Inhibition of the essential oil from Chenopodium ambrosioides L. and α-terpinene on the NorA efflux-pump of Staphylococcus aureus.

This study was carried out to test the essential oil from C. ambrosioides leaves and its main constituent, α-Terpinene, in an antibacterial activity assay. As well, it was evaluated ability reduce resistance to norfloxacin and ethidium bromide was compared the Staphylococcus aureus 1199B whith 1199 wild type strain. The MIC of the C. ambrosioides essential oil and α-Terpinene were determined by microdilution method. The MIC of the essential oil and α-Terpinene presented a value ≥ 1024 µg/mL. However, when associated with antibacterials, the essential oil from C. ambrosioides leaves significantly reduced the MIC of antibiotics and ethidium bromide, characterizing an efflux pump inhibition. The C. ambrosioides essential oil, despite having no direct antibacterial activity against the S. aureus 1199B strain, showed a potentiating action when associated with antibacterial agents, this being attributed to an inhibition of efflux pumps.

Inhibition of the TetK efflux-pump by the essential oil of Chenopodium ambrosioides L. and α-terpinene against Staphylococcus aureus IS-58.

The use of natural products is crucial to suppress the development of these micro-organisms and to reduce the concentration necessary to inhibit these microrganisms, reducing the toxicity risks also. In this study, the essential oil from Chenopodium ambrosioides Leaves and its main constituent α-Terpinene were used in the antibacterial and potentiating activity of antibiotics and ethidium bromide assays, against the bacterial strains Staphylococcus aureus IS-58, carriers of efflux pumps. The Minimum Inhibitory Concentration (MIC) was determined using a microdilution method. The capacity of the aforementioned was also tested in combination with tetracycline and ethidium bromide, with the aim of improving the activity of the antibacterials. The MIC of the C. ambrosioides L. essential oil and of α-Terpinene were above 1024 µg/mL, comprising a clinically irrelevant value. However, when associated with the antibiotics, the C. ambrosioides L. essential oil, significantly decreased the MIC of tetracycline and ethidium bromide. The efflux pump is the only mechanism the bacteria possesses to reduce the toxicity of ethidium bromide, and thus this reduction in the MIC demonstrates that the C. ambrosioides L. essential oil is an effective option in the inhibition of the efflux pump present in these micro-organisms.

The Essential Oil from Origanum vulgare L. and Its Individual Constituents Carvacrol and Thymol Enhance the Effect of Tetracycline against Staphylococcus aureus.

BACKGROUND: In an ongoing project to evaluate essential oils as modulators of antibiotic resistance, the essential oil from Origanum vulgare L. (OVEO), as well as its individual constituents carvacrol (CAR) and thymol (THY), were investigated using Staphylococcus aureus strains possessing efflux mechanisms of resistance to norfloxacin, erythromycin and tetracycline. METHODS: The minimum inhibitory concentration (MIC) values of the antibiotics were determined by agar dilution method, in the absence and in the presence of subinhibitory concentrations of OVEO, CAR or THY. RESULTS: Along with relevant antistaphylococcal activity, OVEO, CAR and THY modulated the activity of tetracycline, i.e. in combination with antibiotics a reduction in the MIC was observed (up to fourfold). CONCLUSIONS: The results presented here represent, as far as we know, the first report of OVEO, CAR and THY as putative efflux pump inhibitors. Broadly, these findings indicate that essential oils could serve as potential sources of compounds capable of modulating drug resistance.

Phototoxic and modulatory effects of natural products from the skin of Rhinella jimi (Stevaux, 2002)

The skin of amphibians possesses a large diversity of biologically active compounds that are associated with the natural defenses of these animals against pathogens. Five different extracts and fractions were obtained from the skin of Rhinella jimi: methanol extract (ME), methanol fractions (MF), chloroform extract of methanol extract (CF), aqueous alkaloid fraction (AAF) and aqueous non-alkaloid fraction (ANAF). All fractions were evaluated with respect to their antibiotic modifying activity in standard bacterial strains and multiresistant clinical isolates. Antagonism was detected with kanamycin and gentamicin when combined with substances obtained from the skin of R. jimi. Phototoxic activity was observed in the methanol and chlorophorm fractions, as well as the aqueous non-alkaloid fraction. The antagonistic action was apparently associated with the protection afforded by the bacterial populations that inhabit the skin of this amphibian, preventing colonization by pathogenic fungi. The phototoxic activity demonstrated by natural products from the skin of R. jimi showed an interruption of the bacterial growth after UV exposure. This could indicate an antibacterial effect activated by the UV light, opening a path for carrying the attack by pathogenic fungi, causing the disease related with the amphibian decline.

Modulation of drug resistance in Staphylococcus aureus by extract of mango (Mangifera indica L., Anacardiaceae) peel

In an ongoing project to evaluate natural compounds isolated from by-products or wastes from vegetables and fruits (edible plants) as modulators of antibiotic resistance, ethanol extract from mango peel was investigated using Staphylococcus aureus strains possessing efflux mechanisms of resistance to norfloxacin, erythromycin and tetracycline. The minimum inhibitory concentrations (MIC) of the antibiotics were determined by the micro dilution assay in the absence and in the presence of sub-inhibitory mango peel extract concentration. Although the extract did not display relevant antibacterial activity (MIC>2048 µg/mL), it modulated the activity of antibiotics, i.e. in combination with antibiotics (at 512 µg/mL), a four-fold reduction in the MIC values for tetracycline and erythromycin was observed. The results presented here indicates that mango peel could serve as a source of potential adjuvant of antibiotics which add value to this mango by-product.

Antimicrobial activity of Mimosa tenuiflora (Willd.) Poir. from Northeast Brazil against clinical isolates of Staphylococcus aureus / Atividade antimicrobiana de Mimosa tenuiflora (Willd.) Poir. do Nordeste do Brasil, contra isolados clínicos de Staphylococcus aureus

Mimosa tenuiflora is a native plant of Northeast Brazil where it is popularly known as ''jurema-preta'' and it is widely used in folk medicine. In this work the anti-Staphylococcus aureus activity of ethanol extract of M tenuiflora was evaluated by determination of minimum inhibitory concentration (MIC) of clinical isolates by the agar dilution method, and by time-kill assay using a reference strain. MIC values against 30 isolates were 0,18 mg/mL (16/30) or 0,36 mg/mL (14/30, and also the reference strain). In the reference strains, at concentrations up to 4x MIC, only bacteriostatic effect was observed, but at 8x MIC a fast bactericidal effect was observed.

A Mimosa tenuiflora é uma planta nativa da região Nordeste do Brasil onde é conhecida como jurema-preta sendo amplamente utilizada na medicina popular. No presente trabalho a atividade anti-Staphylococcus aureus do extrato etanólico da M. tenuiflora foi avaliada pela determinação da concentração inibitória mínima (CIM), pelo método da diluição em agar, em 30 isolados clínicos e pela cinética de inativação com a linhagem referência. Os valores da CIM foram 0,18 mg/mL em 16 isolados e 0,36 mg/mL nos demais, bem como na linhagem referência. A cinética de inativação mostrou apenas efeito bacteriostático nas concentrações do extrato até aquela correspondente a 4x CIM e um rápido efeito bactericida na concentração correspondente a 8x CIM.

In vitro anti-staphylococcal activity of Hyptis martiusii Benth against methicillin-resistant Staphylococcus aureus: MRSA strains / Atividade anti-estafilocócica in vitro de Hyptis martiusii Benth contra linhagens de Staphylococcus aureus resistentes à meticilina: MRSA

This is the first report about the antibacterial activity of Hyptis martiusii Benth. In this study the ethanol extract of H. martiusii was tested for its antimicrobial activity against strains of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The growth of all bacterial strains tested was inhibited by the extract. The diameter of inhibition zones varied from 13 to 20 mm for the extract. The MIC and MBC values ranged from 128 to > 1024mg/mL and 256 to > 1024 mg/mL, respectively. It is therefore suggested that extracts from H. martiusii could be used as an anti-Staphylococcus agent. Compared with methicillin and gentamicin, the extract was more effective, being a promising antibacterial agent.

Este é o primeiro relato de atividade antibacteriana de Hyptis martiusii Benth. Neste estudo, o extrato etanólico de H. martiusii foi avaliado para atividade antimicrobiana contra linhagens de Escherichia coli, Pseudomonas aeruginosa e Staphylococcus aureus. O crescimento de todas as bactérias testadas foi inibido pelo extrato. O diâmetro das zonas de inibição variaram de 13 - 20 mm. Os valores da CIM e CBM variaram de 128 a > 1024 mg/mL e 256 a > 1024 mg/mL, respectivamente. Devido a isso, podemos indicar que o extrato etanólico de H. martiusii pode ser usado como um agente anti-Staphylococcus. Quando comparado com outros antibióticos como meticilina e gentamicina, o extrato foi mais efetivo, demonstrando ser um promissor agente antibacteriano.

Antibiotic activity of the extract of Punica granatum Linn. over bovine strains of Staphylococcus aureus / Atividade antimicrobiana do extrato de Punica granatum Linn. em linhagens de Staphylococcus aureus de origem bovina

A medicina humana e veterinária tem falhado no tratamento de infecções em longo prazo causadas por Staphylococcus aureus associadas ao desenvolvimento de resistência a agentes antimicrobianos. A atividade antimicrobiana do extrato da casca do fruto de Punica granatum Linn. foi avaliada sobre 38 linhagens de S. aureus de origem bovina para a determinação da concentração inibitória mínima (CIM). Das 38 linhagens ensaiadas, 22 são resistentes à penicilina.(PRSA). O extrato de P. granatum apresentou potencial ação antimicrobiana sobre todas as linhagens ensaiadas formando halos de inibição variando de 10 a 36 mm de diâmetro. Os resultados deste estudo confirmam a eficácia do extrato de P. granatum como potencial agente antibacteriano sobre S. aureus e demonstram a importância de se avaliar novas substâncias com potencial antimicrobiano, o que pode contribuir para a terapêutica alternativa em Medicina Veterinária.

Human and veterinary medicines have not been so well succeeded in order to achieving their goals concerning the treatment of infections for long term caused by Staphylococcus aureus linked to resistance development against antibiotic agents. The antibiotic activity of the Punica granatum Linn. fresh fruit pericarp extract was evaluated by the agar diffusion method on 38 S. aureus strains, isolated from apparently healthy lactating cows in farms situated in counties of the semi-arid region of the State of Paraíba, Brazil to determine the minimum inhibitory concentration (MIC). Twenty-two of the thirty-eight strains are penicillin-resistant (PRSA). The extract of P. granatum presented potential antibiotic action over all the assayed strains, forming 10 to 36 mm diameter inhibition zones. This paper's results claim the effectiveness of the extract of P. granatum as a potential antibacterial agent on S. aureus, and display the significance of evaluating new substances with antimicrobial potential, which can contribute to alternative therapeutics for veterinary and medicine.

Composição química e modulação da resistência bacteriana a drogas do óleo essencial das folhas de Rollinia leptopetala R. E. Fries / Chemical composition and modulation of bacterial drug resistance of the essential oil from the leaves of Rollinia leptopetala R. E. Fries

O óleo essencial das folhasde Rollinia leptopetala foi obtido por hidrodestilação em aparelho de Clevenger e a sua composição química foi analisada através de CG-EM. Com essa técnica, foi possível identificar 22 constituintes em uma mistura complexa demonoterpenos (54,5 por cento) e sesquiterpenos (45,5 por cento). O principal componente encontradonas folhas foi o biciclogermacreno (22,47 por cento). O óleo essencial foi avaliado numa linhagem de Staphylococcus aureus portadora de bomba de efluxo responsável pela resistência norfloxacino. Embora o óleo essencial não tenha apresentado atividade antibacteriana relevante in vitro, ele apresentou atividade moduladora da resistência, ou seja, em combinação com o norfloxacino observou-se uma redução de 4x na concentração inibitória mínima do antibiótico, indicando inibição de bomba de efluxo.

The essential oil from the leaves of Rollinia leptopetala was obtained by hydrodistillation in Clevenger's apparatus and its chemical composition was analyzed by GC-MS. With this technique could be identified 22 constituents in a complex mixture of monoterpenes (54.5 percent) and sesquiterpenes (45.5 percent). The main component found in the leaves was the bicyclogermacrene (22.47 percent). The essential oil was assayed against a strain of Staphylococcus aureus possessing efflux mechanism of resistance to norfloxacin. Although the essential oil did not display relevant antibacterial activity in vitro, it modulated the activity of the norfloxacin, i.e. in combination with the antibiotic it was observed a fourfold reduction in the minimum inhibitory concentration for norfloxacin, indicating inhibition of efflux pump.

Atividade antimicrobiana do extrato de Anacardium occidentale Linn. em amostras multiresistentes de Staphylococcus aureus / Antimicrobial activity of the hydroalcoholic extract of Anacardium occidentale Linn. against multi-drug resistant strains of Staphylococcus aureus

Plantas medicinais com propriedades terapêuticas são de grande relevância em todo o mundo, principalmente em países em desenvolvimento. A planta Anacardium occidentale Linn. é largamente usada na medicina tradicional na nossa região, como antidiarréico, para amigdalite, bronquites, artrites, e antiiflamatório. No presente estudo avaliou-se a ação antimicrobiana do extrato hidroalcóolico da casca do caule do cajueiro frente a amostras de Staphylococcus aureus resistentes e sensíveis à meticilina, obtidas a partir de pacientes internados do Hospital Universitário/Universidade Federal da Paraíba. A atividade antimicrobiana foi determinada pelo método de difusão em meio sólido para a determinação da Concentração Inibitória Mínima do extrato, e foi observada no total de 30 amostras, pela presença ou não do halo de inibição. Todas as amostras ensaiadas mostraram-se sensíveis à ação do extrato do cajueiro, com diâmetros dos halos de inibição variando de 10 a 20 mm, demonstrando grande eficácia do cajueiro. Assim, o uso desta planta na nossa região pode inferir uma alternativa terapêutica eficiente e de baixo custo, contra infecções bacterianas causadas por Staphylococcus aureus.

Medicinal plants with therapeutical properties are of great significance in the whole world, especially in developing countries. Anacardium occidentale Linn. is a plant widely used in the traditional medicine in our region against diarrhea, tonsillitis, bronchitis, arthritis, and inflammation. In this paper, the antimicrobial activity of the hydroalcoholic extract of the cashew tree stem was evaluated against samples of meticillin-resistant and meticillin-sensible Staphylococcus aureus, attained from patients interned at Hospital Universitário/Universidade Federal da Paraíba. The antimicrobial activity was determined by the diffusion method in solid milieu to determine the Minimum Inhibitory Concentration (MIC) of the extract, and it was observed in 30 samples the presence or not of inhibition zone. All the assayed samples proved to be sensible to the activity of the extract of the cashew tree, with inhibition zones diameter of 10 to 20 mm, displaying consequently great effectiveness of the extract of the cashew tree stem. Thus, the use of this plant in our region can infer a low cost and efficient therapeutical alternative against bacterial infections caused by Staphylococcus aureus.

Eliminação de resistência a drogas por fluorquinolonas em Staphylococcus aureus de origem bovina / Elimination of resistance to drugs by fluoroquinolones in bovine strains of Staphylococcus aureus

Cepas de Staphylococcus aureus de origem bovina foram submetidas ao tratamento com quatro fluoquinolonas na concentração subinibitória (1/2 x CMI), para avaliar a influência desses agentes sobre plasmídios. A ciprofloxacina mostrou ser a fluorquinolona mais eficiente, eliminando marcas de resistência para estreptomicina, tetraciclina, penicilina e cádmio. A norfloxacina e a pefloxacina eliminaram resistência para penicilina e tetraciclina, respectivamente; no entanto, não foi evidenciada a eliminação de plasmídio com ofloxacina. Os resultados confirmam a eficácia das fluor-quinolonas em eliminar plasmídios de resistência mostrando a importância desses estudos como contribuição para o entendimento da prevenção de linhagens multiresistentes, uma vez que as quinolonas em concentrações subinibitórias podem aumentar a sensibilidade das linhagens a outros agentes antimicrobianos.