Synergistic Activity of Antibiotics and Bioactive Plant Extracts: A Study Against Gram-Positive and Gram-Negative Bacteria

The alarming growth of the number of antibiotic resistant bacteria and difficulties in treatment of infections have initiated a search for new antibacterial compounds and develop new alternative strategies in combating bacterial infections. Plant-derived compounds could exhibit a direct antibacterial activity and/or an indirect activity as antibiotic resistance modifying compounds, which, combined with antibiotics, increase their effectiveness. This ability of plant active substances reflects in modification or blocking of resistance mechanism so that bacterium becomes sensitive to antibiotic or the antibiotic acts when in lower concentrations. The systematic screening of plant-derived bioactive compounds, including those which can synergistically act with antibiotics, as resistance modifying agents represents a potential approach to overcome bacterial resistance. Therefore, the goals of this chapter are (i) an update of literature review on synergism between plant extracts and antibiotics, (ii) presentation of experimental results of synergistic activity of selected plant extracts and antibiotics and (iii) concluding remarks

In vitro synergistic antibacterial activity of Salvia officinalis L. and some preservatives

The aim of this work was to investigate the antibacterial activity of aqueous extracts of the species Salvia officinalis L. and its synergistic action with the preservatives sodium nitrite, sodium benzoate and potassium sorbate in vitro against selected food spoiling bacteria. Synergism was assessed by the checkerboard assay method and quantitatively represented by the FIC index. Synergistic action was established for aqueous extract/sodium benzoate, aqueous extract/potassium sorbate, aqueous extract/sodium nitrite combinations. Synergism was detected in relation to: Agrobacterium tumefaciens, Bacillus subtilis and Proteus sp. Synergism was established at plant extract and preservative concentrations corresponding up to 1/8 MIC values

Synergistic antibacterial activity of Curcuma longa L. and Urtica dioica L. extracts and preservatives

Curcuma longa L. (turmeric) and Urtica dioica L. (common nettle) are well-known medicinal plants. In recent decades, due to its excellent biological activity and low toxicity, significant efforts have been made to research the potential application of these plants. Accordingly, the aim of this study was to investigate the combined effects of preservatives (potassium nitrite and sodium nitrite) and ethanol, acetone, and ethyl acetate extracts of C. longa and U. dioica emphasizing their join, synergistic effects. The eight isolates of foodborne pathogenic bacteria and two reference strains were used. The interactions were tested by the checkerboard method and expressed as fractional inhibitory concentration (FIC) index. FIC index was ranged in intervals from 0.25 to 2.0. The extracts of C. longa showed better synergistic effect with preservatives than U. dioica extracts. Synergism was observed in relation to Staphylococcus aureus ATCC 25923, S. aureus, Bacillus subtilis, and Salmonella typhimurium. In the presence of subinhibitory concentrations (1/4 MIC, 1/8 MIC) of the extracts, the MICs of preservatives have decreased up to 8-fold. In addition, the contents of phenolic compounds (total phenols, flavonoids, tannins, and proanthocyanidins) were determined spectrophotometrically. The higher concentration of phenolic compounds was detected in C. longa extracts than in U. dioica extracts.Publishe

Microbiological indoor air quality in faculty's rooms: Risks on students' health

This study deals with a quantitative and qualitative analysis of indoor airborne microbiota and estimation of microbiological quality of indoor air in faculty's rooms during the summer semester of 2017/18 school year. The concentration of bacteria was significantly higher than the concentration of fungi. The species that belong to human skin microbiota or of environmental origin were identified. According to indoor air quality breakpoints, low to medium/high level of bacterial and fungal air contaminations was noticed.Publishe

Нови методолошки приступ изради и спровођењу просторног плана подручја посебне намене на примеру инфраструктурног коридора ауто-пута Е-80, деоница Ниш-Мердаре

Просторни план подручја посебне намене представља основни инструмент у процесу планирања инфраструктурног коридора ауто-пута. Циљ израде плана јесте дефинисање планског основа и обезбеђење просторних услова за изградњу и функционисање ауто-пута, као и за развој других инфраструктурних система у коридору. У раду је приказана методологија и приступ изради Просторног плана подручја посебне намене инфраструктурног коридора ауто-пута Е-80, деоница Ниш Мердаре. Анализиране су основне специфичности које су резултат примењене методологије, као што су обухват, концепција развоја, појаси и режими заштите, размештај пратећих садржаја, правила уређења и грађења и др. Посебно је наглашена методологија и резултати Стратешке процене утицаја Просторног плана на животну средину, као и значај прописаних мера заштите. Презентован је оквир имплементације Просторног плана одређен истовременом разрадом планских решења на два нивоа, и то стратешком нивоу просторног плана и детаљном нивоу урбанистичког плана. Анализиран је и однос Просторног плана према другим важећим планским документима за планско подручје. Кроз закључке рада указано је на правац даљих истраживања, нарочито у погледу усаглашавања методологије израде планске и техничке документације

In vitro interaction between Agrimonia eupatoria L. extracts and antibiotic

Synergistic activity between water, acetone, ethanol and diethyl ether extract of Agrimonia eupatoria L. and commonly used antibiotic (ampicillin) were evaluated. Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae and Pseudomonas aeruginosa were used. Interaction between plant extracts and antibiotic were tested by checkerboard method and expressed as fractional inhibitory concentration (FIC) index showed indifferent, additive and synergistic effects. Synergism was observed against E. coli for every combination of agents. FICI values were ranged from 0.03 to 0.29. Inhibitory concentration (IC50) was evaluated for every combination of tested extracts and antibiotic and the best combinations for every tested bacteria were combination of diethyl ether extract + ampicillin and combination of acetone extract + ampicillin

Biological activities of extracts from cultivated Granadilla Passiflora alata

Research conducted in this study showed the influence of ethanol, acetone and ethyl acetate extracts of the outgrowth of cultivated Passiflora alata on microorganisms, as well as the antioxidant activity and the concentrations of total phenols, flavonoids and tannins. In vitro antimicrobial activities of extracts were studied on 27 species of microorganisms, of which 17 species of bacteria and 10 species of fungi. The strongest antimicrobial activity was detected on G+ bacteria while the activities on other species were moderate. Ethyl acetate extract showed the strongest effect. The concentrations of total phenols were examined by using Folin-Ciocalteu reagent and the obtained values ranged from 14.04 to 34.22 mg GA/g. By using aluminium chloride method, the concentrations of flavonoids were obtained and the values ranged from 33.19 to 62.30 mg RU/g. In determining the amount of tannins we used the method with buthanol-HCl reagent and the obtained value was 5.1 % of dry matter. The efficiency of antioxidation, which we identified through the reduction of DPPH, was in the range from 808.69 to 1107.79 μg/ml for a particular IC50, and AAI values were between 0.07 and 0.10. The best parameters were shown by ethanol extract. All data were statistically analyzed. Overall, extracts showed potential for further investigation and use

Bioactive extracts of Gentiana asclepiadea: antioxidant, antimicrobial, and antibiofilm activity

Extracts of the aerial parts and roots of the wild-growing medicinal plant Gentiana asclepiadea were analysed for their antimicrobial, antibiofilm, and antioxidant activity with quantification of the total phenolic and total flavonoid content. Antimicrobial activity was tested against pathogenic and spoilage bacteria, yeasts, and moulds using the microdilution method. The strongest antibacterial activity was detected on Bacillus species, where minimum inhibitory concentrations (MICs) of from 0.16 mg/mL to 5 mg/mL were obtained, while antifungal activity was low to moderate, with MICs between 1.25 and 20 mg/mL. In the crystal violet assay, the extracts inhibit 50% biofilm formation in the concentration range of from 2.12 to 37.04 mg/mL. Staphylococcus aureus, S. aureus ATCC 25923, and Pseudomonas aeruginosa ATCC 27853 biofilms were the most sensitive to the presence of extracts. The extracts rich in phenolic compounds showed good DPPH-scavenging activity, with EC50 values between 181.3 and 614.3 μg/mL for extracts of aerial parts and from 426.67 to >1000 μg/mL for root extracts. Even though G. asclepiadea has long been traditionally used, its biological activity is still insufficiently explored, so the obtained results are significant for contributing new knowledge about the plant's medicinal properties

Antimicrobial, antioxidant and antibiofilm activity of extracts of Melilotus officinalis (L.) Pall.

In this paper, the antioxidant and antimicrobial activity, the concentrations of total phenols, flavonoids, tannins and proanthocyanidins in the water, acetone, diethyl ether and ethanol extracts of Melilotus officinalis L. were analysed and their effect on the bacterial biofilm formation. The highest concentration of total phenols (36.25 mgGA/g) and tannins (21.25 mgGA/g) were detected in the water extract. The highest concentration of flavonoids (53.09 mgRU/g) was detected in the acetone extract. Proanthocyanidins were not detected in the water extract, while the highest concentration of these compounds was measured in the acetone extract (3.77 mgCChE/g). The antioxidant and reducing power of the M. officinalis extracts were measured by spectrophotometric method, and all results were compared to vitamin C and water extract of Aronia melanocarpa. The water extract showed the highest antioxidant activity, while the diethyl ether extract the lowest one. The extent of reducing power in the examined extracts was various. The water extract demonstrated the highest activity and the absorbance was from 0.03 to 0.68, while the lowest reducing power was demonstrated in the diethyl ether extract whose absorbance was from 0.04 to 0.20. In vitro antimicrobial activity was tested by microdilution method determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC). 25 microorganisms were examined, including 19 species of bacteria and 6 species of fungi. The extracts showed greater effect on G+ bacteria than on the G- bacteria. The acetone extract showed the highest antimicrobial activity. The acetone extract inhibit the biofilm formation of bacteria Proteus mirabilis and Pseudomonas aeruginosa.Publishe

Escherichia coli biofilm formation and control by phenolic compounds from Salvia officinalis L. extracts

Biofilm is recognized as one of the virulence factors of uropathogenic Escherichia coli. It offers bacteria significantly increased tolerance to antibiotics and makes difficulties in infection eradication. In this study, the biofilm formation ability of clinical isolates of uropathogenic E. coli as well as the antibiofilm activity of the common Garden sage, Salvia officinalis L. extracts were investigated in vitro. The influence of growth conditions (nutrient composition and incubation period) on biofilm formation of E. coli strains was evaluated using crystal violet staining procedure. The tested strains better formed biofilms after a longer incubation period (48 h). In addition, biofilm formation depended on nutrient medium composition. The eight strains were slime producers (Congo red agar assay). The water, ethanol, acetone and diethyl ether S. officinalis extracts were screened for their ability to inhibit the formation and metabolic activity of E. coli biofilms using crystal violet and resazurin assay, respectively. The water extract was not active, while ethanol, acetone and diethyl ether extract exhibited antibiofilm activity (MBIC= 2.5-10 mg/mL). The microscopic visualization of treated E. coli LM1 biofilm has shown morphological and density changes. In addition, the concentrations of phenolic compounds were determined spectrophotometrically. The highest content of total phenolics was found in acetone extract while the flavonoids in water extract.