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Enterococos em amostras de alimentos e águas: avaliação da virulência e do desempenho como indicadores de higiene; Enterococci in samples of food and water: evaluation of their virulence markers and their suitability as hygiene indicators

Malavazi, Bruna Carrer Gomes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 13/09/2007 PT
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65.7%
Enterococcus spp. pertencem ao grupo das bactérias láticas e estão presentes em solos, águas, plantas, microbiota autóctone de vários alimentos e como membros da microbiota intestinal de humanos e animais. Esses microrganismos foram considerados por muito tempo como comensais, mas o aumento da severidade das infecções nosocomiais causadas por enterococos mutirresistentes a antimicrobianos e, a falta de conhecimento sobre seus fatores de virulência geram insegurança na utilização de cepas deste gênero na produção de alimentos como culturas fermentadoras e/ou probióticas. A diferença entre uma cepa de enterococos com potencial patogênico e outra aparentemente segura para uso em processamento de alimentos não é clara, e a probabilidade de que esta última adquira fatores de virulência merece investigação. O objetivo do presente projeto foi determinar características fenotípicas e genotípicas de Enterococcus spp. isolados de amostras de alimentos e águas correlacionando sua presença com indicadores clássicos de higiene e contaminação fecal. De 812 colônias indicativas do gênero enterococos obtidas a partir de 120 amostras de alimentos, 299 isolados (37%) foram presuntivamente caracterizados como Enterococcus spp. Após identificação por PCR...

Comparação de metodologias para a estimativa do número mais provável (NMP) de coliformes em amostras de água; Comparison of methodologies for estimating the most probable number (MPN) of coliform in water samples

Marquezi, Marina Chiarelli
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 24/09/2010 PT
Relevância na Pesquisa
55.68%
Em quase todos os ambientes aquáticos são encontrados diversos microrganismos, entre eles alguns patogênicos ao homem, que tem como rota de transmissão o ciclo fecal-oral. Pelo fato de a água ser o alimento mais consumido pela população, ela está associada a diversos casos de doenças e de riscos à saúde pública. Assim, o controle da qualidade da água antes do seu consumo é essencial, e para a garantia de sua qualidade devem ser feitas análises que buscam indicar a contaminação por material de origem fecal. O grupo de bactérias mais usado para a determinação de contaminação fecal é o grupo coliformes totais, que tem como subgrupo os coliformes termotolerantes. A bactéria Escherichia coli é integrante do grupo coliforme termotolerante, e é a mais indicada para determinação de contaminação fecal pelo fato de estar presente em grande quantidade em fezes de humanos e animais de sangue quente. Para a análise de bactérias do grupo coliformes totais e E. coli há diversos métodos, entre eles o método convencional de fermentação em tubos múltiplos (FTM) e os métodos rápidos Colilert e Colitag. Este trabalho teve como objetivo comparar estes três métodos para tais análises em amostras de água provenientes de pontos com contaminações distintas (abastecimento...

Ocorrência de antibióticos e estudo de resistência microbiana em sistemas aquaculturais do Rio Paraná, Reservatório de Ilha Solteira, na região de Santa Fé do Sul, estado de São Paulo; Occurrence of antibiotics and antimicrobial resistance study in aquaculture systems in Paraná River, Ilha Solteira reservoir, in Santa Fé do Sul area, Sao Paulo state

Monteiro, Sérgio Henrique
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 06/06/2014 PT
Relevância na Pesquisa
55.66%
A aquicultura teve um aumento significativo em todo o mundo nos últimos anos. Muitas classes de antimicrobianos são usadas na aquicultura para o tratamento de infecções causadas por bactérias patogênicas. Entretanto, a contaminação do ambiente, do alimento e a ocorrência de resistência microbiana decorrentes da intensa utilização dos antimicrobianos são motivos de preocupação. Com o objetivo de se saber a ocorrência de antimicrobianos e possíveis formação de resistência microbiana em pisciculturas paulistas, um método rápido, sensível e simples de extração em fase sólida acoplada à cromatografia líquida e espectrometria de massas sequencial (SPE-LC-MS/MS), foi desenvolvido e validado para a determinação simultânea de 12 antimicrobianos (oxitetraciclina, tetraciclina, clortetraciclina, ciprofloxacina, enrofloxacina, sarafloxacina, norfloxacina, florfenicol, cloranfenicol, sulfatizol, sulfadimetoxina e sulfametazina) em água superficial e sedimento. Outro método, utilizando LC-MS/MS, foi elaborado para a determinação dos antimicrobianos em peixes. Paralelamente, também, foi avaliada a seleção de resistência microbiana dessas classes de antimicrobianos em peixe. Os antimicrobianos foram extraídos do sedimento com acetonitrila e tampão citrato...

Avaliação da contaminação de ostras (Crassostrea rhizophorae) por especies de Cryptosporidium e Giardia em um ambiente de estuario do litoral de São Paulo; Evaluation of the contamination of oysters (Crassostrea rhizophorae) by species of Cryptosporidium and Giardia in a estuarine environment from São Paulo coast

Diego Averaldo Guiguet Leal
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/08/2008 PT
Relevância na Pesquisa
55.63%
Moluscos bivalves por serem eficazes organismos filtradores acumulam e concentram substâncias, partículas e até mesmo patógenos em seus tecidos, se os locais onde vivem ou são cultivados receberem cargas de efluentes contaminados. Estes animais atuam como bioindicadores de contaminação fecal e, ao serem ingeridos crus ou mal cozidos, podem transmitir os patógenos acumulados em seus tecidos. Diversos estudos em diferentes países reportaram a presença de protozoários patogênicos como Cryptosporidium e Giardia em moluscos bivalves destinados ao consumo humano, porém, no Brasil estes dados são inexistentes. Diante deste cenário, é interessante e relevante investigar a ocorrência destes protozoários neste tipo de alimento, consumidos em diversas regiões do país. Este estudo teve a finalidade de avaliar a contaminação natural por oocistos e cistos dos protozoários parasitos em moluscos bivalves localizados em um ambiente de estuário do litoral norte do Estado de São Paulo; detectar as formas parasitárias em água de rio e água do mar; verificar se existe correlação entre fatores climáticos, físico-químicos e microbiológicos e a ocorrência natural dos parasitos nestes ambientes aquáticos e verificar se existe correlação entre a qualidade das águas e a contaminação dos moluscos que vivem nesta região. Os exemplares de moluscos foram processados através da homogeneização de tecidos específicos e submetidos a centrífugo-concentração com éter-PBS e as amostras hídricas foram analisadas pela técnica de filtração em membranas. A visualização dos protozoários foi realizada através da reação de imunofluorescência direta e a confirmação da morfologia dos protozoários feita com a utilização de microscopia de contraste de fase e a incorporação de um corante vital (DAPI). Cistos de Giardia foram detectados em 8 das 12 amostras de água do rio e uma amostra continha oocistos de Cryptosporidium. Ambos os patógenos foram detectados na água do mar...

Vending machines: Food safety and quality assessment focused on food handlers and the variables involved in the industry

Raposo, António; Carrascosa, Conrado; Pérez, Esteban; Saavedra, Pedro; Sanjuán, Esther; Millán, Rafael
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /10/2015 ENG
Relevância na Pesquisa
55.64%
"The purpose of this paper was to analyse the quality and safety parameters of food products sold in vending machines. A hygienic-sanitary assessment was conducted on 338 vending machines located on the island of Gran Canaria. Hygiene Assessment System (HAS) surveys, food handler examinations and microbiological (processed food and water) and physicochemical (water) controls were applied, permitting evaluation through the identification of the main risks and/or hazards of the hygienic-sanitary quality of the products sold in vending machines. Despite the positive results obtained from the HAS surveys applied to all the vending machines, achieving a total mean score of 87.6 ± 7.5 out of 100, the microbiological analysis showed that 5.7% of the 105 food samples were contaminated with Listeria monocytogenes, while Salmonella spp., Escherichia coli and Staphylococcus aureus were below the legally permitted limits. The lack of vehicles able to transport perishable food at correct temperatures (<8 °C) and the fact that some refrigerated vending machines were not at an ideal cooling temperature may have contributed to these values. The assessment tools used in this study revealed hygienic deficiencies in the transportation and microbiological quality of the products...

Separation and preconcentration of copper in environmental samples on Amberlite XAD-8 resin after complexation with a carbothioamide derivative

Elvan,Hamide; Ozdes,Duygu; Duran,Celal; Sahin,Deniz; Tufekci,Mehmet; Bahadir,Zekeriyya
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
65.59%
A new solid phase extraction (SPE) method has been developed for the selective separation and preconcentration of Cu (II) ions in food and water samples prior to its flame atomic absorption spectrometry determination. The method is based on the adsorption of the Cu(II) - 2-{[4-Amino-3-(4-methylphenyl-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]acetyl}-N-phenyl hydrazinecarbothioamide complex on Amberlite XAD-8 resin. The metal complex retained on the resin was eluted with 7.5 mL of 2.0 mol L-1 HCl in acetone. The optimum conditions for the SPE of Cu(II) ions were investigated, and the method was subsequently applied to sea water, stream water, rice, tea, and tobacco samples for the determination of Cu(II) levels.

Ligand-less rapidly synergistic cloud point extraction as an efficient method for the separation and preconcentration of trace amounts of lead from food and water samples

Rahnama,Reyhaneh; Eram,Sorour; Jamali,Mohammad Reza
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2014 EN
Relevância na Pesquisa
105.75%
A simple rapidly synergistic cloud point extraction procedure has been developed for the separation and preconcentration of trace amounts of lead from food and water samples by flame atomic absorption spectrometry (FAAS). Rapidly synergistic cloud point extraction (RS-CPE) greatly simplified and accelerated the procedure of traditional cloud point extraction (CPE). This method was accomplished in room temperature in 1 min. Non-ionic surfactant Triton X-114 was used as extractant. Octanol worked as cloud point revulsant and synergic reagent which lowered the cloud point temperature of Triton X-114 and assisted the subsequent extraction process. Some parameters that influenced cloud point extraction and subsequent determination were evaluated in detail, such as sample pH, amounts of octanol, amounts of Triton X-114, type of diluting solvent, extraction time and ionic strength, as well as interferences. Under optimized conditions (pH 8.5, octanol: 10 µL, Triton X-114: 0.04% w/v and diluting solvent: 1 mol L-1 HNO3 in methanol), an enhancement factor of 40 could be obtained, and the detection limit (LOD) for lead was 1.6 µg L-1. Relative standard deviation for ten replicate determinations of the standard solution containing 100 µg L-1 lead was 2.1%. The proposed method was applied for the determination of lead in food (spinach...

Preconcentration and determination of cadmium in water and food samples by in situ surfactant-based solid-phase extraction and flame atomic absorption spectrometry

Jamali,Mohammad Reza; Boromandi,Afsaneh
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 EN
Relevância na Pesquisa
95.73%
In situ surfactant-based solid-phase extraction (ISS-SPE) is proposed as a preconcentration procedure for the determination of cadmium in water and food samples by flame atomic absorption spectrometry. In the present work, cetyltrimethylammonium bromide was used as a cationic surfactant, hexafluorophosphate ion as an ion-pairing agent and 4-benzylpiperidinedithiocarbamate potassium salt (K-4-BPDC) as a chelating agent. Several variables that affect the extraction efficiencies such as pH, type and amount of surfactant, concentration of ion-pairing agent, concentration of chelating agent, ionic strength and extraction time were investigated and optimized. After optimization of the complexation and extraction conditions, an enrichment factor of 40 was obtained. The calibration curve was linear in the range of 1-50 µg L-1 and the limit of detection was 0.3 µg L-1. The relative standard deviation for 20 µg L-1 of cadmium was lower than 2.2%. Validation of the methodology was performed by standard addition method and analysis of certified reference materials. The method was successfully applied to the determination of cadmium in various food and water samples.

Solid-Phase Capture of Proteins, Spores, and Bacteria†

Weimer, B. C.; Walsh, M. K.; Beer, C.; Koka, R.; Wang, X.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /03/2001 EN
Relevância na Pesquisa
65.7%
Current methods for the detection of pathogens in food and water samples generally require a preenrichment step that allows selective enrichment of the test organism. The objective of this research was to eliminate an enrichment step to allow detection of bacteria directly in food and water samples in 30 min. A high-flow-rate, fluidized bed to capture and concentrate large (bacteria and spores) and small (protein) molecules was developed. This format, ImmunoFlow, is volume independent and uses large beads (greater than 3 mm in diameter) when capturing bacteria to prevent sample clogging when testing food samples. Detection of bound targets was done using existing enzyme-linked immunosorbent assay (ELISA) protocols. Four antibodies (anti-Escherichia coli O157:H7, -Bacillus globigii, -bovine serum albumin [BSA], and -ovalbumin [OVA]) were covalently coupled to various glass and ceramic beads. Very small amounts of BSA (<1 ng) and OVA (0.2 to 4.0 μg) were detected. Various industrial and environmental samples were used to observe the effect of the sample composition on the capture of anti-B. globigii and anti-E. coli O157:H7 modified beads. The lower limit of detection for both E. coli O157:H7 and B. globigii was 1 spore/cell independent of the sample size. The activity of anti-B. globigii modified beads declined after 3 days. Anti-E. coli O157:H7 modified beads declined in their capture ability after 2 days in various storage buffers. Storage temperature (4 and 25°C) did not influence the stability. The ImmunoFlow technology is capable of capturing bacteria and spores directly from samples...

Detection of pathogenic Yersinia enterocolitica in foods and water by immunomagnetic separation, nested polymerase chain reactions, and colorimetric detection of amplified DNA.

Kapperud, G; Vardund, T; Skjerve, E; Hornes, E; Michaelsen, T E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1993 EN
Relevância na Pesquisa
65.57%
A two-step polymerase chain reaction (PCR) procedure with two nested pairs of primers specific for the yadA gene of Yersinia enterocolitica was developed. The PCR assay identified all common pathogenic serogroups (O:3, O:5,27, O:8, O:9, O:13, and O:21) from three continents and differentiated pathogenic Y. enterocolitica from Y. pseudotuberculosis and from a variety of nonpathogenic yersiniae representing 25 serogroups and four species. The performance of the method was evaluated with seeded food and water samples. We compared two procedures for sample preparation prior to PCR: one was based on immunomagnetic separation of the target bacteria from the sample, using magnetic particles coated with immunoglobulin antibodies to Y. enterocolitica serogroup O:3, and the other method consisted of a series of centrifugation steps combined with proteinase treatment. Regardless of the method used, the PCR assay was capable of detecting 10 to 30 CFU/g of meat in 10(6)-fold excess of indigenous bacteria. When the samples were enriched overnight in a nonselective medium, the sensitivity was increased to approximately 2 CFU/g, except for samples with an extremely high background flora (> 10(7) CFU/g). We compared gel electrophoretic detection of PCR products with a colorimetric detection method designated DIANA (detection of immobilized amplified nucleic acids)...

Enterotoxigenic Bacteria in Food and Water from an Ethiopian Community

Jiwa, Sadruddin F. H.; Krovacek, Karel; Wadström, Torkel
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1981 EN
Relevância na Pesquisa
85.83%
Food and water samples from an Ethiopian community were screened for the presence of enterotoxin-producing bacteria. Using the Chinese hamster ovary cell assay, 40 of 213 isolates (18.8%) produced heat-labile (LT) enterotoxin. These LT-producing isolates comprised 33 of 177 (18.6%) strains from 24 of 68 food samples (35.3%) and 7 of 36 (19.4%) isolates of 4 of 17 water samples (23.5%). One LT-producing strain each of Salmonella emek and of Shigella dysenteriae was found. Three pseudomonads, all LT producers, produced heat-stable enterotoxin as gauged by the suckling mouse test. Two strains of LT-enterotoxigenic Escherichia coli O68 were found in water samples. No enterotoxigenic E. coli were isolated from food samples, but 13 of the LT-producing strains were Enterobacter, Klebsiella, Serratia, and Proteus species, and 7 food samples yielded more than one species of enterotoxigenic bacterium. Of the enterotoxigenic isolates from food, 15 were oxidase-positive strains of the genera Aeromonas, Pseudomonas, Achromobacter, Flavobacterium, and Vibrio. LT-enterotoxigenic Enterobacter, Acinetobacter, Klebsiella, Proteus, Providencia, and Serratia species represented 20 of the food and water isolates. Culture supernatant fluids of representative strains of oxidase-positive and oxidase-negative species giving positive reactions in Chinese hamster ovary cell tests induced fluid accumulation in rabbit ileal loops. Eight of the food samples and two of the water samples contained more than one isolate or species of enterotoxigenic bacterium. The stability of the LT production by oxidase-positive bacteria and non-E. coli strains was assessed by the rabbit skin and adrenal cell tests after 9 months and 1 year of storage...

Etiology of caries in Papua—New Guinea*: Associations in soil, food and water

Barmes, D. E.; Adkins, B. L.; Schamschula, R. G.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //1970 EN
Relevância na Pesquisa
65.48%
Mineral analyses of garden soils, vegetables, and water samples from 21 villages in the Sepik and Fly River regions of the Territory of Papua and New Guinea, in which the mean prevalence of dental caries ranged from 0 to 29.5% decayed teeth per person, have shown the following relationships between variations in the caries prevalence and the amounts of certain elements:

Investigation of Food and Environmental Exposures Relating to the Epidemiology of Campylobacter coli in Humans in Northwest England▿

Sopwith, Will; Birtles, Andrew; Matthews, Margaret; Fox, Andrew; Gee, Steven; James, Sam; Kempster, Jeanette; Painter, Michael; Edwards-Jones, Val; Osborn, Keith; Regan, Martyn; Syed, Qutub; Bolton, Eric
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
55.67%
This study uses multilocus sequence typing (MLST) to investigate the epidemiology of Campylobacter coli in a continuous study of a population in Northwest England. All cases of Campylobacter identified in four Local Authorities (government administrative boundaries) between 2003 and 2006 were identified to species level and then typed, using MLST. Epidemiological information was collected for each of these cases, including food and recreational exposure variables, and the epidemiologies of C. jejuni and C. coli were compared using case-case methodology. Samples of surface water thought to represent possible points of exposure to the populations under study were also sampled, and campylobacters were typed with multilocus sequence typing. Patients with C. coli were more likely to be older and female than patients with C. jejuni. In logistic regression, C. coli infection was positively associated with patients eating undercooked eggs, eating out, and reporting problems with their water supply prior to illness. C. coli was less associated with consuming pork products. Most of the cases of C. coli yielded sequence types described elsewhere in both livestock and poultry, but several new sequence types were also identified in human cases and water samples. There was no overlap between types identified in humans and surface waters...

Bacteriological Quality of Foods and Water Sold by Vendors and in Restaurants in Nsukka, Enugu State, Nigeria: A Comparative Study of Three Microbiological Methods

Nkere, Chukwuemeka K.; Ibe, Nnenne I.; Iroegbu, Christian U.
Fonte: International Centre for Diarrhoeal Disease Research, Bangladesh Publicador: International Centre for Diarrhoeal Disease Research, Bangladesh
Tipo: Artigo de Revista Científica
Publicado em /12/2011 EN
Relevância na Pesquisa
55.78%
Bacterial count in prepared food or water is a key factor in assessing the quality and safety of food. It also reveals the level of hygiene adopted by food handlers in the course of preparation of such foods. This comparative study evaluated the bacteriological quality of food and water consumed in Nsukka, Enugu state, Nigeria, using three bacteria enumeration methods. Data obtained are assumed to reflect the level of personal and environmental hygiene in the study population. Ten types of foods—beans, yam, abacha, okpa, moimoi, pear, cassava foofoo, rice, agidi, and garri—and 10 water samples were evaluated for bacteriological quality, precisely determining the level of coliform contamination, using the most probable number (MPN), lactose fermentation count (LFC), and Escherichia coli count (ECC) methods. Bacterial counts differed significantly (p<0.05) among the various food samples. However, this did not differ significantly in the three methods used for the enumeration of coliforms, suggesting that any of the three methods could be validly used for such studies with confidence. Escherichia coli and Klebsiella pneumoniae were the two major coliforms identified among 98 coliform isolates obtained from the various food samples...

Safety regulations of food and water implemented in the first year following the Fukushima nuclear accident

Hamada, Nobuyuki; Ogino, Haruyuki; Fujimichi, Yuki
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
65.67%
An earthquake and tsunami of historic proportions caused massive damage across the northeastern coast of Japan on the afternoon of 11 March 2011, and the release of radionuclides from the stricken reactors of the Fukushima nuclear power plant 1 was detected early on the next morning. High levels of radioiodines and radiocesiums were detected in the topsoil and plants on 15 March 2011, so sampling of food and water for monitoring surveys began on 16 March 2011. On 17 March 2011, provisional regulation values for radioiodine, radiocesiums, uranium, plutonium and other transuranic α emitters were set to regulate the safety of radioactively contaminated food and water. On 21 March 2011, the first restrictions on distribution and consumption of contaminated items were ordered. So far, tap water, raw milk, vegetables, mushrooms, fruit, nut, seaweeds, marine invertebrates, coastal fish, freshwater fish, beef, wild animal meat, brown rice, wheat, tea leaves and other foodstuffs had been contaminated above the provisional regulation values. The provisional regulation values for radioiodine were exceeded in samples taken from 16 March 2011 to 21 May 2011, and those for radiocesiums from 18 March 2011 to date. All restrictions were imposed within 318 days after the provisional regulation values were first exceeded for each item. This paper summarizes the policy for the execution of monitoring surveys and restrictions...

Simultaneous Quantification of Multiple Food- and Waterborne Pathogens by Use of Microfluidic Quantitative PCR

Ishii, Satoshi; Segawa, Takahiro; Okabe, Satoshi
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /05/2013 EN
Relevância na Pesquisa
65.65%
The direct quantification of multiple pathogens has been desired for diagnostic and public health purposes for a long time. In this study, we applied microfluidic quantitative PCR (qPCR) technology to the simultaneous detection and quantification of multiple food- and waterborne pathogens. In this system, multiple singleplex qPCR assays were run under identical detection conditions in nanoliter-volume chambers that are present in high densities on a chip. First, we developed 18 TaqMan qPCR assays that could be run in the same PCR conditions by using prevalidated TaqMan probes. Specific and sensitive quantification was achieved by using these qPCR assays. With the addition of two previously validated TaqMan qPCR assays, we used 20 qPCR assays targeting 10 enteric pathogens, a fecal indicator bacterium (general Escherichia coli), and a process control strain in the microfluidic qPCR system. We preamplified the template DNA to increase the sensitivity of the qPCR assays. Our results suggested that preamplification was effective for quantifying small amounts of the template DNA without any major impact on the sensitivity, efficiency, and quantitative performance of qPCR. This microfluidic qPCR system allowed us to detect and quantify multiple pathogens from fecal samples and environmental water samples spiked with pathogens at levels as low as 100 cells/liter. These results suggest that the routine monitoring of multiple pathogens in food and water samples is now technically feasible. This method may provide more reliable information for risk assessment than the current fecal contamination indicator approach.

Microbial diagnostic microarray for food‐ and water‐borne pathogens

Kostić, Tanja; Stessl, Beatrix; Wagner, Martin; Sessitsch, Angela; Bodrossy, Levente
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
65.67%
A microbial diagnostic microarray for the detection of the most relevant bacterial food‐ and water‐borne pathogens and indicator organisms was developed and thoroughly validated. The microarray platform based on sequence‐specific end labelling of oligonucleotides and the pyhylogenetically robust gyrB marker gene allowed a highly specific (resolution on genus/species level) and sensitive (0.1% relative and 104 cfu absolute detection sensitivity) detection of the target pathogens. Validation was performed using a set of reference strains and a set of spiked environmental samples. Reliability of the obtained data was additionally verified by independent analysis of the samples via fluorescence in situ hybridization (FISH) and conventional microbiological reference methods. The applicability of this diagnostic system for food analysis was demonstrated through extensive validation using artificially and naturally contaminated spiked food samples. The microarray‐based pathogen detection was compared with the corresponding microbiological reference methods (performed according to the ISO norm). Microarray results revealed high consistency with the reference microbiological data.

A Multiplex PCR/LDR Assay for Simultaneous Detection and Identification of the NIAID Category B Bacterial Food and Water-borne Pathogens

Rundell, Mark S.; Pingle, Maneesh; Das, Sanchita; Hussain, Aashiq; Ocheretina, Oksana; Charles, Macarthur; Larone, Davise H.; Spitzer, Eric D.; Golightly, Linnie; Barany, Francis
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
65.6%
Enteric pathogens that cause gastroenteritis remain a major global health concern. The goal of this study was to develop a multiplex PCR/LDR assay for the detection of all NIAID category B bacterial food and water-borne pathogens directly from stool specimens. To validate the PCR/LDR assay, clinical isolates of Campylobacter spp., Vibrio spp., Shigella spp., Salmonella spp., Listeria monocytogenes, Yersinia enterocolitica, and diarrheagenic Escherichia coli were tested. The sensitivity and specificity of the assay was assessed using a large number of seeded culture-negative stool specimens and a smaller set of clinical specimens from Haiti. The overall sensitivity ranged from 91 to 100% (median 100%) depending on the species. For the majority of organisms the sensitivity was 100%. The overall specificity based on initial testing ranged from 98% to 100% depending on the species. After additional testing of discordant samples the lowest specificity was 99.4%. PCR/LDR detected additional category B agents (particularly diarrheagenic E. coli) in 11/40 specimens from Haiti that were culture-positive for V. cholerae and in approximately 1% of routine culture-negative stool specimens from a hospital in New York. This study demonstrated the ability of the PCR/LDR assay to detect a large comprehensive panel of category B enteric bacterial pathogens as well as mixed infections. This type of assay has the potential to provide earlier warnings of possible public health threats and more accurate surveillance of food and water-borne pathogens.

Microfluidic Quantitative PCR for Simultaneous Quantification of Multiple Viruses in Environmental Water Samples

Ishii, Satoshi; Kitamura, Gaku; Segawa, Takahiro; Kobayashi, Ayano; Miura, Takayuki; Sano, Daisuke; Okabe, Satoshi
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /12/2014 EN
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65.58%
To secure food and water safety, quantitative information on multiple pathogens is important. In this study, we developed a microfluidic quantitative PCR (MFQPCR) system to simultaneously quantify 11 major human viral pathogens, including adenovirus, Aichi virus, astrovirus, enterovirus, human norovirus, rotavirus, sapovirus, and hepatitis A and E viruses. Murine norovirus and mengovirus were also quantified in our MFQPCR system as a sample processing control and an internal amplification control, respectively. River water contaminated with effluents from a wastewater treatment plant in Sapporo, Japan, was collected and used to validate our MFQPCR system for multiple viruses. High-throughput quantitative information was obtained with a quantification limit of 2 copies/μl of cDNA/DNA. Using this MFQPCR system, we could simultaneously quantify multiple viral pathogens in environmental water samples. The viral quantities obtained using MFQPCR were similar to those determined by conventional quantitative PCR. Thus, the MFQPCR system developed in this study can provide direct and quantitative information for viral pathogens, which is essential for risk assessments.

Molecular and genetic analysis of Cryptosporidium spp. oocysts : sources and genotypes in the environment

Jellison, Kristen L. (Kristen Leigh), 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 233 p.; 8467708 bytes; 8467517 bytes; application/pdf; application/pdf
ENG
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Cryptosporidium parvum is responsible for an acute gastrointestinal disease that is self-limiting in immunocompetent people but potentially life-threatening for the immunocompromised. Until recently, C. parvum was the only species of Cryptosporidium known to cause disease in people, however, reports of C. muris, C. felis, and C. meleagridis in immunocompetent adults have raised questions about the extent to which Cryptosporidium spp. are infectious for humans. Until more is known, presence of any Cryptosporidium oocysts in the environment should be considered a potential public health risk. Cryptosporidium spp. can infect a wide range of animal hosts, and environmental sources may include wildlife, agricultural animals, or human sewage. Transmission of Cryptosporidium spp. via fecally-contaminated food and water has been well-documented, and outbreaks of cryptosporidiosis have occurred around the world. The exogenous stage of the organism, the oocyst, is difficult to remove from drinking water supplies because it is resistant to chlorine disinfection and inefficiently filtered. Therefore, a better understanding of the sources, fate, and transport of oocysts in the environment is critical to protect source waters from oocyst contamination. In this work...