Janus plasmonic-aggregation induced emission nanobeads as high-performance colorimetric-fluorescent probe of immunochromatographic assay for the ultrasensitive detection of staphylococcal enterotoxin B in milk.

Herein, a colorimetric-fluorescent hybrid bifunctional nanobead with Janus structure (J-cf-HBN) was synthesized via one-pot microemulsification. Oleylamine-coated AuNPs and aggregation-induced emission luminogens (AIEgens) were suggested as building blocks to obtain high-performance colorimetric-fluorescent signals. The as-prepared J-cf-HBNs were used as a signal amplification probe to construct an immunochromatographic assay (J-cf-HBNs-ICA) platform for the ultrasensitive detection of staphylococcal enterotoxin B (SEB) in milk samples. Owing to the rational spatial distribution of AuNPs and AIEgens, the J-cf-HBNs present a highly retained photoluminescence and enhanced colorimetric signals. Combined with a pair of highly affinitive anti-SEB antibodies, the J-cf-HBN-ICA platform enabled the fast naked-eye visualization and fluorescent quantitative detection of SEB in various milk matrices. Given the advantages of the dual-mode high-performance J-cf-HBNs, the proposed strip achieved a high sensitivity for SEB qualitative determination with a visual limit of detection (LOD) of 1.56 ng mL-1 and exhibited ultrasensitivity for SEB quantitative detection with a LOD of 0.09 ng mL-1, which is 139-fold lower than that of ELISA using same antibodies. In conclusion, this work provides new insights into the construction of multimode immunochromatographic methods for food safety detection in the field.

Mulberry Leaf-Derived Morin Activates ß-Catenin by Binding to Frizzled7 to Promote Intestinal Stem Cell Expansion upon Heat-Stable Enterotoxin b Injury.

Intestinal stem cells (ISCs) sustain epithelial renewal by dynamically altering behaviors of proliferation and differentiation in response to various nutrition and stress inputs. However, how ISCs integrate bioactive substance morin cues to protect against heat-stable enterotoxin b (STb) produced by Escherichia coli remains an uncertain question with implications for treating bacterial diarrhea. Our recent work showed that oral mulberry leaf-derived morin improved the growth performance in STb-challenged mice. Furthermore, morin supplementation reinstated the impaired small-intestinal epithelial structure and barrier function by stimulating ISC proliferation and differentiation as well as supporting intestinal organoid expansion ex vivo. Importantly, the Wnt/ß-catenin pathway, an ISC fate commitment signal, was reactivated by morin to restore the jejunal crypt-villus architecture in response to STb stimulation. Mechanically, the extracellular morin-initiated ß-catenin axis is dependent or partially dependent on the Wnt membrane receptor Frizzled7 (FZD7). Our data reveal an unexpected role of leaf-derived morin, which represents molecular signaling targeting the FZD7 platform instrumental for controlling ISC regeneration upon STb injury.

Aislamiento de Bacillus cereus en restaurantes escolares de Colombia / Isolation of Bacillus cereus in school restaurants in Colombia

Resumen Introducción. Bacillus cereus es reconocido como un agente patógeno causante de intoxicaciones alimentarias. Se trata de una bacteria de metabolismo aerobio facultativo capaz de formar esporas, lo que le permite sobrevivir a la pasteurización y el calentamiento e, incluso, a la irradiación con los rayos gamma usados para reducir los agentes patógenos de los alimentos. Objetivo. Estudiar la presencia de B. cereus y su toxina diarreica en el arroz y en alimentos a base de cereales, harinas o féculas listos para el consumo en restaurantes escolares de algunos departamentos de Colombia. Materiales y métodos. Se hizo un estudio descriptivo y transversal con alimentos listos para el consumo distribuidos en restaurantes escolares de los departamentos que más notifican enfermedades transmitidas por alimentos al sistema de vigilancia, así como en los de menor notificación. Resultados. Se recolectaron 479 muestras en ocho departamentos, 74 municipios y 363 restaurantes escolares; el 63 % correspondió a muestras de arroz y el 37 % a alimentos como coladas. El 9 % de las muestras analizadas fueron positivas para B. cereus y, en el 91 % de estas, se detectó la toxina diarreica. Conclusiones. En todos los departamentos estudiados se encontró B. cereus. El manejo de materias primas y el inadecuado tratamiento térmico de los alimentos fueron los factores directamente relacionados con las enfermedades transmitidas por alimentos. Es importante reforzar la vigilancia e incentivar la investigación y la notificación de los brotes de enfermedades transmitidas por alimentos para mejorar la calidad de la información, llevar a cabo acciones de comunicación, prevención y coordinación intersectorial, y con los manipuladores, con el fin de adoptar las medidas necesarias que garanticen la inocuidad de los alimentos, así como la eliminación de los factores de riesgo de estas enfermedades.

Abstract Introduction: Bacillus cereus is recognized as a pathogen that causes food poisoning. It is a facultative aerobic metabolism bacterium capable of forming spores, which allows it to survive pasteurization and heating even by the gamma irradiation used to reduce pathogens in food. Objective: To study the presence of Bacillus cereus and its diarrheal toxin in rice and ready-to-eat cereals, flours, and starches in school restaurants in Colombia. Materials and methods: We conducted a descriptive cross-sectional study of ready-to-eat foods distributed in school restaurants in the departments with the most and the least notification of foodborne diseases to the surveillance system. Results: A total of 479 samples were collected from eight departments, 74 municipalities, and 363 school restaurants, 63% of which were rice samples and 37%, starchy food samples; 9% of them tested positive for Bacillus cereus. In 91% of the samples that tested positive, the bacterium was isolated with the presence of the diarrheal toxin. Conclusions: In all the departments with B. cereus in the samples, the factors directly related to food-borne diseases were the handling of raw materials and the poor thermal treatment of food. Strengthening surveillance by stimulating research and reporting on outbreaks of foodborne diseases is important to improve the quality of information, to develop communication, prevention and intersectional coordination and manipulation measures, as well as to take the necessary actions to guarantee the safety of food and to eliminate the risk factors that may contribute to this problem.

Portación de Staphylococcus aureus enterotoxigénico tipo A, en frotis nasofaríngeos en manipuladores de alimentos / Carriage of Staphylococcus aureus among food service workers

Background Staphylococcus aureus produces 11 serotypes of endotoxins that may cause food poisoning. Aim To determine the prevalence of type A enterotoxigenic Staphylococcus aureus carriage among food service workers in Chillan, Chile. Material and Methods Pharyngeal swabs were obtained from 100 food service workers and were cultured in Agar plates. After identifying the presence of Staphylococcus aureus, DNA was extracted to identify type A toxin by conventional PCR. Results Thirty eight percent of samples were colonized with Staphylococcus aureus. Among these, 26% were toxin A producers. Conclusions Half of the sampled workers carried Staphylococcus aureus and a quarter of these produced type A enterotoxin.

Presencia de los genes de toxigenicidad nheA, nheBy nheC en cepas de Bacillus cereus aisladas de leches deshidratadas en Costa Rica / Detection of toxigenic genes nheA, nheB and nheC in Bacillus cereus strains isolated from powdered milk samples in Costa Rica

La leche en polvo es un producto de alto consumo humano que no precisa de ser conservado en frío, no obstante, diversos microorganismos pueden deteriorarlo. En la población costarricense, también se observa este alto consumo, por la facilidad del alimento para transporte, preparación y su costo competitivo. Bacillus cereus es una bacteria potencialmente patógena asociada a este tipo de producto, capaz de desarrollar toxinas dependiendo de la presencia o ausencia de los respectivos genes codificantes. En este estudio se determinó la presencia de los genes toxigénicos nheA, nheB y nheC en cepas de B. cereus aisladas de leche deshidratada vendida en el mercado nacional costarricense.Se examinaron cinco lotes diferentes, de diez marcas comerciales de leche en polvo distribuidos en el área metropolitana de San José Costa Rica. Se procedió a cuantificar B. cereus en las muestras de leche en polvo mediante la técnica de Número Más Probable (NMP) e identificar los aislamientos utilizando el equipo automatizado Vitek®. Adicionalmente, se determinó la presencia de los genes nheA, nheB y nheC mediante la técnica de PCR. La frecuencia de aislamiento de Bacillus cereus en las muestras de leche en polvo analizadas alcanzó un 50%, con cantidades que oscilaron entre 3 y >100 NMP/g. Se recuperaron 19 cepas de B. cereus aisladas, cinco fueron positivas para los tres genes toxigénicos, lo cual revela la presencia de B. cereus potencialmente toxigénico en leches deshidratadas del mercado nacional, lo que representa un riesgo para la salud pública.

Powdered milk is a frequently consumed product that does not need to be kept under cold conditions. Nevertheless, different microorganisms may contaminate it. Powdered milk is a highly consumed product by Costa Rican population, and Bacillus cereus is a potentially pathogenic bacteria associated to it, with the ability to develop toxins depending on the presence of the respective codifying genes. The aim of this study was to determine the presence of the toxigenic genes nheA, nheB and nheC from B. cereus strains, found in powdered milk sold at the Costa Rican national market. Five different lots of ten brands of powdered milk, distributed in the metropolitan area of San José, Costa Rica were analyzed. B cereus load was quantified using the Most Probable Number technique and identified using the Vitek® system. The presence of the toxigenic genes was determined using the PCR technique. The isolation frequency of this bacteria in the powdered milk samples analyzed reached 50%, with populations ranging from 3 to >100 MPN/g. Five out from nineteen strains were found positive for the three toxigenic genes, indicating contamination with potentially toxigenic B. cereus in powdered milk distributed in the national market, and an important risk for public health.

Factors associated with Clostridium difficile diarrhea in a hospital in Beijing, China

Clostridium difficile is the most common cause of hospital-acquired diarrhea in patients treated with antibiotics, chemotherapeutic agents, and other drugs that alter the normal equilibrium of the intestinal flora. A better understanding of the risk factors for C. difficile-associated disease (CDAD) could be used to reduce the incidence of CDAD and the costs associated with its treatment. The aim of this study was to identify the risk factors for CDAD in a cohort of Chinese patients in a Beijing hospital. Medical charts of a total of 130 inpatients (62 males and 68 females) with hospital-acquired diarrhea (45 with CDAD; 85 without CDAD) were retrospectively reviewed. C. difficile toxins A and B were detected in fecal samples using enzyme-linked fluorescence assays. The drugs used by patients with and without CDAD before the onset of diarrhea were compared. Factors that differed significantly between the two groups by univariate analysis were analyzed by multivariate analysis using a logistic regression model. Multivariate analysis showed that cephalosporin treatment was associated with a significantly higher risk of CDAD in hospitalized patients, while treatment with glycopeptides was significantly associated with a reduction in CDAD (P<0.001 for cephalosporin; P=0.013 for glycopeptides). Our data confirmed previous findings that empirical treatment with cephalosporins is positively associated with CDAD compared to individuals using other CDAD-related drugs. Additionally, we showed that treatment with glycopeptides was negatively associated with CDAD, compared to individuals using other CDAD-related drugs.

From Escherichia coli heat-stable enterotoxin to mammalian endogenous guanylin hormones

The isolation of heat-stable enterotoxin (STa) from Escherichia coli and cholera toxin from Vibrio cholerae has increased our knowledge of specific mechanisms of action that could be used as pharmacological tools to understand the guanylyl cyclase-C and the adenylyl cyclase enzymatic systems. These discoveries have also been instrumental in increasing our understanding of the basic mechanisms that control the electrolyte and water balance in the gut, kidney, and urinary tracts under normal conditions and in disease. Herein, we review the evolution of genes of the guanylin family and STa genes from bacteria to fish and mammals. We also describe new developments and perspectives regarding these novel bacterial compounds and peptide hormones that act in electrolyte and water balance. The available data point toward new therapeutic perspectives for pathological features such as functional gastrointestinal disorders associated with constipation, colorectal cancer, cystic fibrosis, asthma, hypertension, gastrointestinal barrier function damage associated with enteropathy, enteric infection, malnutrition, satiety, food preferences, obesity, metabolic syndrome, and effects on behavior and brain disorders such as attention deficit, hyperactivity disorder, and schizophrenia.

Influence of carvacrol and thymol on the physiological attributes, enterotoxin production and surface characteristics of Staphylococcus aureus strains isolated from foods

This study evaluated the influence of the phenolic compounds carvacrol (CAR) and thymol (THY) on some physiological characteristics and on the modulation of the secretion of some staphylococcal virulence factors, that is, coagulase and enterotoxin. This study also investigated possible mechanisms for the establishment of the anti-staphylococcal activity of these compounds. Sublethal concentrations (0.3 and 0.15 µL/mL) of CAR and THY inhibited the activity of the enzymes coagulase and lipase and led to a decrease in salt tolerance. At the tested sublethal concentrations, both CAR and THY led to a total suppression of enterotoxin production. The loss of a 260-nm-absorbing material and an efflux of potassium ions occurred immediately after the addition of CAR and THY at 0.6 and 1.2 µL/mL and increased up to 120 min of exposure. Electron microscopy of cells exposed to CAR and THY (0.6 µL/mL) revealed that individual cells appeared to be deformed, with projections of cellular material. The observations of leakage of cellular material and an altered cell surface suggest that gross damage to a cell's cytoplasmic membrane, which results in a disruption in protein secretion, could be responsible for the anti-staphylococcal properties of CAR and THY.

Growth inhibition of Staphylococcus aureus and escherichia coli strains by neutralizing IgY antibodies from ostrich egg yolk

Ostrich raising around the world have some key factors and farming profit depend largely on information and ability of farmers to rear these animals. Non fertilized eggs from ostriches are discharged in the reproduction season. Staphylococcus aureus and Escherichia coli are microorganisms involved in animal and human diseases. In order to optimize the use of sub products of ostrich raising, non fertilized eggs of four selected birds were utilized for development of polyclonal IgY antibodies. The birds were immunized (200ug/animal) with purified recombinant staphylococcal enterotoxin C (recSEC) and synthetic recRAP, both derived from S. aureus, and recBFPA and recEspB involved in E. coli pathogenicity, diluted in FCA injected in the braquial muscle. Two subsequent immunization steps with 21 days intervals were repeated in 0,85% saline in FIA. Blood and eggs samples were collected before and after immunization steps. Egg yolk immunoglobulins were purified by precipitation with 19% sodium sulfate and 20% ammonium sulphate methodologies. Purified IgY 50µL aliquots were incubated in 850µL BHI broth containing 50µL inoculums of five strains of S. aureus and five strains of E.coli during four hours at 37ºC. Growth inhibition was evaluated followed by photometry reading (DO550nm). Egg yolk IgY preparation from hiperimmunized birds contained antibodies that inhibited significantly (p<0,05) growth of strains tested. Potential use of ostrich IgY polyclonal antibodies as a diagnostic and therapeutic tool is proposed for diseased animals.

Detection of enterotoxin genes of Staphylococcus sp isolated from nasal cavities and hands of food handlers

Food handlers, an important factor in food quality, may contain bacteria that are able to cause foodborne disease. The present study aimed to research coagulase-negative (CNS) and -positive staphylococci (CPS) in 82 food handlers, analyzing nasal and hand swabs, with identification of 62 CNS (75.6 percent) and 20 CPS strains (24.4 percent). Staphylococcal enterotoxins genes were investigated by PCR. In 20 CPS strains, 19 were positive for one or more genes. The percentage of CNS presenting genes for enterotoxins was high (46.8 percent). Despite of the staphylococcal species, the most common gene was sea (35.4 percent), followed by seh and sej (29.2 percent). The detection of new staphylococcal enterotoxins (SEs) genes showed a higher pathogenic potential in this genus. The presence of these gene points out the importance of CNS not only as contaminant bacteria but also as a pathogen.

Ocurrence of staphylococcus aureus and multiplex pcr detection of classic enterotoxin genes in cheese and meat products / Ocorrência de Staphylococcus aureus e detecção por PCR multiplex de genes de enterotoxinas clássicas em queijo e derivados cárneos

Multiplex PCR was used to investigate the presence of enterotoxins genes (sea, seb, sec, sed and see) and femA gene (specific for Staphylococcus aureus) in coagulase-positive staphylococci (CPS) isolated from cheese and meat products. From 102 CPS isolates, 91 were positive for femA, 10 for sea, 12 for sed and four for see.

PCR multiplex foi empregado para investigar a presença de genes de enterotoxinas estafilocócicas (sea, seb, sec, sed e see) e do gene femA, específico para S.aureus, em cepas de estafilococos coagulase positiva (ECP) isoladas de queijos e derivados cárneos. De 102 cepas, 91 foram positivas para femA, 10 para sea, 12 para sed e 4 para see.

Pesquisa de genes de resistência a antimicrobianos beta-lactâmicos e de enterotoxina em cepas de Staphylococcus aureus presentes em amostras de alimentos / Search of antimicrobial beta-lactam resistance genes and enterotoxin genes in Staphylococcus aureus strains present in food samples

Staphylococcus aureus são microrganismos causadores de diversos tipos de doenças. Existem dois grandes agravantes a sua presença: a produção de toxinas e a resistência a antimicrobianos. S. aureus produzem enterotoxinas termolábeis que, quando presentes nos alimentos, podem levar a uma toxinfecção a quem o consumir. Esta espécie também é conhecida por facilmente responder adaptativamente ao uso de drogas tornando-se cada vez mais difícil controlá-la. Um dos maiores responsáveis por esta preocupação são os MRSA (methicillin-resistant Staphylococcus aureus), resistentes a beta-lactâmicos através da produção de uma proteína diferenciada de parede codificada pelo gene mecA. A presença deste patógeno resistente fora do ambiente hospitalar é registrada há alguns anos e pouco a pouco vem se descobrindo que a via alimentar pode ser um meio deste gene se disseminar. Objetivos: procurar pelo gene mecA e o codificador da enterotoxina em Staphylococcus aureus de amostras alimentares para discutir a presença do gene de resistência em uma nova via de transmissão e a validade de apenas se fiscalizar a presença apenas de Staphylococcus coagulase positivo em produtos alimentares como forma de manter o alimento seguro contra toxinfecções. Métodos: Cinquenta e sete amostras de S. aureus provenientes de amostras de quatro tipos de fontes alimentares foram testadas por PCR com primer específico para o gene mecA e para o gene codificador da enterotoxina. Resultados: Destas, cinco (8,8 por cento do total) amostras apresentaram o gene de resistência e onze (19,2 por cento do total) continham o gene codificador da enterotoxina termolábil. Conclusão: A presença do gene de enterotoxina em produtos prontos para consumo e peixe cru de feira é uma realidade, assim como o debate sobre qual a melhor forma de se legislar sobre o assunto que deve ser mantido e melhor avaliado...

Staphylococcus aureus are a bacterium that causes various types of diseases. There are two major aggravating to its presence: the toxins production and antimicrobial resistance. S. aureus produce heat-labile enterotoxina that, when present in food, can lead to poisoning of those who consume. This specie is also known to easily respond adaptively to drug use becoming increasingly difficult to control it. One of the main reasons for this concern are MRSA (methicillin-resistant Staphylococcus aureus) which are resistant to betalactams drugs through a differentiated wall protein production encoded by the mecA gene. The presence of this resistant pathogen outside hospitals has been recorded a few years ago and gradually comes to discover that the food chain can be a way for the gene spread. Objectives: Search for the mecA gene and the enterotoxins encoded gene in Staphylococcus aureus from food samples to discuss the presence of the resistance gene in a new transmission route and the validity of only review the presence of Staphylococcus coagulase positive in food product as a way to keep insurance against food poisoning. Methods: Fifty-seven samples of S. aureus from five different sources of food samples were tested by PCR with specific primer for the mecA gene and the enterotoxins gene. Results: Of these, five (8,8 per cent of total) samples showed the resistance gene and eleven (19,2 per cent of total) contained the gene encoding the heat-labile enterotoxin. Conclusion: The presence of enterotoxin encoded gene in food products ready for consumption and raw fish is a fact and a debate about how best to legislate should be maintained and better evaluated. In the case of the resistance gene, the food chain is really a way where this gene can spread. It is also the first time the mecA gene from food ready for consumption is reported in Brazil and Latin America.

Contagem de Staphylococcus sp. e deteccão de enterotoxinas estafilocócicas e toxina da síndrome do choque tóxico em amostras de leite cru refrigerado / Staphylococcus sp. counting and detection of staphylococcal enterotoxins and toxic shock toxin syndrome from cooled raw milk

Analisaram-se 80 amostras de leite cru refrigerado a 4ºC e estocado por 48 horas em tanques refrigeradores de propriedades rurais do estado de Minas Gerais quanto à contagem e identificacão de Staphylococcus sp. e deteccão de enterotoxinas estafilocócicas (SE) e da toxina da síndrome do choque tóxico (TSST-1). Staphylococcus sp. foi detectado em 100 por cento das amostras de leite de tanque refrigerador em contagens que variaram de 1,0 10(5) a 2,5 10(7) UFC/ml (média = 5,60 log UFC/ml; s = 0,53 e CV = 9,5 por cento). Isolaram-se e identificaram-se 436 estirpes como: S. aureus, S hyicus, S. epidermidis, S. intermedius, S. cohnii, S. sciuri, S. schleirferi e S. delphini. As estirpes de mesmo perfil bioquímico, oriundas da mesma amostra, foram agrupadas (pools) e induzidas a produzir SE e TSST-1. A deteccão dessas enterotoxinas foi feita pelo método optimum sensitivity plate, usando-se técnica de celofane sobre ágar. Identificou-se a producão de SEA, SEB, SEC, SED e de TSST-1 em percentuais variados. Dos 138 pools preparados, 91 produziram, pelo menos, uma toxina isoladamente ou em associacão a outras toxinas. Dos pools enterotoxigênicos, 24,6 por cento eram coagulase positiva e 41,3 por cento, coagulase negativa. A confirmacão de estirpes enterotoxigênicas de Staphylococcus coagulase negativa isoladas de amostras de leite é importante em relacão à saúde pública.

Importância do Staphylococcus aureus nas mastites subclínicas: pesquisa de enterotoxinas e toxina do choque tóxico, e a relação com a contagem de células somáticas / Importance of Staphylococcus aureus in bovine subclinical mastitis: presence of enterotoxins, shock syndrome toxin and relationship with somatic cell count

O Staphylococcus aureus é um dos principais agentes das mastites consideradas contagiosas, apresentando elevada incidência na maioria dos rebanhos leiteiros em vários países. Além de perdas econômicas é importante salientar o aspecto de saúde pública para cepas produtoras de enterotoxinas e da toxina do choque tóxico. A enterotoxina A, relacionada com maior ênfase nos casos de toxinfecções alimentares, pode ser veiculada pelo leite cru, pasteurizado e subprodutos lácteos. A síndrome do choque tóxico é determinada mais freqüentemente pela toxina do choque tóxico, porém as enterotoxinas do tipo B e C também podem ser implicadas. O objetivo deste estudo foi verificar a ocorrência de S.aureus produtores de enteroxinas e da toxina do choque tóxico em amostras de leite de animais com mastite subclínica, e correlacionar estes resultados com a contagem de células somáticas; utilizando a técnica de "celofane over agar" para detecção da TNAase, kit comercial para identificação das enterotxinas e contagem eletrônica de células somáticas. Avaliou-se 209 amostras de leite oriundas de vacas com mastite subclínica por S.aureus, e dentre estas, 209 (98,86 por cento) produziram TNAse, nove amostras (4,39 por cento) foram produtoras de enterotoxinas, sendo que uma (0,49 por cento) dentre elas foi produtora de EED, três (1,46 por cento) de EEC, e três (1,46 por cento) de EEB. Em uma amostra (0,49 por cento), detectou-se concomitantemente EEA e EEB e em outra EEB e EEC. A toxina do choque tóxico não foi encontrada nas cepas avaliadas neste estudo, assim como não houve aumento estatisticamente significativo, na contagem de células somáticas, das amostras de cepas produtoras de enteroxinas.

Virulence factors of non-O1 non-O139 Vibrio cholerae isolated in Córdoba, Argentina / Factores de virulencia de Vibrio cholerae no-O1 no-O139 aislados en Córdoba, Argentina

V. cholerae non-O1 non-O139 serogroups isolated from clinical and environmental sources in Córdoba, Argentina, were analyzed for the presence and expression of virulence genes. Most of the strains studied contained the genes toxR and hlyA, but lacked ctxA, zot, ace, tcpA and stn. The culture supernatants were tested for hemolytic and cytotoxic activity. The enterotoxic potential of the strains was studied in a rabbit ileal loop assay and their genetic profiles were compared by PFGE. The environmental strains varied in their virulence phenotype and showed no-clonal relationships. The clinical strains were highly enterotoxic, hemolytic, proteolytic and showed indistinguishable PFGE profiles, although they differed in their cytotoxic activity. This is the first description, using cell culture and “in vivo” studies, of the virulence properties of non-O1 non-O139 V. cholerae from Argentina.

En este trabajo se analizó la presencia y expresión de genes de virulencia en V. cholerae no-O1 no-O139 de origen clínico y ambiental, aislados en Córdoba, Argentina. La mayoría de las cepas estudiadas contiene los genes toxR y hlyA, pero no ctxA, zot, ace, tcpA y stn. Se analizó la actividad hemolítica y citotóxica de estas cepas en los sobrenadantes de cultivo, así como su potencial enterotóxico en ensayos de asa ileal ligada de conejo. Además, los aislamientos fueron comparados por sus perfiles genéticos en PFGE. Las cepas del medio ambiente mostraron variación en su fenotipo de virulencia y no mostraron relación clonal. Las cepas clínicas fueron muy enterotóxicas, hemolíticas, proteolíticas y mostraron perfiles indistinguibles de PFGE, aunque mostraron diferencias en su actividad citotóxica. En este trabajo se describen por primera vez, utilizando ensayos de cultivo celular e “in vivo”, propiedades de virulencia de V. cholerae no-O1 no-O139 aislados en Argentina.

Importancia de la Deteccion de Enterotoxinas Estafilococicas / The importance of staphylococcal enterotoxins detection

Se presenta un compendio sobre la clasificacion, patogenicidad, obtencion, purificacion, metodos de analisis y otros aspectos de las enterotoxinas estafilococicas y los avances obtenidos en le estudio de estas a nivel internacional y, en particular, en Cuba

Partial isolation and some properties of enterotoxin produced by Bacillus cereus strains

Extracellular proteins produced by Bacillus cereus AL-42 and AL-15 were fractioned by chromatography on QAE-Sephadex and Sephadex G75. This last chromatographic process resulted in three peaks. The major peak showed vascular permeability activity to rabbits, lethality to mice, and cytotoxicity to Vero and Hela cells. The analysis by SDS-PAGE after ultrafiltration confirm recent findings that the enterotoxin is a compound with molecular mass > 30.000

Generalidades sobre enterotoxinas estafilocócicas em alimento / Generalitu about staphylococci enterotoxin in foods

Os estafilococos säo os agentes mais comuns de toxinfecçäo alimentar. A freqüência dos surtos e a severidade dos sintomas caracterizam a intoxicaçäo estafilocócica como um importante risco nos mais variados tipos de alimentos, o que vem merecendo cuidadosa atençäo, embora a doença apresente baixa mortalidade e curta duraçäo. O tratamento térmico destrói a bactéria, porém a toxina termorresistente permanece no alimento, sendo necessário, para se confirmar um surto, a detecçäo direta de enterotoxina no produto implicado. Os métodos disponíveis atualmente, tais como o radioimunoensaio (RIA), a aglutinaçäo de látex (RPLA) e o ensaio imunoenzimático (ELISA) apresentam sensibilidade para detectar enterotoxinas em alimentos envolvidos em surtos, porém, no que concerne ao controle de qualidade, ainda há necessidade de desenvolver técnicas sensíveis para avaliar contaminaçäo por estafilococos enterotoxinas estafilocócicas, bem como as metodologias tradicionais e recentes, propostas para a produçäo e detecçäo de enterotoxinas

Agentes bacterianos causantes de toxo-infecciones de origem alimentario / Bacterial agents as cause of toxo-infections of food origin

Food are considered substances that contribute to maintain the functional equilibrium of living organisms. Many of these products are good substrates to support microbial growth. The normal state of human health will be negatively affected by foods highly contaminated with pathogenic microorganisms or their toxins. Diarrhea, fever and other symptoms may be produced by bacterial infections or bu some of their harmful toxins. Microbial foodborne illnesses are of importance in public health, specially in communities with defective nutrition and when a circle of infection-undernutrition-deficient inmunological response and again infection is established. Infections are diseases caused by pathogenic bacteria (Salmonella, Shigella and others), that entering the body through the mouth with the meals and may produce colonization or invasiveness at intestinal level, as well as tissue pertubations and diarrhea. Intoxications may be caused by preformed toxins in foods, being some of them thermolabile as that of Clostridium botulinum, or thermostable as those of Staphylococcus aureus. Some strains of Clostridium perfringes and Escherichia coli after passing the gastric barrier, are able to produced their respective toxins in the intestinal tract. The synthesis of bacterialtoxins may be coded by genes located in the chromosome or in extrachromosomal plasmids. By adjusting some physico-chemical parameters is posible to control microbial growth of the agents involved in food-borne illnesses. Among those related to intrinsic properties of good are: pH, water activity, potential redox, nutrients and biological structures. Others, depend on external conditions which may influence on their velocity of multiplication such: temperature, relative humidity and presence of gas. Also are of importance the interactions among mixed pipilations, that influence growth kinetics and determine the advantage of one specie over other...