Nanoemulsion is an effective antimicrobial for methicillin-resistant Staphylococcus aureus in infected swine skin burn wounds.

Burns are one of the most common injuries in both civilian and combat settings and are difficult to treat. This is particularly true when the wounds are infected with antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). A new generation of safe, broadly effective, and easily applied anti-infection agents is needed to successfully prevent and treat infections. Nanoemulsions (NEs) are nanometer-sized particles with a positively charged surfactant at their oil-water interface. In the current study, we further investigated antimicrobial NEs as a treatment to address burn wounds infected by MRSA. Specifically, using a porcine skin model, we infected partial thickness thermal burn wounds with MRSA and then treated it with the nanoemulsion formulation (NB-201) or placebo controls. Bacterial viability after treatment was determined, and inflammation indexes in wounds were scored by histopathology. Topical treatment of infected wounds with NB-201 resulted in reduced colony-forming units (CFUs) compared to placebo treatment. In addition, NB-201 was effective in significantly alleviating inflammation in the treated wounds and promoting wound healing. These results indicate that NB-201 is a promising new agent to treat skin burn wounds infected with MRSA. IMPORTANCE: The findings of this study are focused on therapeutic applications of nanotechnology. In the current study, we demonstrated that a nanoemulsion formulation could effectively kill methicillin-resistant Staphylococcus aureus (MRSA) infection in porcine skin burn wounds. Infection of MRSA in burn wound is a common threat to public health and is usually difficult to treat due to limited therapies available. NB-201 was effective in significantly alleviating inflammation in the treated wounds and promoting wound healing. Therefore, the finding of this study has a great potential to make this formulation a novel antimicrobial agent against MRSA.

Metapopulation model of phage therapy of an acute Pseudomonas aeruginosa lung infection.

Infections caused by multidrug resistant (MDR) pathogenic bacteria are a global health threat. Bacteriophages ("phage") are increasingly used as alternative or last-resort therapeutics to treat patients infected by MDR bacteria. However, the therapeutic outcomes of phage therapy may be limited by the emergence of phage resistance during treatment and/or by physical constraints that impede phage-bacteria interactions in vivo. In this work, we evaluate the role of lung spatial structure on the efficacy of phage therapy for Pseudomonas aeruginosa infections. To do so, we developed a spatially structured metapopulation network model based on the geometry of the bronchial tree, including host innate immune responses and the emergence of phage-resistant bacterial mutants. We model the ecological interactions between bacteria, phage, and the host innate immune system at the airway (node) level. The model predicts the synergistic elimination of a P. aeruginosa infection due to the combined effects of phage and neutrophils, given the sufficient innate immune activity and efficient phage-induced lysis. The metapopulation model simulations also predict that MDR bacteria are cleared faster at distal nodes of the bronchial tree. Notably, image analysis of lung tissue time series from wild-type and lymphocyte-depleted mice revealed a concordant, statistically significant pattern: infection intensity cleared in the bottom before the top of the lungs. Overall, the combined use of simulations and image analysis of in vivo experiments further supports the use of phage therapy for treating acute lung infections caused by P. aeruginosa, while highlighting potential limits to therapy in a spatially structured environment given impaired innate immune responses and/or inefficient phage-induced lysis. IMPORTANCE: Phage therapy is increasingly employed as a compassionate treatment for severe infections caused by multidrug-resistant (MDR) bacteria. However, the mixed outcomes observed in larger clinical studies highlight a gap in understanding when phage therapy succeeds or fails. Previous research from our team, using in vivo experiments and single-compartment mathematical models, demonstrated the synergistic clearance of acute P. aeruginosa pneumonia by phage and neutrophils despite the emergence of phage-resistant bacteria. In fact, the lung environment is highly structured, prompting the question of whether immunophage synergy explains the curative treatment of P. aeruginosa when incorporating realistic physical connectivity. To address this, we developed a metapopulation network model mimicking the lung branching structure to assess phage therapy efficacy for MDR P. aeruginosa pneumonia. The model predicts the synergistic elimination of P. aeruginosa by phage and neutrophils but emphasizes potential challenges in spatially structured environments, suggesting that higher innate immune levels may be required for successful bacterial clearance. Model simulations reveal a spatial pattern in pathogen clearance where P. aeruginosa are cleared faster at distal nodes of the bronchial tree than in primary nodes. Interestingly, image analysis of infected mice reveals a concordant and statistically significant pattern: infection intensity clears in the bottom before the top of the lungs. The combined use of modeling and image analysis supports the application of phage therapy for acute P. aeruginosa pneumonia while emphasizing potential challenges to curative success in spatially structured in vivo environments, including impaired innate immune responses and reduced phage efficacy.

Development of cream bases suitable for personalized cosmetic products.

Background and aims: The individualization of cosmetic products or personalized dermatology preparations are in great demand at the present time. Methods: 24 emulsifying cream bases were proposed which were prepared by the classical, automatic and semi-automatic methods, respectively, and the physical stability resulted from the three types of homogenization was taken into account. Texture parameters were also studied for the most stable cream bases in the preformulation stage and the t - statistical test was applied. In order to choose the most optimal preservative, the effectiveness of the NipaEster solution 0.1%, Cosgard and Euxyl® PE 9010 was tested on the strains of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. Results: 9 cream bases were stable through all the preparation methods used, and preservation was achieved with Euxyl® PE 9010. Following the texture parameters, significant differences were observed for the same formula in the case of choosing a different preparation method. Conclusions: Formulas F1, with methyl glucose sesquistearate as emulsifier, F8, with cetearyl glucosite as emulsifier, and F14, with Ceteareth-20 can be used as cream bases for customized products.

Slow-release antimicrobial preservation composite coating based on bamboo-derived xylan-A new way to preserve blueberry freshness.

In recent years, the biocompatibility and environmental friendliness of xylan-based materials have demonstrated great potential in the field of food packaging and coatings. In this study, the cationized xylan based composite coating (CXC) was developed using a hybrid system of cationic-modified bamboo xylan (CMX) and sodium alginate (SA) combined with thyme oil microcapsules (TM). The optimized CXC-B was composed of 1.27 % TM, 2.42 % CMX (CMX: SA = 3:2), and 96.31 % distilled water. When applied to the surface of a blueberry, the CXC-B treatment extended the ambient storage time of the fruit to 10 days while substantially reducing its morbidity (P < 0.05) and protecting its texture, flavor, and nutritional integrity. The resulting composite coating provides a promising solution to the problem of blueberry perishability during ambient storage.

Promising New Targets for the Treatment of Infections Caused by Acinetobacter baumannii: A Review.

Acinetobacter baumannii is a globally disseminated Gram-negative bacterium that causes several types of serious nosocomial infections, the most worrisome being ventilator-associated pneumonia and bacteremia related to using venous catheters. Due to its great ability to form biofilms, combined with its survival for prolonged periods on abiotic surfaces and its potential to acquire and control the genes that determine antibiotic resistance, A. baumannii is at the top of the World Health Organization's priority list of pathogens in urgent need of new therapies. In this sense, this review aimed to present and discuss new molecular targets present in A. baumannii with potential for promising treatment approaches. This review highlights crucial molecular targets, including cell division proteins, membrane synthesis enzymes, and biofilm-associated components, offering promising targets for novel antimicrobial drug development against A. baumannii infections.

Evaluating Antibiotic Misuse and Cost Analysis Among Hospitalized Dengue Virus-Infected Adults: Insights From a Retrospective Cohort Study.

Background: Dengue is a prevalent cause of acute febrile illness, predominantly in Asia, where it necessitates supportive care without the need for antibiotics. This study aimed to evaluate antibiotic usage and analyze hospitalization costs among adults infected with the dengue virus. Methods: This retrospective cohort study was conducted at the Hospital for Tropical Diseases, Thailand, in 2022. Two independent reviewers assessed all adult cases with confirmed dengue from 2016 to 2021. Determinants of inappropriateness were analyzed using Poisson regression. Results: The study included 249 participants with over half presenting with severe dengue or dengue with warning signs upon admission. The cumulative incidence of antibiotic use was 9.3% (95% CI, 8.23-10.47), predominantly involving empirical treatment strategies. Ceftriaxone and doxycycline were the most frequently prescribed antibiotics. Notably, patients who received empirical antibiotics showed no definite or presumed bacterial infections. Among those who received definite strategies, inappropriate durations, including both short treatments and the overuse of broad-spectrum antibiotics, were observed. A private ward admission was identified as a significant predictor of inappropriate use, with an incidence rate ratio of 4.15 (95% CI, 1.16-14.82) compared with intensive care unit admission. Direct medical costs did not differ significantly between appropriate and inappropriate uses. Conclusions: The incidence of antibiotic use among dengue cases was moderate; however, inappropriate use by indication was observed. Antimicrobial stewardship strategies should be encouraged, particularly in patients with dengue with warning signs admitted to a general or private ward. Direct medical costs between appropriate and inappropriate use were comparable.

Development of low-toxicity antimicrobial polycarbonates bearing lysine residues.

Antibiotic resistance has been threatening public health for a long period, while the COVID pandemic aggravated the scenario. To combat antibiotic resistance strains, host defense peptides (HDPs) mimicking molecules have attracted considerable attention. Herein, we reported a series of polycarbonates bearing cationic lysine amino acid residues that could mimic the mechanism of action of HDPs and possess broad-spectrum antimicrobial activity. Moreover, those polymers had negligible toxicity toward red blood cells and mammalian cells. The membrane-disruption mechanism endows the lysine-containing polycarbonates with low possibility of resistance development and the fast killing kinetics, making them promising candidates for antimicrobial development.

Impact of automated pop-up alerts on simultaneous prescriptions of antimicrobial agents and metal cations.

BACKGROUND: Antimicrobial agents (AMAs) are essential for treating infections. A part of AMAs chelate with metal cations (MCs), reducing their blood concentrations. That drug-drug interaction could lead to a reduction of therapeutic efficacy and the emergence of drug-resistant bacteria. However, prescriptions ordering concomitant intake (co-intake) of AMAs and MCs are frequently seen in clinical settings. A method for preventing such prescriptions is urgently needed. METHODS: We implemented pop-up alerts in the hospital's ordering and pharmacy dispensation support system to notify the prescriptions ordering co-intake of AMAs and MCs for physicians and pharmacists, respectively. To assess the effectiveness of the pop-up alerts, we investigated the number of prescriptions ordering co-intake of AMAs and MCs and the number of pharmacist inquiries to prevent co-intake of AMAs and MCs before and after the implementation of pop-up alerts. RESULTS: Before the implementation of pop-up alerts, 84.5% of prescriptions containing AMA and MCs ordered co-intake of AMAs and MCs. Implementing pop-up alerts time-dependently reduced the proportion of prescriptions ordering co-intake of AMAs and MCs to 43.8% and 29.5% one year and two years later, respectively. The reduction of tetracycline-containing prescriptions was mainly significant. Before the implementation of pop-up alerts, the proportion of prescriptions in which pharmacists prevented co-intake of AMAs and MCs was 3.4%. Implementing pop-up alerts time-dependently increased proportions of such prescriptions to 20.9% and 28.2% one year and two years later. CONCLUSION: Implementing pop-up alerts reduced prescriptions ordering co-intake of AMAs and MCs and accelerated pharmacists to prevent co-intake of AMAs and MCs. The implementation of dual pop-up alerts in the hospital's ordering and pharmacy dispensation support system could help prevent co-intake of AMAs and MCs.

Vegetable phylloplane microbiomes harbour class 1 integrons in novel bacterial hosts and drive the spread of chlorite resistance.

Bacterial hosts in vegetable phylloplanes carry mobile genetic elements, such as plasmids and transposons that are associated with integrons. These mobile genetic elements and their cargo genes can enter human microbiomes via consumption of fresh agricultural produce, including uncooked vegetables. This presents a risk of acquiring antimicrobial resistance genes from uncooked vegetables. To better understand horizontal gene transfer of class 1 integrons in these compartments, we applied epicPCR, a single-cell fusion-PCR surveillance technique, to link the class 1 integron integrase (intI1) gene with phylogenetic markers of their bacterial hosts. Ready-to-eat salads carried class 1 integrons from the phyla Bacteroidota and Pseudomonadota, including four novel genera that were previously not known to be associated with intI1. We whole-genome sequenced Pseudomonas and Erwinia hosts of pre-clinical class 1 integrons that are embedded in Tn402-like transposons. The proximal gene cassette in these integrons was identified as a chlorite dismutase gene cassette, which we showed experimentally to confer chlorite resistance. Chlorine-derived compounds such as acidified sodium chlorite and chloride dioxide are used to disinfectant raw vegetables in food processing facilities, suggesting selection for chlorite resistance in phylloplane integrons. The spread of integrons conferring chlorite resistance has the potential to exacerbate integron-mediated antimicrobial resistance (AMR) via co-selection of chlorite resistance and AMR, thus highlighting the importance of monitoring chlorite residues in agricultural produce. These results demonstrate the strength of combining epicPCR and culture-based isolation approaches for identifying hosts and dissecting the molecular ecology of class 1 integrons.

Advancements in peptide-based antimicrobials: A possible option for emerging drug-resistant infections.

In recent years, multidrug-resistant pathogenic microorganisms (MDROs) have emerged as a severe threat to human health, exhibiting robust resistance to traditional antibiotics. This has created a formidable challenge in modern medicine as we grapple with limited options to combat these resilient bacteria. Despite extensive efforts by scientists to develop new antibiotics targeting these pathogens, the quest for novel antibacterial molecules has become increasingly arduous. Fortunately, nature offers a potential solution in the form of cationic antimicrobial peptides (AMPs) and their synthetic counterparts. AMPs, naturally occurring peptides, have displayed promising efficacy in fighting bacterial infections by disrupting bacterial cell membranes, hindering their survival and reproduction. These peptides, along with their synthetic mimics, present an exciting alternative in combating antibiotic resistance. They hold the potential to emerge as a formidable tool against MDROs, offering hope for improved strategies to protect communities. Extensive research has explored the diversity, history, and structure-properties relationship of AMPs, investigating their amphiphilic nature for membrane disruption and mechanisms of action. However, despite their therapeutic promise, AMPs face several documented limitations. Among these challenges, poor pharmacokinetic properties stand out, impeding the attainment of therapeutic levels in the body. Additionally, some AMPs exhibit toxicity and susceptibility to protease cleavage, leading to a short half-life and reduced efficacy in animal models. These limitations pose obstacles in developing effective treatments based on AMPs. Furthermore, the high manufacturing costs associated with AMPs could significantly hinder their widespread use. In this review, we aim to present experimental and theoretical insights into different AMPs, focusing specifically on antibacterial peptides (ABPs). Our goal is to offer a concise overview of peptide-based drug candidates, drawing from a wide array of literature and peer-reviewed studies. We also explore recent advancements in AMP development and discuss the challenges researchers face in moving these molecules towards clinical trials. Our main objective is to offer a comprehensive overview of current AMP and ABP research to guide the development of more precise and effective therapies for bacterial infections.

Antimicrobial Peptides and Their Biomedical Applications: A Review.

The emergence of drug resistance genes and the detrimental health effects caused by the overuse of antibiotics are increasingly prominent problems. There is an urgent need for effective strategies to antibiotics or antimicrobial resistance in the fields of biomedicine and therapeutics. The pathogen-killing ability of antimicrobial peptides (AMPs) is linked to their structure and physicochemical properties, including their conformation, electrical charges, hydrophilicity, and hydrophobicity. AMPs are a form of innate immune protection found in all life forms. A key aspect of the application of AMPs involves their potential to combat emerging antibiotic resistance; certain AMPs are effective against resistant microbial strains and can be modified through peptide engineering. This review summarizes the various strategies used to tackle antibiotic resistance, with a particular focus on the role of AMPs as effective antibiotic agents that enhance the host's immunological functions. Most of the recent studies on the properties and impregnation methods of AMPs, along with their biomedical applications, are discussed. This review provides researchers with insights into the latest advancements in AMP research, highlighting compelling evidence for the effectiveness of AMPs as antimicrobial agents.

Characteristics of Metallic Nanoparticles (Especially Silver Nanoparticles) as Anti-Biofilm Agents.

Biofilm-associated infections account for a large proportion of chronic diseases and pose a major health challenge. Metal nanoparticles offer a new way to address this problem, by impairing microbial growth and biofilm formation and by causing degradation of existing biofilms. This review of metal nanoparticles with antimicrobial actions included an analysis of 20 years of journal papers and patent applications, highlighting the progress over that time. A network analysis of relevant publications showed a major focus on the eradication of single-species biofilms formed under laboratory conditions, while a bibliometric analysis showed growing interest in combining different types of metal nanoparticles with one another or with antibiotics. The analysis of patent applications showed considerable growth over time, but with relatively few patents progressing to be granted. Overall, this profile shows that intense interest in metal nanoparticles as anti-biofilm agents is progressing beyond the confines of simple laboratory biofilm models and coming closer to clinical application. Looking to the future, metal nanoparticles may provide a sustainable approach to combatting biofilms of drug-resistant bacteria.

Comparative Chemical Analysis and Bioactive Properties of Aqueous and Glucan-Rich Extracts of Three Widely Appreciated Mushrooms: Agaricus bisporus (J.E.Lange) Imbach, Laetiporus sulphureus (Bull.) Murill and Agrocybe aegerita (V. Brig.) Vizzini.

Herein we describe the antioxidant, antimicrobial, antibiofilm, anti-inflammatory and wound-healing potential of aqueous and polysaccharide extracts from three widely appreciated mushrooms: Agrocybe aegerita, Laetiporus sulphureus and Agaricus bisporus. Moreover, we present their detailed phenolic, polysaccharide and protein profiles and ATR-FTIR spectra. The study found that polysaccharide extracts (PEs) from mushrooms had higher total and ß-glucan levels than aqueous extracts (AEs), with A. aegerita showing the highest content. L. sulphureus had a higher total protein content, and A. aegerita AE had the highest phenolic content. Our results indicate that all the tested extracts have high potential regarding their bioactive properties, with A. aegerita being the most promising one. Namely, the antibacterial activity assay showed that the development of the skin-infection-causing agent, Staphylococcus aureus, was inhibited with a minimal inhibitory concentration of 4.00 mg/mL and minimal bactericidal concentration of 8.00 mg/mL, while the results regarding wound healing showed that, over the course of 24 h, the A. aegerita extract actively promoted wound closure in the HaCaT keratinocyte cell line model. The anti-inflammatory activity results clearly showed that when we used S. aureus as an inflammation-inducing agent and the A. aegerita aqueous extract in treatment, IL-6 levels reduced to the level of 4.56 pg/mL. The obtained data suggest that the tested mushroom extracts may serve as a source of bioactive compounds, with potential applications in the cosmeceutical, pharmaceutical and food industries. Furthermore, potential skin preparations carefully crafted with mushroom extract may help restore the skin's barrier function, decrease the probability of staph infections and minimize skin irritation.

Carbon-Dots-Mediated Improvement of Antimicrobial Activity of Natural Products.

The development of new microbicidal compounds has become a top priority due to the emergence and spread of drug-resistant pathogenic microbes. In this study, blue-emitting and positively charged carbon dots (CDs), called Du-CDs, were fabricated for the first time utilizing the natural product extract of endophyte Diaporthe unshiuensis YSP3 as raw material through a one-step solvothermal method, which possessed varied functional groups including amino, carboxyl, hydroxyl, and sulfite groups. Interestingly, Du-CDs exhibited notably enhanced antimicrobial activities toward both bacteria and fungi as compared to the natural product extract of YSP3, with low minimum inhibitory concentrations. Moreover, Du-CDs significantly inhibited the formation of biofilms. Du-CDs bound with the microbial cell surface via electronic interaction or hydrophobic interaction entered the microbial cells and were distributed fully inside the cells. Du-CDs caused cell membrane damage and/or cell division cycle interruption, resulting in microbial cell death. Moreover, Du-CDs exhibited an improved antimicrobial effect and accelerated wound healing ability with good biocompatibility in the mouse model. Overall, we demonstrate that the formation of CDs from fungal natural products presents a promising and potential means to develop novel antimicrobial agents with great fluorescence, improved microbiocidal effect and wound healing capacity, and good biosafety for combating microbial infections.

Complete genome sequence of Pseudomonas aeruginosa Y010, a taro rhizosphere strain producing potent antimicrobial agents.

Pseudomonas aeruginosa Y010, isolated from the taro rhizosphere, exhibits great antagonistic abilities against Dickeya strains that cause soft-rot and blackleg diseases of plants by producing potent antimicrobial agents. The complete genome of Y010 was sequenced and annotated, which is 6,415,628 bp in length with 66.39% GC content.

Exploring naphthoquinone and anthraquinone derivatives as antibiotic adjuvants against Staphylococcus aureus biofilms: Synergistic effects of menadione.

Given the ability of Staphylococcus aureus to form biofilms and produce persister cells, making infections difficult to treat with antibiotics alone, there is a pressing need for an effective antibiotic adjuvant to address this public health threat. In this study, a series of quinone derivatives were evaluated for their antimicrobial and antibiofilm activities against methicillin-susceptible and methicillin-resistant S. aureus reference strains. Following analyses using broth microdilution, growth curve analysis, checkerboard assay, time-kill experiments, and confocal laser scanning microscopy, menadione was identified as a hit compound. Menadione exhibited a notable antibacterial profile (minimum inhibitory concentration, MIC = 4-16 µg/ml; minimum bactericidal concentration, MBC = 256 µg/ml) against planktonic S. aureus and its biofilms (minimum biofilm inhibitory concentration, MBIC50 = 0.0625-0.25 µg/ml). When combined with oxacillin, erythromycin, and vancomycin, menadione exhibited a synergistic or additive effect against planktonic cells and biofilms of two S. aureus reference strains and six clinical isolates, highlighting its potential as a suitable adjuvant for further development against S. aureus biofilm-associated infections.

Targeted elimination of Fusobacterium nucleatum alleviates periodontitis.

Background: Fusobacterium nucleatum, a pathobiont in periodontal disease, contributes to alveolar bone destruction. We assessed the efficacy of a new targeted antimicrobial, FP-100, in eradicating F. nucleatum from the oral microbial community in vitro and in vivo and evaluated its effectiveness in reducing bone loss in a mouse periodontitis model. Methods: A multispecies bacterial community was cultured and treated with two concentrations of FP-100 over two days. Microbial profiles were examined at 24-h intervals using 16S rRNA sequencing. A ligature-induced periodontitis mouse model was employed to test FP-100 in vivo. Results: FP-100 significantly reduced Fusobacterium spp. within the in vitro community (p < 0.05) without altering microbial diversity at a 2 µM concentration. In mice, cultivable F. nucleatum was undetectable in FP-100-treated ligatures but persistent in controls. Beta diversity plots showed distinct microbial structures between treated and control mice. Alveolar bone loss was significantly reduced in the FP-100 group (p = 0.018), with concurrent decreases in gingival IL-1ß and TNF-α expression (p = 0.052 and 0.018, respectively). Conclusion: FP-100 effectively eliminates F. nucleatum from oral microbiota and significantly reduces bone loss in a mouse periodontitis model, demonstrating its potential as a targeted therapeutic agent for periodontal disease.

FP-100 eliminates F. nucleatum from an in vitro multispecies microbial community at low doses without affecting bacterial diversity. FP-100 treatment leads to the in vivo elimination of F. nucleatum, reducing alveolar bone loss and levels of pro-inflammatory cytokines in the gingiva. FP-100 is a new antimicrobial to target F. nucleatum-mediated periodontal disease.

Targeting glucosyltransferases to combat dental caries: Current perspectives and future prospects.

The emergence of antimicrobial resistance within bacterial communities poses formidable challenges to existing therapeutic strategies aimed at mitigating biofilm-mediated infections. Recent advancements in this domain have spurred the development of targeted antimicrobial agents, designed to selectively eradicate the primary etiological agents while preserving the beneficial microbial diversity of the oral cavity. Targeting glucosyltransferases (GTFs), which play crucial roles in dental biofilm formation, offers a precise strategy to inhibit extracellular polysaccharide synthesis without compromising oral microbiota. This review article delves into the intricate mechanisms underlying dental caries, with a specific focus on the role of GTFs, enzymes produced by S. mutans. It further provides an overview of current research on GTF inhibitors, exploring their mechanisms of action, efficacy, and potential applications in clinical practice. Furthermore, it discusses the challenges and opportunities in the development of novel GTF inhibitors, emphasizing the need for innovative approaches to combat biofilm-mediated oral diseases effectively.

Novel Insights into the Antimicrobial and Antibiofilm Activity of Pyrroloquinoline Quinone (PQQ); In Vitro, In Silico, and Shotgun Proteomic Studies.

Microbial infections pose a significant global health threat, affecting millions of individuals and leading to substantial mortality rates. The increasing resistance of microorganisms to conventional treatments requires the development of novel antimicrobial agents. Pyrroloquinoline quinone (PQQ), a natural medicinal drug involved in various cellular processes, holds promise as a potential antimicrobial agent. In the present study, our aim was, for the first time, to explore the antimicrobial activity of PQQ against 29 pathogenic microbes, including 13 fungal strains, 8 Gram-positive bacteria, and 8 Gram-negative bacteria. Our findings revealed potent antifungal properties of PQQ, particularly against Syncephalastrum racemosum, Talaromyces marneffei, Candida lipolytica, and Trichophyton rubrum. The MIC values varied between fungal strains, and T. marneffei exhibited a lower MIC, indicating a greater susceptibility to PQQ. In addition, PQQ exhibited notable antibacterial activity against Gram-positive and -negative bacteria, with a prominent inhibition observed against Staphylococcus epidermidis, Proteus vulgaris, and MRSA strains. Remarkably, PQQ demonstrated considerable biofilm inhibition against the MRSA, S. epidermidis, and P. vulgaris strains. Transmission electron microscopy (TEM) studies revealed that PQQ caused structural damage and disrupted cell metabolism in bacterial cells, leading to aberrant morphology, compromised cell membrane integrity, and leakage of cytoplasmic contents. These findings were further affirmed by shotgun proteomic analysis, which revealed that PQQ targets several important cellular processes in bacteria, including membrane proteins, ATP metabolic processes, DNA repair processes, metal-binding proteins, and stress response. Finally, detailed molecular modeling investigations indicated that PQQ exhibits a substantial binding affinity score for key microbial targets, including the mannoprotein Mp1P, the transcriptional regulator TcaR, and the endonuclease PvuRTs1I. Taken together, our study underscores the effectiveness of PQQ as a broad-spectrum antimicrobial agent capable of combating pathogenic fungi and bacteria, while also inhibiting biofilm formation and targeting several critical biological processes, making it a promising therapeutic option for biofilm-related infections.

In Vitro Resistance-Predicting Studies and In Vitro Resistance-Related Parameters-A Hit-to-Lead Perspective.

Despite the urgent need for new antibiotics, very few innovative antibiotics have recently entered clinics or clinical trials. To provide a constant supply of new drug candidates optimized in terms of their potential to select for resistance in natural settings, in vitro resistance-predicting studies need to be improved and scaled up. In this review, the following in vitro parameters are presented: frequency of spontaneous mutant selection (FSMS), mutant prevention concentration (MPC), dominant mutant prevention concentration (MPC-D), inferior-mutant prevention concentration (MPC-F), and minimal selective concentration (MSC). The utility of various adaptive laboratory evolution (ALE) approaches (serial transfer, continuous culture, and evolution in spatiotemporal microenvironments) for comparing hits in terms of the level and time required for multistep resistance to emerge is discussed. We also consider how the hit-to-lead stage can benefit from high-throughput ALE setups based on robotic workstations, do-it-yourself (DIY) continuous cultivation systems, microbial evolution and growth arena (MEGA) plates, soft agar gradient evolution (SAGE) plates, microfluidic chips, or microdroplet technology. Finally, approaches for evaluating the fitness of in vitro-generated resistant mutants are presented. This review aims to draw attention to newly emerged ideas on how to improve the in vitro forecasting of the potential of compounds to select for resistance in natural settings.