Search Results (757)

The genus Mentha (Lamiaceae), comprising aromatic perennial plants widely distributed in temperate regions, holds significant medicinal and commercial value. This study aimed to investigate the chemical profile and bioactivities of hydroalcoholic extracts from Mentha longifolia (L.) L., Mentha pulegium L., and Mentha spicata L. harvested from the Campania region, Southern Italy. Chemical analysis using LC-HRESIMS/MS identified a total of 21 compounds. The extracts, particularly M. pulegium, exhibited notable antioxidant activity, evaluated through DPPH and FRAP assays, probably related to their chemical composition. Both M. pulegium and M. longifolia demonstrated a higher phenolic content, with M. pulegium also containing the highest levels of flavonoids. In addition, the extract’s ability to inhibit biofilm formation was evaluated against several pathogenic strains, including Gram-positive bacteria (Listeria monocytogenes and Staphylococcus aureus) and Gram-negative bacteria (Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli) using crystal violet and MTT assays. All extracts effectively inhibited biofilm formation in A. baumannii and P. aeruginosa, with M. pulegium also showing moderate activity against the metabolism of L. monocytogenes. The pronounced antibacterial and biofilm-inhibitory properties of M. pulegium highlight its potential for pharmaceutical applications. Full article

Acne is a common skin disease that is closely associated with Cutibacterium acnes (C. acnes) and the inflammatory response it induces. Existing antibiotic treatments are often rendered ineffective due to the development of bacterial resistance, while Scutellaria barbata (SLB) has attracted widespread attention for its remarkable anti-inflammatory and antibacterial properties. However, its role in acne treatment has not been comprehensively studied. This study used high-performance liquid chromatography (HPLC) to analyze the bioactive components in a 70% ethanol extract of SLB. The antibacterial activity against C. acnes was systematically evaluated using well diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and biofilm formation assays. Additionally, the effects of SLB on nitric oxide (NO) production and phagocytic activity were tested in RAW 264.7 cells. An acne skin model was established by treating HaCaT keratinocytes with heat-inactivated C. acnes. The results demonstrated that SLB significantly inhibited the growth of C. acnes and disrupted its biofilm formation. Moreover, SLB markedly reduced the secretion of inflammatory cytokines such as interleukin (IL)-6, IL-1β, IL-8, and tumor necrosis factor (TNF)-α in HaCaT keratinocytes stimulated by C. acnes. Moreover, SLB effectively alleviated skin barrier damage caused by C. acnes by suppressing the expression of matrix metalloproteinases (MMPs)-1, -3, -9, and -13. In conclusion, this study demonstrates that SLB possesses potent antibacterial, anti-inflammatory, and barrier-protective properties, making it a promising candidate for developing anti-acne products and exploring alternative antibiotic therapies. Full article

A previous ethnobotanical investigation conducted in Valle Imagna (Northern Italy) highlighted the traditional use of Agrimonia eupatoria L. (Rosaceae) as a disinfectant and wound-healing agent. This use seemed to be linked to a local 18th century manuscript. This species was chosen for a multidisciplinary investigation to validate or refute its traditional use in the valley. Samples from fresh leaves were observed under Scanning Electron and Light Microscopy. The phenolic profiles of an epicuticular aqueous extract of the whole leaves and of infusions and decoctions of leaves and aerial parts were analyzed through Liquid Chromatography–Tandem Mass Spectrometry. The volatile organic compounds (VOCs) of fresh leaves were analyzed through Headspace Solid-Phase Microextraction coupled with Gas Chromatography–Mass Spectrometry. Growth inhibition and adhesion modulation were assessed on Escherichia coli, Staphylococcus aureus, and S. warneri by minimum inhibitory concentration and adhesion assays. Two trichome morphotypes were observed: a capitate with a one-celled rounded head and a capitate with a teo-celled cylindrical head. Both were responsible for producing terpenes, while the cylindrical capitates also produced polyphenols. Thirty-four phenolic compounds were characterized. Luteolin-7-O-glucoside, Catechin, and Epicatechin were common to all five extracts. The VOC profiles highlighted the dominance of (+)-α-Pinene. The infusions and the decoctions had a significant inhibitory activity on E. coli, and the extracts (specifically, the infusion of the leaves and both decoctions) also had a stimulating effect on the biofilm formation of S. warneri. These results already hold particular interest because of the strong connection they have to the traditional use of agrimony described in Valle Imagna. Full article

Background: Implants are integral to modern orthopedic surgery. The outcomes are good, but infections remain a serious issue. Staphylococcus aureus (S. aureus), along with Staphylococcus epidermidis, are predominant pathogens responsible for implant-associated infections, as conventional antibiotic treatments often fail due to biofilm formation or the pathogens’ ability to invade cells and to persist intracellularly. Objectives: This study therefore focused on interactions of S. aureus isolates from infected implants with MG63 and SaOS2 osteoblasts by investigating the adhesion, invasion, and the impact on the bioenergetics of osteoblasts. Methods and Results: We found that the ability of S. aureus to adhere to osteoblasts depends on the isolate and was not associated with a single gene or expression pattern of characteristic adhesion proteins, and further, was not correlated with invasion. However, analysis of invasion capabilities identified better invasion conditions for S. aureus isolates with the SaOS2 osteoblastic cells. Interestingly, metabolic activity of osteoblasts remained unaffected by S. aureus infection, indicating cell survival. In contrast, respiration assays revealed an altered mitochondrial bioenergetic turnover in infected cells. While basal as well as maximal respiration in MG63 osteoblasts were not influenced statistically by S. aureus infections, we found increased non-mitochondrial respiration and enhanced glycolytic activity in the osteoblasts, which was again, more pronounced in the SaOS2 osteoblastic cells. Conclusions: Our findings highlight the complexity of S. aureus-host interactions, where both the pathogen and the host cell contribute to intracellular persistence and survival, representing a major factor for therapeutic failures. Full article

Candida species, normally part of the healthy human flora, can cause severe opportunistic infections when their population increases. This risk is even greater in immunocompromised individuals. Women using intrauterine contraceptive devices (IUDs) are at higher risk for IUD-associated vulvovaginal candidiasis (VVC) because the device provides a surface for biofilm formation. This biofilm formation allows the normal flora to become opportunistic pathogens, leading to symptoms of VVC such as hemorrhage, pelvic pain, inflammation, itching and discharge. VVC is often linked to IUD use, requiring the prompt removal of these devices for effective treatment. This study evaluated the activity of the arginine-rich peptide “protamine” against Candida albicans, Candida tropicalis and Candida krusei isolated from IUD users who had signs of VVC. The antimicrobial activity was measured using the agar disk diffusion and microbroth dilution methods to determine the minimum inhibitory concentration (MIC). The MIC values of protamine against C. albicans, C. tropicalis and C. krusei are 32 μg mL⁻¹, 64 μg mL⁻¹ and 256 μg mL⁻¹, respectively. The determined MIC of protamine was used for a biofilm inhibition assay by crystal violet staining. Protamine inhibited the biofilm formation of the VVC isolates, and its mechanisms were studied through scanning electron microscopy (SEM) and a reactive oxygen species (ROS) assay. The disruption of cell membranes and the induction of oxidative stress appear to be key mechanisms underlying its anti-candidal effects. The results from an in vitro assay support the potential use of protamine as an antibiofilm agent to coat IUDs in the future for protective purposes. Full article

Pseudomonas aeruginosa is an opportunistic pathogen that causes nosocomial infections of the urinary tract, upper respiratory tract, gastrointestinal tract, central nervous system, etc. It is possible to develop bacteremia and sepsis in immunocompromised patients. A major problem in treatment is the development of antibiotic resistance. Therefore, new preparations of natural origin are sought, such as plant extracts, which are phytocomplexes and to which it is practically impossible to develop resistance. Geum urbanum L. (Rosacea) is a perennial herb known for many biological properties. This study aimed to investigate the redox-modulating capacity and effect of ethyl acetate (EtOAc) extracts from roots (EtOAcR) and aerial parts (EtOAcAP) of the Bulgarian plant on the phenotype inhibition of the P. aeruginosa Las/RhI quorum sensing (QS) system, which primarily determines drug resistance in pathogenic bacteria, including biofilm formation, motility, and pigment production. We performed QS assays to account for the effects of the two EtOAc extracts. At sub-minimal inhibitory concentrations (sub-MICs) ranging from 1.56 to 6.25 mg/mL, the biofilm formation was inhibited 85% and 84% by EtOAcR and 62% and 39% by EtOAcAP extracts, respectively. At the same sub-MICs, the pyocyanin synthesis was inhibited by 17–27% after treatment with EtOAcAP and 26–30% with EtOAcR extracts. The motility was fully inhibited at 3.12 mg/mL and 6.25 mg/mL (sub-MICs). We investigated the inhibitory potential of lasI, lasR, rhiI, and rhiR gene expression in biofilm and pyocyanin probes with the PCR method. Interestingly, the genes were inhibited by two extracts at 3.12 mg/mL and 6.25 mg/mL. Antiradical studies, assessed by DPPH, CUPRAC, and ABTS radical scavenging methods and superoxide anion inhibition showed that EtOAcAP extract has effective antioxidant capacity. These results could help in the development of new phytocomplexes that could be applied as biocontrol agents to inhibit the phenotype of the P. aeruginosa QS system and other antibiotic-resistant pathogens. Full article

Vibrios are naturally present in marine ecosystems and are commonly allied with live seafood. Vibrio species frequently cause foodborne infections, with Vibrio parahaemolyticus recently becoming a significant contributor to foodborne illness outbreaks. In response, aniline and 68 of its aniline derivatives were studied due to their antibacterial effects targeting V. parahaemolyticus and Vibrio harveyi. Among these, 4-amino-3-chloro-5-nitrobenzotrifluoride (ACNBF) and 2-iodo-4-trifluoromethylaniline (ITFMA) demonstrated both antibacterial and antibiofilm properties. The minimum inhibitory concentrations (MIC) for ACNBF and ITFMA were 100 µg/mL and 50 µg/mL, respectively, against planktonic cells. The active compounds effectively suppressed biofilm formation in a manner dependent on the dosage. Additionally, these trifluoro-anilines significantly reduced virulence factors such as motility, protease activity, hemolysis, and indole production. Both trifluoro-anilines caused noticeable destruction to the membrane of bacterial cells and, at 100 µg/mL, exhibited bactericidal activity against V. parahaemolyticus within 30 min. Toxicity assays using the Caenorhabditis elegans and seed germination models showed that the compounds displayed mild toxicity. As a result, ACNBF and ITFMA inhibited the growth of both planktonic cells and biofilm formation. Furthermore, these active compounds effectively prevented the formation of biofilm on the surfaces of shrimp and squid models, highlighting their potential use in controlling seafood contamination. Full article

Colistin-resistant Acinetobacter baumannii (COLR-Ab) is an opportunistic pathogen commonly associated with nosocomial infections, and it is difficult to treat with current antibiotics. Therefore, new antimicrobial agents need to be developed for treatment. Based on this information, we investigated the antimicrobial, antibiofilm, and combination activities of p-coumaric acid (p-CA), ferulic acid (FA), and p-methoxycinnamic acid (p-MCA) against five COLR-Ab isolates. p-CA, FA, and p-MCA exhibited antimicrobial activity against COLR-Ab isolates, with minimum inhibitory concentration (MIC) values in the range of 256–128 µg/mL, 1024–512 µg/mL, and 512–128 µg/mL, respectively. The combination effects of the compounds with colistin (COL) were evaluated using a checkerboard synergy test. The combinations exhibited a synergistic effect and caused a 128- to 16-fold decrease in COL MIC values. In addition, the biofilm production capacities of the COLR-Ab isolates and the antibiofilm activities of the compounds were determined using the microtitre plate-based crystal violet (CV) technique. The compounds showed effective antibiofilm activity against strong and moderate biofilm-producing isolates, inhibiting biofilm formation by 77.5% and 19.7%. Spectrometric measurements were used to examine the effect of compounds on membrane permeability; 1.9-, 1.66-, and 1.34-fold increases in absorbance values were observed at MIC concentrations of p-CA, FA, and p-MCA, respectively. Furthermore, morphological changes caused by the compounds in the isolate were observed using scanning electron microscopy (SEM) micrographs. According to the WST assay, the compounds did not show any statistically significant cytotoxic effect on the cells (p > 0.05). These findings indicate that p-CA, FA, and p-MCA may be potential new alternative candidates against resistant A. baumannii. Full article

Background: Thermophilic Campylobacter species are among the main culprits behind bacterial gastroenteritis globally and have grown progressively resistant to clinically important antimicrobials. Many studies have been carried out to explore innovative and alternative strategies to control antibiotic-resistant campylobacters in animal reservoirs and human hosts; however, limited studies have been performed to develop efficient control schemes against Campylobacter biofilms. Methods: This study investigated the antimicrobial and antibiofilm activities of some herbal extracts against multidrug-resistant (MDR) Campylobacter species recovered from different sources using phenotypic and molecular techniques. Results: The overall Campylobacter species prevalence was 21.5%, representing 15.25% and 6.25% for C. jejuni and C. coli, respectively. Regarding C. jejuni, the highest resistance rate was observed for amoxicillin–clavulanic acid and colistin (85.25% each), followed by cefotaxime (83.61%) and tetracycline (81.97%), whereas C. coli isolates showed absolute resistance to cefotaxime followed by erythromycin (92%) and colistin (88%). Remarkably, all Campylobacter isolates were MDR with elevated multiple antimicrobial resistance (MAR) indices (0.54–1). The antimicrobial potentials of green tea (Camellia sinensis), rosemary (Rosmarinus officinalis) and ginger (Zingiber officinale) extracts against MDR Campylobacter isolates were assessed by the disk diffusion assay and broth microdilution technique. Green tea extract showed a marked inhibitory effect against tested isolates, exhibiting growth inhibition zone diameters of 8 to 38 mm and a minimum inhibitory concentration (MIC) range of 1.56–3.12 mg/mL, unlike the rosemary and ginger extracts. Our findings reveal a respectable antibiofilm activity (>50% biofilm formation inhibition) of green tea against the preformed biofilms of Campylobacter isolates. Furthermore, real-time quantitative polymerase chain reaction (RT-qPCR) results showed a significant decrease (p < 0.05) in the expression levels of biofilm biosynthesis gene and its regulator (FlaA and LuxS, respectively) in Campylobacter isolates treated with the green tea extract in comparison with untreated ones. Conclusion: This is the first in vitro approach that has documented the inhibitory activity of green tea extract against MDR-biofilm-producing Campylobacter species isolated from different sources. Further in vivo studies in animals’ models should be performed to provide evidence of concept for the implementation of this alternative candidate for the mitigation of MDR Campylobacter infections in the future. Full article

In this study, we investigated the interactions between Candida auris and C. albicans, C. tropicalis, C. glabrata, and C. krusei in mixed infections. Initially, these interactions were studied qualitatively and quantitatively in dual-species biofilms formed in vitro. The MTT assays, determination of the total CFU/mL, and SEM analysis showed that C. auris interacted differentially with the other Candida spp. during the dual-species biofilm formation. Depending on the stage of the biofilm development, C. auris was found to be a particularly dominant species during its interaction with the C. krusei biofilms but significantly submissive in the C. auris-C. albicans biofilms. These studies were then extended to in vivo host models of experimental candidiasis. G. mellonella larvae were inoculated with monotypic and heterotypic suspensions of Candida. The survival rates and quantification of fungal cells in the hemolymph showed that the highest mortality was exhibited by larvae in the C. auris-C. albicans co-infection (100% mortality after 36 h). The CFU/mL values of C. auris from the larval hemolymph were lower in the interactive groups compared to the mono-species group. As a newly emerging species, C. auris persists in environments in the presence of other Candida species and is involved in both competitive and noncompetitive interactions with other Candida species during biofilm formation and development of experimental candidiasis. Full article

Listeria monocytogenes is a Gram-positive bacterium causing listeriosis, a severe infection responsible for significant morbidity and mortality globally. Its persistence on food processing surfaces via biofilm formation presents a major challenge, as conventional sanitizers and antimicrobials exhibit limited efficacy against biofilm-embedded cells. This study investigates a novel approach combining an engineered polysaccharide-degrading enzyme (CAase) with a bacteriocin (thermophilin 110) produced by Streptococcus thermophilus. Laboratory assays evaluated the effectiveness of this combination in disrupting biofilms and inactivating L. monocytogenes on various surfaces. The results demonstrated that CAase effectively disrupts biofilm structures, while thermophilin 110 significantly reduces bacterial growth and viability. The preliminary trials indicate a dual-action approach offers a potential alternative to conventional treatments, enhancing food safety by effectively controlling Listeria biofilms in food processing environments. Full article

Background/Objectives: According to the One Health concept, wild birds can be indicators of ecosystem pollution and disease incidence. Escherichia coli strains are widespread worldwide, but there are still few reports on the association of human infections with a potential reservoir of highly pathogenic human strains in wild birds. Fecal E. coli with uropathogenic potential (UPEC) can be transmitted between birds and humans and may be a risk factor for urinary tract infections (UTIs). Results: The results showed that above 50% of the isolates were grouped as highly pathogenic, according to Clermont phylogroup classification. Such strains were found to be stronger biofilm producers, with a higher adherence of monocytes than low pathogenic. However, the highest cytotoxicity was observed for strains described as aquatic environmental. Convergence of the results of the analysis of monocyte activation by E. coli strains and the ability to form biofilm by individual phylogroups of the strains tested was demonstrated. Genetic determinants of the uropathogenicity of E. coli (UPEC) correlate with the evidence of strain pathogenicity during monocyte activation in in vitro assays. Methods: In this study, we assessed the virulence potential of environmental strains isolated from wild waterfowl using genetic analysis (Clermont phylogroup classification) and phenotypic methods, including analysis of the human monocyte response to biofilm formation. The estimation of the ability to form biofilms was tested using crystal violet, and the pathogenic potential of strains by monocyte activation assay including changes in morphology, adhesion and cytotoxicity. Conclusions: In conclusion, the virulence of E. coli strains isolated from free-living birds is significant, and they can be considered environmental reservoirs of pathogenic strains. According to our observations, they can be responsible for the dissemination of uropathogenic strains among humans. Full article

This study evaluated the microbial growth profile of subgingival multispecies biofilm on 3D-printable resin-based composites (PRBCs). A 96-well cell plate cultivated a 39-species biofilm associated with periodontitis over 7 days. Cylindrical specimens with 12 mm high and 3 mm diameters were prepared by the PRBC group (Cosmos Temp-Yller; Prizma 3D Bio Crown; Prizma 3D Bio Prov) and an acrylic resin as control. Further, these specimens were immersed in the well plate to allow biofilm formation. After growing for 7 days, the metabolic biofilm activity was evaluated by colorimetric assay and the microbial profile by DNA-DNA hybridization. Kruskal–Wallis and Mann–Whitney tests evaluated each bacteria count and complex group. A greater biofilm formation was observed on PRBC groups than on acrylic resin. The microbiological profile of PRBC was associated with a less pathogenic biofilm, with an absence of a red complex. Acrylic resin showed low biofilm growth, but the biofilm profile was related to periodontal disease, characterized by red-complex bacteria. The selection of PRBC may contribute more effectively to maintaining periodontal health than acrylic resin. Full article

Background: The emergence of antibiotic-resistant bacteria, including Staphylococcus epidermidis, underscores the need for novel antimicrobial agents. Celastrol, a natural compound derived from the plants of the Celastraceae family, has demonstrated promising antibacterial and antibiofilm properties against various pathogens. Objectives: This study aims to evaluate the antibacterial effects, mechanism of action, and antibiofilm activity of celastrol against S. epidermidis, an emerging opportunistic pathogen. Methods: To investigate the mechanism of action of celastrol, its antibacterial activity was evaluated by determining the time–kill curves, assessing macromolecular synthesis, and analysing its impact on the stability and functionality of the bacterial cell membrane. Additionally, its effect on biofilm formation and disruption was examined. Results: Celastrol exhibited significant antibacterial activity with a minimal inhibitory concentration (MIC) of 0.31 μg/mL and minimal bactericidal concentration (MBC) of 15 μg/mL, which is superior to conventional antibiotics used as control. Time–kill assays revealed a concentration-dependent bactericidal effect, with a shift from bacteriostatic activity at lower concentrations to bactericidal and lytic effect at higher concentrations. Celastrol inhibited cell wall biosynthesis by blocking the incorporation of N-acetylglucosamine (NAG) into peptidoglycan. In contrast, the cytoplasmic membrane was only affected at higher concentrations of the compound or after prolonged exposure times. Additionally, celastrol was able to disrupt biofilm formation at concentrations of 0.9 μg/mL and to eradicate pre-formed biofilms at 7.5 μg/mL in S. epidermidis. Conclusions: Celastrol exhibits significant antibacterial and antibiofilm activities against S. epidermidis, with a primary action on cell wall synthesis. Its efficacy in disrupting the formation of biofilms and pre-formed biofilms suggests its potential as a therapeutic agent for infections caused by biofilm-forming S. epidermidis resistant to conventional treatments. Full article

Candida forms a gel-like biofilm in the Foley’s catheter (FC) causing tenacious biofouling and severe urinary tract infections (UTIs). For the first time, a spice extract-based antifungal lock therapy (ALT) has been developed to inhibit the Candida albicans gel matrix in FC. Aqueous extracts of garlic, clove, and Indian gooseberry were used as ALT lock solutions and tested against biofilm-forming multidrug-resistant clinical isolates of C. albicans. Reduction in the gel matrices formation in the catheter was confirmed by Point inoculation, MTT assay, CFU, and SEM analysis at 12 and 24 h of incubation. Garlic was effective in controlling both C. albicans M207 and C. albicans S470; however, clove and gooseberry effectively controlled the latter. As evidenced by CFU assay, there were 82.85% and 99.68% reductions in the growth of C. albicans M207 and S470, respectively, at 24 h of incubation. SEM revealed a switch from the biofilm to the yeast mode and a drastic reduction in cell numbers, with mostly clumped or lysed cells. The study will provide an impetus to the development of novel spice extract-based ALT, reducing the selection pressure on the pathogen and lowering antimicrobial resistance. Further research in this area has the potential to leverage clinical applications. Full article