Multi-enzyme isothermal rapid amplification assay for the detection of Escherichia coli O157∶H7 / 上海预防医学

ObjectiveA rapid enrichment and detection method for Escherichia coli O157∶H7 was developed by using multienzyme isothermal rapid amplification （MIRA） fluorescence method combined with metal organic frameworks immunomagnetic beads. MethodsUsing rfbE gene as the target， the primers， probes and reaction system were screened， and the specificity， sensitivity and practical application of this method were investigated. ResultsThe detection limit of Escherichia coli O157∶H7 was 1.18×105 CFU‧mL-1， and the detection limit of DNA concentration was 9 pg‧μL-1. The detection process was completed in 20 minutes. The test results of 47 strains （24 target strains and 23 non-target strains） were consistent with real-time PCR （RT-PCR）. ConclusionA method based on metal-organic framework immunomagnetic beads enrichment combined with MIRA assay is developed in this study. The method is simple， rapid and suitable for rapid enrichment and detection of Escherichia coli O157∶H7 in food.

Cambios en el perfil protéico de E. coli O157:H7 frente al tratamiento con Ib-M1 e IONP@Ib-M1 / Changes in the protein profile of E. coli O157: H7 against treatment with Ib-M1 and IONP@Ib-M1 / Identificação de alterações no perfil protetor de E. coli O157: H7 contra o tratamento com Ib-M1 e IONP@Ib-M1

Resumen Escherichia coli 0157:H7 es una bacteria patógena reconocida por su capacidad de resistencia a diversos antibióticos; razón por la cual, se generan complicaciones en el tratamiento de infecciones producidas por esta bacteria. El péptido Ib-M1 y el bioconjugado I0NP@Ib-M1 han surgido como una nueva alternativa antimicrobiana contra E. coli 0157:H7. El mecanismo de acción de Ib-Mi e I0NP@Ib-M1 contra esta bacteria aún es desconocido; por lo tanto, el objetivo de esta investigación fue identificar el cambio en el perfil de proteínas de E. coli 0157:H7 luego del tratamiento con Ib-M1 e I0NP@ Ib-M1 como primer paso para determinar su mecanismo de acción. Para esto, se llevó a cabo la obtención de proteínas, posteriormente se realizó una electroforesis bidimensional para finalmente realizar la determinación de la variabilidad de los perfiles proteicos. Una vez obtenidos estos perfiles, se llevó a cabo un análisis de varianza (AN0VA). Se identificaron 72 proteínas expresadas diferencialmente, las cuales pueden relacionarse con el efecto sobre el crecimiento de la bacteria en presencia de Ib-M1 e I0NP@Ib-M. Estas proteínas se encuentran involucradas en procesos de transferencia de grupos acilo (proteína Yhbs), translocación de lipoproteínas (proteína LolA) y transporte de aminoácidos (proteína GpmA), entre otros.

Abstract Escherichia coli 0157: H7 is a pathogenic bacterium which is recognized for the ability to resist multiple antibiotics; accordingly, complications occur in the treatment of infections caused by this bacterium. The Ib-M1 peptide and the I0NP @ Ib-M1 bioconjugate have emerged as a new antimicrobial alternatives against E. coli 0157: H7. The mechanism of action of Ib-M1 and I0NP @ Ib-M1 against this bacterium is still unknown; therefore, the goal of this research was to identify the change in the proteins profile of E. coli 0157: H7 after treatment with Ib-M1 and I0NP @ Ib-M1 as a first step to determine its mechanism of action. For this, the proteins were obtained first, and then a two-dimensional electrophoresis was performed to finally determine the variability of the protein profiles. 0nce the protein profiles were obtained, an analysis of variance (AN0VA) was carried out. 72 differentially expressed proteins were identified, which can be connected to the effect on the bacterium's growth in the presence of Ib-M1 and I0NP @ Ib-M. These proteins are involved in acyl groups transfer processes (Yhbs protein), lipoprotein translocation (LolA protein) and amino acid transport (GpmA protein), among others.

Resumo Escherichia coli O157: H7 é uma bactéria patogênica reconhecida por sua capacidade de resistir a vários antibióticos; razão pela qual, complicações são geradas no tratamento de infecções produzidas por essa bactéria. O peptídeo Ib-M1 livre e imobilizado em nanopartículas magnéticas de óxido de ferro (IONP @ Ib-M1) surgiu como uma nova alternativa antimicrobiana contra E. coli O157: H7 e isolados clínicos desta bactéria. O mecanismo de ação de Ib-M1 e IONP @ Ib-M1 contra E. coli O157: H7 ainda é desconhecido; Portanto, o objetivo desta pesquisa foi identificar a alteração no perfil proteico de E. coli O157: H7 após o tratamento com Ib-M1 e IONP @ Ib-M1 como um primeiro passo para determinar seu mecanismo de ação. Para isso, foi realizada a obtenção das proteínas, posteriormente foi realizada uma eletroforese bidimensional para finalmente determinar a variabilidade dos perfis protéicos. Uma vez obtidos os perfis de proteínas, foi realizada uma análise de variância (ANOVA). Os resultados mostram a identificação de proteínas expressas diferencialmente e que estão envolvidas em processos de transferência de grupos acila (proteína Yhbs), translocação de lipoproteínas (proteína LolA) e transporte de aminoácidos (proteína GpmA), entre outros.

Research progress on antibiotic resistance of Escherichia coli O157:H7 / 预防医学

@#Contamination of foodborne pathogens is the main cause of related diseases. Escherichia coli O157:H7 (E.coli O157:H7), as a representative of pathogenic E.coli, is one of the most severe and commonly reported E.coli in the world, but there is still no effective clinical treatment against the infection. Antibiotics show effective in the early infection of E.coli O157:H7. However, their extensive use has led to drug-resistant bacteria and genes in recent years, which becomes a great threat to public health. This article reviews the research progress of E.coli O157:H7 from the prevalence of antibiotic-resistant bacteria, the resistance mechanism, and the prevention and control methods, in order to provide a reference for its prevention, early clinical treatment and related research.

First detection of Shiga toxin producing Escherichia coli O157:H7 (HlyA gene) and enumeration of most probable number (MPN) of fecal coliforms and Escherichia coli in cage cultured oysters (Crassostrea iredalei) and water from southern Malaysia

Aims@#Escherichia coli O157:H7 is known to be transmitted via fecal-oral route, where water plays a role in the transmission process. Oysters as bivalves, bio accumulate pathogens from the water through filter feeding and are suspected to play a role as disease transmission vector. In Malaysia, the data on oyster’s microbiological quality are limited. Hence, it was vital to conduct oyster related studies in Malaysia. The main objectives of this study include the enumeration of most probable number (MPN) of fecal coliforms and E. coli and isolation of E. coli from oyster (Crassostrea iredalei) and water sample for the detection of 16S rRNA and HlyA (Hemolysin A) genes of E. coli O157:H7. @*Methodology and results@#A total of 120 oysters and water samples (n=6) were collected from a fisherman village located in southern Malaysia. Total fecal coliforms and E. coli were determined using the MPN procedure. Colonies of E. coli were identified based on Gram staining, biochemical test, and PCR detection for the presence of 16S rRNA and HlyA gene of E. coli O157:H7. The enumeration results showed that the MPN of the fecal coliforms and E. coli found in the collected oyster samples do not meet the standard to be directed for human consumption (0.72 ± 0.19 × 104 MPN/100 g and 0.13 ± 0.03 × 10 4 MPN/100 g, respectively). The PCR assays showed that 16 out of the 104 (15.38%) of E. coli isolated from water and oysters showed the presence of HlyA gene. The phylogenetic tree analysis showed there were genetic relationships between the HlyA gene of the E. coli isolated in this study with the ones isolated from calf and human faeces.@*Conclusion, significance and impact of study@#The detection of Shiga toxin producing E. coli O157:H7 (HlyA gene) in cage cultured oysters (C. iredalei) and water from southern Malaysia was first time reported here. In the future, more study can be conducted to study the expression of the HlyA gene and confirm of its identity as E. coli O157:H7 using different target genes such as eaeA (encodes a 94 kD outer membrane protein called intimin) and Stx1 (Shiga toxin, Shigella dysenteriae type 1).

A fluorometric method for direct detection of inorganic polyphosphate in enterohemorrhagic O157:H7 / 南方医科大学学报

OBJECTIVE@#To establish a quantitative fluorescent detection method using DAPI for detecting inorganic polyphosphate (polyP) in enterohemorrhagic Escherichia coli (EHEC) O157:H7.@*METHODS@#The DNA of wild-type strain of EHEC O157:H7 was extracted and purified. DAPI was combined with the extracted DNA and polyP45 standards for measurement of the emission spectra at 360 nm and 415 nm fluorescence spectrophotometry. The fluorescence of DAPI-DNA and DAPI-polyP complexes was detected by fluorescence confocal microscopy to verify the feasibility of DAPI for detecting polyP. To determine the optimal pretreatment protocol for improving the cell membrane permeability, the effects of 6 pretreatments of the cells (namely snap-freezing in liquid nitrogen, freezing at -80 ℃, and freezing at -20 ℃, all followed by thawing at room temperature; heating at 60 ℃ for 10 min; treatment with Triton x-100; and placement at room temperature) were tested on the survival of EHEC O157:H7. The fluorescence values of the treated bacteria were then measured after DAPI staining. A standard calibration curve of polyP standard was established for calculation of the content of polyP in the live cells of wildtype EHEC strain and two mutant strains.@*RESULTS@#At the excitation wavelength of 360 nm, the maximum emission wavelength of DAPI-DNA was 460 nm, and the maximum emission wavelength of DAPI-polyP was 550 nm at the excitation wavelength of 415 nm. The results of confocal microscopy showed that 405 nm excitation elicited blue fluorescence from DAPIDNA complex with the emission wavelength of 425-475 nm; excitation at 488 nm elicited green fluorescence from the DAPIpolyP complex with the emission wavelength of 500-560 nm of. Snap-freezing of cells at -80 ℃ followed by thawing at room temperature was the optimal pretreatment to promote DAPI penetration into the live cells. The standard calibration curve was =1849+127.5 (R=0.991) was used for determining polyP content in the EHEC strains. The experimental results showed that wild-type strain had significantly higher polyP content than the mutant strains with deletion.@*CONCLUSIONS@#We established a convenient quantitative method for direct and reliable detection polyP content to facilitate further study of polyP and its catalytic enzymes in EHEC O157:H7.

Detección y caracterización de Escherichia coli productor de toxina Shiga en ninos atendidos en un hospital pediátrico interzonal de la ciudad de La Plata / Detection and characterization of Shiga toxin-producing Escherichia coli in children treated at an inter-zonal pediatric hospital in the city of La Plata

Escherichia coli productor de toxina Shiga (STEC) es un patógeno transmitido por alimentos que puede causar diarrea acuosa, diarrea sanguinolenta (DS) y síndrome urémico hemolítico (SUH). El objetivo de este estudio fue determinar las características fenotípicas y genotípicas de cepas STEC aisladas de niños con DS y SUH atendidos en un hospital pediátrico de la ciudad de La Plata en el período 2006-2012 y establecer la relación clonal de los aislamientos O157: H7 mediante electroforesis de campo pulsado. El porcentaje de muestras positivas fue de 4,9 y 39,2% en los pacientes que presentaron DS y SUH, respectivamente. Se aislaron 77 cepas STEC de 10 serotipos distintos, con el 100% de recuperación de colonias. El serotipo más frecuente fue O157: H7 (71,4%), seguido por O145: NM (15,6%). El 98,2% de los aislamientos O157: H7 correspondió al biotipo C y fue sensible a los antibióticos ensayados. Todos esos aislamientos presentaron el genotipo stx2, eae, fliC H7, ehxA, iha, efa, toxB, lpfA1-3 y lpfA2-2.Al estudiar la relación clonal de las cepas O157: H7, se identificaron un total de 42 patrones con al menos un 88% de similitud y se establecieron 6 clústeres que agruparon cepas con perfiles idénticos. Los aislamientos eae negativos pertenecieron a los serotipos O59: H19, O102: H6, O174: NM y O174: H21. Las cepas O59: H19 y O174: H21 fueron positivas para el gen aggR. Este estudio muestra que en la ciudad de La Plata y alrededores circulan STEC de diferentes serotipos y genotipos. A pesar de la diversidad genética observada entre los aislamientos O157: H7, algunos fueron indistinguibles por las técnicas de subtipificación utilizadas.

Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen that can cause watery diarrhea, bloody diarrhea (BD), and hemolytic uremic syndrome (HUS). The objective of this study was to determine the phenotypic and genotypic profiles of STEC strains isolated from children with BD and HUS treated at a pediatric hospital in the city of La Plata in the period 2006-2012, and to establish the clonal relationship of O157: H7 isolates by pulsed field electrophoresis. The percentage of positive samples was 4.9% and 39.2% in patients with BD and HUS, respectively. Seventy-seven STEC strains from 10 different serotypes were isolated, with 100% colony recovery, O157: H7 being the most frequent (71.4%) serotype, followed by O145: NM (15.6%). An average of 98.2% of O157: H7 isolates belonged to biotype C and were sensitive to all the antibiotics tested. All of them (100%) carried genotype stx2, eae, fliC H7, ehxA, iha, efa, toxB, lpfA1-3 and lpfA2-2. When the clonal relationship of the O157: H7 strains was studied, a total of 42 patterns with at least 88% similarity were identified, and 6 clusters with identical profiles were established. The eae-negative isolates belonged to serotypes O59: H19, O102: H6, O174: NM and O174: H21. The strains O59: H19 and O174: H21 were positive for the aggR gene. This study shows that STEC of different serotypes and genotypes circulate in the city of La Plata and surroundings. Despite the genetic diversity observed between the O157: H7 isolates, some were indistinguishable by the subtyping techniques used.

Immunogenicity of the nanovaccine containing intimin recombinant protein in the BALB/c mice

PURPOSE: Escherichia coli O157:H7 is one of the most important pathogens which create hemorrhagic colitis and hemolytic uremic syndrome in human. It is one of the most prevalent causes of diarrhea leading to death of many people every year. The first diagnosed gene in the locus of enterocyte effacement pathogenicity island is eae gene. The product of this gene is a binding protein called intimin belonging to the group of external membrane proteins regarded as a good stimulants of the immune system. Chitosan with its lipophilic property is an environmentally friendly agent able to return to the environment. MATERIALS AND METHODS: Intimin recombinant protein was expressed in pET28a vector with eae gene and purification was performed using Ni-NTA and finally the recombinant protein was approved through western blotting. This protein was encapsulated using chitosan nanoparticles and the size of nanoparticles was measured by Zetasizer. Intimin encapsulated was prescribed for three sessions among three groups of oral, injection, and oral-injection using Chitosan nanoparticles. Challenge was performed for all three groups with 108 E. coli O157:H7 bacteria. RESULTS: Intimin produced by chitosan nanoparticles improves immunological responses through the adjuvant nature of chitosan nanoparticles. Chitosan may be used as a carrier for transportation of the prescribed vaccine. Among the mice, encapsulated intimin could be able to provide suitable titers of IgG and IgA by the aid of chitosan nanoparticles. Results of mice challenge showed that decreased the bacterial shedding significantly. CONCLUSION: Results showed that the chitosan nanovaccine with intimin protein may be used as a suitable candidate vaccine against E. coli O157:H7.

Immunofluorescence probe based on fluorescent carbon dots and its application to the special recognition of Escherichia coli / 军事医学

Objective Carbon dots (CDs) are an emerging carbon nano-material which is environmentally-friendly, economical , efficient and stable .Their fluorescence properties can match the semiconductor quantum dot .Moreover , CDs have more excellent biocompatibilities .The purpose of this experiment is to apply CDs to the fluorescent immune probe to make them a new label , which can replace the traditional fluorescent dyes .Methods Using microwave heating method , the high strength fluorescent carbon dots were prepared .Wtih the EDC coupling method , the high strength fluorescent car-bon dots could bond with Escherichia coli antibodies to form a complex immune fluorescent probe .Specific recognition exper-iments were carried out in the model of E.coli O157∶H7.Results CDs were successfully applied to immune recognition of E.coli O157∶H7 and multicolor fluorescence was observed .Conclusion CDs can serve as a label of the fluorescent im-mune probe , and are expected to become a new type of low toxicity biosensor with independent intellectual property rights .

Prevalence of Escherichia Coli O157:H7 and Enterobacteriaceae on Hands of Workers in Halal Cattle Abattoirs in Peninsular Malaysia

Background: Several occupational diseases of multiple origins are encountered among abattoir workers. Presence of indicator microorganisms (coliforms) on hands of workers can be used a gauge for hygienic practices. Methods: A cross-sectional study was performed to assess the prevalence of E.coli and enterobacteriaceae among Halal abattoir workers in some government halal abattoirs of Malaysia. A total of one hundred and sixty-five hand swab samples were collected from workers of Halal abattoirs in Malaysia. The samples were subjected to microbiological analysis for characterisation and serotyping. Results: The results have shown that no Escherichia coli O157:H7 was isolated on the hands of abattoir workers before and after work. However, a total prevalence of 9.7% was recorded for all samples during work. For non-O157:H7, total prevalence of 33.3% during work and 13% after work were obtained. High prevalence was recorded in sample taken during work from Tampin, Jasin and Kemaman (100% each) while low prevalence where observed in Shah Alam, Banting and Ipoh (20% each). Conclusions: Based on the findings the hygienic practices of hand washing among the workers in few locations was found to be low especially after work.

Effect of Lactobacillus sp. isolates supernatant on Escherichia coli O157: H7 enhances the role of organic acids production as a factor for pathogen control / Efeito do sobrenadante de isolados de Lactobacillus sp. sobre Escherichia coli O157: H7 reforça o papel da produção de ácidos orgânicos como fator de controle patogênico

Many attempts have been made to establish the control of foodborne pathogens through Lactobacillus isolates and their metabolism products with success being obtained in several situations. The aim of this study was to investigate the antagonistic effect of eight Lactobacillus isolates, including L. casei subsp. pseudoplantarum, L. plantarum, L. reuteri and L. delbrueckii subsp. delbrueckii, on the pathogenic Escherichia colistrain O157:H7. The inhibitory effect of pure cultures and two pooled cultures supernatants of Lactobacillus on the growth of pathogenic bacteria was evaluated by the spot agar method and by monitoring turbidity. Antimicrobial activity was confirmed for L. reuteri and L. delbrueckii subsp. delbrueckii and for a pool of lactic acid bacteria. The neutralized supernatant of the pool exerted a higher antimicrobial activity than that of the individual strains. Furthermore, D-lactic acid and acetic acid were produced during growth of the Lactobacillus isolates studied.(AU)

Muitas tentativas têm sido feitas para se estabelecer o controle de patógenos de origem alimentar através do uso de estirpes de Lactobacillus e dos seus produtos de metabolismo, com sucesso sendo sucedido em várias situações. O objetivo deste trabalho foi investigar o efeito antagônico do sobrenadante de culturas de oito isolados de Lactobacillus, incluindo L. casei subsp. pseudoplantarum, L. plantarum L. reuteri e L. delbrueckii subsp. delbrueckii, sobre Escherichia coli amostra O157:H7. Os efeitos inibidores de culturas puras e de dois "pools" de cultura de Lactobacillus sobre o crescimento da bactéria foram avaliados através do método de inibição em ágar e através do monitoramento da turbidez da cultura bacteriana. A atividade antimicrobiana foi confirmada para Lactobacillus reuteri e Lactobacillus delbrueckii subsp. delbrueckii e para o "pool" de bactérias acido-láctica. O sobrenadante neutralizado do "pool" de Lactobacillus exerceu uma atividade antimicrobiana mais elevada do que aquela das estirpes individuais. Além disso, ácido D-láctico e ácido acético foram produzidos durante o crescimento dos Lactobacillus estudados(AU)

Development of Droplet Digital Polymerase Chain Reaction for Quantifying Escherichia Coli O157:H7 / 分析化学

A droplet digital polymerase chain reaction ( ddPCR) method for quantifying E. coli O157:H7 by targeting rfbE gene was developed. The probe concentration in ddPCR was optimized and the linearity range, precision, limit of detection ( LOD) and limit of quantification ( LOQ) were also evaluated. The optimized probe concentration was 300 nmol/L. The ddPCR response was linear over the E. coli O157:H7 genome DNA concentration range from 4 to 1. 25×105 copies in 20 μL ddPCR system and the linear correlation coefficient (R2) was 0. 999. The ddPCR precision (RSD) was less than 5% over the DNA concentration range from 760 to 88400 copies/20 μL. The LOD and LOQ was 3 copies in 20 μL and 4 copies in 20 μL, respectively. Specificity test showed that the ddPCR was specific for detecting E. coli O157:H7. Both ddPCR and standard real time quantitative PCR showed the same results for 16 real samples of chicken meat, pork and beef, which indicated that ddPCR method was suitable for detection of E. coli O157:H7 in food.

Development of up-converting phosphor technology based lateral flow assay for quan-titative detection of foodborne pathogens / 军事医学

Objective To develop an up-converting phosphor technology based lateral flow (UPT-LF) assay for rapid detection of Salmonella paratyphi A, S.paratyphi B, Escherichia coli O157 ∶H7 and Vibrio parahaemolyticus. Methods With up-converting phosphor nano-particles ( UCP-NPs ) as the bio-marker, four double-antibody-sandwich mode based UPT-LF strips for detecting the above mentioned four pathogens were prepared respectively and their sensitivi-ty, accuracy, linearity and specificity were evaluated .Furthermore, the feasibility of detecting bacteria in food samples was evaluated by different food samples artificially contaminated with less than 10 CFU target pathogens .Results The sensitivi-ty of UPT-LF assays for four pathogens was 105 ~106 CFU/ml with excellent specificity .The four strips had a good linear response with the linear fitting coefficient of determination (r) for each target pathogen ranging from 0.985 to 0.996.The positive rate of detecting pathogens from samples was acceptable .Conclusion The four developed UPT-LF strips provide a new choice for rapid , specific and sensitive and quantitative detection of S.paratyphi A , S.paratyphi B, E.coli O157∶H7 and V.parahemolyticus.

Prevalence of shiga toxins (stx1, stx2), eaeA and hly genes of Escherichia coli O157:H7 strains among children with acute gastroenteritis in southern of Iran

OBJECTIVE@#To survey the prevalence severe diarrhea arising from these bacteria in children under 5 years old in Marvdasht.@*METHODS@#In this study faecal sample from 615 children aged <5 years old who were hospitalized for gastroenteritis in Fars hospitals in Iran were collected and then enriched in Escherichia coli (E. coli) broth and modified tryptone soy broth with novobiocin media. Fermentation of sorbitol, lactose and β -glucoronidase activity of isolated strains was examined by CT-SMAC, VRBA and chromogenic media respectively. Then isolation of E. coli O157:H7 have been confirmed with the use of specific antisera and with multiplex PCR method presence of virulence genes including: stx1, stx2, eaeA, hly has been analyzed.@*RESULTS@#E. coli O157:H7 was detected in 7 (1.14%) stool specimens. A significant difference was seen between detection rate of isolated bacteria from age groups 18-23 months and other age groups (P=0.004). Out of considered virulence genes, only 1 of the isolated strains (0.16%) the stx1 and eaeA genes were seen and also all isolated bacteria had resistance to penicillin, ampicillin and erythromycin antibiotics.@*CONCLUSIONS@#We found that children < 2 years of age were at highest risk of infection with E. coli O157:H7. Regarding severity of E. coli O157:H7 pathogenesis, low infectious dose and lack of routine assay for detection of these bacteria in clinical laboratory, further and completed studies on diagnosis and genotyping of this E. coli O157:H7 strain has been recommended.

Prevalence of shiga toxins (stx1, stx2), eaeA and hly genes of Escherichia coli O157: H7 strains among children with acute gastroenteritis in southern of Iran

Objective: To survey the prevalence severe diarrhea arising from these bacteria in children under 5 years old in Marvdasht. Methods: In this study faecal sample from 615 children aged 1, stx2, eaeA, hly has been analyzed. Results: E. coli O157:H7 was detected in 7 (1.14%) stool specimens. A significant difference was seen between detection rate of isolated bacteria from age groups 18-23 months and other age groups (P=0.004). Out of considered virulence genes, only 1 of the isolated strains (0.16%) the stx1 and eaeA genes were seen and also all isolated bacteria had resistance to penicillin, ampicillin and erythromycin antibiotics. Conclusions: We found that children < 2 years of age were at highest risk of infection with E. coli O157:H7. Regarding severity of E. coli O157:H7 pathogenesis, low infectious dose and lack of routine assay for detection of these bacteria in clinical laboratory, further and completed studies on diagnosis and genotyping of this E. coli O157:H7 strain has been recommended.

In vitro Antibacterial Activity of Aqueous Extracts of Cashew (Anacardium occidentale L.) Fruit Peels Using Bioautography Method.

Aims: Bark, leaves and gum of cashew (Anacardium occidentale L.) have been reported to be effective in curtailing the growing problems of resistance of bacterial pathogens. The in vitro activity of aqueous extracts of cashew apple peels was determined in this study against two clinically important pathogens. Place and Duration of Study: The work was conducted at the Department of Microbiology, Ekiti State University, Ado-Ekiti, Nigeria and processed immediately. This study was carried out between June, 2009 and January, 2010. Methodology: Bioautographic method was used to test the antibacterial activity of aqueous (cold and hot water) extracts of cashew apple peels on Escherichia coli O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA). The zones of inhibition of the extracts were compared. Results: The activity of the fifth hour hot water extract was highest with zones of inhibition of 415.48 and 346.30 sq. mm against E. coli O157:H7 and MRSA respectively. E. coli O157:H7 was more susceptible to the extract with the zone of inhibition ranging between 176.79 and 283.53 sq. mm while that of MRSA was153.94 - 346.30 sq. mm. The 5 h extract of cold water was more potent on the test organisms with 615.75 and 490.87 sq. mm diameters of inhibition on E. coli O157:H7 and MRSA respectively. Cold water extracts produced more active compounds (13 biologically active spots) that inhibited the growth of the test organisms than the hot water extracts, with six spots. Conclusion: The extracts of the peels of the cashew apple against the test organisms are promising. However, the nature and mechanisms of action of the biologically active compounds in the extracts are still open to investigation.

Sequence analysis of TraE in the novel conjugative plasmid pO157_Sal detected in Escherichia coli O157∶H7 / 中华传染病杂志

Objective To analyze the sequence of the novel conjugative plasmid pO157_Sal detected in outbreak isolates of Escherichia coli O157∶H7 .Methods The traE genes of the outbreak isolates in China were amplified by polymerase chain reaction (PCR) and the products were sequenced .The TraE sequences of Escherichia coli O157 ∶ H7 strains from other sources were retrieved from GenBank . Phylogenetic tree based on the TraE sequences was constructed by Neibhor-joining analysis .The whole plasmid sequences of pO157_Sal and pEC4115 were compared .Results The sequences of traE gene were identical among the Chinese isolates . There were homologous sequences of TraE in Escherichia coli O157∶H7 isolates from different sources .Twenty-one out of the 52 pO157_Sal genes were homologous to genes of pEC4115 with amino acid level identity ranging from 28% to 51% .Conclusions Although similar TraE sequences and similar plasmid are found in Escherichia coli O157∶H7 isolates from different sources ,pO157_Sal is only observed in Chinese outbreak isolates .The TraE sequences are conservative among the outbreak isolates ,indicating they are from the same specific source .

Antibacterial effects of carvacrol against Staphylococcus aureus and Escherichia coli O157:H7 / 동물의과학연구지

The objective of this study was to investigate the antimicrobial effects of carvacrol (CV) against Staphylococcus aureus (S. aureus) and Escherichia coli O157:H7 (E. coli O157:H7) strains in milk. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of CV against S. aureus and E. coli O157:H7 were determined. In addition, bactericidal kinetics and antimicrobial activity of CV against the aforementioned pathogens in milk over a period of 2 weeks were investigated. CV exhibited antibacterial activity against both foodborne pathogens tested. The MIC and MBC of CV against S. aureus were 15.0 and 20 mg/mL, respectively, whereas those against E. coli O157:H7 were 16.0 and 32 mg/mL, respectively. In time-kill assays, CV at MBC reduced the number of S. aureus and E. coli O157:H7 in milk to undetectable levels within 24 hr. The antibacterial effects of CV persisted for 14 days without any loss of activity. Results of this study suggest that CV has a potential antibacterial activity against foodborne pathogens such as S. aureus and E. coli O157:H7 in milk.

Escherichia coli O157:H7: local epidemiology and disease spectrum in Brazil

Escherichia coli O157: H7 is one of the most important foodborne pathogens nowadays, since it has been responsible for severe outbreaks worldwide. Event hough this food pathogen has been isolated in many countries, Brazilian foods were considered E. coli O157:H7-free until recently. However, the presence of E. coli O157:H7 has been reported in diverse foods produced in Brazil and an increasing number of isolation from cattle feces has been observed, demonstrating that this pathogen is present in different parts of Brazil, and severe foodborne outbreaks mayoccur in the near future if adequate control measures are not implemented

Doenças crônicas e a internalização de microorganismos patogênicos / Chronic diseases and the internalization of pathogenic microorganisms

Em todo o mundo, a incidência de doenças crônicas não transmissíveis (DCNT) vem aumentando devido às mudanças no estilo de vida. Estudos comprovam que o consumo de frutas, legumes e verduras reduzem a incidência de doenças crônicas não transmissíveis na população devido à presença de fibras, antioxidantes e compostos bioativos, que aumentam as defesas orgânicas estimulando a proteção contra as agressões por radicais livres, contribuindo para diminuir o risco de doença cardiovascular e degenerativa. O aumento no consumo de produtos frescos tem sido acompanhado por uma maior incidência de surtos alimentares. Alguns micro-organismos patogênicos como Salmonella, Escherichia coli e alguns tipos de virus, apresentam a capacidade de se internalizar, levando à colonização da planta. Este artigo teve o propósito de iniciar uma discussão acerca do incentivo ao consumo de produtos frescos, os quais podem contribuir para veicular doenças transmitidas por alimentos. Foram consultadas as bases eletrônicas: Lilacs, Scielo, Scirus e Scopus, sendo selecionados artigos em intervalo de 30 anos (1982-2012). Com base nas contribuições dos artigos algumas considerações são apresentadas acerca das diferentes formas de internalização microbiana para partes comestíveis de produtos frescos e como os micro-organismos internalizados não são efetivamente removidos por tratamentos da superfície.

Worldwide, the incidence of noncommunicable diseases (NCDs) is increasing due changes in lifestyles. Studies confirm consumption of fruits and vegetables reduce the incidence of noncommunicable diseases in the population due to the presence of fiber, antioxidants and bioactive compounds that increase the organic defenses stimulating protection against attacks by free radicals, helping to reduce the risk of cardiovascular disease and degenerative. The increased consumption of fresh products has been accompanied by a higher incidence of food borne outbreaks. Some pathogens such as Salmonella, Escherichia coli and some types of virus, have the ability to internalize, leading to colonization of the plant. This article has the purpose of initiate a discussion about the incentive to consumption of fresh products which can help convey foodborne diseases.The electronic databases consulted were: Lilacs, Scielo, Scirus e Scopus, were selected studies over a period of 30 years (1982-2012). Based on their contributions some considerations are presented about the various types of microbial internalization for edible plant parts and how microorganisms internalized are not effectively removed by surface treatment.

Aislamiento y caracterización de Escherichia coli O157:H7 a partir de carne molida de bovino en Lima-Perú

El objetivo del estudio fue aislar y caracterizar E. coli O157:H7 a partir de carne molida fresca de bovino obtenida en diferentes mercados de abastos. Se analizaron 195 muestras; para el aislamiento y enumeración de E. coli se utilizó la técnica del Numero Más probable mediante tubos múltiples; para el aislamiento y caracterización de E. coli O157:H7 el enriquecimiento selectivo y el análisis bioquímico, las colonias características se confirmaron mediante pruebas serológicas. Para determinar la presencia de shigatoxina (stx1, stx2) e intimina (eae A) se empleó la técnica de PCR multiplex en tiempo real y para enterohemolisina la prueba de hemólisis. El 87.18% de la muestras fue positivo para E. coli y el 77.95% presentó un recuento igual o superior a 50 NMP/g. Se obtuvieron 3 (1.54%) cepas de E. coli O157:H7, una stx1 +/ stx2 +/ eaeA - y enterohemolisina -, una stx 1 +/ stx2 -/ eaeA + y enterohemolisina - y la otra stx1 -/ stx2 -/ eaeA - y enterohemolisina +. También se obtuvieron 4 cepas (2.05%) de E. coli O157 no H7, ninguna presentó factores de virulencia. El estudio reveló el riesgo potencial de que E. coli O157:H7 afecte a la población de Lima

The aim of the study was to isolate and characterize E. coli O157: H7 from fresh ground beef obtained in different food markets. 195 samples were analyzed, for isolation and enumeration of E. coli was used most probable number technique using multiple tubes, for the isolation and characterization of E. coli O157: H7 selective enrichment and biochemical analysis, characteristic colonies were confirmed serologically. To determine the presence of shigatoxin (stx1, stx2) and intimin (eaeA) was done with multiplex real time PCR and for enterohemolysin the hemolysis test. The 87.18% of the samples were positive for E. coli and 77.95% had a count greater than or equal to 50 NMP/g. Were obtained 3 (1.54%) strains of E. coli O157: H7, one stx1 +/ stx2 +/eaeA - and enterohemolysin -, one stx1 +/stx2 -/eaeA + and enterohemolysin - and the other stx1 -/stx2 -/eaeA - and enterohemolysin +. Also obtained 4 (2.05%) strains of E. coli O157 non H7, no virulence factors presented. The study found that the risk potential E. coli O157: H7 affecting the population of Lima