Crystal Violet Assay Research Articles

Efficacy of colistin-based combinations against pandrug-resistant whole-genome-sequenced Klebsiella pneumoniae isolated from hospitalized patients in Egypt: an in vitro/vivo comparative study

BackgroundColistin resistance significantly constrains available treatment options and results in the emergence of pandrug-resistant (PDR) strains. Treating PDR infections is a major public health issue. A promising solution lies in using colistin-based combinations. Despite the availability of in vitro data evaluating these combinations, the in vivo studies remain limited.ResultsThirty colistin-resistant Klebsiella pneumoniae (ColRKp) isolates were collected from hospitalized patients. Colistin resistance was detected using broth microdilution, and antimicrobial susceptibility was tested using the Kirby-Bauer method against 18 antibiotics. Extremely high resistance levels were detected, with 17% of the isolates being PDR. Virulence profiling, assessed using Anthony capsule staining, the string test, and the crystal violet assay, indicated the predominance of non-biofilm formers and non-hypermucoid strains. The isolates were screened for mcr genes using polymerase chain reaction. Whole-genome sequencing (WGS) and bioinformatics analysis were performed to characterize the genomes of PDR isolates. No plasmid-borne mcr genes were detected, and WGS analysis revealed that PDR isolates belonged to the high-risk clones: ST14 (n = 1), ST147 (n = 2), and ST383 (n = 2). They carried genes encoding extended-spectrum β-lactamases and carbapenemases, blaCTX-M-15 and blaNDM-5, on conjugative IncHI1B/IncFIB plasmids, illustrating the convergence of virulence and resistance genes. The most common mechanism of colistin resistance involved alterations in mgrB. Furthermore, deleterious amino acid substitutions were also detected within PhoQ, PmrC, CrrB, ArnB, and ArnT. Seven colistin-containing combinations were compared using the checkerboard experiment. Synergy was observed when combining colistin with tigecycline, doxycycline, levofloxacin, ciprofloxacin, sulfamethoxazole/trimethoprim, imipenem, or meropenem. The efficacy of colistin combined with either doxycycline or levofloxacin was assessed in vitro using a resistance modulation assay, and in vivo, using a murine infection model. In vitro, doxycycline and levofloxacin reversed colistin resistance in 80% and 73.3% of the population, respectively. In vivo, the colistin + doxycycline combination demonstrated superiority over colistin + levofloxacin, rescuing 80% of infected animals, and reducing bacterial bioburden in the liver and kidneys while preserving nearly intact lung histology.ConclusionsThis study represents the first comparative in vitro and in vivo investigation of the efficacy of colistin + doxycycline and colistin + levofloxacin combinations in clinical PDR ColRKp isolates characterized at a genomic level.

Eradication of Biofilms on Catheters: Potentials of Tamarix ericoides Rottl. Bark Coating in Preventing Catheter-Associated Urinary Tract Infections (CAUTIs)

Catheter-associated urinary tract infections (CAUTIs) cause serious complications among hospitalized patients due to biofilm-forming microorganisms which make treatment ineffective by forming antibiotic-resistant strains. As most CAUTI-causing bacterial pathogens have already developed multidrug resistance, there is an urgent need for alternative antibacterial agents to prevent biofilms on catheter surfaces. As a trial to find out such a potential agent of natural origin, the bark of Tamarix ericoides Rottl., a little-known plant from the Tamaricaceae family, was examined for its antibacterial and antibiofilm activities against one of the major, virulent, CAUTI-causing bacterial pathogens: Enterococcus faecalis. The methanolic T. ericoides bark extract was analyzed for its antibacterial activity using the well diffusion method and microdilution method. Killing kinetics were calculated using time–kill assay, and the ability of biofilm formation and its eradication upon treatment with the T. ericoides bark extract was studied by crystal violet assay. GC-MS analysis was performed to understand the phytochemical presence in the extract. A in vitro bladder model study was performed using extract-coated catheters against E. faecalis, and the effect was visualized using CLSM. The changes in the cell morphology of the bacterium after treatment with the T. ericoides bark extract were observed using SEM. The biocompatibility of the extract towards L929 cells was studied by MTT assay. The anti-E. faecalis activity of the extract-coated catheter tube was quantified by viable cell count method, which exposed 20% of growth after five days of contact with E. faecalis. The anti-adhesive property of the T. ericoides bark extract was studied using CLSM. The extract showed potential antibacterial activity, and the lowest inhibitory concentration needed to inhibit the growth of E. faecalis was found to be 2 mg/mL. The GC-MS analysis of the methanolic fractions of the T. ericoides bark extract revealed the presence of major phytochemicals, such as diethyl phthalate, pentadecanoic acid, methyl 6,11-octadecadienoate, cyclopropaneoctanoic acid, 2-[(2-pentylcyclopropyl) methyl]-, methyl ester, erythro-7,8-bromochlorodisparlure, etc., that could be responsible for the antibacterial activity against E. faecalis. The killing kinetics of the extract against E. faecalis was calculated and the extract showed promising antibiofilm activity on polystyrene surfaces. The T. ericoides bark extract effectively reduced the E. faecalis mature biofilms by 75%, 82%, and 83% after treatment with 1X MIC (2 mg/mL), 2X MIC (4 mg/mL), and 3X MIC (6 mg/mL) concentrations, respectively, which was further confirmed by SEM analysis. The anti-adhesive property of the T. ericoides bark extract studied using CLSM revealed a reduction in the biofilm thickness, and the FDA and PI combination revealed the death of 80% of the cells on the extract-coated catheter tube. In addition, SEM analysis showed extensive damage to the E. faecalis cells after the T. ericoides bark extract treatment, and it was not cytotoxic. Hence, after further studies, T. ericoides bark extract with potential antibacterial, antibiofilm, and anti-adhesive activities can be developed as an alternative agent for treating CAUTIs.

Unveiling the antibacterial action of ambroxol against Staphylococcus aureus bacteria: in vitro, in vivo, and in silico investigation

It is critical to find novel therapeutic approaches owing to the dissemination of multidrug resistance (MDR) in pathogenic bacteria, particularly Staphylococcus aureus. FDA-drug repurposing is an important therapeutic tactic to fight MDR bacteria. Here, we inspected the antibacterial activity of ambroxol against clinical MDR S. aureus isolates. Using the broth microdilution method, ambroxol revealed minimum inhibitory concentrations (MICs) of 0.75 to 1.5 mg/mL. Also, it revealed antibiofilm action on 42.17% of the isolates by crystal violet assay. A scanning electron microscope was employed to study the antibiofilm action of ambroxol. It revealed that the association between the cells was interrupted by ambroxol, and the biofilm construction was devastated. Moreover, qRT-PCR was utilized to elucidate the consequence of ambroxol on the gene expression of efflux and biofilm. Remarkably, ambroxol has downregulated the expression of cna, fnb A, ica, nor A, nor B genes. Ambroxol’s in vivo antibacterial action was investigated using S. aureus infected burn infection. Interestingly, ambroxol has improved the histological features of the skin tissues, significantly diminished the bacterial burden, and increased the wound healing percentage. Also, it revealed a significant reduction in the immunohistochemical staining of tumor necrosis factor-alpha. Finally, the in silico investigations were performed to elucidate the potential of ambroxol on five possible targets of S. aureus. Ambroxol showed good affinities on the five investigated targets in S. aureus, with CrtM being the highest, proposing its probable role in the mechanisms for ambroxol’s action on S. aureus.

Purified α-Amylase from Bacillus cereus exhibits antibiofilm and antiquorum sensing activities against uropathogenic Escherichia coli, Downregulating fimH, and papC virulence genes: implications for urinary tract infections

Background and aimPathogenic Escherichia coli is a known harmful microorganism that takes advantage of favorable conditions to cause various infections in healthcare settings, such as bloodstream infections related to catheters, as well as infections in the urinary and respiratory tracts. E. coli utilizes biofilm development as a means to enhance its virulence and pathogenicity. This work aims to investigate the antibiofilm activity of α-amylase enzyme against uropathogenic E. coli (UPEC) and its effect on biofilm-regulatory genes.MethodologyIn this study, we evaluated the antibiofilm activity of α-amylase enzyme by spectrophotometric microtiter plate analysis and confocal laser scanning microscopy. Also, the antibacterial activity of the test enzyme was evaluated by measuring the MIC and MBC levels against UPEC. The quorum-quenching activity of α-amylase enzyme was assessed using a qRT-PCR to evaluate the impact on biofilm-regulatory genes.ResultsBased on our results, purified α-amylase showed MIC and MBC levels ranged between 128 and 512 µg /ml against UPEC isolates using broth microdilution assay. Crystal violet assay revealed MBIC of 128 µg/ml and MBEC of 256 µg/ml for the purified α-amylase. When the biofilm was analyzed by confocal laser scanning microscope, our results showed inhibition of biofilm thickness (56%) and live/dead cell percentages (43/55%). Furthermore, analysis of the effect on the expression of biofilm-encoding genes showed downregulation of both fimH and papC genes by 57 and 25%, respectively, upon treatment of UPEC with ½ of the MIC (64 µg/ml).ConclusionsThe results demonstrate that our purified α-amylase from B. cereus exhibits promising antibiofilm activities against UPEC at both phenotypic as well as genotypic levels. These findings suggest that this enzyme may serve as a natural effective tool for removing bacterial biofilms, potentially offering new therapeutic avenues for treating infections caused by UPEC.

Anti-Inflammatory and Anti-proliferative Role of Essential Oil of Leaves of Cleistocalyx operculatus (Roxb.) Merr. & Perry.

Phytochemicals have long remained an essential component of the traditional medicine system worldwide. Advancement of research in phytochemicals has led to the identification of novel constituents and metabolites from phytochemicals, performing various vital functions ranging from antimicrobial properties to anticarcinogenic roles. This plant is traditionally used by local people to manage inflammation. In this study, we aim to extract and chemically profile the essential oil from the leaves of Cleistocalyx operculatus (Roxb.) Merr. & Perry and study of the anti-inflammatory and anti-proliferative role of essential oil. The hydro distillation method was used for the extraction of essential oil, and the GC-MS was applied for the chemical profiling. The percentage of cell viability was calculated using a crystal violet assay, colony formation assay was performed using Semiquantitative PCR, Propodium iodite staining was used for cell death assay, and Western blotting was used to determine antibodies and proteins. Schrodinger 2015 software was used for molecular docking. Myrcene, a monoterpene, constitutes 56% of the oil and could be attributed to its anti-inflammatory potential. Treatment of LPS-challenged mouse macrophages RAW264.7 cells with essential oil resulted in a decline in the inflammatory markers, such as IL-1β, TNFα, iNOS, COX-2, and NFκB. Further, essential oil inhibited cancer PC-3, A431, A549, and MCF-7 cell lines at concentrations lower than normal PNT2 and HEK-293 cell lines. This decline in proliferative potential can be attributed to a decline in anti-apoptotic proteins, such as procaspase 3 and PARP, an increase in CKIs, such as p21, and a decline in the Akt signaling responsible for survival. The essential oil of the plant Cleistocalyx operculatus may be a potential lead for anti-inflammatory and anti-proliferative function.

Clinical laboratory evaluation of the Hologic Panther Aptima BV and CV/TV assays for the diagnosis of vaginitis in Dunedin, Aotearoa New Zealand.

Vaginitis presentations are common, but traditional diagnostic methods are imperfect. Molecular methods for bacterial vaginosis (BV) and vulvovaginal candidiasis (CV) are increasingly available but not commonly utilized in Aotearoa New Zealand. We evaluated the Hologic Aptima BV and CV/Trichomonas vaginalis (TV) assays against our current methods (Gram stain, yeast culture, and Hologic Aptima TV assay) and performed a retrospective BV clinical audit. The BV Aptima assay performed well with high sensitivity (97.5%) and specificity (96.3%) when the indeterminate BV category was excluded. BV indeterminate samples were almost evenly split between positive and negative results when tested on the Aptima BV assay. BV Gram stain interpretation was error prone, with 20% of samples discordant on duplicate examination. Although the Aptima CV assay was highly sensitive, it lacked specificity compared with Gram stain (83.5%) but was similar to culture (91.2%). Our BV clinical audit showed that patients with a BV indeterminate result were less likely to be treated for BV than those with a positive result, meaning more women may be treated for BV if this assay were implemented. Overall, implementation may improve laboratory workflow and consistency of reporting, but cost may be a barrier. The clinical impact of changing methods needs to be considered.IMPORTANCEIn this paper, we evaluate the performance of the Aptima molecular assays against current Gram stain and culture methods, as well as a clinical audit to determine the potential clinical impact of implementation. Although molecular methods are increasingly used in other countries, New Zealand has not yet adopted this approach. Importantly, we found Gram stain for bacterial vaginosis (BV) to be error prone, with 20% of Gram stain results discordant on repeat examination. We show the potential for molecular methods to increase BV diagnoses and improve reproducibility and consistency of reporting which, according to our clinical audit results, would lead to more women being treated for this dysbiosis condition overall.

SLFN12 Expression Significantly Effects the Response to Chemotherapy Drugs in Triple-Negative Breast Cancer.

Schlafen12 (SLFN12) is an intermediate human Schlafen protein shown to correlate with survivability in triple-negative breast cancer (TNBC). SLFN12 causes differential expressions of significant cancer genes, but how they change in response to chemotherapy remains unknown. Our aim is to identify the effect of chemotherapy on genes that improve TNBC outcomes and other SLFN family members following SLFN12 knockout or overexpression. We overexpressed SLFN12 using a lentiviral vector and knocked out SLFN12 (AdvShSLFN12) using a hairpin adenovirus in MDA-MB-231 TNBC cells. Cells were treated with camptothecin, paclitaxel, zoledronic acid, or carboplatin to evaluate the SLFN12 signature cancer genes associated with improved TNBC outcomes using qPCR. Additionally, cells were treated alone and in combination with AdvShSLFN12, IFN-α2 (known SLFN12 stimulator), carboplatin, and paclitaxel. After treatment, the viable cell numbers were analyzed utilizing a colorimetric crystal violet assay for cell viability. The SLFN family and SLFN12 cancer signature gene mRNA expressions were analyzed by RT-qPCR. Treating SLFN12-overexpressing TNBC cells with chemotherapy agents resulted in the differential expressions of eight cancer-related genes. Notably, GJB3 was downregulated following treatment with each chemotherapeutic drug. Inducing SLFN12 with IFN-α2 resulted in decreased cell viability and increased SLFN12 mRNA levels following treatment with paclitaxel or carboplatin. These results suggest that SLFN12 overexpression significantly affects the expressions of genes driving phenotypic changes in response to chemotherapy and influences additional SLFN family members following IFN-α2 treatment. This may contribute to improving the survival of patients with SLFN12 overexpression. Additionally, patient SLFN12 levels can be used as a factor when pursuing personalized chemotherapy treatments.

Biofilm Inhibition Activity of Fennel Honey, Fennel Essential Oil and Their Combination.

The eradication of bacterial biofilms remains a persistent challenge in medicine, particularly because an increasing number of biofilms exhibit resistance to conventional antibiotics. This underscores the importance of searching for novel compounds that present antibacterial and biofilm inhibition activity. Various types of honey and essential oil were proven to be effective against a number of biofilm-forming bacterial strains. The current study demonstrated the effectiveness of the relatively unexplored fennel honey (FH), fennel essential oil (FEO), and their combination against biofilm-forming bacterial strains Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and Escherichia coli, with a series of in vitro experiments. The authenticity of FH and FEO was checked with light microscopy and gas chromatography-mass spectrometry, respectively. Minimum inhibitory concentrations were determined using the microdilution method, and antibiofilm activity was assessed with crystal violet assay. Structural changes in bacterial cells and biofilms, induced by the treatments, were monitored with scanning electron microscopy. FEO and FH inhibited the biofilm formation of each bacterial strain, with FEO being more effective compared to FH. Their combination was the most effective, with inhibitory rates ranging between 87 and 92%, depending on the bacterial strain. The most sensitive bacterium was E. coli, while P. aeruginosa was the most resistant. These results provide justification for the combined use of honey and essential oil to suppress bacterial biofilms and can serve as a starting point to develop an effective surface disinfectant with natural ingredients.

Exploring time-killing and biofilm inhibition potential of bioactive proteins extracted from two varieties of Pleurotus ostreatus.

Dental caries, caused by oral microbial pathogens, are a global health concern, further exacerbated by the presence of methicillin-resistant Staphylococcus aureus (MRSA). Bioactive proteins and peptides (BAPs) exhibit potent antimicrobial properties, targeting multiple cellular mechanisms within pathogens, reducing the likelihood of resistance development. Given the antimicrobial potential of BAPs, this study aimed to compare the efficacy of BAPs extracted from cultivated (Pleurotus ostreatus, PoC) and wild (Pleurotus ostreatus, PoW) mushrooms against pathogens responsible for dental caries. BAPs were extracted from both PoC and PoW using a TCA-acetone method. Antimicrobial activities were tested against seven bacteria and one fungus using agar well diffusion and MIC determination. Antibiofilm activity was assessed via modified CV assay, while DPPH and erythrocyte lysis tests evaluated free radical scavenging. PoC showed superior antimicrobial efficacy, with lower MIC and MBC values, and disrupted biofilm integrity at increasing concentrations. PoW exhibited better antioxidant activity with higher DPPH scavenging, though its antimicrobial efficacy was slightly lower than PoC. Both PoC and PoW BAPs inhibited dental pathogens, with PoC showing stronger inhibition against MRSA and nystatin-resistant Candida albicans. This suggests BAPs may target additional cellular mechanisms beyond membranes, PBPs, and ergosterols. Despite PoW's stronger antioxidant properties, both BAPs had comparable antibiofilm activity. These findings suggest complementary actions of BAPs from PoC and PoW both, in treating dental caries, offering broad-spectrum antimicrobial and antioxidant benefits.

Diverse antifungal potency of terbinafine as a therapeutic agent against Exophiala dermatitidis in vitro

Exophiala dermatitidis (E. dermatitidis), which causes skin or respiratory disease, is occasionally fatal in immunocompromised patients. Here, we report the unique antifungal potency of terbinafine (TRB), which targets squalene epoxidase, against E. dermatitidis (SQLEED) using various in vitro approaches. The versatile antifungal activities, including fungicidal activity, biofilm formation inhibition, biofilm eradication activity, and the combination effect of TRB, posaconazole (PSC), and amphotericin B (AmB) with great antifungal potency against E. dermatitidis were evaluated using crystal violet and cell viability assay. TRB formed an H-bond through Y102 in SQLEED in the binding model. E. dermatitidis hyphae elongated and attached to a cell scaffold, forming a membrane-like biofilm. TRB and PSC showed more potent antibiofilm activities than AmB, and exhibited post-antifungal effects without incubation against E. dermatitidis conidia, reducing growth at lower concentrations. In contrast, AmB exhibited strong dose- and time-dependent killing and biofilm-eradication activities. The combination of TRB and PSC was more effective than that of TRB and AmB or PSC and AmB. Although the tissue migration of TRB must be considered, these data suggest that TRB and PSC may be useful agents and a potent combination in severely immunocompromised patients with refractory and systemic E. dermatitidis infection.

Surface-functionalized UIO-66-NH2 for dual-drug delivery of vancomycin and amikacin against vancomycin-resistant Staphylococcus aureus

BackgroundConventional antibacterial compounds can inhibit the growth of microorganisms, but their adverse effects and the development of drug limit their widespread use. The current study aimed to synthesize PEG-coated UIO-66-NH2 nanoparticles loaded with vancomycin and amikacin (VAN/AMK-UIO-66-NH2@PEG) and evaluate their antibacterial and anti-biofilm activities against vancomycin-resistant Staphylococcus aureus (VRSA) clinical isolates.MethodsThe VAN/AMK-UIO-66-NH2@PEG were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) to determine their size, polydispersity index (PDI), encapsulation efficiency (EE%), zeta-potential, drug release profile, and physical stability. Antibacterial activity was evaluated using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill assays. Biofilm formation by VRSA was assessed using the crystal violet (CV) and minimum biofilm eradication concentration (MBEC) assays. The effect of sub-MIC concentrations of the formulations on the expression of biofilm-related genes (icaA, icaD) and resistance-related genes (mecA, vanA) was investigated using quantitative real-time polymerase chain reaction (RT-qPCR).ResultsAs demonstrated by MIC, MBC and time-kill assay, the VAN/AMK-UIO-66-NH2@PEG nanoparticles exhibited enhanced antibacterial activity against VRSA isolates compared to free drugs and prepared formulations. Furthermore, CV and MBEC tests indicated that the VAN/AMK-UIO-66@NH2/PEG can reduce biofilm formation dramatically compared to VAN/AMK and VAN/AMK-UIO-66@NH2, due to its great drug release properties. This study also found that the expression level of the mecA, vanA, icaA, and icaD genes in VAN/AMK-UIO-66@NH2/PEG treated VRSA isolates was substantially decreased compared to other groups.ConclusionsThese findings highlighted the efficiency of VAN/AMK-UIO-66@NH2/PEG in combating antimicrobial resistance and biofilm formation in VRSA isolates. Future studies, particularly in vivo models, are necessary to evaluate the safety, efficacy, and clinical applicability of these nanoparticles for the treatment of bacterial infections.

Deciphering FUR-regulated gene networks in Klebsiella pneumoniae using FUR knockout mutant

Klebsiella pneumoniae is a nosocomial pathogen causing life-threatening infections worldwide. It possesses many virulence properties and the ferric uptake regulator (FUR) is the transcription factor that regulates the expression of various genes in K. pneumoniae. FUR binds to a conserved 19 bp sequence, called the FUR box, for either positive or negative regulation of the gene. FUR alters gene expression according to iron availability and also participates in virulence, colonization & toxin secretion in K. pneumoniae. FUR deletion mutant is an interesting model to understand the virulence factors. In the present study, we identified the genes containing putative FUR boxes (>50 % sequence homology) from the genome of K. pneumoniae M33. FUR deletion mutant for K. pneumoniae M33 was created using lambda red recombinase system using the plasmids- pACBSR-hyg, pMDIAI, and pFLP-hyg. The mutant (M33∆FUR) was characterized using various assays like CAS assay, string test, crystal violet assay to access siderophore production, capsule synthesis and biofilm formation respectively. FUR box was present upstream of 18 genes with distinct functions. In the FUR knockout mutant, M33∆FUR an increase in expression of iron transport and siderophore related genes feoC, fhuA, fepB and fes was observed whereas genes feoA, cirA, fecA, fepA and entC were down-regulated. Genes related to biofilm (fimA and mrkD) were downregulated whereas genes related to capsular polysaccharide (rcsA and rcsB) were upregulated upon FUR deletion. Among other genes murG and sucA were downregulated and priB and srlB were upregulated upon FUR deletion. This study shows that FUR regulates many genes involved in virulence, either positively or negatively.

Anti-biofilm potential of red pitahaya betacyanins against Streptococcus mutans, Actinomyces viscosus and Aggregatibacter actinomycetemcomitans

This study investigated the antibiofilm effects of betacyanin fraction (BF) from red pitahaya against Streptococcus mutans, Actinomyces viscosus, and Aggregatibacter actinomycetemcomitans, key pathogens in oral biofilm formation. Betacyanin purification employed column chromatography, and characterization was performed using liquid chromatography-mass spectrometry. Crystal violet assay and scanning electron microscopy demonstrated significant inhibition of early biofilm formation and disruption of preformed biofilms using BF (0.94–15 mg/mL). Anti-adhesion assays on artificial teeth indicated potent betacyanin-mediated inhibition of both sucrose-dependent and -independent bacterial attachment. Notably, growth curve and pH drop assays revealed that BF hindered pH reduction for all tested bacteria without suppressing their growth. Tetrazolium-based cytotoxicity assays showed minimal toxicity towards normal human gingival fibroblasts (HGF-1) at 0.78–12.5 mg/mL. These findings demonstrate the potential of red pitahaya betacyanins as promising antibiofilm agents for oral health, targeting both initial and mature stages of biofilm development.

Flash chromatographic isolation of garcinol and isogarcinol from Garcinia indica Choisy (kokum) fruit and evaluation of their potential antibiofilm activity

The present study describes the isolation and separation of isogarcinol and garcinol from kokum fruit by flash chromatography using water (containing 0.1 % formic acid) and methanol mixed with acetonitrile (1:1) with UV detection at 254 nm and was characterised by HR-MS and NMR studies. These were further subjected to antimicrobial studies on Staphylococcus aureus FR1722 and Listeria monocytogenes Scott A by agar diffusion assay and broth microdilution method wherein the MIC (Minimum Inhibitory Concentration) of garcinol and isogarcinol were, 20 μg/mL and 50 μg/mL for S. aureus FR1722 and 50 μg/mL and 100 μg/mL for L. monocytogenes Scott A respectively. Further, studies on the control of biofilm growth were tested using MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide) assay followed by Crystal Violet (CV) assay, which showed up to 80 % inhibition. In addition, the biofilm eradication as evaluated by bright field microscopy and the metabolic activity were also carried out against these bacterial strains and the experimental details are presented.

Rosmarinic Acid Exhibits Antifungal and Antibiofilm Activities Against Candida albicans: Insights into Gene Expression and Morphological Changes.

Candida species, opportunistic pathogens that cause various infections, pose a significant threat due to their ability to form biofilms that resist antifungal treatments and immune responses. The increasing resistance of Candida spp. and the limited availability of effective treatments have prompted the research of natural compounds as alternative therapies. This study assessed the antifungal properties of RA against Candida species, focusing on its impact on C. albicans biofilms and the underlying mechanisms. The antifungal efficacy of RA was evaluated using the CLSI M27-A3 microdilution method on both fluconazole-susceptible and -resistant strains. Biofilm formation by C. albicans was assessed through a crystal violet assay, while its antibiofilm activity was analyzed using an MTT assay and field emission scanning electron microscopy (FESEM). Gene expression related to biofilm formation was studied using quantitative real-time PCR (qRT-PCR), and statistical analysis was performed with an ANOVA. Among the 28 Candida strains tested, RA exhibited minimum inhibitory concentration (MIC) values ranging from 160 to 1280 μg/mL. At a 640 μg/mL concentration, it significantly reduced the expression of genes associated with adhesion (ALS3, HWP1, and ECE1), hyphal development (UME6 and HGC1), and hyphal cAMP-dependent protein kinase regulators (CYR1, RAS1, and EFG1) in RAS1-cAMP-EFG1 pathway (p < 0.05). FESEM analysis revealed a reduction in hyphal networks and disruptions on the cell surface. Our study is the first to demonstrate the effects of RA on C. albicans adhesion, hyphae development, and biofilm formation through gene expression analysis with findings supported by FESEM. This approach distinguishes our study from previous studies on the effect of RA on Candida. However, the high MIC values of RA limit its antifungal potential. Therefore, more extensive research using innovative methods is required to increase the antifungal effect of RA.

Multi-metal resistance and antibiotic susceptibility of biofilm forming bacteria isolated from Kuzhikandam Creek in Kochi, southwest part of India

The purpose of this work was to characterize and identify the bacteria isolated from highly polluted locations that could potentially be able to withstand extremely toxic heavy metals. The study area selected for bacterial isolation from sediment samples was Kuzhikandam Creek, a tributary of the Periyar River and one of the world’s most hazardous hotspots, located in Kochi’s Eloor industrial region. Heavy metal analysis of chromium, copper, and lead in sediment samples was performed, and the results showed that the concentrations were greater than permissible limits. Several metal-resistant bacteria were isolated from sediments, which, upon further screening in solid media at different concentrations of chromium, copper, and lead, found three highly resistant species (S1B1, S2B2, and S3B3), one from each site. The phenotypic and biochemical characterization of these bacteria was examined using standard procedures. The ability of these species to generate biofilm was examined using methods like the crystal violet assay (qualitative assessment) and also using the scanning electron microscope. The antibiotic susceptibility of these species was tested with six different antibiotics, which are used in various disease treatments. These isolates, sequenced using the 16S rRNA Sanger dideoxy method, have been identified as Staphylococcus arlettae, Bacillus paramycoides, and Cellulosimicrobium funkei.

Single-agent Adavosertib Shows Anticancer Effects Against Colorectal Cancer Cells.

Colorectal cancer (CRC) is the third most common malignancy and the second most common cause of cancer-related deaths worldwide. Adavosertib (AZD1775), a small molecule inhibitor of WEE1 kinase, abrogates G2/M cell cycle arrest and induces double-stranded DNA breaks. According to previous findings, adavosertib, in combination with other DNA-damaging agents, causes premature mitosis and cell death in p53-mutated cancer cells mainly via abrogation of the G2/M cell cycle checkpoint. This study aims to evaluate the inhibition of WEE1 kinase by adavosertib as monotherapy in the TP53-wildtype human CRC cell line HCT116. In this study, HCT116 cells were treated with different concentrations of adavosertib for 24 to 72 hours. Cell viability was assessed by Water-Soluble Tetrazolium 1 (WST-1) assay and crystal violet assays. Cell migration was evaluated by the wound healing assay. Cell cycle distribution and apoptosis were analyzed by flow cytometry. The IC50 value of adavosertib for the HCT116 cell line was 0.1310 μM. Adavosertib monotherapy (both 0.125 and 0.250 μM) significantly reduced cell viability, inhibited cell migration and abrogated intra-S phase cell cycle arrest. In addition, 0.250 μM of adavosertib significantly induced apoptosis in HCT116 cells. Adavosertib effectively inhibits the TP53-wildtype HCT116 cells via the abrogation of intra-S phase cell cycle arrest. Our findings suggest that adavosertib monotherapy may be a potential targeted therapy for CRC.

Cytocompatibility, Antibacterial, and Anti-Biofilm Efficacy of Grape Seed Extract and Quercetin Hydrogels Against a Mature Endodontic Biofilm Ex Vivo Model.

Background/Objectives: To assess the cytocompatibility, antibacterial and anti-biofilm efficacy of grape seed extract (GSE) and quercetin hydrogels versus calcium hydroxide (CH) as intracanal medications (ICMs) against an endodontic ex vivo biofilm model. Methods: Single-rooted teeth (n = 50) were prepared and sterilized before being infected with E. faecalis to develop a mature biofilm. They were divided into five equal groups according to the ICM used: G1: medicated with CH paste, G2: medicated with GSE hydrogel, G3: medicated with quercetin hydrogel, G4: positive control group that was infected and not medicated, and G5: negative control group that was neither infected nor medicated. After 1 week, the ICM was removed, and the root canals were cultured to assess the antibacterial efficacy by counting the colony-forming units and the anti-biofilm efficacy by the crystal violet assay. Dead/live bacterial viability was assessed by CFLSM examination, while the cytocompatibility was assessed using the MTT assay. Results: CH had the best antibacterial efficacy, followed by GSE and quercetin hydrogels (p < 0.001). Regarding the anti-biofilm efficacy, GSE was superior, followed by quercetin and CH (p < 0.001). CFLSM examination showed CH and GSE hydrogel to be highly effective in comparison to the positive control (p < 0.0001), with no statistical difference between them (p > 0.05). CH showed significantly higher cell viability percentages using a 500 μg/mL, while quercetin and GSE started to show cell viability > 70% at concentrations of 125 μg/mL and 62.5 μg/mL. Conclusions: CH fulfilled the ideal requirements of ICM as being both antibacterial and non-cytotoxic compared to the other materials tested.

Biofilm formation and drug susceptibility of biofilm Candida spp. clinically isolated from nasopharyngeal cancer patients in Vietnam.

The biofilm formation has been widely recognized as one of the main mechanisms of antimicrobial resistance development in microorganisms. However, few studies are focusing on this phenomenon in Candida spp. in clinical settings, especially on immuno-compromised patients. In this study, both the rate of biofilm formation in those patients and its drug susceptibility in initial and mature biofilm were assessed using crystal violet assay and dilution method. The results demonstrated that the biofilm formation rate was similar between albicans and non-albicans Candida. However, the biofilm formation capacity was more pronounced in non-albicans Candida, especially, C. glabrata. As expected, there was a significant relationship between biofilm formation and drug resistance. In addition, our study reconfirmed that the age of high concentration of antifungal agents only affected Candida before its biofilm formation regardless of its biofilm formation capacity. In the contrary, once the biofilm was formed even elevated drug concentrations did not show sufficient efficacy, highlighting a need for high dosage at the early stage of treatment for those patients. The results of this study highlighted the importance of using appropriate antifungal agents for Candida treatment before the formation of biofilm.

In vitro and computational investigation of antioxidant and anticancer properties of Streptomyces coeruleofuscus SCJ extract on MDA-MB-468 triple-negative breast cancer cells

This study aimed to explore the antioxidant potential of the ethyl acetate extract of Streptomyces coeruleofuscus SCJ strain, along with its inhibitory effects on the triple-negative human breast carcinoma cell line (MDA-MB-468). The ethyl acetate extract’s total phenolic and flavonoid contents were quantified, and its antioxidant activity was investigated using DPPH (1,1-Diphenyl-2-picrylhydrazyl), ABTS (2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid), and FRAP (Ferric Reducing Antioxidant Power) assays. Furthermore, the cytotoxic effect of the organic extract from Streptomyces coeruleofuscus SCJ on MDA-MB-468 cancer cells was assessed via the crystal violet assay. In tandem, a thorough computational investigation was conducted to explore the pharmacokinetic properties of the identified components of the extract, utilizing the SwissADME and pKCSM web servers. Additionally, the molecular interactions between these components and Estrogen Receptor Beta, identified as a potential target, were probed through molecular docking studies. The results revealed that ethyl acetate extract of SCJ strain exhibited remarkable antioxidant activity, with 39.899 ± 1.56% and 35.798 ± 0.082% scavenging activities against DPPH and ABTS, respectively, at 1 mg/mL. The extract also displayed significant ferric reducing power, with a concentration of 1.087 ± 0.026 mg ascorbic acid equivalents per mg of dry extract. Furthermore, a strong positive correlation (p < 0.0001) between the antioxidant activity, the polyphenol and the flavonoid contents. Regarding anticancer activity, the SCJ strain extract demonstrated significant anticancer activity against TNBC MDA-MB-468 cancer cells, with an inhibition percentage of 62.76 ± 0.62%, 62.67 ± 0.93%, and 58.07 ± 4.82% at 25, 50, and 100 µg/mL of the extract, respectively. The HPLC-UV/vis analysis revealed nine phenolic compounds: gallic acid, sinapic acid, p-coumaric acid, cinnamic acid, trans-fereulic acid, syringic acid, chloroqenic acid, ellagic acid, epicatechin. Streptomyces coeruleofuscus SCJ showed promise for drug discovery, exhibiting antioxidant and anticancer effects.