Different extracts of Zingiber officinale decrease Enterococcus faecalis infection in Galleria mellonella

Antibiofilm action of Persea americana glycolic extract over Acinetobacter baumannii and absence of toxicity in Galleria mellonella

OBJECTIVES

This study aimed to evaluate the antibiofilm activity and toxicity of the glycolic extract of Persea americana "P. americana" over multidrug-resistant strains of Acinetobacter baumannii "A. baumannii" as alternative therapy to be investigated.

METHODS

A bacterial inoculum of each bacterial strain (4a, 5a, 9a, 12a, ATCC 19606) of A. baumannii was prepared and adjusted by the spectrophotometer. The microdilution broth method was performed to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). P. americana glycolic extracts were obtained of the tree stalk and leaves. The biofilm viability was tested by MTT assay after 5 min exposure. The toxicity of the extracts was tested by invertebrate model Galleria mellonella. The data were analyzed by ANOVA, Tukey test and log-rank method (α=0.05).

RESULTS

The extract showed an inhibitory and bactericidal action over all the tested strains with the lowest MIC value observed for the reference strain (3.12 mg/mL). The extract did not demonstrate toxicity in any of the tested concentrations (12.5, 25 and 50 mg/mL) in Galleria mellonella larvae, with a survival percentage above 80% after 168 h.

CONCLUSIONS

The glycolic extract of P. americana has microbicidal and antibiofilm activity on multidrug-resistant clinical strains of A. baumannii and showed low toxicity for the invertebrate model G. mellonella.

The biocompatibility and antifungal effect of Rosmarinus officinalis against Candida albicans in Galleria mellonella model

This study was performed to evaluate the biocompatibility and antifungal effect of Rosmarinus officinalis against Candida albicans in Galleria mellonella model. Five different concentrations of R. officinalis glycolic extract (50; 25; 12.5 e 6.25 mg/mL) were used to evaluate its biocompatibility in G. mellonella model, in which the nystatin suspension (100; 50; 25; 12.5 e 6.25%) was used as a control group. The antifungal action of R. officinalis glycolic extract was evaluated on C. albicans for 72, 48 and 12 h at two different phases: (1) using the extract as therapeutic agent; and (2) using the extract as prophylactic agent. PBS was used as a negative control group. G. mellonella survival curves were plotted using the Kaplan–Meier method and statistical analysis was performed using the log-rank test (Mantel–Cox) and the significance level was set at (α ≤ 0.05). There was no significant difference among the groups in which all were biocompatible except of a significant death rate of 26.6% with nystatin 100%. In phase 1, it was found that after 7 days, there was no statistically significant difference among the prophylactic treatment groups. In phase 2, the groups of R. officinalis 6.25 mg/mL for 72 h and R. officinalis of 12.5 mg/mL for 24 h promoted the survival rate of the larvae in comparison with the control group with a significant difference (p = 0.017) and (p = 0.032) respectively. Therefore, R. officinalis extract is biocompatible in different concentrations and can be used as a prophylactic agent against fungal infection.

Natural latex serum: characterization and biocompatibility assessment using Galleria mellonella as an alternative in vivo model

Natural latex serum (NLS) is one of the natural rubber latex fractions from Hevea brasiliensis tree, which is formed by centrifuged serum and is composed of proteins, acids, nucleotides, salts and carbohydrates. The proteins present in NLS have demonstrated several interesting biological properties, including angiogenic, healing, osteogenic, anti-inflammatory, antimicrobial, in addition to inducing neovascularization, bone formation and osseointegration. Thus, we proposed to characterize NLS by physicochemical techniques and to investigate the biocompatibility by toxicological assays and safety test in Galleria mellonella. Infrared spectrum showed vibrational bands characteristic of amide I, II and III that are linked to the protein content, which was confirmed by the High Performance Liquid Chromatography profile and by the Electrophoresis analysis. This material did not exhibit hemolytic (rate <0.5%) and cytotoxic effects (viability >70%) and was able to enhance the proliferation of fibroblasts (>600%) after 3 days. The pronounced proliferative effect observed in fibroblast cells can be explained by the presence of the fibroblast growth factor (FGF) like protein revealed by the Western blot test. Moreover, NLS did not provoke toxic effects (survival ∼ 80%) on the G. mellonella model, indicating that it is a biocompatible and safe material.

Genomics and Virulence of Fonsecaea pugnacius, Agent of Disseminated Chromoblastomycosis

Among agents of chromoblastomycosis, Fonsecaea pugnacius presents a unique type of infection because of its secondary neurotropic dissemination from a chronic cutaneous case in an immunocompetent patient. Neurotropism occurs with remarkable frequency in the fungal family Herpotrichiellaceae, possibly associated with the ability of some species to metabolize aromatic hydrocarbons. In an attempt to understand this new disease pattern, were conducted genomic analysis of Fonsecaea pugnacius (CBS 139214) performed with de novo assembly, gene prediction, annotation and mitochondrial genome assembly, supplemented with animal infection models performed with Tenebrio molitor in Mus musculus lineages BALB/c and C57BL/6. The genome draft of 34.8 Mb was assembled with a total of 12,217 protein-coding genes. Several proteins, enzymes and metabolic pathways related to extremotolerance and virulence were recognized. The enzyme profiles of black fungi involved in chromoblastomycosis and brain infection were analyzed with the Carbohydrate-Active Enzymes (CAZY) and peptidases database (MEROPS). The capacity of the fungus to survive inside Tenebrio molitor animal model was confirmed by histopathological analysis and by presence of melanin and hyphae in host tissue. Although F. pugnacius was isolated from brain in a murine model following intraperitoneal infection, cytokine levels were not statistically significant, indicating a profile of an opportunistic agent. A dual ecological ability can be concluded from presence of metabolic pathways for nutrient scavenging and extremotolerance, combined with a capacity to infect human hosts.

Diffusion of hydroxyl ion on external root surface using different irrigating solutions: An In vitro study

AIMS

The aim of this study was to evaluate the diffusion of hydroxyl ion to the external root surface using different irrigating solutions and intracanal medication with calcium hydroxide.

MATERIALS AND METHODS

Sixty bovine tooth roots were randomly divided into six experimental groups (n = 10), according to the irrigating substance used during biomechanical preparation: 12% glycolic propolis extract (PROP); 20% glycolic ginger extract (GENG); 2% sodium hypochlorite with surfactant (NaOClS); 2% chlorhexidine gel (CLX); 2.5% sodium hypochlorite (NaOCl); and physiological saline solution. After filling the root canals with calcium hydroxide paste, pH measurements were taken directly at the external cavities over time intervals of up to 30 days.

STATISTICAL ANALYSIS USED

Data were submitted to two-way ANOVA and Tukey's test (P < 0.05).

RESULTS

The pH of the external root surface was increased when the surfactant associated with NaOCl was used. However, the pH values were very close for the different groups. Hydroxyl ion diffusion up to the external root surface did not exceed the pH value of 8.5, and in the hollow passage of the canal, the pH was higher than 12.

CONCLUSIONS

Hydroxyl ion diffusion of calcium hydroxide paste through the dentinal tubules up to the external root surface allows minimal alkalinization of this surface, and it is greater when using NaOCl with surfactant during biomechanical preparation.

Evaluation of Phage Therapy in the Context of Enterococcus faecalis and Its Associated Diseases

Bacteriophages (phages) or bacterial viruses have been proposed as natural antimicrobial agents to fight against antibiotic-resistant bacteria associated with human infections. Enterococcus faecalis is a gut commensal, which is occasionally found in the mouth and vaginal tract, and does not usually cause clinical problems. However, it can spread to other areas of the body and cause life-threatening infections, such as septicemia, endocarditis, or meningitis, in immunocompromised hosts. Although E. faecalis phage cocktails are not commercially available within the EU or USA, there is an accumulated evidence from in vitro and in vivo studies that have shown phage efficacy, which supports the idea of applying phage therapy to overcome infections associated with E. faecalis. In this review, we discuss the potency of bacteriophages in controlling E. faecalis, in both in vitro and in vivo scenarios. E. faecalis associated bacteriophages were compared at the genome level and an attempt was made to categorize phages with respect to their suitability for therapeutic application, using orthocluster analysis. In addition, E. faecalis phages have been examined for the presence of antibiotic-resistant genes, to ensure their safe use in clinical conditions. Finally, the domain architecture of E. faecalis phage-encoded endolysins are discussed.

Recent Advances in the Use of Galleria mellonella Model to Study Immune Responses against Human Pathogens

The use of invertebrates for in vivo studies in microbiology is well established in the scientific community. Larvae of Galleria mellonella are a widely used model for studying pathogenesis, the efficacy of new antimicrobial compounds, and immune responses. The immune system of G. mellonella larvae is structurally and functionally similar to the innate immune response of mammals, which makes this model suitable for such studies. In this review, cellular responses (hemocytes activity: phagocytosis, nodulation, and encapsulation) and humoral responses (reactions or soluble molecules released in the hemolymph as antimicrobial peptides, melanization, clotting, free radical production, and primary immunization) are discussed, highlighting the use of G. mellonella as a model of immune response to different human pathogenic microorganisms.

A Model for Trans-Kingdom Pathogenicity in Fonsecaea Agents of Human Chromoblastomycosis

The fungal genus Fonsecaea comprises etiological agents of human chromoblastomycosis, a chronic implantation skin disease. The current hypothesis is that patients acquire the infection through an injury from plant material. The present study aimed to evaluate a model of infection in plant and animal hosts to understand the parameters of trans-kingdom pathogenicity. Clinical strains of causative agents of chromoblastomycosis (Fonsecaea pedrosoi and Fonsecaea monophora) were compared with a strain of Fonsecaea erecta isolated from a living plant. The clinical strains of F. monophora and F. pedrosoi remained concentrated near the epidermis, whereas F. erecta colonized deeper plant tissues, resembling an endophytic behavior. In an invertebrate infection model with larvae of a beetle, Tenebrio molitor, F. erecta exhibited the lowest survival rates. However, F. pedrosoi produced dark, spherical to ovoidal cells that resembled muriform cells, the invasive form of human chromoblastomycosis confirming the role of muriform cells as a pathogenic adaptation in animal tissues. An immunologic assay in BALB/c mice demonstrated the high virulence of saprobic species in animal models was subsequently controlled via host higher immune response.

Influence of Zingiber officinale Extract on Push-Out Bond Strength of Glass-Fiber Post

The aim of this study was to evaluate in vitro the influence of 20% glycolic ginger extract on the bond strength of glass-fiber post cemented with etch-and-rinse or self-etching resin cement. Forty-eight bovine roots were standardized (17±0.5 mm) and randomly divided into two groups, according to irrigant used during biomechanical preparation: NaOCl: 1% sodium hypochlorite and GEN: 20% glycolic ginger extract. Root canal was prepared and randomly assigned to one of two subgroups (n=12), according to luting protocol: self-etching (RelyX U200) and etch-and-rinse (RelyX ARC). After 48 h, the roots were sectioned perpendicularly (4 in cervical third and 3 in middle third) and submitted to push-out bond strength test (50 kgf load cell, 1.0 mm/min). Failure mode was analyzed in SEM and stereomicroscopy. Data were analyzed by three-way ANOVA and Tukey tests (p<0.05). ANOVA revealed that there were no significant differences between U200 (2.01±0.17)B and ARC (1.93±0.12)B in GEN group, and at the cervical third for both irrigants, 2.69±0.16A and 2.54±0.17A, respectively. Middle third showed lower bond strength than cervical third, regardless the irrigant. Overall, the cervical third regardless the irrigant employed and the association between NaOCl and ARC, presented better adhesive performance.

Immunomodulatory effect of photodynamic therapy in Galleria mellonella infected with Porphyromonas gingivalis

Porphyromonas gingivalis is an important pathogen in the development of periodontal disease. Our study investigated if the treatment with antimicrobial photodynamic therapy (aPDT) that employs a nontoxic dye, followed by irradiation with harmless visible light can attenuate the experimental infection of P. gingivalis in Galleria mellonella. Firstly, different concentrations of P. gingivalis ranging from 10² to 10⁶ cells/larva were injected into the animal to obtain a lethal concentration. Next, the following groups of G. mellonella infected with P. gingivalis were evaluated: inoculation of the photosensitizer and application of laser (P + L+), inoculation of physiologic solution and application of laser (P-L+), inoculation the photosensitizer without laser (P + L-) and inoculation of physiologic solution without Laser (P-L-). The effects of aPDT on infection by P. gingivalis were evaluated by survival curve analysis and hemocytes count. A lethal concentration of 10⁶ cells/larva was adopted for evaluating the effects of aPDT on experimental infection with P. gingivalis. We found that after 120 s of PDT application, the death of G. mellonella was significantly lower compared to the control groups (p = 0.0010). Moreover, the hemocyte density in the P+L+ group was increased by 9.6 × 10⁶ cells/mL (2.62-fold increase) compared to the infected larvae with no treatment (L-P- group) (p = 0.0175). Finally, we verified that the aPDT led to a significant reduction of the number of P. gingivalis cells in G. mellonella hemolymph. In conclusion, PDT application was effective against P. gingivalis infection by increasing the survival of G. mellonella and was able to increase the circulating hemocytes indicating that PDT activates the G. mellonella immune system.

Immunity of the greater wax moth Galleria mellonella

Investigation of insect immune mechanisms provides important information concerning innate immunity, which in many aspects is conserved in animals. This is one of the reasons why insects serve as model organisms to study virulence mechanisms of human pathogens. From the evolutionary point of view, we also learn a lot about host-pathogen interaction and adaptation of organisms to conditions of life. Additionally, insect-derived antibacterial and antifungal peptides and proteins are considered for their potential to be applied as alternatives to antibiotics. While Drosophila melanogaster is used to study the genetic aspect of insect immunity, Galleria mellonella serves as a good model for biochemical research. Given the size of the insect, it is possible to obtain easily hemolymph and other tissues as a source of many immune-relevant polypeptides. This review article summarizes our knowledge concerning G. mellonella immunity. The best-characterized immune-related proteins and peptides are recalled and their short characteristic is given. Some other proteins identified at the mRNA level are also mentioned. The infectious routes used by Galleria natural pathogens such as Bacillus thuringiensis and Beauveria bassiana are also described in the context of host-pathogen interaction. Finally, the plasticity of G. mellonella immune response influenced by abiotic and biotic factors is described.

Punica granatum L. (Pomegranate) Extract: In Vivo Study of Antimicrobial Activity against Porphyromonas gingivalis in Galleria mellonella Model

Due to the increase of bacterial resistance, medicinal alternatives are being explored. Punica granatum L. is an effective herbal extract with broad spectrum of action and bactericidal, antifungal, anthelmintic potential and being able to modulate the immune response. The aim was to evaluate the antimicrobial activity of pomegranate glycolic extract (PGE) against the periodontal pathogen Porphyromonas gingivalis by using Galleria mellonella as in vivo model. Fifteen larvae were used per group. Injection of high concentration (200, 100, and 25 mg/mL) of PGE showed a toxic effect, leading them to death. A suspension of P. gingivalis (10⁶ cells/mL) was inoculated in the left last proleg and PGE (12.5, 6.25, 3.1, and 2.5 mg/mL) were injected into the right proleg. The larvae were then kept at 37°C under the dark. Injection of PGE at any dose statistically improved larvae survival rates. The data were analysed (log-rank test, Mantel-Cox, P < 0.05) and showed that all concentrations of PGE (12.5, 6.25, 3.1, and 2.5 mg/mL) presented higher larval survival rates, with significant statistical difference in relation to control group (P. gingivalis). In conclusion, the PGE had antimicrobial action against P. gingivalis in vivo model using G. mellonella.