Unraveling resistance mechanisms in combination therapy: A comprehensive review of recent advances and future directions

Antibiotic killing of drug-induced bacteriostatic cells

There is a long-standing belief that bacteriostatic drugs are inherently antagonistic to the action of bactericidal antibiotics. This belief is primarily because the action of most bactericidal antibiotics requires the target bacteria to be growing. Since bacteriostatic drugs stop the growth of treated bacteria, these drugs would necessarily work against one another. Our results question this long-standing belief by demonstrating conditions where sequential treatment with a bacteriostatic then bactericidal antibiotic is as or more effective than treatment with a bactericidal drug alone. These results raise the need to investigate the pharmacodynamics of the joint action of bacteriostatic and bactericidal antibiotics in vitro and in vivo.

Molybdenum Disulfide Nanocomposites for Cancer Diagnosis and Therapeutics: Biosensors, Bioimaging, and Phototherapy

Molybdenum disulfide (MoS₂) nanomaterials have attracted significant interest in cancer diagnosis and therapy due to their unique physicochemical properties. Due to its extensive surface area and adaptable structure, MoS₂ may engage with pharmaceuticals and biomolecules via covalent and non-covalent interactions. This versatility enhances the sensitivity of identifying specific biomarkers, colloidal stability, and tumor-targeting capabilities. In the near-infrared (NIR) spectrum, MoS₂ exhibits strong optical absorption and efficient photothermal conversion, making it suitable for NIR-driven phototherapy and regulated medication release. Functionalized MoS₂ nanocomposites react differently to the tumor microenvironment, which improves treatment effectiveness by increasing drug accumulation at cancer sites and decreasing off-target effects on healthy tissues. Recent developments in MoS₂-based nanocomposites for cancer detection and treatment are reviewed in this study, with particular attention paid to their uses in photothermal therapy, photodynamic therapy, biosensing, and bioimaging. Additionally, it looks at the difficulties and potential applications of MoS₂ nanocomposites in cancer.

Synergistic Antibacterial Activity of Amorolfine Combined with Colistin Against Acinetobacter baumannii

Emerging resistance to colistin in Acinetobacter baumannii is concerning because of the limited therapeutic options for this important clinical pathogen. Given the shortage of new antibiotics, one strategy that has been proven to be therapeutically effective is to overcome antibiotic-resistant pathogens by combining existing antibiotics with another antibiotic or non-antibiotic. This study was designed to investigate the potential synergistic antibacterial activity of amorolfine, a morpholine antifungal drug, in combination with colistin against A. baumannii. In this work, antibiotic susceptibility testing, checkerboard assays, and time-kill curves were used to investigate the synergistic efficacy of colistin combined with amorolfine. The molecular mechanisms of combination therapy were analyzed using fluorometric assays, UV-vis spectroscopy, and molecular docking. Finally, we evaluated the in vivo efficacy of combination therapy against A. baumannii. In brief, the combination therapy showed significant synergistic activity against A. baumannii (FICI = 0.094). In addition, the combination of amorolfine improved the membrane disruption of colistin, and amorolfine exhibited the capacity of binding to DNA. Moreover, in a mouse sepsis model, this combination therapy increased survival compared to colistin monotherapy. Our findings demonstrated that amorolfine serves as a potential colistin adjuvant against Acinetobacter baumannii.

Unraveling the triad of immunotherapy, tumor microenvironment, and skeletal muscle biomechanics in oncology

The intricate interaction between skeletal muscle biomechanics, the tumor microenvironment, and immunotherapy constitutes a pivotal research focus oncology. This work provides a comprehensive review of methodologies for evaluating skeletal muscle biomechanics, including handheld dynamometry, advanced imaging techniques, electrical impedance myography, elastography, and single-fiber experiments to assess muscle quality and performance. Furthermore, it elucidates the mechanisms, applications, and limitations of various immunotherapy modalities, including immune checkpoint inhibitors, adoptive cell therapy, cancer vaccines, and combined chemoimmunotherapy, while examining their effects on skeletal muscle function and systemic immune responses. Key findings indicate that although immunotherapy is effective in augmenting antitumor immunity, it frequently induces muscle-related adverse effects such as weakness, fatigue, or damage, primarily mediated by cytokine release and immune activation. This work underscores the significance of immune niches within the tumor microenvironment in influencing treatment outcomes and proposes strategies to optimize therapy through personalized regimens and combinatorial approaches. This review highlights the need for further research on the formation of immune niches and interactions muscle-tumor. Our work is crucial for advancing the efficacy of immunotherapy, reducing adverse effects, and ultimately improving survival rates and quality of life of patients with cancer.

Three-Dimensional Quantitative Structure-Activity Relationship, Antimicrobial Activity, and Molecular Docking Studies of C-14 Chiral Matrine Derivatives as Potential Antibiotics

Antibiotic resistance is recognized as one of the top ten global public health threats, posing a significant challenge to human health. The stereochemistry of chiral molecules, alongside their specific interactions with biological targets, provides essential insights for the development of novel antibacterial agents, This study investigated the antibacterial activity of 32 previously synthesized 14-position chiral matrine derivatives. Among these derivatives, compound Q4 exhibited the strongest activity against Propionibacterium acnes, with a minimum inhibitory concentration (MIC) of 0.007 mg/mL, surpassing that of the positive control (MIC = 0.016 mg/mL). Additionally, compounds Q20 and Q2 demonstrated antibacterial activities comparable to the positive controls. The results indicated that R-configured compounds exhibited significantly greater antibacterial potency than their S-configured counterparts. A systematic analysis using three-dimensional quantitative structure-activity relationship (3D-QSAR) modeling elucidated the relationship between molecular structure and antibacterial activity, emphasizing the predominance of steric fields over electrostatic fields, in alignment with experimental observations. Furthermore, molecular docking confirmed the binding interactions between compound Q4 and the target protein. In conclusion, We identified a series of matrine derivatives with notable antibacterial activity and constructed a 3D-QSAR model based on their MIC values. Among these, Q4 emerged as a promising antibacterial agent, warranting further development.

A mechanistic, functional, and clinical perspective on targeting CD70 in cancer

The oncoimmunology research has witnessed notable advancements in recent years. Reshaping the tumor microenvironment (TME) approach is an effective method to improve antitumor immune response. The T cell-mediated antitumor response is crucial for favorable therapeutic outcomes in several cancers. The United States Food and Drug Administration (FDA) has approved immune checkpoint inhibitors (ICIs) for targeting the immune checkpoint proteins (ICPs) expressed in various hematological and solid malignancies. The ICPs are T cell co-inhibitory molecules that block T cell activation and, thus, antitumor response. Currently, most of the FDA-approved ICIs are antagonistic antibodies of programmed death-ligand 1 (PD-L1), programmed cell death protein 1 (PD-1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). In contrast to ICPs, the T cell costimulatory molecules are required for T cell activation, expansion, and effector function. However, the abrupt expression of these costimulatory molecules in tumors presents a concern for T cell-mediated antitumor response. One of the T cell costimulatory molecules, the cluster of differentiation 70 (CD70), has emerged as a druggable target in various hematological and solid malignancies due to its role in T cell effector function and immune evasion. The present review describes the expression of CD70, factors affecting the CD70 expression, the physiological and clinical relevance of CD70, and the current approaches to target CD70 in hematological and solid malignancies.

Harnessing anti-infective efficacy of Cinnamomum verum in synergy with β-lactam and fluoroquinolones drugs to combat virulence and biofilms of Pseudomonas aeruginosa PAO1

Multidrug resistance (MDR) Gram-negative bacteria are increasingly resistant to multiple antibiotics, posing a serious challenge to infection control and treatment. Combining plant-derived bioactives with antibiotics offers a promising approach to overcome the challenges posed by MDR pathogens like Pseudomonas aeruginosa. This study investigated the synergistic effects of Cinnamomum verum with beta-lactam and fluoroquinolones against P. aeruginosa PAO1. The ethyl acetate fraction of C. verum (CVEF) was obtained through fractionation in organic solvents with progressively higher polarity. The interaction of CVEF with selected antibiotics was assessed by checkerboard synergy assay. The effects of synergistic combinations on pyocyanin, pyoverdine, protease, EPS production, and biofilm development were measured using spectroscopic assays. CVEF combined with cefepime, ceftazidime, and levofloxacin significantly enhanced antibacterial efficacy with FICIs between 0.156 and 0.5. The most active combinations i.e., CVEF-cefepime and CVEF-ceftazidime inhibited viable cell count of growth by 3.6 and 4.2 log10 CFU/ml respectively. The combination also inhibited virulence factors (>75 %) and biofilms (>80 %) at lower 1/2 × FICs. The viable count of biofilm cells was also reduced from 6.4 to 3.3 and 3.6 log10 CFU/ml. Membrane permeability was decreased by 60.34 % and biofilm cell viability by 22.53-38.44 %. Key phytochemicals analyzed by GC/MS and LC/MS/MS, include cinnamaldehyde, trans-chlorogenic acid, quercetin, and quercetin 3'-O-glucuronide. In molecular docking investigations, quercetin 3'-O-glucuronide had the highest binding affinity with quorum sensing (QS) and biofilm-associated protein. The findings suggest CVEF, in combination with antibiotics, effectively targets resistance phenotypes of P. aeruginosa, impairing growth, virulence, and biofilms. This supports further research into natural compounds alongside antibiotics to treat drug-resistant infections.

Harnessing biotechnology for penicillin production: Opportunities and environmental considerations

Since the discovery of antibiotics, penicillin has remained the top choice in clinical medicine. With continuous advancements in biotechnology, penicillin production has become cost-effective and efficient. Genetic engineering techniques have been employed to enhance biosynthetic pathways, leading to the production of new penicillin derivatives with improved properties and increased efficacy against antibiotic-resistant pathogens. Advances in bioreactor design, media formulation, and process optimization have contributed to higher yields, reduced production costs, and increased penicillin accessibility. While biotechnological advances have clearly benefited the global production of this life-saving drug, they have also created challenges in terms of waste management. Production fermentation broths from industries contain residual antibiotics, by-products, and other contaminants that pose direct environmental threats, while increased global consumption intensifies the risk of antimicrobial resistance in both the environment and living organisms. The current geographical and spatial distribution of antibiotic and penicillin consumption dramatically reveals a worldwide threat. These challenges are being addressed through the development of novel waste management techniques. Efforts are aimed at both upstream and downstream processing of antibiotic and penicillin production to minimize costs and improve yield efficiency while lowering the overall environmental impact. Yield optimization using artificial intelligence (AI), along with biological and chemical treatment of waste, is also being explored to reduce adverse impacts. The implementation of strict regulatory frameworks and guidelines is also essential to ensure proper management and disposal of penicillin production waste. This review is novel because it explores the key remaining challenges in antibiotic development, the scope of machine learning tools such as Quantitative Structure-Activity Relationship (QSAR) in modern biotechnology-driven production, improved waste management for antibiotics, discovering alternative path to reducing antibiotic use in agriculture through alternative meat production, addressing current practices, and offering effective recommendations.

Prevention and potential remedies for antibiotic resistance: current research and future prospects

The increasing threat of antibiotic resistance and shrinking treatment options for infections have pushed mankind into a difficult position. The looming threat of the return of the pre-antibiotic era has caused a sense of urgency to protect and conserve the potency of antibiotic therapy. One of the perverse effects of antibiotic resistance is the dissemination of its causative agents from non-clinically important strains to clinically important strains and vice versa. The popular saying "Prevention is better than cure" is appropriate for tackling antibiotic resistance. On the one hand, new and effective antibiotics are required; on the other hand, better measures for the use of antibiotics, along with increased awareness in the general public related to antibiotic use, are essential. Awareness, especially of appropriate antibiotic use, antibiotic resistance, its dissemination, and potential threats, can help greatly in controlling the use and abuse of antibiotics, and the containment of antibiotic resistance. Antibiotic drugs' effectiveness can be enhanced by producing novel antibiotic analogs or adding adjuvants to current antibiotics. Combinatorial therapy of antibiotics has proven successful in treating multidrug-resistant (MDR) bacterial infections. This review aims to highlight the current global situation of antibiotic resistance and discuss the methods used to monitor, prevent, inhibit, or reverse bacterial resistance mechanisms in the fight against antibiotic resistance.

Antibiotic killing of drug-induced bacteriostatic cells

Synopsis

Background

There is a long-standing belief that bacteriostatic drugs are inherently antagonistic to the action of bactericidal antibiotics. This belief is primarily due to the fact that the action of most bactericidal antibiotics requires the target bacteria to be growing. Since bacteriostatic drugs stop the growth of treated bacteria, these drugs would necessarily work against one another. We have recently shown that bacteria treated with high concentrations of bacteriostatic drugs retain some metabolic activity, dividing on average once per day.

Objectives

We seek to determine if this low level of growth is sufficient to allow for bactericidal antibiotics of different classes to still kill after bacteria are treated with bacteriostatic drugs.

Methods

We first treated Escherichia coli and Staphylococcus aureus with two different bacteriostatic drugs, followed by one of three bactericidal drugs of three different classes. The density of these bacteria was tracked over six days to determine the amount of killing that occurred.

Results

Our results question this long-standing belief by demonstrating conditions where sequential treatment with a bacteriostatic then bactericidal antibiotic is as or more effective than treatment with a bactericidal drug alone.

Conclusions

These results raise the need to investigate the pharmacodynamics of the joint action of bacteriostatic and bactericidal antibiotics in vitro and in vivo.

High Prevalence of Colistin-Resistant Encoding Genes Carriage among Patients and Healthy Residents in Vietnam

Background and Objectives: We aimed to investigate the carriage of colistin-resistant genes among both patients with a history of antibiotic exposure and apparently healthy adults with no recent healthcare contact. Materials and Methods: Stool swabs were collected from healthy people, and specimens were collected at the infection foci from the patients. Eleven primer/probe sets were used to perform the Multiplex Real-Time PCR assay with the QuantiNova Multiplex Probe PCR kit for screening the carriage of colistin-resistant genes (mcr-1 to mcr-10) and 16S rRNA gene as internal control. Results: In total, 86 patients and 96 healthy residents were included. Twenty two patients (25.9%) were positive with at least one colistin-resistance encoding gene. The mcr-1 gene was the most frequent (16.5%), followed by mcr-9, mcr-6, and mcr-4 genes, where the prevalence was 11.8%, 10.6%, and 9.4%, respectively. No patient was positive with mcr-3, mcr-7, and mcr-8 genes. Eight patients (9.4%) were positive with multiple colistin-encoding genes. Twenty-three healthy people (24.0%) were positive with at least one colistin-resistance encoding gene, and the mcr-10 gene was the most frequent (27.0%), followed by the mcr-1, mcr-8, and mcr-9 genes, where the prevalence was 24.3%, 21.6%, and 13.5%, respectively. No person was positive with the mcr-2 and mcr-5 genes. Conclusions: Our findings underscore the urgent need for enhanced surveillance, infection control measures, and stewardship interventions to mitigate the spread of colistin resistance in Vietnam.

Climate warming promotes collateral antibiotic resistance development in cyanobacteria

Both cyanobacterial blooms and antibiotic resistance have aggravated worldwide and posed a great threat to public health in recent years. As a significant source and reservoir of water environmental resistome, cyanobacteria exhibit confusing discrepancy between their reduced susceptibility and their chronic exposure to antibiotic mixtures at sub-inhibitory concentrations. How the increasing temperature affects the adaptive evolution of cyanobacteria-associated antibiotic resistance in response to low-level antibiotic combinations under climate change remains unclear. Here we profiled the antibiotic interaction and collateral susceptibility networks among 33 commonly detected antibiotics in 600 cyanobacterial strains isolated from 50 sites across four eutrophicated lakes in China. Cyanobacteria-associated antibiotic resistance level was found positively correlated to antibiotic heterogeneity across all sites. Among 528 antibiotic combinations, antagonism was observed for 62 % interactions and highly conserved within cyanobacterial species. Collateral resistance was detected in 78.5 % of pairwise antibiotic interaction, leading to a widened or shifted upwards mutant selection window for increased opportunity of acquiring second-step mutations. We quantified the interactive promoting effect of collateral resistance and increasing temperature on the evolution of both phenotypic and genotypic cyanobacteria-associated resistance under chronic exposure to environmental level of antibiotic combinations. With temperature increasing from 16 °C to 36 °C, the evolvability index and genotypic resistance level increased by 1.25 - 2.5 folds and 3 - 295 folds in the collateral-resistance-informed lineages, respectively. Emergence of resistance mutation pioneered by tolerance, which was jointly driven by mutation rate and persister fraction, was found to be accelerated by increased temperature and antibiotic switching rate. Our findings provided mechanic insights into the boosting effect of climate warming on the emergence and development of cyanobacteria-associated resistance against collateral antibiotic phenotypes.