Levofloxacin combined with cellulase can eradicate bacille Calmette-Guerin biofilm infection / 南方医科大学学报

OBJECTIVE@#To investigate the inhibitory effects of levofloxacin (LEV) combined with cellulase against bacille CalmetteGuerin (BCG) biofilms in vitro.@*METHODS@#The mature growth cycle of BCG biofilms was determined using the XTT method and crystal violet staining. BCG planktonic bacteria and BCG biofilms were treated with different concentrations of LEV and cellulose alone or jointly, and the changes in biofilm biomass were quantified with crystal violet staining. The mature BCG biofilm was then treated with cellulase alone for 24 h, and after staining with SYTO 9 and Calcofluor White Stain, the number of viable bacteria and the change in cellulose content in the biofilm were observed with confocal laser scanning microscopy. The structural changes of the treated biofilm were observed under scanning electron microscopy.@*RESULTS@#The MIC, MBC and MBEC values of LEV determined by broth microdilution method were 4 μg/mL, 8 μg/mL and 1024 μg/mL, respectively. The combined treatment with 1/4×MIC LEV and 2.56, 5.12 or 10.24 U/mL cellulase resulted in a significant reduction in biofilm biomass (P < 0.001). Cellulase treatments at the concentrations of 10.24, 5.12 and 2.56 U/mL all produced significant dispersion effects on mature BCG biofilms (P < 0.001).@*CONCLUSION@#LEV combined with cellulose can effectively eradicate BCG biofilm infections, suggesting the potential of glycoside hydrolase therapy for improving the efficacy of antibiotics against biofilmassociated infections caused by Mycobacterium tuberculosis.

Preparation, Characterization Of Silver-Nanoparticles From Seed Coat Exudates Of Celastrus Paniculatus Willd. And Their Bactericidal And Biofilm Inhibition Effects

We are reporting a novel approach for preparing silver nanoparticles with seed coat exudates of Celastrus paniculatus Willd, a medicinal plant traditionally used for the treatment of skin diseases, fever, leprosy and neurological disorders. HPTLC study revealed that aqueous, soluble seed coat exudates contain phenolics, alakaloids and flavonoids. The formation, crystalline nature and morphology of the nanoparticles were identified by UV–Vis spectroscopy, X-ray Diffraction (XRD) analysis, Transmission Electron Microscopy (TEM) and selected-area electron diffraction (SAED). Functional group stretching of aqueous soluble extracts was identified by using FTIR. Results revealed that nanosilver particles are spherical, range in size from 10 to 82 nm and crystalize in face-centered cubic structures. Surface-enhanced Raman spectra analysis showed that AgNP are capped with bioactive molecules from exudates and that they may act as precursors of the reduction of silver nitrate from the metallic state (Ag+) to the atomic state (Ag0). We also examined the minimal inhibitory concentration for bacteria Escherichia coli and Bacillus subtilis using a resazurin color assay. Nanosilver strongly inhibited the bacterial growth, leading to MIC values of 40µg/ml and 60µg/ml for the bacteria, respectively. The colony screening method and inhibition kinetics of biofilm formation in the Klebsiella pneumoniae strain were also studied using the tube method and a quantitative microplate assay. SEM analysis and quantification of the EPS revealed a fivefold decrease in concentration in treated compared to untreated. The inhibition response was duly reflected in SEM images.

Antifungal activity of some Sternbergia taxa: effects on germ tube and biofilm formation

Natural products are rapidly becoming the primary sources of novel antimicrobial agents, as resistance to existing antimicrobial agents is increasing. Apart from determining the antimicrobial activity of natural products, it is also important to understand their effects on the virulence factors of microorganisms. This study aimed to determine the antimicrobial activity of Sternbergia species prevalent in Turkey and investigate their role in the inhibition of germination tube and biofilm formation, both of which are known to be important virulence factors of Candida albicans. The antimicrobial activities of the plant extracts were evaluated using bore-plate and broth microdilution method. The extracts' capacity to inhibit the formation of the germ-tube was also evaluated. The findings of our study revealed that Sternbergia lutea, Sternbergia vernalis possessed antimicrobial activities, with MIC values ranging between 0.048 mg/mL and 0.39 mg/mL. The highest antimicrobial activity was observed against Candida dubliniensis (0.048 mg/mL). While evaluating the inhibition of fungal germination activities, S. vernalis extract (at a concentration of 0.09 mg/mL) was found to be the most effective against C. albicans ATCC 90028 strain. The results also indicated that S. vernalis extracts at sub-MIC levels inhibited germ tube formation and modulated the tail-length of germinated cells, both of which are important virulence factors of C. albicans. Furthermore, the inhibition of biofilm-formation was also investigated, and it was found that two Sternbergia spp. extracts at or below MIC levels inhibited biofilm formation.

Inhibitory effect of 18β-glycyrrhetinic acid on the biofilm formation of Streptococcus mutans / 대한구강보건학회지

OBJECTIVES: The present study aimed at investigating the potential of using 18β-glycyrrhetinic acid against the cariogenic characteristics of Streptococcus mutans UA159. METHODS: The effects of 18β-glycyrrhetinic acid on biofilm formation and acid production were evaluated; the latter are indicators of cariogenicity of S. mutans. Biofilm architecture was also analyzed by scanning electron microscopy (SEM), and changes in gene expression related to biofilm formation were studied by quantitative RT-PCR. RESULTS: Treatment with 18β-glycyrrhetinic acid at a concentration of 20 µg/ml inhibited biofilm formation by 95% in the absence of sucrose and 60% in its presence, reduced acid production by 88.8%, and significantly suppressed the gene expression of comDE, gbpB, gtfC and vicR, which are thought to be involved in the virulence of S. mutans. CONCLUSIONS: These results suggest that 18β-glycyrrhetinic acid could be used as a complementary or alternative agent for preventing dental caries by interfering with the virulence properties of S. mutans without affecting the viability of the bacterial population.

Synthesis of Selenium Nanoparticles by Bacillus laterosporus Using Gamma Radiation.

Aim: This study shows the possible synthesis of Selenium Nanoparticles (SeNPs) in aerobic optimized conditions using Bacillus laterosporus (B. laterosporus) bacterial strain. Methodology: B. laterosporus was used to reduce selenium ions (selenite anions) to SeNPs by fermentation in Luria-Bertani Enrichment (EM) medium. Optimization of fermentation conditions using two-level full factorial design was performed. SeNPs were further characterized by UV-Vis., DLS, TEM, FT-IR, EDX and XRD analysis. SeNPs synthesis by Gamma irradiated B. laterosporus cells at different radiation doses was reported. Evaluation the probability of B. laterosporus to synthesis SeNPs by fermentation in skimmed milk aerobically. A microtiterplate assay was used to evaluate the ability of SeNPs to inhibit the biofilm formation of Pseudomonas aeruginosa. Evaluating the antimicrobial activity of some antibiotic agents upon addition of SeNPs was performed. Results: B. laterosporus reduced the soluble, toxic, colorless selenium ions to the insoluble, non-toxic, red elemental SeNPs. Statistical analysis showed that the results were normally distributed. Temperature, incubation period and pH were significant factors in the fermentation process, in which the maximum SeNPs produced (8.37μmole/ml) was at temperature 37ºC, incubation period 48hr, pH7. The Gamma radiation exposure dose 1.5kGy gave the maximum SeNPs produced (10.01 μmole/ml). A pink color appear in the fermented milk revealing the formation of SeNPs-enriched milk. SeNPs inhibit the biofilm formation of Pseudomonas aeruginosa with a percentage reduction of 99.7%. SeNPs increase the antibacterial activity of fucidic acid by 13.6% and 28.5% against Escherichia coli and Staphylococcus aureus respectively. But with Gentamycin sulphate, no change in the antibacterial activity. Conclusion: SeNPs can be synthesized aerobically by the probiotic B. laterosporus bacterial strain. SeNPs can be incorporated in nutraceuticals and functional foods like milk also can be used to inhibit the bacterial biofilm formation and can be added to some antibacterial creams to enhance their antimicrobial activity.

Identification of natural compounds which inhibit biofilm formation in clinical isolates of Klebsiella pneumoniae.

Klebsiella pneumoniae, an important opportunistic pathogen, exists as a biofilm in persistent infections and in-dwelling medical devices. With the objective of identifying natural compounds inhibiting biofilm formation in K. pneumoniae, 35clinical isolates were screened,out of which 7 strong biofilm producers were identified. Six natural compounds were tested for their inhibitory effects on bacterial growth and biofilm formation by determining the minimum inhibitory concentration and minimum concentration for biofilm inhibition (MBIC) for each compound. The results show that reserpine followed by linoleic acid, were the most potent biofilm inhibitors. Reserpine, an efflux pump inhibitor was effective at biofilm inhibition at a concentration of 0.0156 mg/mL, 64-fold lower concentration than its MIC. Linoleic acid, an essential fatty acid was effective as a biofilm inhibitor at 0.0312 mg/mL, which is 32-fold lower than its MIC. Berberine, another plant derived antimicrobial, chitosan and eugenol had an MBIC value of 0.0635 mg/mL. Curcumin, a natural phenolic compound was effective at biofilm inhibition at a concentration of 0.25 mg/mL, which is 50 fold less than its MIC. Notably, the MIC and MBIC data on these 6 natural compounds was reproducible in all seven high biofilm forming isolates of K. pneumoniae. The present report is a comprehensive comparative analysis of the dose dependent inhibition of various natural compounds on biofilm formation in K. pneumoniae.

Screening of medicinal plants for antibacterial activities on Staphylococcus aureus strains isolated from bovine mastitis / Screening de plantas medicinais com atividade antimicrobiana contra cepas de Staphylococcus aureus isoladas de mastite bovina

Staphylococcus aureus is the main causative agent of bovine mastitis. The activity of several extracts from ten medicinal plants traditionally used in Brazil as antiseptic was investigated against fifteen strains of Staphylococcus aureus isolated from animals with mastitis manifestation by the disc diffusion method and broth microdilution assay. The interference of the extracts on cell in the form of adherent colonies was also evaluated. MIC values ranged from 0.5 mg/mL to 1.0 mg/mL and biofilm inhibitory concentration (BIC) were between 0.25 mg/mL and 0.8 mg/mL. Results revealed the potential of extracts of Senna macranthera, Artemisia absinthium, Cymbopogon nardus and Baccharis dracunculifolia as antibacterial agents against S. aureus strains isolated from bovine mastitis and support the possible use of these phytotherapic agents in the clinical management of the disease.

Staphylococcus aureus é o principal agente causador de mastite bovina. A atividade de diversos extratos de dez plantas medicinais tradicionalmente usadas no Brasil como anti-sépticas foi investigada contra quinze cepas de Staphylococcus aureus isoladas de animais com manifestação de mastite pelo método de difusão em ágar e ensaio de microdiluição. A interferência dos extratos na célula bacteriana em forma de colônias aderidas também foi avaliada. Os valores de MIC variaram de 0.5 mg/mL a 1.0 mg/mL e a concentração inibitória de biofilme (BIC) variou de 0.25 mg/mL a 0.8 mg/mL. Os resultados revelaram o potencial dos extratos de Senna macranthera, Artemisia absinthium, Cymbopogon nardus e Baccharis dracunculifolia como agentes antibacterianos contra cepas de S. aureus isolados de mastite bovina e suportam o possível uso destas plantas no manejo clínico da doença.