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1.
Food Microbiol ; 105: 103885, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35473968

RESUMO

Cucumber is usually eaten as a raw vegetable and easily contaminated by pathogenic microorganisms; the contamination process includes colonization, proliferation, and biofilm formation. In this study, plate counting was used to determine the stage of E. coli O157:H7 colonization/proliferation in cucumber epidermis and fruit. Expression of E. coli genes associated with adhesion, movement and oxidative stress response during colonization and proliferation in cucumber was evaluated with fluorescence real-time quantitative PCR. Scanning electron microscopy imaging was used to observe biofilm formation over time in different cucumber tissues at 4 °C and 25 °C. During colonization (at 0-45 and 0-30 min in epidermis and fruit, respectively), escV, fliC, espA, escN, espF, espG, espZ, nleA, tir, and ycbR genes were upregulated. The escC was downregulated, while map and espH expression did not vary. During proliferation (after 45 and 30 min in epidermis and fruit, respectively), fliC was downregulated, whereas the outer membrane protein intimin gene and oxidative stress genes rpoS and sodB were upregulated. During storage, 25 °C was more favorable for biofilm formation than 4 °C. The ability of biofilm formation on the vascular system was the strongest, and the biofilm on epidermis sloughed off earlier than that on other tissues. Clarifying the process of E. coli O157:H7 contaminating cucumbers provided useful information for the development of prevention and control methods of fresh-cut cucumber.


Assuntos
Cucumis sativus , Escherichia coli O157 , Proteínas de Escherichia coli , Biofilmes , Cucumis sativus/metabolismo , Proteínas de Escherichia coli/genética , Frutas/metabolismo
2.
Food Microbiol ; 105: 104013, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35473974

RESUMO

Effects of thyme essential oil (TEO) emulsion (TEE) with cationic charge formulated using cetylpyridinium chloride (CPC) on attachment strength and inactivation of Listeria monocytogenes and Escherichia coli O157:H7 on romaine lettuce surface were examined in this study. Regardless of the inoculation time (2 h and 24 h), pathogen attachment was stronger on the adaxial surface of the romaine lettuce than on the abaxial surface because of the lower roughness of the former. Moreover, attachment strength increased with increasing inoculation time. TEE washing had the strongest inhibitory effect on pathogen attachment at 2 h when compared with that of TEO, CPC, and sodium hypochlorite (SH), demonstrating a 3.32 and 2.53 log-reduction in the size of the L. monocytogenes and E. coli O157:H7 populations, respectively, compared to the control samples. Additionally, the TEE washing effects were maintained even after inoculation for 24 h, and it decreased attachment to adaxial surface of the samples. These results indicate that TEE could be a good alternative to SH in improving the microbiological safety of romaine lettuce.


Assuntos
Escherichia coli O157 , Listeria monocytogenes , Óleos Voláteis , Thymus (Planta) , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Alface/microbiologia , Óleos Voláteis/farmacologia
3.
Artigo em Inglês | MEDLINE | ID: mdl-35457298

RESUMO

The occurrence of diarrheal infections depends on the level of water and sanitation services available to households of immunocompromised individuals and children of less than five years old. It is therefore of paramount importance for immunocompromised individuals to be supplied with safe drinking water for better health outcomes. The current study aimed at ascertaining the probability of infection that Escherichia coli, Salmonella typhimurium, Shigella dysenteriae, Vibrio cholerae, and rotavirus might cause to rural dwellers as compared to urban dwellers. Both culture-based and molecular-based methods were used to confirm the presence of target microorganisms in drinking water samples, while Beta-Poisson and exponential models were used to determine the health risk assessment. Results revealed the presence of all targeted organisms in drinking water. The estimated health risks for single ingestion of water for the test pathogens were as follows: 1.6 × 10-7 for S. typhimurium, 1.79 × 10-4 for S. dysenteriae, 1.03 × 10-3 for V. cholerae, 2.2 × 10-4 for E. coli O157:H7, and 3.73 × 10-2 for rotavirus. The general quantitative risk assessment undertaken in this study suggests that constant monitoring of household container-stored water supplies is vital as it would assist in early detection of microbial pathogens. Moreover, it will also allow the prompt action to be taken for the protection of public health, particularly for immunocompromised individuals and children who are prone to higher risk of infections.


Assuntos
Água Potável , Escherichia coli O157 , Vibrio cholerae , Criança , Pré-Escolar , Humanos , Fatores de Risco , África do Sul , Microbiologia da Água , Abastecimento de Água
4.
Cell Rep ; 39(1): 110614, 2022 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-35385749

RESUMO

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is an important extracellular human pathogen. The initial adherence of EHEC to host cells is a major cue for transcriptional induction of the locus of enterocyte effacement (LEE) genes to promote colonization and pathogenesis, but the mechanism through which this adherence is sensed and the LEE is induced remains largely elusive. Here, we report a complete signal transduction pathway for this virulence activation process. In this pathway, the outer-membrane lipoprotein NlpE senses a mechanical cue generated from initial host adherence and activates the BaeSR two-component regulatory system; the response regulator BaeR then directly activates the expression of airA located on O-island-134 and encoding a LEE transcriptional activator. Disruption of this pathway severely attenuates EHEC O157:H7 virulence both in vitro and in vivo. This study provides further insights into the evolution of EHEC pathogenesis and the host-pathogen interaction.


Assuntos
Escherichia coli Êntero-Hemorrágica , Infecções por Escherichia coli , Escherichia coli O157 , Proteínas de Escherichia coli , Aderência Bacteriana , Proteínas da Membrana Bacteriana Externa/metabolismo , Escherichia coli Êntero-Hemorrágica/genética , Escherichia coli O157/genética , Escherichia coli O157/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Regulação Bacteriana da Expressão Gênica , Humanos , Lipoproteínas/genética , Lipoproteínas/metabolismo , Fosfoproteínas/metabolismo , Virulência/genética
5.
Food Res Int ; 155: 111026, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35400423

RESUMO

Sanitation of water, food, and food contact surfaces is essential for the safety of food supply. Lack of stability of sanitizers in the presence of organic content and lack of targeted binding of sanitizers to biofilms can reduce effectiveness of sanitizers and increase the risk of contamination of food. Therefore, this study evaluated the development, characterization, and application of gelatin microgel based chlorine delivery system for improving both stability of chlorine based sanitizer and targeted binding of sanitizer to biofilms. The results illustrate that cross-linked gelatin microgels rapidly bind chlorine to form a halamine bond. The total chlorine loading was 5.05% per gram of gelatin microgels. Chlorine bound to gelatin microgels was stable in the presence of high organic content up to 2,000 mg/L and in a powder form for 5 weeks under refrigerated conditions. Gelatin microgel particles significantly improve the inactivation of bacteria in the presence of organic content compared to equivalent concentration of free chlorine. Gelatin microgel particles had affinity to bind biofilms with 26.5% and 22.9% to the L. innocua and E. coli O157:H7 biofilms, respectively. In bacterial biofilm models, more than 6 log CFU/cm2 of L. innocua and E. coli O157:H7 were inactivated within 60 min using chlorine charged gelatin microgel particles while equivalent free chlorine could only achieve 4 log CFU/cm2 inactivation during the same period. Overall, the results demonstrate potential of protein microgels for effective binding and delivery of chlorine to improve sanitation of wash water with suspended organics and food contact surfaces.


Assuntos
Desinfetantes , Escherichia coli O157 , Microgéis , Biofilmes , Cloro/farmacologia , Contagem de Colônia Microbiana , Desinfetantes/química , Desinfetantes/farmacologia , Contaminação de Alimentos , Gelatina , Água
6.
BMC Genomics ; 23(1): 275, 2022 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-35392797

RESUMO

BACKGROUND: Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a pathogen known to reside in cattle feedlots. This retrospective study examined 181 STEC O157:H7 strains collected over 23 years from a closed-system feedlot. All strains were subjected to short-read sequencing, with a subset of 36 also subjected to long-read sequencing. RESULTS: Over 96% of the strains fell into four phylogenetically distinct clades. Clade membership was associated with multiple factors including stx composition and the alleles of a well-characterized polymorphism (tir 255 T > A). Small plasmids (2.7 to 40 kb) were found to be primarily clade specific. Within each clade, chromosomal rearrangements were observed along with a core phageome and clade specific phages. Across both core and mobile elements of the genome, multiple SNP alleles were in complete linkage disequilibrium across all strains within specific clades. Clade evolutionary rates varied between 0.9 and 2.8 SNP/genome/year with two tir A allele clades having the lowest evolutionary rates. Investigation into possible causes of the differing rates was not conclusive but revealed a synonymous based mutation in the DNA polymerase III of the fastest evolving clade. Phylogenetic trees generated through our bioinformatic pipeline versus the NCBI's pathogen detection project were similar, with the two tir A allele clades matching individual NCBI SNP clusters, and the two tir T allele clades assigned to multiple closely-related SNP clusters. CONCLUSIONS: In one ecological niche, a diverse STEC O157:H7 population exhibited different rates of evolution that associated with SNP alleles in linkage disequilibrium in the core genome and mobile elements, including tir 255 T > A.


Assuntos
Infecções por Escherichia coli , Escherichia coli O157 , Alelos , Animais , Bovinos , Ecossistema , Infecções por Escherichia coli/epidemiologia , Escherichia coli O157/genética , Filogenia , Estudos Retrospectivos
7.
Biosens Bioelectron ; 207: 114214, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35349894

RESUMO

Foodborne pathogens are major public health concerns worldwide. Paper-based microfluidic devices are versatile, user friendly and low cost. We report a novel paper-based single input channel microfluidic device that can detect more than one whole-cell foodborne bacteria at the same time, and comes with quantitative reading via image analysis. This microfluidic paper-based multiplexed aptasensor simultaneously detects E. coli O157:H7 and S. Typhimurium. Custom designed particles provide colorimetric signal enhancement and false results prevention. Several aptamers were screened and the highest-affinity aptamers were optimized and employed for detection of these bacteria in solution, both in a buffer as well as pear juice. Image analysis was used to read and quantify the colorimetric signal and measure bacteria concentration, thus rendering this paper based microfluidic device quantitative. The colorimetric results show linearity over a wide concentration range (102CFU/mL to 108CFU/mL) and a limit of detection (LOD) of 103CFU/mL and 102CFU/mL for E. coli O157:H7 and S. Typhimurium, respectively. An insignificant change in colorimetric response for non-target bacteria indicates the aptasesnors are specific. The reported multiplexed colorimetric paper-based microfluidic devices is likely to perform well for on-site rapid screening of pathogenic bacteria in water and food products.


Assuntos
Técnicas Biossensoriais , Escherichia coli O157 , Bactérias , Microbiologia de Alimentos , Dispositivos Lab-On-A-Chip , Microfluídica
8.
Anal Methods ; 14(16): 1562-1570, 2022 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-35357389

RESUMO

Escherichia coli O157:H7 (E. coli O157:H7) is an enterohemorrhagic E. coli (EHEC), which has been issued as a major threat to public health worldwide due to fatal contamination of water and food. Thus, its rapid and accurate detection has tremendous importance in environmental monitoring and human health. In this regard, we report a simple and sensitive electrochemical DNA biosensor by targeting Z3276 as a genetic marker in river water. The surface of the designed gold electrode was functionalized with gold nanostars and an aminated specific sensing probe of E. coli O157:H7 to fabricate the genosensor. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were applied for electrochemical characterization and detection. The synthesized gold nanostars were characterized using different characterization techniques. The fabricated DNA-based sensor exhibited a high selective ability for one, two, and three-base mismatched sequences. Regeneration, stability, selectivity, and kinetics of the bioassay were investigated. Under optimal conditions, the fabricated genosensor exhibited a linear response range of 10-5 to 10-17 µM in the standard sample and 7.3 to 1 × 10-17 µM in water samples with a low limit of quantification of 0.01 zM in water samples. The detection strategy based on silver plated gold nanostars and DNA hybridization improved the sensitivity and specificity of the assay for E. coli O157:H7 detection in real water samples without filtration. The detection assay has the advantages of high selectivity, sensitivity, low amounts of reagents, short analysis time, commercialization, and potential application for the determination of other pathogenic bacteria.


Assuntos
Técnicas Biossensoriais , Escherichia coli O157 , Técnicas Biossensoriais/métodos , DNA , Escherichia coli O157/química , Escherichia coli O157/genética , Ouro/química , Humanos , Água
9.
Biosens Bioelectron ; 206: 114150, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35278850

RESUMO

Despite their potential for signal amplification in immunochromatographic assays (ICAs) with Au nanoparticles (AuNPs) as probes, metal growth methods are of limited practical applicability given their complex non-specificity and lack of robust growth schemes. Here, we propose a novel method of polyallylamine hydrochloride (PAH)-mediated metal growth for the detection of Escherichia coli O157:H7 by AuNP-ICA. The developed method relies on the highly controlled growth of Cu shells on the AuNP core and allows one to achieve highly enhanced colorimetric signals by controlling PAH as the growth framework. The introduction of PAH eliminates the non-specific adsorption of Cu ions on the nitrocellulose membrane and thus provides maximized and effective signal-to-noise ratios to achieve a detection limit of 9.8 CFU/mL for E. coli O157:H7. Moreover, the newly developed detection method exhibits good reproducibility (coefficient of variation <13%), remarkable stability, and practical applicability. The PAH-mediated signal enhancement system paves the way to the realization of stable metal growth methods based on Au, Ag, and other metals and is well suited for the rapid, stable, and sensitive detection of food-borne pathogens using the AuNP-ICA platform.


Assuntos
Técnicas Biossensoriais , Escherichia coli O157 , Nanopartículas Metálicas , Microbiologia de Alimentos , Ouro/química , Imunoensaio , Nanopartículas Metálicas/química , Reprodutibilidade dos Testes
10.
Arch Microbiol ; 204(4): 231, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-35355138

RESUMO

Shiga-toxin-producing Escherichia coli (STEC) strains of the serogroup O157 are foodborne pathogens associated with severe clinical disease. As antibiotics are counter-indicated for treatment of these infections, they represent prime candidates for targeted application of bacteriophages to reduce infection burden. In this study, we characterised lytic bacteriophages representing three phage genera for activity against E. coli O157 strains. The phages vb_EcoM_bov9_1 (Tequatrovirus), vb_EcoM_bov11CS3 (Vequintavirus), and vb_EcoS_bov25_1D (Dhillonvirus) showed effective lysis of enterohaemorrhagic E. coli EHEC O157:H7 strains, while also exhibiting activity against other strains of the O157 serogroup, as well as of the 'big six' (STEC) serogroups, albeit with lower efficiency. They had a burst size of 293, 127 and 18 per cell and a latent period of 35, 5 and 30 min, respectively. In situ challenge experiments using the O157 Sakai strain on minced beef showed a reduction by 2-3-fold when treated with phages at a 0.1 MOI (multiplicity of infection), and approximately 1 log reduction when exposed to MOI values of 10 and 100. A cocktail of the phages, applied at 10 × and 100 × MOI showed 2 to 3 log reduction when samples were treated at room temperature, and all treatments at 37 °C with 100 × MOI resulted in a 5 to 6 log reduction in cell count. Our results indicate that the phages vb_EcoM_bov9_1 and vb_EcoM_bov11CS3, which have higher burst sizes, are promising candidates for biocontrol experiments aimed at the eradication of E. coli O157 strains in animals or foodstuff.


Assuntos
Bacteriófagos , Escherichia coli O157 , Escherichia coli Shiga Toxigênica , Siphoviridae , Animais , Bovinos , Myoviridae
11.
Foodborne Pathog Dis ; 19(4): 272-280, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35263171

RESUMO

Salmonella, Escherichia coli O157, and Shigella flexneri are typical foodborne pathogens in ground beef, which can cause severe infection even when present as a single cell. Flow cytometry (FCM) methods are widely applied in the rapid detection of pathogens in food products. In this study, we report an FCM-based method for detecting single cells of Salmonella, E. coli O157, and S. flexneri in 25 g ground beef samples. We fluorescently labeled specific antibodies that could effectively identify bacterial cells, prepared single-cell samples by serial dilution, and optimized the pre-enrichment time. The results showed that 7 h of pre-enrichment is appropriate for sensitive single-cell detection by FCM. Finally, we evaluated this method in artificially contaminated and retail beef samples. This study outlines a novel highly sensitive FCM-based method to detect Salmonella, E. coli O157, and S. flexneri in beef samples within 8 h that can be applied to the rapid and multiplexed detection of foodborne pathogens.


Assuntos
Escherichia coli O157 , Produtos da Carne , Animais , Bovinos , Citometria de Fluxo , Microbiologia de Alimentos , Produtos da Carne/microbiologia , Salmonella , Shigella flexneri
12.
ACS Appl Mater Interfaces ; 14(10): 12662-12673, 2022 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-35239326

RESUMO

Cyclodextrin metal-organic frameworks (CD-MOFs) possess great potential in environmental applications due to their high specific surface area and good biocompatibility properties. However, the hydrophilicity of the CD-MOF hinders its ability to maintain a sustained release in water as a carrier. In this study, we prepared a CD-MOF that has codelivery ability for both phytochemicals [caffeic acid (CA)] and silver nanoparticles (Ag NPs) and further incorporated this material (CA@Ag@CD-MOF) into the polydimethylsiloxane (PDMS) matrix to construct a hybrid membrane. This hybrid membrane could effectively maintain the release capacity of the CD-MOF in water, while endowing PDMS with swelling ability in water. The hybrid membrane can achieve a sustained release for up to 48 h in water. In addition, the elastic modulus of the hybrid membrane increases by nearly 100%, and the swelling degree of the hybrid membrane in water increases by 42% compared with that of the pure PDMS membrane, indicating better mechanical properties. The hybrid membrane exhibits excellent antibacterial effects on Escherichia coli O157:H7 (E. coli O157:H7) and Staphylococcus aureus (S. aureus). We expect that this work will be beneficial to the delivery research of the CD-MOF in more environmental scenarios, especially in water treatment.


Assuntos
Escherichia coli O157 , Nanopartículas Metálicas , Estruturas Metalorgânicas , Antibacterianos/química , Antibacterianos/farmacologia , Preparações de Ação Retardada/farmacologia , Dimetilpolisiloxanos , Nanopartículas Metálicas/química , Estruturas Metalorgânicas/química , Estruturas Metalorgânicas/farmacologia , Prata/química , Prata/farmacologia , Staphylococcus aureus
13.
Food Res Int ; 154: 111013, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35337571

RESUMO

Escherichia coli O157:H7 EDL933 exposed to low-shear modeled microgravity (LSMMG) and normal gravity (NG) was used for a transcriptomic analysis. The modified Gompertz model (R2 = 0.81-0.99) showed an increased growth rate of E. coli O157:H7 under LSMMG. The mechanism of this active growth was associated with highly upregulated genes in nutrient and energy metabolism, including the TCA cycle, glycolysis, and pyruvate metabolism. Green fluorescent protein-labeled E. coli O157:H7 also formed significantly thick biofilms (fluorescent unit: NG, 1,263; LSMMG, 1,533; P = 0.0473) under LSMMG, whereas bacterial mobility decreased slightly (P = 0.0310). The transcriptomic analysis revealed that genes encoding glycogen biosynthesis (glgCAP operon) were upregulated (1.40 to 1.82 of log fold change [FC]) due to the downregulation of csrA (2.17 of log FC), which is the global regulator of biofilm formation of E. coli. We also identified 52 genes in E. coli O157:H7 EDL933 that were involved in the secretion pathway, 32 of which showed ≥2-fold significant changes in transcription levels after cultivation under LSMMG. Notably, all downregulated genes belonged to the type III and VI secretion systems, indicating that host cell contact secretion was dysregulated in the LSMMG cultures compared to the NG cultures. LSMMG also stimulates the pathogenicity of E. coli O157:H7 via transcriptional upregulation of Shiga toxin 1 (1.36 to 2.81 log FC) and toxin HokB (6.1 log FC). Our results suggest LSMMG affects bacterial growth, biofilm formation, and E. coli O157:H7 pathogenicity at some transcriptional levels, which indicates the importance of understanding biological consequences.


Assuntos
Toxinas Bacterianas , Escherichia coli O157 , Proteínas de Escherichia coli , Ausência de Peso , Toxinas Bacterianas/metabolismo , Escherichia coli O157/metabolismo , Proteínas de Escherichia coli/metabolismo , Redes e Vias Metabólicas , Proteínas de Ligação a RNA/metabolismo , Proteínas Repressoras/metabolismo , Toxina Shiga I
14.
Anal Methods ; 14(14): 1414-1419, 2022 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-35311849

RESUMO

Immunoassays based on enzyme-labeled antibodies have been widely used in the food safety field. However, the production process of enzyme-labeled antibodies is complicated and the low storage stability limits their application. Herein, antibody-horseradish peroxidase (HRP) co-assembled nanocomposites (AHC NCs) with outstanding advantages such as enhanced stability, lower cost, and substrate affinity were successfully prepared via a one-pot green method. Then the AHC NCs were employed as an alternative to traditional enzyme-labeled antibodies to develop a chemiluminescence enzyme immunoassay (CLEIA) toward Escherichia coli (E. coli) O157:H7. Under optimal conditions, E. coli O157:H7 can be detected in a linear range from 1 × 103 CFU mL-1 to 5 × 106 CFU mL-1, while the limit of detection (LOD) is as low as 2.2 × 102 CFU mL-1 (3σ). A series of repeatability studies showed reproducible results with a coefficient of variation of less than 7%. In addition, the proposed CLEIA was successfully applied to the analysis of spiked samples (tap water) and gave quantitative recoveries from 93.72% to 100.72%. This work demonstrates that the developed CLEIA can be applied as a universal platform for specific detection of diversified analytes.


Assuntos
Técnicas Biossensoriais , Escherichia coli O157 , Nanocompostos , Anticorpos , Técnicas Biossensoriais/métodos , Imunoensaio/métodos , Luminescência
15.
J Food Sci ; 87(4): 1475-1488, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35292980

RESUMO

Refrigerated pickles are characterized by crisp, crunchy texture, opaque flesh, and fresh flavor. Typically produced without a thermal process, microbial safety relies on preventive controls, brine composition, and sufficient hold time prior to consumption. We hypothesized that brief blanching of whole cucumbers prior to pickling could provide an additional hurdle for pathogenic microbes without negatively impacting finished product quality. Blanch treatments (15, 90, or 180 s) in 80°C water were conducted in duplicate on two lots of cucumbers prior to cutting into spears, acidifying, and storing at 4°C. Enumeration of total aerobes, lactic acid bacteria, and glucose-fermenting coliforms was conducted for fresh and blanched cucumber. Texture, color, cured appearance development, and volatile compound profiles were analyzed for fresh and blanched cucumber and corresponding pickle products during refrigerated storage. The 90 s blanch consistently achieved a minimum 2-log reduction in cucumber microbiota and a predicted 5-log reduction of Escherichia coli O157:H7 up to 1.1 mm into the cucumber fruit. Blanching had no impact on tissue firmness during refrigerated storage for 1 year (p > 0.098). There were no differences in flavor-active lipid oxidation products (E,Z)-2,6-nonadienal and (E)-2-nonenal, and consumers (n = 110) were unable to differentiate between control and 90 s blanched cucumber pickles stored for 62 days. Exocarp color and mesocarp opacity were preserved by the blanching treatment, potentially extending product shelf life. This method offers processors an option for reducing the risk of microbial contamination while maintaining the quality attributes associated with refrigerated cucumber pickles. PRACTICAL APPLICATION: Refrigerated pickles do not undergo thermal processing, which can leave them vulnerable to microbial contamination. This study illustrates that adding a brief blanching step in refrigerated pickle processing can reduce indigenous microbiota without negatively impacting quality attributes. This blanching process could assist pickled vegetable manufacturers in providing additional safeguards for consumers while maintaining a high-quality product.


Assuntos
Cucumis sativus , Escherichia coli O157 , Contagem de Colônia Microbiana , Cucumis sativus/microbiologia , Frutas
16.
Front Immunol ; 13: 807959, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35250980

RESUMO

Shiga toxin-producing Escherichia coli O157:H7 is a virulent strain causing severe gastrointestinal infection, hemolytic uremic syndrome and death. To date there are no specific therapies to reduce progression of disease. Here we investigated the effect of pooled immunoglobulins (IgG) on the course of disease in a mouse model of intragastric E. coli O157:H7 inoculation. Intraperitoneal administration of murine IgG on day 3, or both on day 3 and 6, post-inoculation improved survival and decreased intestinal and renal pathology. When given on both day 3 and 6 post-inoculation IgG treatment also improved kidney function in infected mice. Murine and human commercially available IgG preparations bound to proteins in culture filtrates from E. coli O157:H7. Bound proteins were extracted from membranes and peptide sequences were identified by mass spectrometry. The findings showed that murine and human IgG bound to E. coli extracellular serine protease P (EspP) in the culture filtrate, via the IgG Fc domain. These results were confirmed using purified recombinant EspP and comparing culture filtrates from the wild-type E. coli O157:H7 strain to a deletion mutant lacking espP. Culture filtrates from wild-type E. coli O157:H7 exhibited enzymatic activity, specifically associated with the presence of EspP and demonstrated as pepsin cleavage, which was reduced in the presence of murine and human IgG. EspP is a virulence factor previously shown to promote colonic cell injury and the uptake of Shiga toxin by intestinal cells. The results presented here suggest that IgG binds to EspP, blocks its enzymatic activity, and protects the host from E. coli O157:H7 infection, even when given post-inoculation.


Assuntos
Infecções por Escherichia coli , Escherichia coli O157 , Proteínas de Escherichia coli , Imunoglobulina G , Serina Proteases , Animais , Proteínas de Escherichia coli/metabolismo , Imunoglobulina G/metabolismo , Camundongos , Serina/metabolismo , Serina Endopeptidases/metabolismo , Serina Proteases/metabolismo
17.
Epidemiol Infect ; 150: e52, 2022 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-35241189

RESUMO

Shiga toxin-producing Escherichia coli (STEC) serogroup O157 is a zoonotic, foodborne gastrointestinal pathogen of major public health concern. We describe the epidemiology of STEC O157 infection in England by exploring the microbiological and clinical characteristics, the demographic and geographical distribution of cases, and examining changes in environmental exposures over 11 years of enhanced surveillance. Enhanced surveillance data including microbiological subtyping, clinical presentations and exposures were extracted for all cases resident in England with evidence of STEC O157 infection, either due to faecal culture or serology detection. Incidence rates were calculated based on mid-year population estimates from the Office of National Statistics (ONS). Demographics, geography, severity and environmental exposures were compared across the time periods 2009-2014 and 2015-2019. The number of cases reported to national surveillance decreased, with the mean cases per year dropping from 887 for the period 2009-2014 to 595 for the period 2015-2019. The decline in STEC O157 infections appears to be mirrored by the decrease in cases infected with phage type 21/28. Although the percentage of cases that developed HUS decreased, the percentage of cases reporting bloody diarrhoea and hospitalisation remained stable. The number of outbreaks declined over time, although more refined typing methods linked more cases to each outbreak. Integration of epidemiological data with microbiological typing data is essential to understanding the changes in the burden of STEC infection, assessment of the risks to public health, and the prediction and mitigation of emerging threats.


Assuntos
Infecções por Escherichia coli , Escherichia coli O157 , Escherichia coli Shiga Toxigênica , Diarreia/epidemiologia , Diarreia/microbiologia , Infecções por Escherichia coli/microbiologia , Humanos , Sorogrupo
18.
Appl Environ Microbiol ; 88(7): e0009822, 2022 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-35285244

RESUMO

Escherichia coli outbreaks linked to wheat flour consumption have kept emerging in recent years, which necessitated an antimicrobial step being incorporated into the flour production process. The objectives of this in vivo study were to holistically evaluate the sanitizing efficacy of thermal treatment at 60 and 70°C against the "big six" E. coli strains (O26:H11, O45:H2, O103:H11, O111, O121:H19, and O145) in wheat flour and to assess the strain-specific metabolic responses using nuclear magnetic resonance (NMR) spectroscopy. The 70°C treatment temperature indiscriminatingly inactivated all strains by over 4.3-log CFU/g within 20 min, suggesting the high sanitization effectiveness of this treatment temperature, whereas the treatment at 60°C inactivated the strains to various degrees during the 1-h process. The most resistant strains at 60°C, O26 and O45, were characterized by amino acid and sugar depletion, and their high resistance was attributed to the dual effects of activated heat shock protein (HSP) synthesis and promoted glycolysis. O121 also demonstrated these metabolic changes, yet its thermal resistance was largely impaired by the weakened membrane structure and diminished osmotic protection due to phosphorylcholine exhaustion. In contrast, O111, O145, and O103 presented a substantial elevation of metabolites after stress at 60°C; their moderate thermal resistance was mainly explained by the accumulation of amino acids as osmolytes. Overall, the study enhanced our understanding of the metabolic responses of big six E. coli to heat stress and provided a model for conducting NMR-based metabolomic studies in powdered food matrices. IMPORTANCE "Big six" Escherichia coli strains have caused several outbreaks linked to wheat flour consumption in the last decade, revealing the vital importance of adopting an antimicrobial treatment during the flour production process. Therefore, the present study was carried out to evaluate the efficacy of a typical sanitizing approach, thermal treatment, against the big six strains in wheat flour along with the underlying antimicrobial mechanisms. Findings showed that thermal treatment at 60 and 70°C could markedly mitigate the loads of all strains in wheat flour. Moreover, activated heat shock protein synthesis combined with expedited glycolysis and enhanced osmotic protection were identified as two major metabolic alteration patterns in the E. coli strains to cope with the heat stress. With the responses of big six in wheat flour to thermal treatment elucidated, scientific basis for incorporating a thermal inactivation step in wheat flour production was provided.


Assuntos
Infecções por Escherichia coli , Escherichia coli O157 , Escherichia coli Shiga Toxigênica , Farinha , Microbiologia de Alimentos , Proteínas de Choque Térmico/metabolismo , Espectroscopia de Ressonância Magnética , Triticum
19.
Food Microbiol ; 104: 104010, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35287798

RESUMO

Escherichia coli O157:H7 is one of the most important foodborne pathogens that can persist in leafy green vegetables and subsequently produce biofilms. Biofilm formation is an ongoing concern in the food industry as biofilms are relatively resistant to a variety of antimicrobial treatments. In the present study, we evaluated the combined effects of phage FP43 and mild-heated slightly acidic hypochlorous water (SAHW) in reducing established biofilms on lettuce. Prior to the sequential treatments involving phage-SAHW and SAHW-phage for long-term storage, equal inoculum densities of E. coli O157:H7 and E. coli O91:H- were added on iceberg lettuce surfaces and the lettuce samples were stored at 10 °C for 48 h to allow biofilm formation. The sequential treatment with phage FP43 and SAHW significantly decreased the number of adhered cells, especially the combination of phage FP43 at 25 °C for 2 h and mild-heated SAHW, which considerably eliminated E. coli viable biofilm cells to undetectable levels (>3 log CFU/piece). However, the biofilms were not completely removed, as evidenced via SEM observation. Additionally, sequential treatment with SAHW and phage caused continuous reductions in viable counts, decreasing the viability of E. coli O157:H7 and total E. coli to the lower limit of detection after incubation for 5 d. Meanwhile, bacterial regrowth was observed after treatment with SAHW alone. These results indicated that the combination of phage and SAHW could be considered as a promising strategy to control the formation of E. coli O157:H7 biofilms on lettuce.


Assuntos
Bacteriófagos , Escherichia coli O157 , Biofilmes , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Temperatura Alta , Alface/microbiologia , Água/farmacologia
20.
Food Microbiol ; 104: 103978, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35287807

RESUMO

Shiga toxin producing Escherichia coli (STEC) are common etiological agents of food borne illnesses and outbreaks, most often caused by consuming contaminated beef products, followed by raw vegetables and dairy products. Patients infected with E. coli O157 are more likely hospitalized than patients infected with non-O157 STEC, making E. coli O157 an important target for microbiological interventions. We show that a cocktail of bacteriophages EP75 and EP335 effectively reduces E. coli O157 on beef, romaine lettuce, spinach, and zucchini. Treatment of contaminated beef with either 2 × 107 or 1 × 108 PFU/cm2 of bacteriophage cocktail EP75/EP335 resulted in reductions of 0.8-1.1 log10 CFU/cm2 and 0.9-1.3 log10 CFU/cm2, respectively (P < 0.0001). Similarly, bacteriophage treatments of contaminated romaine lettuce, zucchini, or spinach showed significant (P < 0.05) E. coli O157 reductions of 0.7-1.9 log10 CFU/cm2 (2 × 107 PFU/cm2), and 1.4-2.4 log10 CFU/cm2 (1 × 108 PFU/cm2). An E. coli O157 reduction of 0.9 log10 and 2.0 log10 was observed already 30 min after phage application of 1 × 108 PFU/cm2 on beef and romaine lettuce, respectively. These data show that bacteriophages EP75 and EP335 can be effectively used as a processing aid on beef and vegetables, and thereby can aid industry to reduce the risk of E. coli O157 food poisoning.


Assuntos
Bacteriófagos , Escherichia coli O157 , Animais , Bovinos , Contagem de Células , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Humanos , Verduras
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