-539-Thr, Tyr-493-His, and Ile-543-Thr, have been strongly linked to delayed parasite clearance following ACT treatment. This study aimed to investigate polymorphisms within the pfKelch13 gene (also known as the K13-propeller or K13 gene) in four regions of Côte d'Ivoire. Côte d'Ivoire experiences year-round malaria transmission and has utilized ACTs for over a decade. Methods: From September 2013 to July 2014, samples were collected from patients residing in Abidjan (south), Ayamé (southeast), Man (west), and Korhogo (north) who presented with microscopically confirmed uncomplicated malaria. Following Plasmodium falciparum DNA extraction, nested PCR was employed to amplify an 849 bp fragment of the pfKelch13 gene. Amplicons were subsequently sequenced and analyzed using BioEdit software. Results: 531 DNA sequences were analyzed including 301 (58.7%) from Abidjan, 61(11.5%) from Ayamé, 93 (17.5%) from Man and 76 (13.4%) from Korhogo. Only 20 isolates carrying 22 mutations were observed including 6 non-synonymous single-nucleotide polymorphisms (nsSNP): 4 in Abidjan (Asp-535-Met; Ala-578-Ser; Phe-583-Ser and Ile-601-Thr) and 2 in Korhogo (Asp-559-Asn and Val-510-Met). Only synonymous SNP (sSNP) were identified in the two other Towns. The proportion of mutated pfK13 sequences is 3.8% (20/531). Conclusion: The identification of non-synonymous mutations in this study underscores the importance of heightened surveillance for potential ACT resistance in Plasmodium falciparum within Côte d'Ivoire. Combining in vitro assays, such as the Ring-stage Survival Assay, with molecular testing will be crucial for definitively determining the phenotypic impact of these mutations on parasite susceptibility to ACTs.

Temporal genomics in Southern Zambia shows rising prevalence of Plasmodium falciparum mutations linked to delayed clearance after artemisinin-lumefantrine treatment

The emergence of antimalarial drug resistance is an impediment to malaria control and elimination in Africa. Analysis of temporal trends in molecular markers of resistance is critical to inform policy makers and guide malaria treatment guidelines. In a low and seasonal transmission region of southern Zambia, we successfully genotyped 85.5% (389/455) of Plasmodium falciparum samples collected between 2013 and 2018 from 8 spatially clustered health centres using molecular inversion probes (MIPs) targeting key drug resistance genes. Aside from one sample from 2016 carrying K13 622I, no other World Health Organization-validated or candidate artemisinin partial resistance (ART-R) mutations were observed. However, in the more recent years (2016–2017) five novel K13-propeller-domain mutations, C532S, A578S, Q613E, D680N and G718S were identified at low prevalence. Moreover, 13% (CI, 9.6–17.2) of isolates had the AP2MU 160N mutation, which has been associated with delayed clearance following artemisinin combination therapy in Africa. This mutation increased in prevalence between 2015 and 2018 and bears a genomic signature of selection. During this time period, there was an increase in the MDR1 NFD haplotype that is associated with reduced susceptibility to lumefantrine. Sulfadoxine-pyrimethamine polymorphisms were near fixation. While validated ART-R mutations are rare, a mutation associated with slow parasite clearance in Africa appears to be under selection in southern Zambia.

Emerging threat of artemisinin partial resistance markers (pfk13 mutations) in Plasmodium falciparum parasite populations in multiple geographical locations in high transmission regions of Uganda

BackgroundArtemisinin-based combination therapy (ACT) is currently recommended for treatment of uncomplicated malaria. However, the emergence and spread of partial artemisinin resistance threatens their effectiveness for malaria treatment in sub-Saharan Africa where the burden of malaria is highest. Early detection and reporting of validated molecular markers (pfk13 mutations) in Plasmodium falciparum is useful for tracking the emergence and spread of partial artemisinin resistance to inform containment efforts.MethodsGenomic surveillance was conducted at 50 surveillance sites across four regions of Uganda in Karamoja, Lango, Acholi and West Nile from June 2021 to August 2023. Symptomatic malaria suspected patients were recruited and screened for presence of parasites. In addition, dried blood spots (DBS) were collected for parasite genomic analysis with PCR and sequencing. Out of 563 available dried blood spots (DBS), a random subset of 240 P. falciparum mono-infections, confirmed by a multiplex PCR were selected and used for detecting the pfk13 mutations by Sanger sequencing using Big Dye Terminator method. Regional variations in the proportions of pfk13 mutations were assessed using the chi square or Fisher’s exact tests while Kruskal–Wallis test was used to compare absolute parasite DNA levels between wild type and mutant parasites.ResultsOverall, 238/240 samples (99.2%) contained sufficient DNA and were successfully sequenced. Three mutations were identified within the sequenced samples; pfk13 C469Y in 32/238 (13.5%) samples, pfk13 A675V in 14/238 (5.9%) and pfk13 S522C in (1/238 (0.42%) samples across the four surveyed regions. The prevalence of pfk13 C469Y mutation was significantly higher in Karamoja region (23.3%) compared to other regions, P = 0.007. The majority of parasite isolates circulating in West Nile are of wild type (98.3), P = 0.002. Relative parasite DNA quantity did not differ in samples carrying the wild type, C469Y and A675V alleles (Kruskal–Wallis test, P = 0.6373).ConclusionDetection of validated molecular markers of artemisinin partial resistance in multiple geographical locations in this setting provides additional evidence of emerging threat of artemisinin partial resistance in Uganda. In view of these findings, periodic genomic surveillance is recommended to detect and monitor levels of pfk13 mutations in other regions in parallel with TES to assess potential implication on delayed parasite clearance and associated treatment failure in this setting. Future studies should consider identification of potential drivers of artemisinin partial resistance in the different malaria transmission settings in Uganda.

Leveraging mathematical modeling framework to guide regimen strategy for phage therapy

Bacteriophage (phage) cocktail therapy has been relied upon more and more to treat antibiotic-resistant infections. Understanding of the complex kinetics between phages, target bacteria, and the emergence of phage resistance remain hurdles to successful clinical outcomes. Building upon previous mathematical concepts, we develop biologically-motivated nonlinear ordinary differential equation models to explore single, cocktail, and sequential phage treatment modalities. While the optimal pairwise phage treatment strategy was the double simultaneous administration of two highly potent and asymmetrically binding phage strains, it appears unable to prevent the evolution of resistance. This treatment regimen did have a greater lysis efficiency, promoted higher phage population sizes, reduced bacterial density the most, and suppressed the evolution of resistance the longest compared to all other treatments strategies tested. Conversely, the combination of phages with polar potencies allows the more efficiently replicating phages to monopolize susceptible host cells, thereby quickly negating the intended compounding effect of cocktails. Together, we demonstrate that a biologically-motivated modeling-based framework can be leveraged to quantify the effects of each phage’s properties to more precisely predict treatment responses.

What role does antibiotic resistance play in secondary endodontic infections?

The systematic review utilised multiple electronic databases to gather relevant literature, including PubMed, Scopus, EMBASE, Web of Science, and Medline. The search was conducted focusing on clinical studies where Enterococcus strains were isolated to assess their antimicrobial resistance. The search strategy was designed based on the PICO model, targeting patients with secondary/persistent endodontic infections (SPEI) and evaluating the resistance profiles of Enterococci to systemic antibiotics. A total of 584 studies were initially identified through database searches. After removing duplicates, 517 studies were excluded based on title and abstract screening, leading to the final inclusion of 11 clinical trials that met the eligibility criteria. The studies were conducted in various countries, including Brazil, Lithuania, Poland, Germany, Sweden, the United States, and Japan. The focus was on permanent teeth with post-treatment apical periodontitis undergoing endodontic retreatment. Data extraction was performed independently by two reviewers, who compiled details such as authorship, year of publication, country of study, sample groups, bacterial strains tested, antibiotics used, and resistance outcomes. The risk of bias was assessed using the ROB-2 platform, and all studies were considered to have a low risk of bias, with occasional minor deficiencies noted. The analysis revealed fluctuating resistance profiles of Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) to various antibiotics over time. E. faecalis isolated from teeth with SPEI showed intermediate resistance to 16 antibiotics. The most effective antibiotics identified were the combination of amoxicillin and clavulanate, followed by amoxicillin and benzylpenicillin. In patients with penicillin allergies, moxifloxacin and azithromycin were suggested as alternatives, albeit with caution due to their varying resistance levels. The antibiotics demonstrating the highest resistance patterns against E. faecalis included clindamycin, gentamicin, metronidazole, and rifampicin, which are contraindicated in SPEI cases. Ongoing monitoring of antibiotic resistance patterns is crucial for effective endodontic treatment protocols. The emergence of resistance among Enterococci, particularly E. faecalis, necessitates regular susceptibility testing to inform clinical decisions and improve treatment outcomes. The findings underscore the need for health professionals to stay informed about the evolving resistance landscape to ensure safe and effective therapeutic regimens in endodontics.

IGF2BP3-dependent N6-methyladenosine modification of USP49 promotes carboplatin resistance in retinoblastoma by enhancing autophagy via regulating the stabilization of SIRT1.

Retinoblastoma (RB) poses significant challenges in clinical management due to the emergence of resistance to conventional chemotherapeutic agents, particularly carboplatin (CBP). In this study, we investigated the molecular mechanisms underlying CBP resistance in RB, with a focus on the role of autophagy and the influence of ubiquitin-specific peptidase 49 (USP49). We observed upregulation of USP49 in RB tissues and cell lines, correlating with disease progression. Functional assays revealed that USP49 promoted aggressive proliferation and conferred CBP resistance in RB cells. Furthermore, USP49 accelerated tumor growth and induced CBP resistance in vivo. Mechanistically, we found that USP49 facilitated CBP resistance by promoting autophagy activation. In addition, we identified insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3)-mediated N6-methyladenosine (m6A) modification of USP49 as a regulatory mechanism, wherein IGF2BP3 upregulated USP49 expression in an m6A-dependent manner. Moreover, USP49 stabilized SIRT1, a protein associated with CBP resistance and autophagy, by inhibiting its ubiquitination and degradation. Rescue experiments confirmed the pivotal role of SIRT1 in USP49-mediated CBP resistance. Our findings delineate a novel molecular network involving USP49-mediated autophagy in promoting CBP resistance in RB, offering potential targets for therapeutic intervention to enhance treatment efficacy and improve outcomes for RB patients.