Phytochemical screening of extracts from Spiranthera odoratissima A. St.-Hil. (Rutaceae) leaves and their in vitroantioxidant and anti-Listeria monocytogenes activities

Spiranthera odoratissima A. St.-Hil (Rutaceae), a shrub whose common name is manacá do Cerrado in Brazilian Portuguese, is about 1-m high and has been used by folk medicine to treat stomachache, kidney and liver infections, headache, rheumatism and as a blood purifier. This study aimed at preparing hexane, ethyl acetate, methanolic, hydroethanolic and aqueous extracts from S. odoratissima leaves, at carrying out preliminary phytochemical screening and at evaluating their in vitroantioxidant and anti-Listeria monocytogenesactivities. Antioxidant activity was evaluated by the DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2-azinobis-3-ethybenzothiazoline-6-sulfonate) and FRAP (ferric reducing antioxidant power) methods. Antibacterial activity was investigated against L. monocytogenesand Minimum Inhibitory Concentration (MIC) values of plant extracts were calculated by the broth microdilution method with the use of 96-well plates. In aqueous, methanolic, hydroethanolic, ethyl acetate and hexane extracts from S. odoratissima leaves, the following classes of compounds were investigated: organic acids, reducing sugars, flavonoids, saponin compounds, coumarin compounds, phenolics, tannins, purine compounds, catechins, flavonol derivatives, sesquiterpene lactonesand anthraquinones. All plant extracts, except the hexane one, exhibited high antioxidant activity. Regarding antibacterial activity, the most polar extracts showed high activity against L. monocytogenes; their MIC values ranged between 12.5 and 62.5 μg mL-1, while the hexane one exhibited low activity (MIC = 1000 μgmL-1). In short, extracts from S. odoratissima leaves may be consideredpromising sources of secondary metabolites with relevant antioxidant and antibacterial activities.

Ação de bacteriocinas de bactérias láticas no controle de Listeria monocytogenes e no aumento da vida de prateleira de mortadela fatiada / Use of bacteriocins from lactic acid bacteria in the control of Listeria monocytogenes and in the shelf life extension of sliced mortadella

As bacteriocinas são peptídeos antimicrobianos produzidos por algumas bactérias, que atuam como bio-conservantes e têm grande potencial de aplicação em produtos cárneos. Estudos mostram que as bacteriocinas de bactérias lácticas (BAL) a serem utilizadas em um determinado alimento são mais eficientes quando produzidas por bactérias lácticas isoladas do mesmo tipo de alimento. Este estudo objetivou obter novas BAL produtoras de bacteriocinas a partir de mortadela fatiada, caracterizar as bacteriocinas produzidas, obter a bacteriocina semi-purificada e verificar seu potencial de aplicação in vitro e in situ no controle de Listeria monocytogenes e na vida de prateleira (VDP) de mortadela fatiada. Foram obtidos 19 isolados de BAL comprovadamente produtoras de bacteriocinas, que foram avaliadas quanto ao espectro de ação frente a uma grande variedade de bactérias Gram positivas e Gram negativas, e estabilidade em diferentes pH. As que apresentaram melhor estabilidade e inibiram maior número de bactérias foram avaliadas quanto a estabilidade térmica e resistência a diferentes agentes químicos e concentrações de NaCl. As que apresentaram maior resistência foram submetidas a testes de otimização da produção da bacteriocina em diferentes combinações de tempo/temperatura. Com base nestes resultados, selecionou-se um isolado que identificado como Lactobacillus curvatus pelo sequenciamento do gene 16S e confirmado por reações de PCR com primers específicos. A bacteriocina produzida por este isolado foi submetida a uma purificação por extração ácida e aplicada em fatias de mortadela experimentalmente contaminadas com um pool de cepas de Listeria monocytogenes, observando-se as contagens deste patógeno durante o armazenamento em refrigeração (7°C) por 40 dias em embalagem à vácuo. Paralelamente, foi realizada contagem de bactérias láticas para avaliar o efeito da bacteriocina nesta população, responsável pela VDP deste produto. A bacteriocina parcialmente purificada foi ...

Bacteriocins are peptides with antimicrobial properties produced by some bacteria, that act as bio-preservatives with great potential of application in meat products. Several studies show that bacteriocins from lactic acid bacteria (LAB) to be used in a specific food product have a better performance when produced by LAB isolated from the same kind of product. This study aimed to obtain new bacteriocinogenic LAB from sliced Bologna, to characterize the bacteriocins produced, to obtain a semi-purified bacteriocin, and to verify its potential of application in vitro and in situ in the control of Listeria monocytogenes and in the shelf-life of sliced bologna. 19 bacteriocin producer LAB, were evaluated as to spectrum of action against a great variety of Gram positives and Gram negatives bacteria and pH stability. The ones with better stability and that inhibited a larger number of bacteria were evaluated according to its thermal stability and resistance against different chemical agents and NaCl concentrations. The ones that showed better resistance were submitted to tests to optimize the bacteriocin production in different combinations of time and temperature. Based on these results, one was selected, identified as Lactobacillus curvatus by gene 16S sequencing and confirmed by PCR reactions with specific primers. The bacteriocin produced by this strain was submitted to partial purification by acid extraction and was applied in mortadella slices experimentally contaminated with a pool of L. monocytogenes strains, observing the counts of this pathogen along refrigerated (7ºC) storage fo r 40 days in vacuum package. Parallel, it was done LAB counts to evaluate the effect of the bacteriocin on this population, responsible for limiting the shelf life of this product. The semi-purified bacteriocin was able to reduce 1 log cicle of the initial population of L. monocytogenes in the sliced mortadella, which was maintained during the 40 days of analysis. Along the whole...

Intracellular Bacterial Infection and Invariant NKT Cells

The invariant (i) natural killer (NK)T cells represent a unique subset of T lymphocytes which express the V alpha14 chain of the T cell receptor (TCR), that recognizes glycolipid antigens presented by the nonpolymorphic major histocompatibility complex (MHC) class I-like antigen presentation molecule CD1d, and they participate in protection against some microbial pathogens. Although iNKT cells have originally been regarded as T cells co-expressing NKR-P1B/C (NK1.1: CD 161), they do not seem to consistently express this marker, since NK1.1 surface expression on iNKT cells undergoes dramatic changes following facultative intracellular bacterial infection, which is correlated with functional changes of this cell population. Accumulating evidence suggests that NK1.1 allows recognition of "missing-self", thus controling activation/inhibition of NK1.1-expressing cells. Therefore, it is tempting to suggest that iNKT cells participate in the regulation of host immune responses during facultative intracellular bacterial infection by controlling NK1.1 surface expression. These findings shed light not only on the unique role of iNKT cells in microbial infection, but also provide evidence for new aspects of the NK1.1 as a regulatory molecule on these cells.

Infección perinatal por listeria monocytogenes: presentación de casos clínicos, ¿transmisión en la sala de atención inmediata? / Perinatal infection by listeria monocytogenes: presentation of clinical cases, transmission in care facilities

Entre de las infecciones perinatales la infección por Listeria monocytogenes (Lm) es de muy baja frecuencia y con características clínicas poco especificas que la diferencien de otras infecciones perinatales. Se presenta en la mayoría de los casos como síndrome febril similar a un estado gripal, principalmente en pacientes inmunodeprimidos (usuarios de corticoides, infectados con infectados con VIH, etc.). Se presenta también como parto prematuro, óbito fetal o como sufrimiento fetal agudo en el período periparto. Al hacer el diagnóstico por laboratorio, la similitud de la Lm con otras bacterias en cultivo y en examen directo llevan frecuentemente a establecer un diagnóstico erróneo, por lo que se requiere medios enriquecidos cuando el cultivo es tomado de medios no estériles como flujo endocervical y vaginal. Generalmente el diagnóstico se establece en la madre en forma retrospectiva una vez que el recién nacido presenta las consecuencias de la infección, sin embargo, existen series de casos en los que la infección se ha diagnosticado durante el embarazo, incluso a partir de las 15 semanas con buen resultado luego del tratamiento perinatal con antibióticos. En este trabajo se presentan dos casos clínicos reportados en el Hospital San Juan de Dios en Septiembre 2004 en los que se postula la transmisión nosocomial como mecanismo más probable de infección y una revisión sobre la infección por Lm durante el embarazo.

Coinfection with listeria monocytogenes potentlxtes the response of balb/c mice against leishmania major

The protection against L. major is dependent on the stimulation of an anti-leishmanial T helper 1 [Th1] response and the production of interferon-gamma [IFN-gamma]. BALB/c mice develop a Th2 response and fatal infection with Leishmania major. Strategies that boost IL-12 production have shown to be protective. The innate response to Listeria monocytogenes is associated with IL-12 production. The co- infection of BALB/c mice with L. Monocytogenes attenuates the course of L. Major infection. In this study, 8-16 weeks old female BALB/c mice were used. The lesion sizes were smaller and co-infected mice out-survived the controls injected with L. major alone. The parasite load was reduced at the site of injection, in draining lymph nodes [LN] and spleen. During the first week of infection, in vitro Leishmania re-stimulated LN cells from co-infected mice produced higher levels of IFN-7 and undetectable levels of IL-4 compared with the controls. Significant IL-4 mRNA expression was detected in LN cells of the controls, but not in the co-infected mice

Inquérito soro-epidemiológico antilistéria em Uberaba, MG / A seroepidemiological investigation of listerosis in Uberaba, MG

From a total of 445 individuals, 17.1 per cent had antibodies against L. monocytogenes detected by the agglutination tube test. They were separated in seven groups: bloods donnors (n = 50), Hospital visitors (n = 40), frigorific workers (n = 28), aviculture workers (n = 87), herdsman (n = 31), agriculture students (n = 60) and street-sweepers (n = 51). L1/2a serotype was predominant. Individuals from urban areas (19.5 per cent) and those who had less contact with animals (21.7 per cent) had significantly positive serology when compared with individuals from rural areas (9.4 per cent) and those who had close contact with animals (13.2 per cent). The overall picture is individuals of more specialized occupations had more frequently (25.9 per cent) anti listeria antibodies similar to the results observed in developed countries where listeriosis is a public health problem in urban areas.

A simple method for evaluation of delayed hypersensitivity in mice

A determinaçäo da presença de reaçöes de hipersensibilidade retardada (RHR) em camundongos é habitualmente feita pela evidenciaçäo do aumento de espessura de um dos coxins plantares posteriores, inoculado com o antígeno, comparado com o coxim contralateral, inoculado com soluçäo salina. Essa avaliaçäo é, no entanto, difícil devido a dificuldade inerente à leitura do teste. Visando à avaliaçäo de um método alternativo de pesquisa das RHR, camundongos foram imunizados com Listeria monocytogenes e submetidos ao teste 4 dias, 1, 2, e 4 semanas após a imunizaçäo. Tanto a diferença de espessura, quanto a de peso entre os dois coxins posteriores, de cada animal, foram determinadas. Para avaliaçäo da sensibilidade do novo método foi demonstrada a coincidência do aparecimentos das RHR e da resistência adquirida à reinfecçäo pelo mesmo organismo, por medio do teste de depuraçäo esplênica de germes inoculados por via intraperitoneal. O método proposto mostrou-se de fácil realizaçäo e de leitura precisa apresentando, ainda, boa correlaçäo com o teste de depuraçäo esplênica e com as determinaçöes do aumento de espessura