Determinación de Listeria monocytogenes en dos variedades de quesos artesanales, comeercializados en los mercados La Tiendona, Central y San Miguelito

Se realizó un análisis microbiológico a dos variedades de quesos (fresco y duro blando), comercializado en los mercados de la Tiendona, Central y San Miguelito. Se tomó en cuenta los parámetros utilizados dentro del Reglamento Técnico Centro americano (RTCA) 67.04.50:08 (Alimentos. Criterios microbiológicos para la inocuidad de alimentos) de quesos madurados y no madurados el cual dice que por cada 25 g de muestra, la Listeria monocytogenes debe ser “ausente”. Para determinar las dos variedades de quesos se utilizó una guía de observación, para determinar la presencia o ausencia de Listeria monocytogenes se analizó por medio de la metodología descrita por el BAM (Manual de Análisis Bacteriológico de la Administración de Drogas y Alimentos (FDA). Se realizó un conteo en placa para la determinación de la sobrevivencia de la L. monocytogenes; haciendo una comparación del día 1 y a los 5 días, sometiendo la bacteria a ciertas condiciones de temperatura. Todos los análisis respectivos fueron realizados en el Laboratorio de Microbiología de Alimentos del Centro de Investigación y Desarrollo en Salud (CENSALUD) de la Universidad de El Salvador. Los resultados obtenidos de los análisis, demostraron que el 25% de las dos variedades de quesos analizados no cumplen con los parámetros requeridos del RTCA (67.04.50:08), se demostró que la L. monocytogenes sobrevive a condiciones de temperatura de 4 °C. Se consideró que los quesos fresco y duro blando no son aptos para el consumo humano, se recomienda que el ministerio de salud aumente el monitoreo y de capacitaciones para mejorar las condiciones higiénicas en los puestos de los mercados, además de supervisar que empleen leche pasteurizada en la elaboración de queso así como prohibir el consumo de quesos de dudosa procedencia.

Eficácia de películas edíveis suplementadas com componentes de óleos essenciais no controlo de Listeria monocytogenes e Salmonella enterica Typhimurium

Dissertação de Mestrado, Engenharia Biológica, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2014

Stress response and autolytic behaviour of Listeria monocytogenes isolated from portuguese cheese

Tese de dout. em Biologia, especialidade de Microbiologia, Unidade de Ciências e Tecnologias Agrárias, Univ. do Algarve, 2000

Caracterização molecular de cepas de Listeria monocytogenes oriundas de corte bovino e abatedouros frigoríficos de bovinos localizado no Distrito Federal

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-Graduação em Saúde Animal, 2016.

A bioengineered nisin derivative, M21A, in combination with food grade additives eradicates biofilms of Listeria monocytogenes

The burden of foodborne disease has large economic and social consequences worldwide. Despite strict regulations, a number of pathogens persist within the food environment, which is greatly contributed to by a build-up of resistance mechanisms and also through the formation of biofilms. Biofilms have been shown to be highly resistant to a number of antimicrobials and can be extremely difficult to remove once they are established. In parallel, the growing concern of consumers regarding the use of chemically derived antimicrobials within food has led to a drive toward more natural products. As a consequence, the use of naturally derived antimicrobials has become of particular interest. In this study we investigated the efficacy of nisin A and its bioengineered derivative M21A in combination with food grade additives to treat biofilms of a representative foodborne disease isolate of Listeria monocytogenes. Investigations revealed the enhanced antimicrobial effects, in liquid culture, of M21A in combination with citric acid or cinnamaldehyde over its wild type nisin A counterpart. Subsequently, an investigation was conducted into the effects of these combinations on an established biofilm of the same strain. Nisin M21A (0.1 μg/ml) alone or in combination with cinnamaldehyde (35 μg/ml) or citric acid (175 μg/ml) performed significantly better than combinations involving nisin A. All combinations of M21A with either citric acid or cinnamaldehyde eradicated the L. monocytogenes biofilm (in relation to a non-biofilm control). We conclude that M21A in combination with available food additives could further enhance the antimicrobial treatment of biofilms within the food industry, simply by substituting nisin A with M21A in current commercial products such as Nisaplin® (Danisco, DuPont).

Effetto delle alte pressioni di omogeneizzazione sul volatiloma e profilo in acidi grassi di membrana di Listeria monocytogenes Scott A

Nella mia sperimentazione ho studiato i meccanismi di risposta, in termini di modificazione a livello delle membrane citoplasmatiche e in termini di rilascio di molecole volatili, messi in atto da Listeria. monocytogenes (Scott A) quando sottoposta in fase stazionaria a diversi trattamenti ad alta pressioni di omogeneizzazione compresi tra 0.1 e 200 MPa. I dati della mia tesi hanno consentito di evidenziare i meccanismi di risposta di un importante patogeno alimentare quando sottoposto ad una tecnologia proposta in alternativa al trattamento termico al fine di ridurre il danno termico degli alimenti preservandone le caratteristiche nutrizionali, funzionali ed organolettiche, senza effetti negativi sulla loro sicurezza e shelf-life. Inoltre, hanno dimostrato che L. monocytogenes risponde al trattamento iperbarico modificando in prima istanza la composizione in acidi grassi e producendo delle ossilipine al crescere dello stress. Alle condizioni di stress più stringenti adottate diventano fondamentali in L. monocytogenes anche la produzione di molecole volatili quali alcoli ed esteri sia per bilanciare il potenziale redox cellulare sia per eliminare molecole estremamente tossiche quali gli acidi grassi rilasciati dai meccanismi messi in atto alle condizioni meno stressanti di pressione

Trattamenti mediante tecnologie basate sul plasma di carote julienne

Prodotti di IV gamma a base di frutta e verdura minimamente trattati o pronti all'uso non possono essere considerati sicuri da un punto di vista microbiologico e sono stati spesso associati a casi di tossinfezione. Per tali episodi è stato evidenziato che la qualità dell'acqua utilizzata per il lavaggio è una fase critica. D'altra parte è noto che la disinfezione è una delle fasi di lavorazione più importanti per i prodotti minimamente trattati in quanto ha effetti diretti sulla qualità dei prodotti finiti, sulla sicurezza e la loro shelf-life. Tradizionalmente, l'industria di IV gamma ha impiegato i composti derivati del cloro per la fase di disinfezione in virtù della loro efficacia, semplicità d'uso e basso costo. Tuttavia vi è una diffusa tendenza ad eliminare i prodotti a base di cloro a causa soprattutto della preoccupazione in relazione ai rischi ambientali e sanitari per il consumatore associati alla formazione di sottoprodotti alogenati cancerogeni. Tra le varie tecnologie emergenti, proposte come alternative al cloro, il plasma ha presentato buone potenzialità in virtù delle specie chimiche che lo compongono, principalmente specie reattive dell’ossigeno e dell’azoto, che sembrano essere responsabili di stress ossidativo alle cellule microbiche, con conseguenti danni per DNA, proteine e lipidi. L’obiettivo generale di questo elaborato finale è stato quello di valutare la possibilità di utilizzare la tecnologia del plasma per la decontaminazione superficiale di carote julienne. In particolare si sono presi in considerazione trattamenti diretti in cui il vegetale è stato esposto al plasma per differenti tempi compresi tra 5 e 40 minuti. Inoltre, si è utilizzo il plasma per il trattamento di acqua che è stata successivamente impiegata per il lavaggio delle carote julienne. L'efficacia di entrambe le modalità di trattamento è stata verificata nei confronti sia della microflora naturalmente contaminante le carote, sia di alcuni microrganismi patogeni che possono essere associati a tale vegetale: Listeria monocytogenes, Salmonella Enteritidis ed Escherichia coli.

Sterilization by pure oxygen plasma and by oxygen-hydrogen peroxide plasma: An efficacy study

Plasma is an innovative sterilization method characterized by a low toxicity to operators and patients, and also by its operation at temperatures close to room temperatures. The use of different parameters for this method of sterilization and the corresponding results were analyzed in this study. A low-pressure inductive discharge was used to study the plasma sterilization processes. Oxygen and a mixture of oxygen and hydrogen peroxide were used as plasma source gases. The efficacy of the processes using different combinations of parameters such as plasma-generation method, type of gas, pressure, gas flow rate, temperature, power, and exposure time was evaluated. Two phases were developed for the processes, one using pure oxygen and the other a mixture of gases. Bacillus subtilis var. niger ATCC 9372 (Bacillus atrophaeus) spores inoculated on glass coverslips were used as biological indicators to evaluate the efficacy of the processes. All cycles were carried out in triplicate for different sublethal exposure times to calculate the D value by the enumeration method. The pour-plate technique was used to quantify the spores. D values of between 8 and 3 min were obtained. Best results were achieved at high power levels (350 and 40oW) using pure oxygen, showing that plasma sterilization is a promising alternative to other sterilization methods. (c) 2007 Elsevier B.V. All rights reserved.

Survey of Listeria spp. in matched clinical, food and refrigerator samples at home level in Brazil

Listeria monocytogenes is a bacterial pathogen that represents a serious threat during pregnancy and several cases of listeriosis have been linked to the consumption of contaminated foods worldwide. In Brazil, there is no report of foodborne listeriosis, despite some sporadic cases of infection by this bacterium occur. In general in our country, there is no awareness of medical personnel to instruct moms-to-be to avoid high risk foods. In the present study, a total of 141 samples were surveyed for the presence of Listeria spp., including cervicovaginal samples of patients, foods and home refrigerators. No clinical sample was positive for Listeria spp., but it was isolated from two refrigerators. L. monocytogenes was detected in two food samples out of five positive ones for Listeria spp. In conclusion, it was shown the presence of contaminated food items at home level and the lack of information on the risks of listeriosis, indicating the need of implementation of food safety education programs. (C) 2007 Elsevier Ltd. All rights reserved.

Quantification of Listeria spp. contamination on shell and flesh of cooked black tiger prawns (Penaeus monodon)

Aims: To quantify Listeria levels on the shell and flesh of artificially contaminated cooked prawns after peeling, and determine the efficacy of Listeria innocua as a model for L. monocytogenes in this system. Methods and Results: A L. monocytogenes and L. innocua strain were inoculated separately onto cooked black tiger prawns using two protocols ( immersion or swabbing with incubation). Prawns were peeled by two methods ( gloved hand or scalpel and forceps) and numbers of Listeria on shells, flesh and whole prawn controls were determined. Prawns were exposed to crystal violet dye to assess the penetration of liquids. Regardless of preparation method or bacterial strain there were ca 1log(10) CFU more Listeria per shell than per peeled prawn. Dye was able to penetrate to the flesh in all cases. Conclusions: Shell-on prawns may be only slightly safer than shell-off prawns. Listeria innocua is an acceptable model for L. monocytogenes in this system. Significance and Impact of the Study: Reduced risk from L. monocytogenes on prawns can only be assured by adequate hygiene or heating.

Evaluation of phenotypic markers associated with pathogenicity in the genus Listeria

A total of 130 Listeria strains were tested in order to evaluate lecithinase production and capacity for Congo red adsorption as markers of pathogenicity. The strains were identified according to acid production from sugars and by the CAMP test and the data were correlated with the ability to produce keratoconjunctivitis in guinea pigs. L. monocytogenes cultures presented 51.8% and 88.8% positivity rates for Congo red adsorption and lecithinase production, respectively, whereas 80.8% and 100% for L. innocua cultures were negative for the two test, respectively

Pesquisa sobre a ocorrência de histeria monocytogenes em fezes humanas

Foi pesquisada em 107 amostras de fezes procedentes de indivíduos com distúrbios intestinais a presença de Listeria monocytogenes. Como processo de enriquecimento, as fezes foram semeadas em caldo triptose fosfatado e mantidas a 4ºC durante 1 mês. Ao findar este prazo, foram os espécimes semeados em quatro meios seletivos: 1) Agar triptosado com 5 mcg/ml de Polimixina; 2) Agar triptosado com 50 cmg/ml de ácido nalidixico; 3) Meio de Ralovich e cols (Agar com 5% de soro normal de cavalo, acrescido de 50 mcg/ml de ácido nalidixico e 50 mcg/ml de tripaflavina (Bayer); 4) Uma modificação do meio de Ralovich (Agar triptosado, contendo 40 mcg/ml de ácido nalidixico, 50 mcg/ml de acetato de tálio, 25 mcg/ml de tripaflavina e 0,3% de extrato de levedura). Para reconhecimento das colônias suspeitas nos diferentes meios, fez-se uso da técnica de Henry. A identificação primária se baseou na observação da motilidade e nas características morfotintoriais, senão a seguir, confirmada através das provas bioquímicas e sorológicas. Três amostras de Listeria monocytogenes foram isoladas, caracterizando- se duas no sorotipo 4b e uma no tipo 1/2a.

Listeria brain abscess, Pneumocystis pneumonia and Kaposi's sarcoma after temozolomide.

BACKGROUND: A 55-year-old man with glioblastoma multiforme was treated with continuous, dose-dense temozolomide. This therapy was curtailed after three cycles because of nausea, asthenia, and neuropsychological deterioration. During a subsequent course of radiotherapy, the patient developed fever, headaches, and cutaneous lesions. INVESTIGATIONS: Physical examination, cerebral MRI, brain biopsy, skin biopsy, immunohistochemistry, bronchoscopy with bronchoalveolar lavage, and laboratory tests. DIAGNOSIS: Severe temozolomide-induced immunosuppression, exacerbated by corticosteroids, with profound T-cell lymphocytopenia and simultaneous opportunistic infections with Pneumocystis jiroveci pneumonia, brain abscess with Listeria monocytogenes, and cutaneous Kaposi's sarcoma. MANAGEMENT: Discontinuation of temozolomide, discontinuation of radiotherapy, antibiotic treatment with amoxicillin and gentamicin, and administration of atovaquone and pentamidine.

AVALIAÇÃO DE MÉTODOS PARA A DETECÇÃO DE LISTERIA EM QUEIJOS

Com o objetivo de avaliar os métodos de enriquecimento, semeadura direta e número mais provável (NMP), este último segundo o sistema do tubo Fung-Yu e segundo a técnica convencional, para a detecção de Listeria monocytogenes, foram analisadas 103 amostras de diferentes tipos de queijos (minas frescal, ricota, gorgonzola, roquefort, brie, camembert e cheddar) fabricados e comercializados na cidade do Rio de Janeiro, Brasil. O método de enriquecimento permitiu a detecção de L. monocytogenes em 11 (10.8%) amostras, enquanto o do NMP e da semeadura direta apenas em 3 (2.9%) e 2 (1.9%), respectivamente. O sistema Fung-Yu e a técnica convencional para proceder o método do NMP tiveram a mesma eficácia, em termos de sensibilidade e tempo, na detecção de L. monocytogenes e demais espécies do mesmo gênero. A eficiência dos meios seletivos indicadores testados variou em função da contaminação do queijo, sendo o ágar Mox mais sensível e mais seletivo que o Palcam para as amostras de queijos que apresentaram elevado nível de contaminação. Já para os demais tipos de queijos analisados ambos apresentaram a mesma eficiência. Das 103 amostras analisadas, 11 (10.8%) estavam contaminadas com L. monocytogenes, 13 (12.7%) com L. innocua, 6 (5.8%) com L grayi, e 1 (0.97%) com L. welshimeri, sendo L. monocytogenes evidenciada em amostras de queijos gorgonzola, roquefort e minas frescal.

Chlorella vulgaris up-modulation of myelossupression induced by lead: The role of stromal cells

In this study, Chlorella vulgaris (CV) was examined for its chelating effects on the ability of bone marrow stromal cell layer to display myeloid progenitor cells in vitro in lead-exposed mice, using the long-term bone marrow culture (LTBMC). In addition, the levels of interleukin (IL)-6, an important hematopoietic stimulator, as well as the numbers of adherent and non-adherent cells were also investigated. Mice were gavage treated daily with a single 50 mg/kg dose of CV for 10 days, concomitant to continuous offering of 1300 ppm lead acetate in drinking water. We found that CV up-modulates the reduced ability of stromal cell layer to display myeloid progenitor cells in vitro in lead-exposed mice and restores both the reduced number of non-adherent cells and the ability of stromal cells from these mice to produce IL-6. Monitoring of lead poisoning demonstrated that CV treatment significantly reduced lead levels in blood and tissues, completely restored the normal hepatic ALA levels, decreased the abnormally high plasma ALA and partly recovered the liver capacity to produce porphyrins. These findings provide evidence for a beneficial use of CV for combination or alternative chelating therapy to protect the host from the damage induced by lead poisoning. (C) 2008 Elsevier Ltd. All rights reserved.