Anti-Biofilm Activity of Assamsaponin A, Theasaponin E1, and Theasaponin E2 against Candida albicans.

Biofilm formation plays a crucial role in the pathogenesis of Candida albicans and is significantly associated with resistance to antifungal agents. Tea seed saponins, a class of non-ionic triterpenes, have been proven to have fungicidal effects on planktonic C. albicans. However, their anti-biofilm activity and mechanism of action against C. albicans remain unclear. In this study, the effects of three Camellia sinensis seed saponin monomers, namely, theasaponin E1 (TE1), theasaponin E2 (TE2), and assamsaponin A (ASA), on the metabolism, biofilm development, and expression of the virulence genes of C. albicans were evaluated. The results of the XTT reduction assay and crystal violet (CV) staining assay demonstrated that tea seed saponin monomers concentration-dependently suppressed the adhesion and biofilm formation of C. albicans and were able to eradicate mature biofilms. The compounds were in the following order in terms of their inhibitory effects: ASA > TE1 > TE2. The mechanisms were associated with reductions in multiple crucial virulence factors, including cell surface hydrophobicity (CSH), adhesion ability, hyphal morphology conversion, and phospholipase activity. It was further demonstrated through qRT-PCR analysis that the anti-biofilm activity of ASA and TE1 against C. albicans was attributed to the inhibition of RAS1 activation, which consequently suppressed the cAMP-PKA and MAPK signaling pathways. Conversely, TE2 appeared to regulate the morphological turnover and hyphal growth of C. albicans via a pathway that was independent of RAS1. These findings suggest that tea seed saponin monomers are promising innovative agents against C. albicans.

Copper affects virulence and diverse phenotypes of uropathogenic Proteus mirabilis.

BACKGROUND: Copper plays a role in urinary tract infection (UTI) and urinary copper content is increased during Proteus mirabilis UTI. We therefore investigated the effect of copper on uropathogenic P. mirabilis and the underlying mechanisms, focusing on the virulence associated aspects. METHODS: Mouse colonization, swarming/swimming assays, measurement of cell length, flagellin level and urease activity, adhesion/invasion assay, biofilm formation, killing by macrophages, oxidative stress susceptibility, OMPs analysis, determination of MICs and persister cell formation, RT-PCR and transcriptional reporter assay were performed. RESULTS: We found that copper-supplemented mice were more resistant to be colonized in the urinary tract, together with decreased swarming/swimming, ureases activity, expression of type VI secretion system and adhesion/invasion to urothelial cells and increased killing by macrophages of P. mirabilis at a sublethal copper level. However, bacterial biofilm formation and resistance to oxidative stress were enhanced under the same copper level. Of note, the presence of copper led to increased ciprofloxacin MIC and more persister cell formation against ampicillin. In addition, the presence of copper altered the outer membrane protein profile and triggered expression of RcsB response regulator. For the first time, we unveiled the pleiotropic effects of copper on uropathogenic P. mirabilis, especially for induction of bacterial two-component signaling system regulating fitness and virulence. CONCLUSION: The finding of copper-mediated virulence and fitness reinforced the importance of copper for prevention and therapeutic interventions against P. mirabilis infections. As such, this study could facilitate the copper-based strategies against UTI by P. mirabilis.

ZntA maintains zinc and cadmium homeostasis and promotes oxidative stress resistance and virulence in Vibrio parahaemolyticus.

Although metals are essential for life, they are toxic to bacteria in excessive amounts. Therefore, the maintenance of metal homeostasis is critical for bacterial physiology and pathogenesis. Vibrio parahaemolyticus is a significant food-borne pathogen that mainly causes acute gastroenteritis in humans and acute hepatopancreatic necrosis disease in shrimp. Herein, we report that ZntA functions as a zinc (Zn) and cadmium (Cd) homeostasis mechanism and contributes to oxidative stress resistance and virulence in V. parahaemolyticus. zntA is remarkably induced by Zn, copper, cobalt, nickel (Ni), and Cd, while ZntA promotes V. parahaemolyticus growth under excess Zn/Ni and Cd conditions via maintaining Zn and Cd homeostasis, respectively. The growth of ΔzntA was inhibited under iron (Fe)-restricted conditions, and the inhibition was associated with Zn homeostasis disturbance. Ferrous iron supplementation improved the growth of ΔzntA under excess Zn, Ni or Cd conditions. The resistance of ΔzntA to H2O2-induced oxidative stress also decreased, and its virulence was attenuated in zebrafish models. Quantitative real-time PCR, mutagenesis, and ß-galactosidase activity assays revealed that ZntR positively regulates zntA expression by binding to its promoter. Collectively, the ZntR-regulated ZntA is crucial for Zn and Cd homeostasis and contributes to oxidative stress resistance and virulence in V. parahaemolyticus.

Analyzing the safety of the parasiticide fungus Mucor circinelloides: first insights on its virulence profile and interactions with the avian gut microbial community.

Parasiticide fungi are considered an accurate, sustainable, and safe solution for the biocontrol of animal gastrointestinal (GI) parasites. This research provides an initial characterization of the virulence of the native parasiticide fungus Mucor circinelloides (FMV-FR1) and an assessment of its impact on birds' gut microbes. The genome of this fungus was sequenced to identify the genes coding for virulence factors. Also, this fungus was checked for the phenotypic expression of proteinase, lecithinase, DNase, gelatinase, hemolysin, and biofilm production. Finally, an in vivo trial was developed based on feeding M. circinelloides spores to laying hens and peacocks three times a week. Bird feces were collected for 3 months, with total genomic DNA being extracted and subjected to long-read 16S and 25S-28S sequencing. Genes coding for an iron permease (FTR1), iron receptors (FOB1 and FOB2), ADP-ribosylation factors (ARFs) (ARF2 and ARF6), and a GTPase (CDC42) were identified in this M. circinelloides genome. Also, this fungus was positive only for lecithinase activity. The field trial revealed a fecal microbiome dominated by Firmicutes and Proteobacteria in laying hens, and Firmicutes and Bacteroidetes in peacocks, whereas the fecal mycobiome of both bird species was mainly composed of Ascomycetes and Basidiomycetes fungi. Bacterial and fungal alpha-diversities did not differ between sampling time points after M. circinelloides administrations (P = 0.62 and P = 0.15, respectively). Although findings from this research suggest the lack of virulence of this M. circinelloides parasiticide isolate, more complementary in vitro and in vivo research is needed to conclude about the safety of its administration to birds, aiming at controlling their GI parasites.IMPORTANCEA previous study revealed that the native Mucor circinelloides isolate (FMV-FR1) can develop parasiticide activity toward coccidia oocysts, one of the most pathogenic GI parasites in birds. However, ensuring its safety for birds is of utmost importance, namely by studying its virulence profile and potential effect on commensal gut microbes. This initial study revealed that although this M. circinelloides isolate had genes coding for four types of virulence factors-iron permease, iron receptors, ADP-ribosylation factors, and GTPase-and only expressed phenotypically the enzyme lecithinase, the administration of its spores to laying hens and peacocks did not interfere with the abundances and diversities of their gut commensal bacteria and fungi. Although overall results suggest the lack of virulence of this M. circinelloides isolate, more complementary research is needed to conclude about the safety of its administration to birds in the scope of parasite biocontrol programs.

Disclosing the Functional Potency of Three Oxygenated Monoterpenes in Combating Microbial Pathogenesis: From Targeting Virulence Factors to Chicken Meat Preservation.

During the last few decades, there has existed an increased interest in and considerable consumer preference towards using natural and safe compounds derived from medicinal plants as alternatives to synthetic preservatives to combat microbial pathogenicity. In this regard, the present study investigated the possible synergistic interactions of the anti-foodborne bacterial capacity of linalool (L), eucalyptol (E), and camphor (C). The antibacterial synergistic effect was determined against Staphylococcus aureus, Listeria monocytogenes, Salmonella enterica Typhimurium, and Escherichia coli. The optimal predicted mixture showed the highest antibacterial activity at 33.5%, 33.2%, and 33.4% of L, E, and C, respectively. Molecular docking simulations displayed that the studied monoterpenes have effective antibacterial inhibitory effects by impeding specific virulence factors such as sortase A, listeriolysin O, L, D-Transpeptidase, and polyphosphate kinase. The selected triple combination of L, E, and C was applied as a natural preservative in minced chicken breast meat. In this regard, 1 MIC (16 µg/mL), 1.5 MIC (24 µg/mL), and 2 MIC (32 µg/mL) of L. monocytogenes were used, and the microbiological, physicochemical, and sensory analyses were monitored for 14 days of storage at 4 °C. The L/E/C mixture at different levels could delay lipid and protein oxidation, inhibit the microorganisms, and maintain the sensory attributes. Additionally, by using chemometric tools, strong connections between physicochemical properties, microbiological parameters, and organoleptic attributes were established. Concisely, this research confers the importance of the use of blended monoterpenes and highlights their antibacterial mode of action, effectiveness, and synergistic effects as a powerful and safe bio-preservative formulation in chicken meat products.

L-arginine supplementation abrogates hypoxia-induced virulence of Staphylococcus aureus in a murine diabetic pressure wound model.

Diabetic foot ulcers (DFUs) are the most common complications of diabetes resulting from hyperglycemia leading to ischemic hypoxic tissue and nerve damage. Staphylococcus aureus is the most frequently isolated bacteria from DFUs and causes severe necrotic infections leading to amputations with a poor 5-year survival rate. However, very little is known about the mechanisms by which S. aureus dominantly colonizes and causes severe disease in DFUs. Herein, we utilized a pressure wound model in diabetic TALLYHO/JngJ mice to reproduce ischemic hypoxic tissue damage seen in DFUs and demonstrated that anaerobic fermentative growth of S. aureus significantly increased the virulence and the severity of disease by activating two-component regulatory systems leading to expression of virulence factors. Our in vitro studies showed that supplementation of nitrate as a terminal electron acceptor promotes anaerobic respiration and suppresses the expression of S. aureus virulence factors through inactivation of two-component regulatory systems, suggesting potential therapeutic benefits by promoting anaerobic nitrate respiration. Our in vivo studies revealed that dietary supplementation of L-arginine (L-Arg) significantly attenuated the severity of disease caused by S. aureus in the pressure wound model by providing nitrate. Collectively, these findings highlight the importance of anaerobic fermentative growth in S. aureus pathogenesis and the potential of dietary L-Arg supplementation as a therapeutic to prevent severe S. aureus infection in DFUs.IMPORTANCES. aureus is the most common cause of infection in DFUs, often resulting in lower-extremity amputation with a distressingly poor 5-year survival rate. Treatment for S. aureus infections has largely remained unchanged for decades and involves tissue debridement with antibiotic therapy. With high levels of conservative treatment failure, recurrence of ulcers, and antibiotic resistance, a new approach is necessary to prevent lower-extremity amputations. Nutritional aspects of DFU treatment have largely been overlooked as there has been contradictory clinical trial evidence, but very few in vitro and in vivo modelings of nutritional treatment studies have been performed. Here we demonstrate that dietary supplementation of L-Arg in a diabetic mouse model significantly reduced duration and severity of disease caused by S. aureus. These findings suggest that L-Arg supplementation could be useful as a potential preventive measure against severe S. aureus infections in DFUs.

Plant-Origin Components: New Players to Combat Antibiotic Resistance in Klebsiella pneumoniae.

Klebsiella pneumoniae (Kpn) is an opportunistic pathogen that causes intrahospital complications such as pneumonia, liver abscesses, soft tissue infections, urinary infections, bacteraemia, and, in some cases, death. Since this bacterium has a higher frequency than other Gram-negative pathogens, it has become an important pathogen to the health sector. The adaptative genome of Kpn likely facilitates increased survival of the pathogen in diverse situations. Therefore, several studies have been focused on developing new molecules, synergistic formulations, and biomaterials that make it possible to combat and control infections with and dispersion of this pathogen. Note that the uncontrolled antibiotic administration that occurred during the pandemic led to the emergence of new multidrug-resistant strains, and scientists were challenged to overcome them. This review aims to compile the latest information on Kpn that generates intrahospital infections, specifically their pathogenicity-associated factors. Furthermore, it explains the natural-product-based treatments (extracts and essential oils) developed for Kpn infection and dispersion control.

Distribution patterns and influential factors of pathogenic bacteria in freshwater aquaculture sediments.

Pathogenic bacteria, the major causative agents of aquaculture diseases, are a serious impediment to the aquaculture industry. However, the bioinformatics of pathogenic bacteria and virulence factors (VFs) in sediments, an important component of freshwater aquaculture ecosystems, are not well characterized. In this study, 20 sediment samples were collected from fish pond sediments (FPS), shrimp field sediments (SFS), fish pond sediment control (FPSC), and shrimp field sediment control (SFSC). Molecular biological information was obtained on a total of 173 pathogenic bacteria, 1093 virulence factors (VFs), and 8475 mobile genetic elements (MGEs) from these samples. The results indicated that (1) aquaculture patterns and sediment characteristics can affect the distribution of pathogenic bacteria. According to the results of the Kruskal-Wallis H test, except for Mycobacterium gilvum, there were significant differences (P < 0.05) among the four sediment types in the average abundance of major pathogenic bacteria (top 30 in abundance), and the average abundance of major pathogenic bacteria in the four sediment types followed the following pattern: FPS > SFS > FPSC > SFSC. (2) Pathogenic bacteria are able to implement a variety of complex pathogenic mechanisms such as adhesion, invasion, immune evasion, and metabolic regulation in the host because they carry a variety of VFs such as type IV pili, HSI-I, Alginate, Colibactin, and Capsule. According to the primary classification of the Virulence Factor Database (VFDB), the abundance of VFs in all four types of sediments showed the following pattern: offensive VFs > non-specific VFs > defensive VFs > regulation of virulence-related genes. (3) Total organic carbon (TOC), total phosphorus (TP), available phosphorus (AP), nitrite, and nitrate were mostly only weakly positively correlated with the major pathogenic bacteria and could promote the growth of pathogenic bacteria to some extent, whereas ammonia was significantly positively correlated with most of the major pathogenic bacteria and could play an important role in promoting the growth and reproduction of pathogenic bacteria. (4) Meanwhile, there was also a significant positive correlation between CAZyme genes and major pathogenic bacteria (0.62 ≤ R ≤ 0.89, P < 0.05). This suggests that these pathogenic bacteria could be the main carriers of CAZyme genes and, to some extent, gained a higher level of metabolic activity by degrading organic matter in the sediments to maintain their competitive advantage. (5) Worryingly, the results of correlation analyses indicated that MGEs in aquaculture sediments could play an important role in the spread of VFs (R = 0.82, P < 0.01), and in particular, plasmids (R = 0.75, P < 0.01) and integrative and conjugative elements (ICEs, R = 0.65, P < 0.05) could be these major vectors of VFs. The results of this study contribute to a comprehensive understanding of the health of freshwater aquaculture sediments and provide a scientific basis for aquaculture management and conservation.

Mechanistic research: Selenium regulates virulence factors, reducing adhesion ability and inflammatory damage of Helicobacter pylori.

BACKGROUND: The pathogenicity of Helicobacter pylori is dependent on factors including the environment and the host. Although selenium is closely related to pathogenicity as an environmental factor, the specific correlation between them remains unclear. AIM: To investigate how selenium acts on virulence factors and reduces their toxicity. METHODS: H. pylori strains were induced by sodium selenite. The expression of cytotoxin-associated protein A (CagA) and vacuolating cytotoxin gene A (VacA) was determined by quantitative PCR and Western blotting. Transcriptomics was used to analyze CagA, CagM, CagE, Cag1, Cag3, and CagT. C57BL/6A mice were infected with the attenuated strains subjected to sodium selenite induction, and H. pylori colonization, inflammatory reactions, and the cell adhesion ability of H. pylori were assessed. RESULTS: CagA and VacA expression was upregulated at first and then downregulated in the H. pylori strains after sodium selenite treatment. Their expression was significantly and steadily downregulated after the 5th cycle (10 d). Transcriptome analysis revealed that sodium selenite altered the levels affect H. pylori virulence factors such as CagA, CagM, CagE, Cag1, Cag3, and CagT. Of these factors, CagM and CagE expression was continuously downregulated and further downregulated after 2 h of induction with sodium selenite. Moreover, CagT expression was upregulated before the 3rd cycle (6 d) and significantly downregulated after the 5th cycle. Cag1 and Cag3 expression was upregulated and downregulated, respectively, but no significant change was observed by the 5th cycle. C57BL/6A mice were infected with the attenuated strains subjected to sodium selenite induction. The extent of H. pylori colonization in the stomach increased; however, sodium selenite also induced a mild inflammatory reaction in the gastric mucosa of H. pylori-infected mice, and the cell adhesion ability of H. pylori was significantly weakened. CONCLUSION: These results demonstrate that H. pylori displayed virulence attenuation after the 10th d of sodium selenite treatment. Sodium selenite is a low toxicity compound with strong stability that can reduce the cell adhesion ability of H. pylori, thus mitigating the inflammatory damage to the gastric mucosa.

In silico investigation of cholesterol-lowering drugs to find potential inhibitors of dehydrosqualene synthase in Staphylococcus aureus.

Staphylococcus aureus is a lethal pathogen that can cause various bacterial infections. This study targets the CrtM enzyme of S. aureus, which is crucial for synthesizing golden carotenoid pigment: staphyloxanthin, which provides anti-oxidant activity to this bacterium for combating antimicrobial resistance inside the host cell. The present investigation quests for human SQS inhibitors against the CrtM enzyme by employing structure-based drug design approaches including induced fit docking (IFD), molecular dynamic (MD) simulations, and binding free energy calculations. Depending upon the docking scores, two compounds, lapaquistat acetate and squalestatin analog 20, were identified as the lead molecules exhibit higher affinity toward the CrtM enzyme. These docked complexes were further subjected to 100 ns MD simulation and several thermodynamics parameters were analyzed. Further, the binding free energies (ΔG) were calculated for each simulated protein-ligand complex to study the stability of molecular contacts using the MM-GBSA approach. Pre-ADMET analysis was conducted for systematic evaluation of physicochemical and medicinal chemistry properties of these compounds. The above study suggested that lapaquistat acetate and squalestatin analog 20 can be selected as potential lead candidates with promising binding affinity for the S. aureus CrtM enzyme. This study might provide insights into the discovery of potential drug candidates for S. aureus with a high therapeutic index. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03862-y.

Transcriptomic analysis of Vibrio alginolyticus challenged by Rhizoma coptidis reveals mechanisms of virulence genes.

Rhizoma coptidis, a Chinese herbal medicine widely used to treat various bacterial infections, has the potential to develop antibiotic substitutes to overcome the drug resistance of Vibrio alginolyticus. To study the inhibitory effect of R. coptidis on V. alginolyticus, we sequenced the transcriptomes of three groups of samples of wild-type V. alginolyticus (CK) and V. alginolyticus, which were stressed by 5 mg/mL R. coptidis for 2 h (RC_2 h) and 4 h (RC_4 h). CK was compared with RC_2 h and RC_4 h, respectively, and a total of 1565 differentially expressed genes (DEGs) (988 up-regulated and 577 down-regulated) and 1737 DEGs (1152 up-regulated and 585 down-regulated) were identified. Comparing RC_2 h with RC_4 h, 156 DEGs (114 up-regulated and 42 down-regulated) were identified. The ability of biofilm formation and motility of V. alginolyticus altered upon with different concentrations of R. coptidis. Interestingly, relative expression patterns of virulence genes appeared statistically significantly varied, upon different concentrations of R. coptidis extract. DEGs were annotated to the Gene Ontology (GO) database for function enrichment analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, the results showed that the main enriched pathways, was those related to the virulence of V. alginolyticus. This study provides a new perspective for understanding the complex pathogenic mechanism of V. alginolyticus. R. coptidis could potnetially be used as alternative or complimnetary to antibiotics to treat infections after further research.

Effect of the Pulsatilla decoction n-butanol extract on vulvovaginal candidiasis caused by Candida glabrata and on its virulence factors.

Vulvovaginal candidiasis (VVC) caused by Candida glabrata (C. glabrata) is more persistent and resistant to treatment than when caused by Candida albicans (C. albicans) and has been on the rise in recent years. The n-butanol extract of Pulsatilla Decoction (BEPD) has been shown to be effective in treating VVC caused by C. glabrata, but the underlying mechanism of action remains unclear. In this study, the experimenter conducted in vitro and in vivo experiments to explore the effects of BEPD on the virulence factors of C. glabrata, as well as its efficacy, with a focus on possible immunological mechanism in VVC caused by C. glabrata. The contents of Anemoside B4, Epiberberine, Berberine, Aesculin, Aesculetin, Phellodendrine and Jatrorrhizine in BEPD, detected by high-performance liquid chromatography, were 31,736.64, 13,529.66, 105,143.72, 19,406.20, 4952.67, 10,317.03, 2489.93 µg/g, respectively. In vitro experiments indicated that BEPD moderately inhibited the growth of C. glabrata, its adhesion, and biofilm formation, and affected the expression of efflux transporters in the biofilm state. In vivo experiments demonstrated that BEPD significantly reduced vaginal inflammatory manifestation and the release of proinflammatory cytokines and LDH in mice with VVC caused by C. glabrata. Moreover, it inhibited the Phosphorylation of EGFR, ERK, P38, P65, and C-Fos proteins. The results suggested that although BEPD moderately inhibits the growth and virulence factors of C. glabrata in vitro, it can significantly reduce vaginal inflammation by down-regulating the EGFR/MAPK signaling pathway in mice with VVC infected by C. glabrata.

Roles of crrAB two-component regulatory system in Klebsiella pneumoniae: growth yield, survival in initial colistin treatment stage, and virulence.

OBJECTIVES: Alternation of the colistin resistance-regulating two-component regulatory system (crrAB) is a colistin-resistance mechanism in Klebsiella pneumoniae (K. pneumoniae), but its role in bacteria is not fully understood. METHODS: Twelve colistin-susceptible K. pneumoniae clinical isolates were included in this study: six crrAB-positive and six crrAB-negative. We deleted the crrAB genes from two crrAB-positive isolates and complemented them. We measured the growth yields by determining growth curves in lysogeny broth and minimal media with or without Fe2+. In vitro selection rates for colistin resistance were determined by exposure to colistin, and survival rates against high concentrations of colistin (20 mg/L) at the early stage of growth (20 min) were investigated. Virulence was determined using a serum bactericidal assay and Galleria mellonella larval infection. RESULTS: The presence of crrAB was not associated with colistin resistance and did not increase the in vitro selection rate of colistin resistance after exposure. The growth yield of crrAB-positive isolates was higher in lysogeny broth media and increased when Fe2+ was added to minimal media. The crrAB-positive isolates showed higher survival rates in the early stages of exposure to high colistin concentrations. Decreased serum resistance was identified in the crrAB-deleted mutants. More G. mellonella larvae survived when infected by crrAB-deleted mutants, and higher survival rates of bacteria were identified within the larvae infected with wild-type than crrAB-deletant isolates. CONCLUSION: Through rapid response to external signals, crrAB would provide advantages for K. pneumoniae survival by increasing the final growth yield and initial survival against colistin treatment. This may partly contribute to the bacterial virulence.

Plant-derived virulence arresting drugs as novel antimicrobial agents: Discovery, perspective, and challenges in clinical use.

Antimicrobial resistance (AMR) emerges as a severe crisis to public health and requires global action. The occurrence of bacterial pathogens with multi-drug resistance appeals to exploring alternative therapeutic strategies. Antivirulence treatment has been a positive substitute in seeking to circumvent AMR, which aims to target virulence factors directly to combat bacterial infections. Accumulated evidence suggests that plant-derived natural products, which have been utilized to treat infectious diseases for centuries, can be abundant sources for screening potential virulence-arresting drugs (VADs) to develop advanced therapeutics for infectious diseases. This review sums up some virulence factors and their actions in various species of bacteria, as well as recent advances pertaining to plant-derived natural products as VAD candidates. Furthermore, we also discuss natural VAD-related clinical trials and patents, the perspective of VAD-based advanced therapeutics for infectious diseases and critical challenges hampering clinical use of VADs, and genomics-guided identification for VAD therapeutic. These newly discovered natural VADs will be encouraging and optimistic candidates that may sustainably combat AMR.

Review of treatment options for a multidrug-resistant fungus: Candida auris.

Candida auris is a widely distributed, highly lethal, multidrug-resistant fungal pathogen. It was first identified in 2009 when it was isolated from fluid drained from the external ear canal of a patient in Japan. Since then, it has caused infectious outbreaks in over 45 countries, with mortality rates approaching 60%. Drug resistance is common in this species, with a large proportion of isolates displaying fluconazole resistance and nearly half are resistant to two or more antifungal drugs. In this review, we describe the drug resistance mechanism of C. auris and potential small-molecule drugs for treating C. auris infection. Among these antifungal agents, rezafungin was approved by the US Food and Drug Administration (FDA) for the treatment of candidemia and invasive candidiasis on March 22, 2023. Ibrexafungerp and fosmanogepix have entered phase III clinical trials.

Efeito de extratos vegetais de Hamamelis virginiana, Persea americana, Cynara scolymus L e Stryphnodendron barbatiman Msobre a expressão fenotípica dos fatores de virulência em biofilmes de Candida albicans / Effect of Hamamelis virginiana, Persea americana, Cynara scolymus L and Stryphnodendron barbatiman M plant extracts on the phenotypic expression of virulence factors in biofilms of the Candida albicans

Objetivo: Analisar a expressão fenotípica de fatores de virulência em biofilmes de Candida albicans frente a extratos glicólicos de plantas. Material e Métodos: Os biofilmes de Candida albicans (ATCC 18804) obtidos a partir de incubação de 48 horas foram expostos por 5 minutos e 24 horas a diferentes concentrações de extratos glicólicos de Hamamelis virginiana e Persea americana, Cynara scolymus L e Stryphnodendron barbatiman M, a fim de verificar a ação antifúngica da proteinase, fosfolipase e hemolisina. Resultados: Todos os extratos foram eficazes na redução do biofilme. Em contato por 5 minutos. os extratos reduziram 50% do biofilme. Após 24 horas. o extrato de Persea americana apresentou o biofilme em 90%, seguido de Cynara scolymus, que o interrompeu em 85%. Houve mudança na intensidade da proteinase após 5 minutos e 24 horas, com uma atividade enzimática média de 0,69 em comparação com o controle de 0,49. Cynara scolymus foi o extrato com maior concentração média de 100 mg/ml; a intensidade da fosfolipase foi alterada com Stryphnodendron barbatiman sendo mais efetivo em 24 horas em relação ao controle (p< 0,0001). A secreção de hemolisina foi modificada por Hamamelis virginiana (12,5 mg/ml) após 5 minutos de exposição e em 24 horas. todos os extratos foram capazes de causar alterações na secreção. Conclusão: Os extratos testados apresentam potencial antifúngico em biofilmes de Candida albicans, implicando em redução significativa dos fatores de virulência. Assim, estes podem ser indicados como uma ferramenta terapêutica alternativa para reduzir a morbidade dessas infecções, já que em ambos os tempos de exposição investigados, eles foram capazes de reduzir a secreção enzimática do fungo (AU)

Objective: Analyze the phenotypic expression of virulence factors in Candida albicans biofilms against plant glycolicextracts. Material and Methods: The biofilms of Candida albicans (ATCC 18804) obtained from incubation for 48 hours were exposed for 5 minutes and 24 hours to different concentrations of glycolic extracts of Hamamelis virginiana and Persea americana, Cynara scolymus L and Stryphnodendron barbatiman M, in order to verify the antifungal activity of the proteinase, phospholipase and hemolysin. Results: All extracts were effective in reducing biofilm. In contact for 5 minutes. the extracts reduced 50% of the biofilm. After 24 hours, the Persea americanaextract showed the biofilm at 90%, followed by Cynara scolymus, which interrupted it at 85%, There was a change in proteinase intensity after 5 minutes and 24 hours. with an average enzymatic activity of 0.69 compared to the control of 0.49. Cynara scolymus was the extract with the highest mean concentration of 100 mg/ml; the phospholipase intensity was changed with Stryphnodendron barbatiman being more effective in 24 hours compared to the control (p< 0.0001). The hemolysin secretion was modified by Hamamelis virginiana (12.5 mg/ml) after 5 minutes of exposure, and in 24 hours. all extracts were capable to cause changes in secretion. Conclusion: The tested extracts have antifungal potential in Candida albicans biofilms, implying a significant reduction in virulence factors. Thus, these can be indicated as an alternative therapeutic tool to reduce the morbidity of these infections, as in both investigated exposure times. they were able to reduce theenzymatic secretion of the fungus (AU)

Antimicrobial and anti-virulence activities of 4-shogaol from grains of paradise against gram-negative bacteria: Integration of experimental and computational methods.

ETHNOPHARMACOLOGICAL RELEVANCE: Bacterial resistance to antibiotics is a growing global concern, highlighting the urgent need for new antimicrobial candidates. Aframomum melegueta was traditionally used for combating urinary tract and soft tissue infections, which implies its potential as an antimicrobial agent. AIM OF STUDY: This study was designed to explore the antibacterial and anti-virulence capabilities of 4-shogaol isolated from A. melegueta seeds versus gram-negative bacteria: Serratia marcescens, Klebsiella pneumoniae, Acinetobacter baumannii, and the clinically important pathogen Pseudomonas aeruginosa. MATERIALS AND METHODS: 4-Shogeol was isolated from A. melegueta seeds and its MICs were determined for Acinetobacter baumannii (ATCC-17978), Pseudomonas aeruginosa (ATCC-27853), Klebsiella pneumoniae (ATCC-700603), and Serratia marcescens clinical isolate. The anti-efflux activity and effect on the bacterial cell membrane for the compound were evaluated. Furthermore, the anti-virulence activities of the compound were evaluated. The effects of 4-shogeol at sub-MIC on bacterial motility, biofilm formation, and production of virulent enzymes and pigments were assessed. The anti-quorum sensing activities of 4-shogeol were evaluated virtually and by quantification its effect on the expression of quorum sensing encoding genes. The in vivo protection assay was conducted to evaluate the effect of 4-shogaol on the P. aeruginosa capacity to induce pathogenesis in mice. Finally, the effect of shogaol-antibiotics combination was assessed. RESULTS: The research revealed that 4-shogaol's antibacterial action primarily involves disrupting the bacterial cell membrane and efflux pumps. It also exhibited significant anti-virulence effects by reducing biofilm development and repressing virulence factors production, effectively protecting mice against P. aeruginosa infection. Furthermore, when combined with antibiotics, 4-shogaol demonstrated synergistic effects, leading to reduced minimum inhibitory concentrations (MICs) against P. aeruginosa. Its anti-virulence properties were linked to its ability to disrupt bacterial quorum sensing (QS) mechanisms, as evidenced by its interaction with QS receptors and downregulation of QS-related genes. Notably, in silico analysis indicated that 4-shogaol exhibited strong binding affinity to different P. aeruginosa QS targets. CONCLUSION: These findings suggest that 4-shogaol holds promise as an effective anti-virulence agent that can be utilized in combination with antibiotics for treating severe infections caused by gram-positive bacteria.

Modulation of quorum sensing and biofilm of Gram-negative bacterial pathogens by Cinnamomum zeylanicum L.

The development of antibiotic resistant microbial pathogens has become a global health threat and a major concern in modern medicine. The problem of antimicrobial resistance (AMR) has majorly arisen due to sub-judicious use of antibiotics in health care and livestock industry. A slow progress has been made in last two decades in discovery of new antibiotics. A new strategy in combatting AMR is to modulate or disarm the microbes for their virulence and pathogenicity. Plants are considered as promising source for new drugs against AMR pathogens. In this study, fraction-based screening of the Cinnamomum zeylanicum extract was performed followed by detailed investigation of antiquorum sensing and antibiofilm activities of the most active fraction that is, C. zeylanicum hexane fraction (CZHF). More than 75% reduction in violacein pigment of C. violaceum 12472 was overserved. CZHF successfully modulated the virulence of Pseudomonas aeruginosa PAO1 by 60.46%-78.35%. A similar effect was recorded against Serratia marcescens MTCC 97. A broad-spectrum inhibition of biofilm development was found in presence of sub-MICs of CZHF. The colonization of bacteria onto the glass coverslips was remarkably reduced apart from the reduction in exopolymeric substances. Alkaloids and terpenoids were found in CZHF. GC/MS analysis revealed the presence of cinnamaldehyde dimethyl acetal, 2-propenal, coumarin, and α-copaene as major phytocompounds. This study provides enough evidence to support potency of C. zeylanicum extract in targeting the virulence of Gram -ve pathogenic bacteria. The plant extract or active compounds can be developed as successful drugs after careful in vivo examination to target microbial infections. RESEARCH HIGHLIGHTS: Hexane fraction of Cinnamomum zeylanicum is active against QS and biofilms. The broad-spectrum antibiofilm activity was further confirmed by microscopic analysis. Dimethyl acetal, 2-propenal, coumarin, α-copaene, and so forth are major phytocompounds.

Attenuation of quorum sensing regulated virulence functions and biofilm of pathogenic bacteria by medicinal plant Artemisia annua and its phytoconstituent 1, 8-cineole.

The emergence of multidrug resistance (MDR) in bacterial pathogens is a serious public health concern. A significant therapeutic target for MDR infections is the quorum sensing-regulated bacterial pathogenicity. Determining the anti-quorum sensing abilities of certain medicinal plants against bacterial pathogens as well as the in-silico interactions of particular bioactive phytocompounds with QS and biofilm-associated proteins were the objectives of the present study. In this study, 6 medicinal plants were selected based on their ethnopharmacological usage, screened for Anti-QS activity and Artemisia annua leaf extract (AALE) demonstrated pigment inhibitory activity against Chromobacterium violaceum CV12472. Further, the methanol active fraction significantly inhibited the virulence factors (pyocyanin, pyoverdine, rhamnolipid and swarming motility) of Pseudomonas aeruginosa PAO1 and Serratia marcescens MTCC 97 at respective sub-MICs. The inhibition of biofilm was determined using a microtiter plate test and scanning electron microscopy. Biofilm formation was impaired by 70%, 72% and 74% in P. aeruginosa, C. violaceum and S. marcescens, respectively at 0.5xMIC of the extract. The phytochemical content of the extract was studied using GC-MS and 1, 8-cineole was identified as major bioactive compound. Furthermore, 1, 8-cineole was docked with quorum sensing (QS) proteins (LasI, LasR, CviR, and rhlR) and biofilm proteins (PilY1 and PilT). In silico docking and dynamics simulations studies suggested interactions with QS-receptors CviR', LasI, LasR, and biofilm proteins PilY1, PilT for anti-QS activity. Further, 1, 8-cineole demonstrated 66% and 51% reduction in violacein production and biofilm formation, respectively to validate the findings of computational analysis. Findings of the present investigation suggests that 1, 8-cineole plays a crucial role in the QS and biofilm inhibitory activity demonstrated by Artemisia annua extract. RESEARCH HIGHLIGHTS: Artemisia annua leaf extract (AALE) methanol fraction demonstrated broad-spectrum QS and biofilm inhibition Scanning electron microscopy (SEM) confirmed biofilm inhibition Molecular docking and simulation studies suggested positive interactions of 1,8-cineol with QS-receptors and biofilm proteins.

Exploring Monkeypox: prospects for therapeutics through computational-aided drug discovery.

Monkeypox virus (MPXV) has emerged as a significant public health concern due to its potential for human transmission and its severe clinical manifestations. This review synthesizes findings from peer-reviewed articles spanning the last two decades, shedding light on diverse aspects of MPXV research. The exploration commences with an analysis of transmission dynamics, including zoonotic and human-to-human transmission, and potential reservoir hosts. Detailed insights into viral replication mechanisms illuminate its influence on disease progression and pathogenicity. Understanding the genomic and virion structure of MPXV is pivotal for targeted interventions. Genomic characteristics contributing to virulence are examined, alongside recent advancements in virion structure elucidation through cutting-edge imaging techniques. Emphasizing combat strategies, the review lists potential protein targets within the MPXV lifecycle for computer-aided drug design (CADD). The role of protein-ligand interactions and molecular docking simulations in identifying potential drug candidates is highlighted. Despite the absence of approved MPXV medications, the review outlines updates on ongoing small molecules and vaccine development efforts, spanning traditional and innovative platforms. The evolving landscape of computational drug research for MPXV is explored, encompassing advanced algorithms, machine learning, and high-performance computing. In conclusion, this review offers a holistic perspective on MPXV research by integrating insights spanning transmission dynamics to drug design. Equipping researchers with multifaceted understanding underscore the importance of innovative methodologies and interdisciplinary collaborations in addressing MPXV's challenges as research advances.