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Willis C, Jørgensen F, Cawthraw SA, Aird H, Lai S, Kesby M, Chattaway M, Lock I, Quill E, Raykova G. A survey of Salmonella, Escherichia coli and antimicrobial resistance in frozen, part-cooked, breaded or battered chicken products on retail sale in the United Kingdom. J Appl Microbiol 2023; 134:7150679. [PMID: 37133419 DOI: 10.1093/jambio/lxad093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 03/02/2023] [Accepted: 04/28/2023] [Indexed: 05/04/2023]
Abstract
AIM Frozen, breaded chicken products have been implicated in Salmonella outbreaks, and may be incorrectly perceived as ready-to-eat, leading to mishandling or undercooking by consumers. This study aimed to assess the prevalence of Salmonella and antimicrobial resistant (AMR) E. coli in these products. METHODS AND RESULTS Samples of frozen, raw or partly cooked, coated chicken products were collected between April and July 2021 from retailers in the UK and tested for Salmonella spp., generic Escherichia coli, extended spectrum beta-lactamase-producing, colistin-resistant and carbapenem-resistant E. coli. One isolate of each bacterial type from each sample was selected for minimum inhibitory concentration determination for a range of antimicrobials. Salmonella was detected in 5 of 310 (1.6%) samples, identified as Salmonella Infantis in three samples and S. Java in two. One S. Infantis isolate was multi-drug resistant, while the other Salmonella isolates were each resistant to at least one class of antimicrobials. Generic E. coli were detected in 113 samples (36.4%), with multi-drug resistance being demonstrated in 20.0% of these. E. coli with the ESBL phenotype were detected in 15 (4.8%) of samples and the AmpC phenotype in 2 (0.6%). A colistin resistant E. coli was isolated from one sample; this possessed the mcr-1 gene. No carbapenem-resistant E. coli were detected. The five Salmonella-positive samples from this study, together with 20 Salmonella-positive products from an earlier study in 2020/2021, were cooked according to the manufacturers' instructions. Following cooking, Salmonella was not detected in any samples. CONCLUSIONS This survey demonstrates continued contamination of frozen, coated chicken products with Salmonella, and provides data on the prevalence of AMR in these products.
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Affiliation(s)
- C Willis
- UK Health Security Agency (UKHSA), Food Water and Environmental Microbiology Laboratory Porton, Porton Down, Salisbury
| | - F Jørgensen
- UK Health Security Agency (UKHSA), Food Water and Environmental Microbiology Laboratory Porton, Porton Down, Salisbury
| | - S A Cawthraw
- Department of Bacteriology, Animal and Plant Health Agency (APHA - Weybridge), Woodham Lane, Addlestone, UK
| | - H Aird
- UKHSA, Food Water and Environmental Microbiology Laboratory York, National Agri-Food Innovation Campus, York
| | - S Lai
- UKHSA, Food Water and Environmental Microbiology Services, Colindale, London
| | - M Kesby
- UK Health Security Agency (UKHSA), Food Water and Environmental Microbiology Laboratory Porton, Porton Down, Salisbury
| | - M Chattaway
- Gastrointestinal Bacteria Reference Unit, UKHSA, London
| | - I Lock
- Fera Science Ltd, Sand Hutton, York
| | - E Quill
- Fera Science Ltd, Sand Hutton, York
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McLAUCHLIN J, Aird H, Amar CFL, Jenkins C, Jørgensen F, Lai S, Willis C. Microbiological Quality of Ready-to-Eat Salad Products Collected from Retail and Catering Settings in England during 2020 to 2021. J Food Prot 2022; 85:1680-1689. [PMID: 35776061 DOI: 10.4315/jfp-22-116] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 06/25/2022] [Indexed: 11/11/2022]
Abstract
ABSTRACT Salad and other fresh produce were collected in England from retail and catering businesses during 2020 to 2021 and were tested for Salmonella, Shiga toxin-producing Escherichia coli (STEC), Listeria, Bacillus cereus, and E. coli. Of the 604 samples collected, 57% were from retail settings and 43% were from catering settings; 61% were either salad leaves or salad leaves mixed with other products. Equal numbers of samples were prepacked or loose, and 50% were refrigerated at the time of sampling. Combining results for all microbiological parameters, 84% were interpreted as satisfactory, 12% were interpreted as borderline, and 4% were interpreted as unsatisfactory. One sample (prepacked leaves, cucumber, and tomato from a caterer) was categorized as unacceptable and potentially injurious because of detection of STEC O76; no STEC from human infections in the United Kingdom matched this isolate. No Salmonella enterica was detected, but Listeria monocytogenes was recovered from 11 samples: 1 at 20 CFU/g and the remainder at <20 CFU/g. B. cereus was detected at borderline levels (103 to ≤105 CFU/g) in 9% of samples and at an unsatisfactory level (>105 CFU/g) in one sample. E. coli was detected in 3% of samples at borderline levels (20 to ≤102 CFU/g) and in 4% at unsatisfactory levels (>102 CFU/g). There was a significant association between detection of L. monocytogenes and borderline or unsatisfactory levels of E. coli. There were no specific risk profiles associated with products with the higher levels of B. cereus, STEC, or Listeria, but elevated levels of E. coli were predominantly confined to loose products from the United Kingdom collected from caterers in summer or autumn 2021 and may have resulted from relaxation of COVID-19 restrictions. Among the L. monocytogenes isolates, only one matched those from human cases and was recovered from a prepacked mixed salad from a catering business in 2021. This isolate was the same strain as that responsible for a multicountry outbreak (2015 to 2018) associated with Hungarian-produced frozen sweet corn; no link to the outbreak food chain was established. HIGHLIGHTS
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Affiliation(s)
- J McLAUCHLIN
- Food Water and Environmental Microbiology Services, UK Health Security Agency, 61 Colindale Avenue, London NW9 5EQ, UK
| | - H Aird
- Food Water and Environmental Microbiology Laboratory York, York Biotech Campus, UK Health Security Agency, Sand Hutton, York YO41 1LZ, UK
| | - C F L Amar
- Gastrointestinal Bacteria Reference Unit, National Infection Service, UK Health Security Agency, 61 Colindale Avenue, London NW9 5EQ, UK
| | - C Jenkins
- Gastrointestinal Bacteria Reference Unit, National Infection Service, UK Health Security Agency, 61 Colindale Avenue, London NW9 5EQ, UK
| | - F Jørgensen
- Food Water and Environmental Microbiology Laboratory Porton, UK Health Security Agency, Manor Farm Road, Porton, Salisbury SP4 0JG, UK
| | - S Lai
- Food Water and Environmental Microbiology Laboratory London, UK Health Security Agency, 61 Colindale Avenue, Colindale, London NW9 5EQ, UK
| | - C Willis
- Food Water and Environmental Microbiology Laboratory Porton, UK Health Security Agency, Manor Farm Road, Porton, Salisbury SP4 0JG, UK
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Willis C, McLAUCHLIN J, Aird H, Jørgensen F, Lai S, Sadler-Reeves L. Assessment of the Microbiological Quality and Safety of Unpasteurized Milk Cheese for Sale in England between 2019 and 2020. J Food Prot 2022; 85:278-286. [PMID: 34669925 DOI: 10.4315/jfp-21-247] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 10/18/2021] [Indexed: 11/11/2022]
Abstract
ABSTRACT Cheese made with unpasteurized milk has been associated with outbreaks of illness. However, there are limited data on the prevalence of Shiga toxin-producing Escherichia coli (STEC) in these products and a lack of clarity over the significance of E. coli as a general indicator of hygiene in raw milk cheeses. The aim of this study was to provide further data to address both of these issues, as well as assessing the overall microbiological quality of raw milk cheeses available to consumers in England. A total of 629 samples of cheese were collected from retailers, catering premises, and manufacturers throughout England. The majority (80%) were made using cow's milk, with 14% made from sheep's milk and 5% from goat's milk. Samples were from 18 different countries of origin, with the majority originating from either the United Kingdom (40%) or France (35%). When interpreted against European Union microbiological criteria and United Kingdom guidance, 82% were considered to be of satisfactory microbiological quality, 5% were borderline, and 12% were unsatisfactory. Four samples (0.6%) were potentially injurious to health due to the isolation of STEC from one, >104 CFU/g of coagulase-positive staphylococci in two, and >100 CFU/g of Listeria monocytogenes in the fourth sample. Indicator E. coli and Listeria species were detected more frequently in soft compared with hard cheese. Higher levels of indicator E. coli were significantly associated with a greater likelihood of detecting Shiga toxin genes (stx1 and/or stx2). HIGHLIGHTS
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Affiliation(s)
- C Willis
- UK Health Security Agency, Food Water and Environmental Microbiology Laboratory Porton, Manor Farm Road, Porton Down, Salisbury, UK SP4 0JG
| | - J McLAUCHLIN
- UK Health Security Agency, Food Water and Environmental Microbiology Services, Colindale Avenue, Colindale, London, UK NW9 5EQ
| | - H Aird
- UK Health Security Agency, Food Water and Environmental Microbiology Laboratory York, National Agri-Food Innovation Campus, Sand Hutton, York, UK YO41 1LZ
| | - F Jørgensen
- UK Health Security Agency, Food Water and Environmental Microbiology Laboratory Porton, Manor Farm Road, Porton Down, Salisbury, UK SP4 0JG
| | - S Lai
- UK Health Security Agency, Food Water and Environmental Microbiology Services, Colindale Avenue, Colindale, London, UK NW9 5EQ
| | - L Sadler-Reeves
- UK Health Security Agency, Field Services, South East, Level 2, Civic Centre, Tannery Lane, Ashford, UK TN23 1PL
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Babacan O, Harris SA, Pinho RM, Hedges A, Jørgensen F, Corry JEL. Factors affecting the species of Campylobacter colonizing chickens reared for meat. J Appl Microbiol 2020; 129:1071-1078. [PMID: 32248631 DOI: 10.1111/jam.14651] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/18/2020] [Accepted: 03/26/2020] [Indexed: 01/05/2023]
Abstract
AIM To investigate factors influencing Campylobacter spp. colonization of broiler chickens. METHODS AND RESULTS Campylobacters were isolated from caeca from 319 flocks of two different breeds (199 Cobb and 120 Hubbard), reared as standard (199), Freedom Food/corn fed (57), free-range (47) or organic (16). The standard category exclusively used Cobb birds slaughtered at 38-41 days. The Freedom Food/corn-fed and free-range Hubbard birds were slaughtered at 49-56 days and the organic flocks at 70 days. Campylobacters were picked at random from direct plates. Both breed of chicken (Hubbard) and age at slaughter were independently associated with increased likelihood of colonization by Campylobacter coli rather than Campylobacter jejuni, but breed could not be separated from other aspects of husbandry with the data available. CONCLUSIONS Chickens are frequently colonized by C. jejuni and C. coli and most human infections originate from poultry. In most developed countries approximately 90% of human infections are caused by C. jejuni, but fewer than 10% by C. coli. This might be due to C. coli being less pathogenic than C. jejuni to humans, and/or to chicken meat carrying fewer C. coli than C. jejuni. More investigations are needed into these aspects before it can be concluded that slaughtering older birds from slower-growing breeds would reduce the risk of human Campylobacter disease. SIGNIFICANCE AND IMPACT OF THE STUDY Meat from certain breeds of poultry are predominantly colonized by C. coli rather than C. jejuni. More research is needed to understand the impact this may have on the number and severity of human campylobacter infections.
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Affiliation(s)
- O Babacan
- Bristol Veterinary School, University of Bristol, Bristol, UK.,Department of Veterinary Science, Kepsut Vocational School, Balıkesir University, Kepsut, Balıkesir, Turkey
| | - S A Harris
- Foodborne Zoonoses Unit, Health Protection Agency, School of Clinical Veterinary Science, University of Bristol, Bristol, UK
| | - R M Pinho
- Bristol Veterinary School, University of Bristol, Bristol, UK
| | - A Hedges
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - F Jørgensen
- Foodborne Zoonoses Unit, Health Protection Agency, School of Clinical Veterinary Science, University of Bristol, Bristol, UK
| | - J E L Corry
- Bristol Veterinary School, University of Bristol, Bristol, UK
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McLauchlin J, Aird H, Elliott A, Forester E, Jørgensen F, Willis C. Microbiological quality of raw drinking milk and unpasteurised dairy products: results from England 2013-2019. Epidemiol Infect 2020; 148:e135. [PMID: 32406346 PMCID: PMC7374804 DOI: 10.1017/s0950268820001016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 03/21/2020] [Accepted: 05/11/2020] [Indexed: 11/06/2022] Open
Abstract
The aim of this study was to review microbiology results from testing >2500 raw drinking milk and dairy products made with unpasteurised milk examined in England between 2013 and 2019. Samples were collected as part of incidents of contamination, investigation of infections or as part of routine monitoring and were tested using standard methods for a range of both pathogens and hygiene indicators. Results from testing samples of raw cow's milk or cheese made from unpasteurised milk for routine monitoring purposes were overall of better microbiological quality than those collected during incident or investigations of infections. Results from routine monitoring were satisfactory for 62% of milks, 82% of cream, 100% of ice-cream, 51% of butter, 63% of kefir and 79% of cheeses, with 5% of all samples being considered potentially hazardous. Analysis of data from cheese demonstrated a significant association between increasing levels of indicator Escherichia coli with elevated levels of coagulase positive staphylococci and decreased probability of isolation of Shiga toxin-producing E. coli. These data highlight the public health risk associated with these products and provide further justification for controls applied to raw drinking milk and dairy products made with unpasteurised milk.
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Affiliation(s)
- J. McLauchlin
- Public Health England, National Infection Service, Food Water and Environmental Microbiology Services, Colindale, London, UK
| | - H. Aird
- Public Health England, National Infection Service, Food Water and Environmental Microbiology Laboratory York, National Agri-Food Innovation Campus, York, UK
| | - A. Elliott
- Public Health England, National Infection Service, Food Water and Environmental Microbiology Laboratory Porton, Porton Down, Salisbury, UK
- Public Health England, National Infection Service, Field Services, South West, Bristol, UK
| | - E. Forester
- Public Health England, National Infection Service, Food Water and Environmental Microbiology Laboratory York, National Agri-Food Innovation Campus, York, UK
- Public Health England, National Infection Service, Field Services, North West Office, Liverpool, UK
| | - F. Jørgensen
- Public Health England, National Infection Service, Food Water and Environmental Microbiology Laboratory Porton, Porton Down, Salisbury, UK
| | - C. Willis
- Public Health England, National Infection Service, Food Water and Environmental Microbiology Laboratory Porton, Porton Down, Salisbury, UK
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McLauchlin J, Aird H, Andrews N, Chattaway M, de Pinna E, Elviss N, Jørgensen F, Larkin L, Willis C. Public health risks associated with Salmonella contamination of imported edible betel leaves: Analysis of results from England, 2011-2017. Int J Food Microbiol 2019; 298:1-10. [PMID: 30889473 DOI: 10.1016/j.ijfoodmicro.2019.03.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/10/2019] [Accepted: 03/09/2019] [Indexed: 01/06/2023]
Abstract
Fresh betel leaves (Piper betle L.), imported into the UK are a traditional ready-to-eat food consumed by Asian populations. We report here the consolidation of routinely collected data to model the public health risks from consumption of this food. Amongst 2110 samples collected at Border Inspection, wholesale, catering or retail, Salmonella was detected in 488 (23%) of samples tested between 2011 and 2017 and was the most commonly Salmonella-contaminated ready-to-eat food examined by Public Health England during this period. Using data from multiple samples (usually 5) tested per consignment sampled at Border Inspection, contamination levels were calculated by most probable number: seasonal, temporal and country specific differences were detected. Quantitative contamination data was used to estimate the levels present at retail, and a β-Poisson dose response model the probability of illness was calculated. Using data for products imported from India, the probability of acquiring infection following a single exposure (comprising of a single leaf) was estimated to be between 0.00003 (January-March) and 0.0001 (July-September). Using British Asian population data for individuals over 30 years of age in England in 2011, two estimates of consumption were modelled as 2.1 and 12.8 million servings per annum. Results from the model estimated 160 cases (range 102 to 242) and 960 cases (range 612 to 1456) per year in England for the two consumption estimates and equated to 34 (range 22 to 51) and 204 (range 130 to 310) salmonellosis cases per year reported to national surveillance. Salmonella from 475 of the contaminated samples were further characterised which showed a heterogeneous population structure with 46 S. enterica subsp. Enterica serovars, together with S. enterica subs diarizonae and salamae identified. Isolates from individual consignments were diverse and close genetic relationships between independent isolates were very rare except from within an individual consignment. There were no outbreaks detected as associated with betel leaf consumption. However analysis by whole genome sequencing of the 2014-17 data identified two cases where the clinical isolate had <5 single nucleotide polymorphism differences to isolates from betel leaves which is indicative of a likely epidemiological link and common source of contamination. Due to the diversity of the Salmonella contaminating this product, associations between salmonellosis cases and betel leaf consumption will appear sporadic and unlikely to be detected by current surveillance strategies based on outbreak detection.
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Affiliation(s)
- J McLauchlin
- Public Health England Food Water and Environmental Microbiology Services, National Infection Service, Colindale, London NW9 5EQ, UK; University of Liverpool, Institute of Infection and Global Health, Waterhouse Building, 1-5 Brownlow Street, Liverpool L69 3GL, UK.
| | - H Aird
- Public Health England Food Water and Environmental Microbiology Laboratory York, National Infection Service, National Agri-Food Innovation Campus, York YO41 1LZ, UK
| | - N Andrews
- Public Health England Statistics, Modelling and Economics Department, National Infection Service, 61 Colindale Avenue, London NW9 5EQ, UK
| | - M Chattaway
- Public Health England Gastrointestinal Bacteria Reference Unit, National Infection Service, 61 Colindale Avenue, London NW9 5EQ, UK
| | - E de Pinna
- Public Health England Gastrointestinal Bacteria Reference Unit, National Infection Service, 61 Colindale Avenue, London NW9 5EQ, UK
| | - N Elviss
- Public Health England Food Water and Environmental Microbiology Laboratory London, National Infection Service, Colindale, London NW9 5EQ, UK
| | - F Jørgensen
- Public Health England Food Water and Environmental Microbiology Laboratory Porton, National Infection Service, Porton Down, Salisbury SP4 0JG, UK
| | - L Larkin
- Public Health England, Gastrointestinal Infections Department, National Infection Service, London, NW9 5EQ, UK
| | - C Willis
- Public Health England Food Water and Environmental Microbiology Laboratory Porton, National Infection Service, Porton Down, Salisbury SP4 0JG, UK
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McLauchlin J, Aird H, Charlett A, Chattaway M, Elviss N, Hartman H, Jenkins C, Jørgensen F, Larkin L, Sadler-Reeves L, Willis C. Imported edible leaves collected at retail sale in England during 2017 with an emphasis on betel and curry leaves: microbiological quality with respect toSalmonella, Shiga-toxin-producingE. coli(STEC) and levels ofEscherichia coli. J Appl Microbiol 2018; 125:1175-1185. [DOI: 10.1111/jam.13931] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 05/21/2018] [Accepted: 05/23/2018] [Indexed: 11/29/2022]
Affiliation(s)
- J. McLauchlin
- Public Health England Food Water and Environmental Microbiology Services; National Infection Service; London UK
- Institute of Infection and Global Health; University of Liverpool; Liverpool UK
| | - H. Aird
- Public Health England Food Water and Environmental Microbiology Laboratory York; National Infection Service; York UK
| | - A. Charlett
- Public Health England Statistics, Modelling and Economics Department; National Infection Service; London UK
| | - M. Chattaway
- Public Health England Gastrointestinal Bacteria Reference Unit; National Infection Service; London UK
| | - N. Elviss
- Public Health England Food Water and Environmental Microbiology Laboratory London; National Infection Service; London UK
| | - H. Hartman
- Public Health England Gastrointestinal Bacteria Reference Unit; National Infection Service; London UK
| | - C. Jenkins
- Public Health England Gastrointestinal Bacteria Reference Unit; National Infection Service; London UK
| | - F. Jørgensen
- Public Health England Food Water and Environmental Microbiology Laboratory Porton; National Infection Service; Salisbury UK
| | - L. Larkin
- Public Health England; Gastrointestinal Infections Department; National Infection Service; London UK
| | - L. Sadler-Reeves
- Public Health England Food Water and Environmental Microbiology Laboratory Porton; National Infection Service; Salisbury UK
| | - C. Willis
- Public Health England Food Water and Environmental Microbiology Laboratory Porton; National Infection Service; Salisbury UK
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Willis C, Jørgensen F, Aird H, Elviss N, Fox A, Jenkins C, Fenelon D, Sadler-Reeves L, McLauchlin J. An assessment of the microbiological quality and safety of raw drinking milk on retail sale in England. J Appl Microbiol 2018; 124:535-546. [PMID: 29215775 DOI: 10.1111/jam.13660] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 11/27/2017] [Accepted: 11/27/2017] [Indexed: 01/02/2023]
Abstract
AIMS This study aimed to review the microbiological results for raw drinking milk (RDM) samples submitted to Public Health England laboratories between 2014 and 2016 in order to produce up-to-date data on the microbiological safety of RDM and inform future risk assessments on its sale. METHODS AND RESULTS A total of 902 samples of RDM were collected from retail sale in England for microbiological examination. Overall, 454 of 770 samples (59·0%) taken for routine monitoring were of a satisfactory quality, whilst eight (1·0%) were 'unsatisfactory and potentially injurious to health' due to the presence of Shiga toxin-producing Escherichia coli, Campylobacter or elevated levels of Listeria monocytogenes or coagulase-positive staphylococci. In contrast, 16 of 114 (14·0%) of samples taken in follow-up to a previous unsatisfactory result and 5 of 18 (27·8%) of samples related to illness were potentially injurious. A total of 229 of 902 samples (25·4%) gave unsatisfactory results due to elevated aerobic colony counts and/or coliforms, whilst 139 of 902 samples (15·4%) were of borderline quality due to coagulase-positive staphylococci. Listeria monocytogenes was detected at levels of <100 CFU per ml in 66 of 902 samples (7·3%) and other Listeria species in 44 of 902 samples (4·9%). CONCLUSIONS Pathogens and/or indicators of poor hygiene were present in almost half of samples examined. Cows' milk samples gave a significantly greater proportion of unsatisfactory results compared to milk from other species (i.e. goat, sheep, buffalo, camel). SIGNIFICANCE AND IMPACT OF THE STUDY These results demonstrate the importance of maintaining strict controls on the production and sale of this product.
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Affiliation(s)
- C Willis
- Public Health England Food Water and Environmental Microbiology Laboratory Porton, Salisbury, UK
| | - F Jørgensen
- Public Health England Food Water and Environmental Microbiology Laboratory Porton, Salisbury, UK
| | - H Aird
- Public Health England Food Water and Environmental Microbiology Laboratory York, York, UK
| | - N Elviss
- Public Health England Food Water and Environmental Microbiology Laboratory London, Colindale, London, UK
| | - A Fox
- Public Health England Food Water and Environmental Microbiology Laboratory York, York, UK
| | - C Jenkins
- Gastrointestinal Bacteria Reference Unit, Public Health England, Colindale, London, UK
| | - D Fenelon
- Public Health England Food Water and Environmental Microbiology Laboratory London, Colindale, London, UK
| | - L Sadler-Reeves
- Public Health England Food Water and Environmental Microbiology Laboratory Porton, Salisbury, UK
| | - J McLauchlin
- Public Health England Food Water and Environmental Microbiology Services, Colindale, London, UK.,Institute of Infection and Global Health, University of Liverpool, Liverpool, UK
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Jørgensen F. Separation of Dirac's Hamiltonian by Van Vleck transformation. Mol Phys 2017. [DOI: 10.1080/00268976.2016.1239845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Pedersen AE, Holmstrøm K, Jørgensen F, Jensen SS, Gad M. Development of assay platforms for in vitro screening of Treg modulating potential of pharmacological compounds. Immunopharmacol Immunotoxicol 2014; 37:63-71. [PMID: 25367176 DOI: 10.3109/08923973.2014.977449] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CD4 + CD25+ regulatory T cells (Tregs) are believed to be pivotal in controlling chronic inflammation as well as in opposing the effect of cancer immunotherapy. Therefore, identification of novel drug compounds that interfere with Treg function is of high priority together with research that investigates Treg modulation by current drugs. For such research as well as for novel cell based therapies based on Treg infusions, rapid in vitro assays as well as functional assays based on inhibitory capacity of Tregs are required. Here, we report on such assays using highly pure fluorescence-activated cell sorting (FACS) sorted CD4 + CD25(high)CD127(dim/-)CD45RA+ naïve Treg cells followed by in vitro expansion. We report on the use of these cells in a short-term assay based on Treg mediated inhibition of the early effector T cell activation markers CD69 and CD154. Additionally, we investigate the use of highly pure Tregs in a functional assay based on Treg mediated inhibition of effector T cell proliferation. We report highly reproducible Treg function in assays that test the effect of well-known model compounds such as CpG-A, anti-IL-6R (tocilizumab), anti-TNF-α (adalimumab) or a combination of IL-6 and TNF-α. In conclusion, these assays have the potential for use in pharmacological screening and discovery in relation to drug development in immunology.
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Affiliation(s)
- Anders Elm Pedersen
- Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark and
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Refsgaard JC, Auken E, Bamberg CA, Christensen BSB, Clausen T, Dalgaard E, Effersø F, Ernstsen V, Gertz F, Hansen AL, He X, Jacobsen BH, Jensen KH, Jørgensen F, Jørgensen LF, Koch J, Nilsson B, Petersen C, De Schepper G, Schamper C, Sørensen KI, Therrien R, Thirup C, Viezzoli A. Nitrate reduction in geologically heterogeneous catchments--a framework for assessing the scale of predictive capability of hydrological models. Sci Total Environ 2014; 468-469:1278-1288. [PMID: 23953482 DOI: 10.1016/j.scitotenv.2013.07.042] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 05/28/2013] [Accepted: 07/13/2013] [Indexed: 06/02/2023]
Abstract
In order to fulfil the requirements of the EU Water Framework Directive nitrate load from agricultural areas to surface water in Denmark needs to be reduced by about 40%. The regulations imposed until now have been uniform, i.e. the same restrictions for all areas independent of the subsurface conditions. Studies have shown that on a national basis about 2/3 of the nitrate leaching from the root zone is reduced naturally, through denitrification, in the subsurface before reaching the streams. Therefore, it is more cost-effective to identify robust areas, where nitrate leaching through the root zone is reduced in the saturated zone before reaching the streams, and vulnerable areas, where no subsurface reduction takes place, and then only impose regulations/restrictions on the vulnerable areas. Distributed hydrological models can make predictions at grid scale, i.e. at much smaller scale than the entire catchment. However, as distributed models often do not include local scale hydrogeological heterogeneities, they are typically not able to make accurate predictions at scales smaller than they are calibrated. We present a framework for assessing nitrate reduction in the subsurface and for assessing at which spatial scales modelling tools have predictive capabilities. A new instrument has been developed for airborne geophysical measurements, Mini-SkyTEM, dedicated to identifying geological structures and heterogeneities with horizontal and lateral resolutions of 30-50 m and 2m, respectively, in the upper 30 m. The geological heterogeneity and uncertainty are further analysed by use of the geostatistical software TProGS by generating stochastic geological realisations that are soft conditioned against the geophysical data. Finally, the flow paths within the catchment are simulated by use of the MIKE SHE hydrological modelling system for each of the geological models generated by TProGS and the prediction uncertainty is characterised by the variance between the predictions of the different models.
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Abstract
Airborne electromagnetics (AEMs) is increasingly being used across the globe as a tool for groundwater and environmental management. Focus is on ensuring the quality of the source data, their processing and modeling, and the integration of results with ancillary information to generate accurate and relevant products. Accurate processing and editing of raw AEM data, the topic of this article, is one of the crucial steps in obtaining quantitative information for groundwater modeling and management. In this article, we examine the consequences that different levels of processing of helicopter transient electromagnetic method data have on the resulting electrical models and subsequently on hydrogeological models. We focus on different approaches used in the industry for processing of the raw data and show how the electrical resistivity-depth models, which is the end "geophysical" product (after data inversion) of an AEM survey, change with different levels of processing of the raw data. We then extend the study to show the impact on some of the hydrogeological parameters or models, which can be derived from the geophysical results. The consequences of improper handling of raw data to groundwater and environmental management can be significant and expensive.
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Affiliation(s)
- Andrea Viezzoli
- Aarhus Geophysics Aps, C.F. Møllers, Allé 4, Aarhus C 8000, Denmark.
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Sabourin D, Skafte-Pedersen P, Søe MJ, Hemmingsen M, Alberti M, Coman V, Petersen J, Emnéus J, Kutter JP, Snakenborg D, Jørgensen F, Clausen C, Holmstrøm K, Dufva M. The MainSTREAM component platform: a holistic approach to microfluidic system design. ACTA ACUST UNITED AC 2012; 18:212-28. [PMID: 23015520 DOI: 10.1177/2211068212461445] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A microfluidic component library for building systems driving parallel or serial microfluidic-based assays is presented. The components are a miniaturized eight-channel peristaltic pump, an eight-channel valve, sample-to-waste liquid management, and interconnections. The library of components was tested by constructing various systems supporting perfusion cell culture, automated DNA hybridizations, and in situ hybridizations. The results showed that the MainSTREAM components provided (1) a rapid, robust, and simple method to establish numerous fluidic inputs and outputs to various types of reaction chips; (2) highly parallel pumping and routing/valving capability; (3) methods to interface pumps and chip-to-liquid management systems; (4) means to construct a portable system; (5) reconfigurability/flexibility in system design; (6) means to interface to microscopes; and (7) compatibility with tested biological methods. It was found that LEGO Mindstorms motors, controllers, and software were robust, inexpensive, and an accessible choice as compared with corresponding custom-made actuators. MainSTREAM systems could operate continuously for weeks without leaks, contamination, or system failures. In conclusion, the MainSTREAM components described here meet many of the demands on components for constructing and using microfluidics systems.
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Affiliation(s)
- David Sabourin
- DTU Nanotech, Dept. of Micro- and Nanotechnology, Technical University of Denmark, Kgs. Lyngby, Denmark
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Toscano MJ, Sait L, Jørgensen F, Nicol CJ, Powers C, Smith AL, Bailey M, Humphrey TJ. Sub-clinical infection with Salmonella in chickens differentially affects behaviour and welfare in three inbred strains. Br Poult Sci 2011; 51:703-13. [PMID: 21161776 DOI: 10.1080/00071668.2010.528748] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
1. Much evidence exists detailing how animals respond to pathogen challenge, yet information explaining how the various behavioural, immunological, and physiological systems in chickens interplay during such challenges remains limited. 2. To gain an understanding of this interplay while controlling for genetic variation, the current study collected a variety of behavioural, physiological and immunological measures from three inbred lines (P, O and N) of laying hens before and after a sub-clinical infection with Salmonella enterica Typhimurium at 56 d of age. For comparison, an equal number of control birds were inoculated with a Salmonella-free broth. To identify an underlying profile, which might result in reduced susceptibility to infection, data were also collected in the pre-infection period. Post-infection blood and faeces were collected at 1-d post infection (dpi) and faeces again at 8 dpi. Animals were killed 15 d after infection and faeces, caecal contents, and spleen were examined for the presence of Salmonella. 3. Statistical analysis was performed to identify pre- and post-infection differences between genetic lines, changes in bird behavioural patterns between the two periods, and associations between a positive test for Salmonella and the various response measures. 4. Tissues from Line P birds were more often negative for Salmonella than those from birds of other lines, though this was inconsistent and tissue-dependent. The P line was also characterised by relatively greater serum concentrations of immunoglobulins at 1 dpi and α(1)-acid glycoprotein at 15 dpi. In addition, P line birds were more timid and their growth was reduced during the pre-infection period suggesting the possibility of a profile with reduced susceptibility to the bacterial challenge. 5. The current work has identified correlations between attributes of chicken strains and improved clearance. Future work using hypothesis-based testing will be required to determine whether the identified correlations are causally related.
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Affiliation(s)
- M J Toscano
- Animal Behaviour and Welfare Group, University of Bristol, Langford, Bristol, BS40 5DU, UK.
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Steensgaard M, Svenningsen P, Tinning AR, Nielsen TD, Jørgensen F, Kjaersgaard G, Madsen K, Jensen BL. Apical serine protease activity is necessary for assembly of a high-resistance renal collecting duct epithelium. Acta Physiol (Oxf) 2010; 200:347-59. [PMID: 20645929 DOI: 10.1111/j.1748-1716.2010.02170.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
AIM We hypothesized that the serine protease prostasin is necessary for differentiation of a high-resistance renal collecting duct epithelium governed by glucocorticoid. METHODS Postnatal rat kidney and adult human kidney was used to study the expression and localization of prostasin. The murine collecting duct cell line (M-1) was cultured in Snapwell inserts to investigate the significance of prostasin for the development of transepithelial electrical resistance (TER). RESULTS In the cortex and medulla of rat kidney, prostasin mRNA and protein increased significantly between birth and weaning (day 21) and was detected in collecting ducts. Immunoreactive prostasin was associated with collecting ducts and loops of Henle in human kidney. In rat, adrenalectomy at day 10 had no effect on prostasin mRNA level in kidney at day 20. Cultured M-1 cells exhibited parallel increases in prostasin mRNA, protein and TER 5 days after seeding. Apical addition of the serine protease inhibitor aprotinin to M-1 cell cultures inhibited development of TER and led to aberrant localization of E-cadherin. This effect was mimicked by the protease inhibitor nafamostat. Apical addition of phospholipase C to cleave glycosylphosphatidylinositol (GPI) anchors released prostasin to the medium and attenuated development of TER with time of culture. Disruption of lipid rafts by methyl-β-cyclodextrin attenuated development of TER in M-1 cells. Omission of dexamethasone impaired development of TER in M-1 cells, while prostasin protein abundance and E-cadherin distribution did not change. CONCLUSION Apical, GPI-anchored, lipid raft-associated serine protease activity, compatible with prostasin, is necessary for the development of a high-resistance collecting duct epithelium.
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Affiliation(s)
- M Steensgaard
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark
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Abstract
This controlled investigation of 27 volunteers compared the effect of cold and lukewarm tap water and carbonated water on the passage through the esophagus of a large circular tablet containing barium sulphate and of the same size and specific gravity as an acetylsalicylic acid tablet (Kodimagnyl). The influence of yoghurt on the passage of the same tablet was also examined. The investigation emphasized the importance of taking tablets together with 100 ml of liquid. A comparison of the transit times for tablets taken together with 100 ml of cold carbonated water and 100 ml of lukewarm tap water showed a significantly better passage when the tablets were taken with cold carbonated water (p = 0.01). A similar advantage of carbonated liquids was seen when tablets were taken with 25 ml of lukewarm tap water as compared with 25 ml of cold carbonated water (p = 0.01). Administration of a tablet in a tablespoon of yoghurt is a good alternative, even though the bioavailability of certain preparations may be reduced.
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Nielsen PE, Jørgensen F. An unusual young male with exercise induced, severe hypertensive spikes. What's the diagnosis? Acta Med Scand Suppl 2009; 677:158-62. [PMID: 6583999 DOI: 10.1111/j.0954-6820.1984.tb08655.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Thysell H, Bygren P, Bengtsson U, Lindholm T, Norlin M, Jonsson M, Brun C, Larsen S, Jørgensen F, Sjöholm A, Laurell AB. Immunosuppression and the additive effect of plasma exchange in treatment of rapidly progressive glomerulonephritis. Acta Med Scand 2009; 212:107-14. [PMID: 7148502 DOI: 10.1111/j.0954-6820.1982.tb03180.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Attempts were made to evaluate the separate effect on kidney function of immunosuppressive treatment (IS) and plasma exchange (PE) in 27 patients with rapidly progressive glomerulonephritis (RPGN). Twenty-four of the patients were treated with PE. Initial IS was supplemented with PE within 6-12 days in 5 patients, and after at least 14 days in 13. Because of suspected septicemia, 2 patients were first treated with PE, and IS was not initiated until the possibility of septicemia had been excluded. In 4 severely ill patients wih rapid clinical deterioration, both treatments were started simultaneously. Twenty patients improved during one or both treatments, 4 with IS alone, 2 with IS and doubtfully with PE, 3 with IS and probably also with PE, 5 both with IS and PE and one with PE alone. In 5 patients the individual effects of IS and PE could not be evaluated. In another 2 patients the combined treatment seemed to influence the course favourably. In the remaining 7 patients the effect of the treatment was doubtful or nil. Two further patients with Goodpasture's syndrome were treated. They were admitted late, and both kinds of treatment were instituted simultaneously. One of them died in respiratory insufficiency, the other remained oliguric while the pulmonary changes faded. Thus, PE added a positive effect to IS in several patients with RPGN. The treatment had few and mostly mild side-effects.
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Abstract
A 72-year-old woman suffered from giant cell arteritis (GCA) which developed into lingual infarction and monocular blindness. Temporary obscuration of vision and lingual symptoms such as increasing malaise, pain and intermittent claudication may precede the catastrophic results of arteritis. Emphasis is laid on early recognition and treatment of GCA.
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Balsløv JT, Brun C, Jensen KB, Jørgensen F, Jørgensen HE, Larsen M, Lorenzen I, Thomsen ÅC. CYTOSTATIC TREATMENT OF GLOMERULAR DISEASES. ACTA ACUST UNITED AC 2009. [DOI: 10.1111/j.0954-6820.1973.tb10614.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Karatzas K, Hocking P, Jørgensen F, Mattick K, Leach S, Humphrey T. Effects of repeated cycles of acid challenge and growth on the phenotype and virulence ofSalmonella enterica. J Appl Microbiol 2008; 105:1640-8. [DOI: 10.1111/j.1365-2672.2008.03909.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Jørgensen F, Stephens P, Knøchel S. The effect of osmotic shock and subsequent adaptation on the thermotolerance and cell morphology ofListeria monocytogenes. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1365-2672.1995.tb03137.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Jørgensen F, Nybroe O, Knøchel S. Effects of starvation and osmotic stress on viability and heat resistance ofPseudomonas fluorescensAH9. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1365-2672.1994.tb03083.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Allen VM, Bull SA, Corry JEL, Domingue G, Jørgensen F, Frost JA, Whyte R, Gonzalez A, Elviss N, Humphrey TJ. Campylobacter spp. contamination of chicken carcasses during processing in relation to flock colonisation. Int J Food Microbiol 2007; 113:54-61. [PMID: 17007949 DOI: 10.1016/j.ijfoodmicro.2006.07.011] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 04/19/2006] [Accepted: 07/06/2006] [Indexed: 11/16/2022]
Abstract
The presence and numbers of campylobacters on chicken carcasses from 26 slaughter groups, originating from 22 single-house flocks and processed in four UK plants, were studied in relation to the level of flock colonisation determined by examining the caecal contents of at least ten birds per group. The prevalence of campylobacters on carcasses from five campylobacter-negative flocks processed just after other negative flocks was low (</=30%). Campylobacters were isolated from 90 to 100% of carcasses from three flocks which were partly colonised, with 5, 5 and 30% of caecal contents positive, and which were processed after fully colonised flocks. All carcasses from the remaining fully colonised flocks were contaminated with campylobacters, and they had significantly (P<0.001) higher numbers per carcass (average of 5.3 log(10) cfu; range: 1.3 to >8.0 log(10) cfu) than carcasses originating from low prevalence flocks (average of 2.3 log(10) cfu; range: <1.1 to 4.1 log(10) cfu). There was a reduction in the numbers of campylobacters on carcasses between plucking and chilling in eight of ten fully colonised flocks. In another eight flocks, a significant (P<0.001) decrease (0.8 log(10) cfu) in the number of campylobacters on carcasses from just before to after chilling was detected. Campylobacter spp. could be isolated from aerosols, particles and droplets in considerable numbers in the hanging-on, defeathering and evisceration areas but not in the chillers. This was the case even when campylobacters were not isolated from the target flock. Campylobacters on carcasses from two partly colonised flocks were either the same subtype, as determined by speciation, Multi-Locus Sequence Typing (MLST) and flaA Restricted Fragment Length Polymorphism (RFLP) typing, as those in the fully colonised flocks processed previously, although not necessarily the most prevalent ones; or were the same subtypes as those found in the caeca of the flock itself. The prevalences of the different campylobacter subtypes found on carcasses from two fully colonised flocks did not closely reflect those found in the caeca. MLST combined with flaA RFLP provided a good method for ascertaining the relatedness of strains isolated from carcasses and caecal contents. This study showed that carcass contamination is related to the within-flock prevalence of campylobacter colonisation, but that contamination from previously processed flocks was also significant, especially on carcasses from low prevalence flocks. Forced dry air cooling of carcasses reduced contamination levels.
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Affiliation(s)
- V M Allen
- School of Clinical Veterinary Science, University of Bristol, Langford, Bristol, BS40 5DU, UK
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Bull SA, Allen VM, Domingue G, Jørgensen F, Frost JA, Ure R, Whyte R, Tinker D, Corry JEL, Gillard-King J, Humphrey TJ. Sources of Campylobacter spp. colonizing housed broiler flocks during rearing. Appl Environ Microbiol 2006; 72:645-52. [PMID: 16391102 PMCID: PMC1352183 DOI: 10.1128/aem.72.1.645-652.2006] [Citation(s) in RCA: 196] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Accepted: 11/02/2005] [Indexed: 11/20/2022] Open
Abstract
The study aimed to identify sources of campylobacter in 10 housed broiler flocks from three United Kingdom poultry companies. Samples from (i) the breeder flocks, which supplied the broilers, (ii) cleaned and disinfected houses prior to chick placement, (iii) the chickens, and (iv) the environments inside and outside the broiler houses during rearing were examined. Samples were collected at frequent intervals and examined for Campylobacter spp. Characterization of the isolates using multilocus sequence typing (MLST), serotyping, phage typing, and flaA restriction fragment length polymorphism typing was performed. Seven flocks became colonized during the growing period. Campylobacter spp. were detected in the environment surrounding the broiler house, prior to as well as during flock colonization, for six of these flocks. On two occasions, isolates detected in a puddle just prior to the birds being placed were indistinguishable from those colonizing the birds. Once flocks were colonized, indistinguishable strains of campylobacter were found in the feed and water and in the air of the broiler house. Campylobacter spp. were also detected in the air up to 30 m downstream of the broiler house, which raises the issue of the role of airborne transmission in the spread of campylobacter. At any time during rearing, broiler flocks were colonized by only one or two types determined by MLST but these changed, with some strains superseding others. In conclusion, the study provided strong evidence for the environment as a source of campylobacters colonizing housed broiler flocks. It also demonstrated colonization by successive campylobacter types determined by MLST during the life of a flock.
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Affiliation(s)
- S A Bull
- Food Microbiology Collaborating Unit, Health Protection Agency (HPA), University of Bristol, Langford, Bristol BS40 5DU, United Kingdom.
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Jørgensen F, Kroese ABA. Ion channel regulation of the dynamical instability of the resting membrane potential in saccular hair cells of the green frog (Rana esculenta). ACTA ACUST UNITED AC 2005; 185:271-90. [PMID: 16266369 DOI: 10.1111/j.1365-201x.2005.01495.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS We investigated the ion channel regulation of the resting membrane potential of hair cells with the aim to determine if the resting membrane potential is poised close to instability and thereby a potential cause of the spontaneous afferent spike activity. METHODS The ionic mechanism and the dynamic properties of the resting membrane potential were examined with the whole-cell patch clamp technique in dissociated saccular hair cells and in a mathematical model including all identified ion channels. RESULTS In hair cells showing I/V curves with a low membrane conductance flanked by large inward and outward rectifying potassium conductances, the inward rectifier (K(IR)), the delayed outward rectifier (K(V)) and the large conductance, calcium-sensitive, voltage-gated potassium channel (BK(Ca)) were all activated at rest. Under current clamp conditions, the outward current through these channels balanced the inward current through mechano-electrical transduction (MET) and Ca2+ channels. In 45% (22/49) of the cells, the membrane potential fluctuated spontaneously between two voltage levels determined by the voltage extent of the low membrane conductance range. These fluctuations were not influenced by blocking the MET channels but could be reversibly stopped by increasing [K+]o or by blocking of K(IR) channels. Blocking the BK(Ca) channels induced regular voltage oscillations. CONCLUSIONS Two intrinsic dynamical instabilities of V(m) are present in hair cells. One of these is observed as spontaneous voltage fluctuations by currents through K(IR), K(V) and h-channels in combination with a steady current through MET channels. The other instability shows as regenerative voltage changes involving Ca2+ and K(V) channels. The BK(Ca) channels prevent the spontaneous voltage fluctuations from activating the regenerative system.
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Affiliation(s)
- F Jørgensen
- IMB, Physiology & Pharmacology, University of Southern Denmark, Odense, Denmark.
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Abstract
The relationship between membrane potential and cation channels in juxtaglomerular (JG) cells is not well understood. Here we review electrophysiological and molecular studies of JG cells demonstrating the presence of large voltage-sensitive, calcium-activated potassium channels (BK(Ca)) of the ZERO splice variant, which is also activated by cAMP. These channels explain the hyperpolarization, which has been observed after stimulation of renin release with cAMP. In addition, there is now evidence that JG cells express functional L-type voltage-dependent calcium channels (Ca(v) 1.2), which in situations with strong depolarization lead to calcium influx and inhibition of renin release. In most in vivo situations the membrane potential is probably protected against depolarization by the BK(Ca) channels.
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Affiliation(s)
- U G Friis
- Physiology and Pharmacology, Institute of Medical Biology, University of Southern Denmark, Odense, Denmark
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Jørgensen F, Hansen OC, Stougaard P. Enzymatic conversion of d-galactose to d-tagatose: heterologous expression and characterisation of a thermostable l-arabinose isomerase from Thermoanaerobacter mathranii. Appl Microbiol Biotechnol 2004; 64:816-22. [PMID: 15168095 DOI: 10.1007/s00253-004-1578-6] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2003] [Revised: 01/14/2004] [Accepted: 01/16/2004] [Indexed: 11/29/2022]
Abstract
The ability to convert D-galactose into D-tagatose was compared among a number of bacterial L-arabinose isomerases ( araA). One of the most efficient enzymes, from the anaerobic thermophilic bacterium Thermoanaerobacter mathranii, was produced heterologously in Escherichia coli and characterised. Amino acid sequence comparisons indicated that this enzyme is only distantly related to the group of previously known araA sequences in which the sequence similarity is evident. The substrate specificity and the Michaelis-Menten constants of the enzyme determined with L-arabinose, D-galactose and D-fucose also indicated that this enzyme is an unusual, versatile L-arabinose isomerase which is able to isomerise structurally related sugars. The enzyme was immobilised and used for production of D-tagatose at 65 degrees C. Starting from a 30% solution of D-galactose, the yield of D-tagatose was 42% and no sugars other than D-tagatose and D-galactose were detected. Direct conversion of lactose to D-tagatose in a single reactor was demonstrated using a thermostable beta-galactosidase together with the thermostable L-arabinose isomerase. The two enzymes were also successfully combined with a commercially available glucose isomerase for conversion of lactose into a sweetening mixture comprising lactose, glucose, galactose, fructose and tagatose.
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Affiliation(s)
- F Jørgensen
- Bioneer A/S, Kogle Allé 2, 2970 Hørsholm, Denmark
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Cogan TA, Jørgensen F, Lappin-Scott HM, Benson CE, Woodward MJ, Humphrey TJ. Flagella and curli fimbriae are important for the growth of Salmonella enterica serovars in hen eggs. Microbiology (Reading) 2004; 150:1063-1071. [PMID: 15073315 DOI: 10.1099/mic.0.26791-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica serovar Enteritidis is unable to multiply in the albumen of fresh eggs and must gain access to the yolk contents in order to multiply to a high level (>106 c.f.u. per ml egg contents). As human Salmonella infections resulting from the consumption of infected eggs more frequently involve serovar Enteritidis phage type (PT) 4 than other serovars or PTs, a number of isolates of various S. enterica serovars were examined for their ability to multiply to a high level in eggs over a period of 8 days storage at 20 °C. Their behaviour was compared to that of a range of defined fimbrial and flagella mutants of S. Enteritidis. Strains that did not express flagella were unable to multiply in eggs, and those deficient for curli fimbriae, including strains of S. Enteritidis PT6, displayed high-level growth in significantly fewer eggs than those able to express curli. Most S. Enteritidis strains multiplied to a high level in between 5 and 10 % of eggs during 8 days storage. One PT4 strain, though, showed high levels of growth in more than 25 % of eggs over this period, significantly higher than the other PTs or the two other isolates of PT4 tested. This ability may be important for the association of PT4 infection with the consumption of eggs.
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Affiliation(s)
- T A Cogan
- Food Microbiology Collaborating Unit, Health Protection Agency, School of Clinical Veterinary Science, University of Bristol, Langford, Bristol BS40 5DT, UK
| | - F Jørgensen
- Food Microbiology Collaborating Unit, Health Protection Agency, School of Clinical Veterinary Science, University of Bristol, Langford, Bristol BS40 5DT, UK
| | - H M Lappin-Scott
- School of Biological and Chemical Sciences, University of Exeter, Exeter, Devon EX5 4PS, UK
| | - C E Benson
- Laboratory of Microbiology, Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania 19348-1692, USA
| | - M J Woodward
- Department of Bacterial Diseases, Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB, UK
| | - T J Humphrey
- Division of Farm Animal Science, School of Clinical Veterinary Science, University of Bristol, Langford, Bristol BS40 5DT, UK
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Varela D, Simon F, Riveros A, Jørgensen F, Stutzin A. The volume-activated chloride current depends on phospholipase C activation and intracellular calcium mobilization. Adv Exp Med Biol 2004; 559:141-145. [PMID: 18727235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- D Varela
- Centro de Estudios Moleculares de la Célula & Instituto de Ciencias Biomédicas, Facultad de Medicina Universidad de Chile, Santiago-6530499, Santiago-Chile.
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Varela D, Simon F, Riveros A, Jørgensen F, Stutzin A. The Volume-Activated Chloride Current Depends on Phospholipase C Activation and Intracellular Calcium Mobilization. Cell Volume and Signaling 2004. [DOI: 10.1007/0-387-23752-6_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Mattick KL, Bailey RA, Jørgensen F, Humphrey TJ. The prevalence and number of Salmonella in sausages and their destruction by frying, grilling or barbecuing. J Appl Microbiol 2002; 93:541-7. [PMID: 12234336 DOI: 10.1046/j.1365-2672.2002.01721.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To determine the prevalence and number of Salmonella and Campylobacter in sausages and to evaluate their destruction during cooking. METHODS AND RESULTS One hundred and sixty-two packs of uncooked economy or catering sausages, comprising 53 packs of frozen and 109 of chilled sausages, were purchased in Devon between March and July 2000. All were tested for the presence of Salmonella and 51 packs of chilled sausages were also examined for the presence of Campylobacter spp. To investigate the heat tolerance of Salmonella enterica serovar Typhimurium DT104 in sausage-meat, chilled, handmade and frozen sausages were inoculated with approx. 1.5 x 10(4) bacterial cells per sausage (approximately 300 cfu g(-1)) and then cooked by frying, grilling or barbecuing. The levels of creatinine kinase, lactate dehydrogenase and alkaline phosphatase in uncooked and cooked sausages were measured to evaluate their potential as indicators of adequate cooking and, therefore, pathogen elimination. Salmonella were detected in 7.5% of frozen and 9.1% of the chilled sausages (8.6% overall) but Campylobacter spp. were not isolated. After cooking, a visual assessment suggested that all of the sausages were thoroughly cooked. Despite this, barbecuing and frying sometimes allowed Salmonella cells to survive and the temperature profiles during cooking indicated that the lethal range was sometimes not reached. The enzyme levels tested were not reliable indicators of the inactivation of bacterial pathogens because Salmonella were sometimes isolated from sausages with low values of all three enzymes. CONCLUSIONS Salmonella spp. are present in a significant proportion of sausages and are not always killed during the cooking process. SIGNIFICANCE AND IMPACT OF THE STUDY These findings have clear implications for public health.
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Affiliation(s)
- K L Mattick
- PHLS Food Microbiology Research Unit, Heavitree, Exeter, UK
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Abstract
Ikaite tufa columns from the Ikka Fjord in south-western Greenland constitute a natural, stable environment at low temperature and with a pH ranging from neutral at the exterior to very alkaline (pH 10.4) at the interior of the column. Phylogenetic analysis of culturable organisms revealed ten different isolates representing three of the major bacterial divisions. Nine of the isolates showed 94-99% similarity to known sequences, whereas one isolate displayed a low degree of similarity (less than 90%) to a Cyclobacterium species. Seven of the isolates were shown to be cold active alkaliphiles, whereas three isolates showed optimal growth at neutral pH. Phylogenetic analysis of DNA isolated directly from the ikaite material demonstrated the presence of a microbial flora more diverse than the culturable isolates. Whereas approximately half of the phylotypes showed 90-99% similarity to known meso- or thermophilic alkaliphiles, the rest of the sequences displayed less than 90% similarity when compared to known 16S rRNA gene sequences in databases. Thus, in the present paper, we demonstrate that ikaite columns that host a specialized macroscopic flora and fauna also contain a unique, cold active, alkaliphilic microflora.
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Affiliation(s)
- Peter Stougaard
- Biotechnological Institute, Department of Enzyme Technology, Kogle Allé 2, DK-2970 Hørsholm, Denmark.
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Jørgensen F, Bailey R, Williams S, Henderson P, Wareing DRA, Bolton FJ, Frost JA, Ward L, Humphrey TJ. Prevalence and numbers of Salmonella and Campylobacter spp. on raw, whole chickens in relation to sampling methods. Int J Food Microbiol 2002; 76:151-64. [PMID: 12038572 DOI: 10.1016/s0168-1605(02)00027-2] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Salmonella and Campylobacter continue to be major foodborne pathogens and raw poultry is considered to be an important source of these bacteria. In this study, the prevalence and numbers of Salmonella and Campylobacter spp. in relation to isolation/sampling methods were determined in 241 whole raw chickens purchased from retail outlets in England during the winters of 1998/1999 (101 chickens) and 1999/2000 (140 chickens). The packaging of the 140 chickens was also examined for the presence of the above pathogens. The prevalence and numbers of enterococci were examined in 21 of the 101 chickens. In total, Salmonella and Campylobacter spp. were present in 25% and 83% of the chickens, respectively. Salmonella were isolated from a sample representing both the inside and outside of the packaging in 19% of the chickens, while the corresponding figure for Campylobacter spp. was 56%. Both of these pathogens were isolated from the outside of the packaging in 6% of the chickens. Salmonella was more frequently isolated from samples containing chicken skin in comparison with those containing carcass-rinse fluid only. Two chickens (0.8%) were positive for Salmonella by direct enumeration methods with contamination levels of log10 3.8 and 4.5 colony forming units (cfu) per carcass, respectively. The most prevalent serotypes were S. Hadar, S. Enteritidis and S. Indiana and two different serotypes were identified in 5/20 salmonella-positive chickens. Resistance to at least one antibiotic was found in 70% of the strains, 46% were multiresistant (resistant to > or = four drugs) and 52% showed a lowered susceptibility to ciprofloxacin. The likelihood of isolating Campylobacter spp. from neck-skin, carcass-rinse or carcass-rinse plus whole skin samples was similar, Campylobacter spp. were found in higher levels in carcass-rinse or carcass-rinse plus whole skin samples than in neck-skin. The log10 cfu of Campylobacter spp. were 2.70-4.99 in 18% of the chickens and 5.00-6.99 in 20%. Campylobacter isolates (425) comprised Campylobacter jejuni (98%) and C. coli (2%) and 98 different sero/phagetypes of these two species were identified. Resistance to at least one antibiotic was found in 73% of the strains and 13% were multiresistant. Thirteen percent of the strains showed lowered susceptibility to ciprofloxacin, while 4.9% were resistant to erythromycin. Vancomycin-resistant enterococci (VRE), able to grow on agar containing 15 mg l(-1) vancomycin (VRE15), were present in 19 chickens. The log10 cfu of VRE15 was 2.90-3.99 in 10 chickens and between 4.00 and 4.99 in two chickens. The data presented here contribute to risk assessment and highlight the need to continue to emphasise the safe handling of raw retail poultry.
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Affiliation(s)
- F Jørgensen
- Food Microbiology Rsearch Unit, Public Health Laboratory, Heavitree, Exeter, UK.
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37
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Slader J, Domingue G, Jørgensen F, McAlpine K, Owen RJ, Bolton FJ, Humphrey TJ. Impact of transport crate reuse and of catching and processing on Campylobacter and Salmonella contamination of broiler chickens. Appl Environ Microbiol 2002; 68:713-9. [PMID: 11823211 PMCID: PMC126660 DOI: 10.1128/aem.68.2.713-719.2002] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2001] [Accepted: 10/16/2001] [Indexed: 11/20/2022] Open
Abstract
The influence of transport, catching, and processing on contamination of broiler chickens with Salmonella and Campylobacter was investigated. Transport crates were reused with high frequency and were often still contaminated with Salmonella and Campylobacter when they arrived at the farm despite the fact that they were washed at the factory, and thus they were a potential route of infection. These organisms contaminated the feathers of previously Campylobacter- and Salmonella-negative birds going to the processing plant and were isolated from processed carcasses, albeit at a low frequency. The Campylobacter types which were the predominant organisms on the live birds when they arrived at the processing plant were not necessarily the types that were most frequently isolated from processed carcasses. This finding may reflect cross-contamination that occurred during processing or differences in the tolerance of the strains to the hostile environments that the bacteria experienced. The process of catching and putting the birds in crates significantly increased the chance of contamination with Campylobacter (P < 0.001).
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Affiliation(s)
- J Slader
- PHLS Food Microbiology Research Unit, Heavitree, Exeter, Church Lane, Devon EX2 5AD, UK
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38
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Jørgensen F, Hansen OC, Stougaard P. High-efficiency synthesis of oligosaccharides with a truncated beta-galactosidase from Bifidobacterium bifidum. Appl Microbiol Biotechnol 2001; 57:647-52. [PMID: 11778873 DOI: 10.1007/s00253-001-0845-z] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An exceptionally large beta-galactosidase, BIF3, with a subunit molecular mass of 188 kDa (1,752 amino acid residues) was recently isolated from Bifidobacterium bifidum DSM20215 [Møller et al. (2001) Appl Environ Microbiol 67:2276-2283]. The BIF3 polypeptide comprises a signal peptide followed by an N-terminal beta-galactosidase region and a C-terminal galactose-binding motif. We have investigated the functional importance of the C-terminal part of the BIF3 sequence by deletion mutagenesis and expression of truncated enzyme variants in Escherichia coli. Deletion of approximately 580 amino acid residues from the C-terminal end converted the enzyme from a normal, hydrolytic beta-galactosidase into a highly efficient, transgalactosylating enzyme. Quantitative analysis showed that the truncated beta-galactosidase utilised approximately 90% of the reacted lactose for the production of galacto-oligosaccharides, while hydrolysis constituted a 10% side reaction. This 9:1 ratio of transgalactosylation to hydrolysis was maintained at lactose concentrations ranging from 10% to 40%, implying that the truncated beta-galactosidase behaved as a "true" transgalactosylase even at low lactose concentrations.
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Affiliation(s)
- F Jørgensen
- Department of Enzyme Technology, Biotechnological Institute, Hørsholm, Denmark
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39
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Mattick KL, Jørgensen F, Legan JD, Lappin-Scott HM, Humphrey TJ. Improving recovery of Salmonella enterica serovar typhimurium DT104 cells injured by heating at different water activity values. J Food Prot 2001; 64:1472-6. [PMID: 11601692 DOI: 10.4315/0362-028x-64.10.1472] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study describes the evaluation of potentially more sensitive methods for the recovery of Salmonella cells injured by heating (54 to 60 degrees C) at different water activity values (0.65 to 0.90, reduced using equal portions of glucose and fructose). These methods included gradual rehydration, the use of diluting media with added solutes or blood, the addition of blood to plating agar, and the use of different incubation temperatures and times. Gradual rehydration of cells that had been challenged at low water activity (0.65 and 0.70) and high temperature markedly improved recovery, measured as a >50% increase in the time to obtain a 3-log10 reduction in cell numbers, compared to dilution into media with a high water activity. Adding sucrose, glycerol, or blood to the diluting media (maximal recovery diluent) did not improve recovery, but a plating agar containing blood recovered approximately 38% more cells than nutrient agar. Prolonged incubation of agar plates allowed recovery of injured Salmonella cells that presumably had extended lag periods, with significantly higher recovery rates after 48 h incubation at 37 degrees C than after 24 h (P = 0.05). This work highlights that by recovering Salmonella using a method specific to the nature of the injury, a better prediction of food safety and the success of food processing can be made.
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Affiliation(s)
- K L Mattick
- PHLS Food Microbiology Research Unit, Heavitree, Exeter, UK.
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40
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Mattick KL, Jørgensen F, Wang P, Pound J, Vandeven MH, Ward LR, Legan JD, Lappin-Scott HM, Humphrey TJ. Effect of challenge temperature and solute type on heat tolerance of Salmonella serovars at low water activity. Appl Environ Microbiol 2001; 67:4128-36. [PMID: 11526015 PMCID: PMC93139 DOI: 10.1128/aem.67.9.4128-4136.2001] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2000] [Accepted: 06/11/2001] [Indexed: 11/20/2022] Open
Abstract
Salmonella spp. are reported to have an increased heat tolerance at low water activity (a(w); measured by relative vapor pressure [rvp]), achieved either by drying or by incorporating solutes. Much of the published data, however, cover only a narrow treatment range and have been analyzed by assuming first-order death kinetics. In this study, the death of Salmonella enterica serovar Typhimurium DT104 when exposed to 54 combinations of temperature (55 to 80 degrees C) and a(w) (rvp 0.65 to 0.90, reduced using glucose-fructose) was investigated. The Weibull model (LogS = -bt(n)) was used to describe microbial inactivation, and surface response models were developed to predict death rates for serovar Typhimurium at all points within the design surface. The models were evaluated with data generated by using six different Salmonella strains in place of serovar Typhimurium DT104 strain 30, two different solutes in place of glucose-fructose to reduce a(w), or six low-a(w) foods artificially contaminated with Salmonella in place of the sugar broths. The data demonstrate that, at temperatures of > or =70 degrees C, Salmonella cells at low a(w) were more heat tolerant than those at a higher a(w) but below 65 degrees C the reverse was true. The same patterns were generated when sucrose (rvp 0.80 compared with 0.90) or NaCl (0.75 compared with 0.90) was used to reduce a(w), but the extent of the protection afforded varied with solute type. The predictions of thermal death rates in the low-a(w) foods were usually fail-safe, but the few exceptions highlight the importance of validating models with specific foods that may have additional factors affecting survival.
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Affiliation(s)
- K L Mattick
- PHLS Food Microbiology Research Unit, Heavitree, Exeter EX2 5AD, United Kingdom.
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41
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Abstract
The effects of extracellular and intracellular pH (pHo and pHi respectively) on the regulatory volume decrease (RVD) response and on the volume-sensitive K+ and Cl- currents (IK,vol and ICl,vol respectively) were studied in Ehrlich ascites tumour cells. Alkaline pHo accelerated and acidic pHo decelerated the RVD response significantly. Intra- and extracellular alkalinisation increased the amplitude of IK,vol whereas acidification had an inhibitory effect. The magnitude of ICl,vol was not affected by changes in pHi or pHo. A significant reduction in the activation time for IK,vol after hypotonic cell swelling was observed upon moderate intracellular alkalinisation (to pHi 7.9). A further increase in pHi to 8.4 resulted in the spontaneous activation of an IK under isotonic conditions which resembled IK,vol with respect to its pharmacological profile and current/voltage (I/V) relation. Noise analysis demonstrated that the increased amplitude of IK,vol at alkaline pH resulted mainly from an increase in the number of channels (N) contributing to the current. The channel open probability, Po, was largely unaffected by pH. The pH dependence and the biophysical and pharmacological properties of IK,vol are similar to those of the cloned tandem pore-domain acid-sensitive K+ (TASK) channels, and in the current study the presence of TASK-1 was confirmed in Ehrlich cells.
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Affiliation(s)
- C Hougaard
- August Krogh Institute, Biochemical Department, Copenhagen , Denmark
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42
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Møller PL, Jørgensen F, Hansen OC, Madsen SM, Stougaard P. Intra- and extracellular beta-galactosidases from Bifidobacterium bifidum and B. infantis: molecular cloning, heterologous expression, and comparative characterization. Appl Environ Microbiol 2001; 67:2276-83. [PMID: 11319112 PMCID: PMC92867 DOI: 10.1128/aem.67.5.2276-2283.2001] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three beta-galactosidase genes from Bifidobacterium bifidum DSM20215 and one beta-galactosidase gene from Bifidobacterium infantis DSM20088 were isolated and characterized. The three B. bifidum beta-galactosidases exhibited a low degree of amino acid sequence similarity to each other and to previously published beta-galactosidases classified as family 2 glycosyl hydrolases. Likewise, the B. infantis beta-galactosidase was distantly related to enzymes classified as family 42 glycosyl hydrolases. One of the enzymes from B. bifidum, termed BIF3, is most probably an extracellular enzyme, since it contained a signal sequence which was cleaved off during heterologous expression of the enzyme in Escherichia coli. Other exceptional features of the BIF3 beta-galactosidase were (i) the monomeric structure of the active enzyme, comprising 1,752 amino acid residues (188 kDa) and (ii) the molecular organization into an N-terminal beta-galactosidase domain and a C-terminal galactose binding domain. The other two B. bifidum beta-galactosidases and the enzyme from B. infantis were multimeric, intracellular enzymes with molecular masses similar to typical family 2 and family 42 glycosyl hydrolases, respectively. Despite the differences in size, molecular composition, and amino acid sequence, all four beta-galactosidases were highly specific for hydrolysis of beta-D-galactosidic linkages, and all four enzymes were able to transgalactosylate with lactose as a substrate.
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Affiliation(s)
- P L Møller
- Biotechnological Institute, Kogle Allé 2, DK-2970 Hørsholm, Denmark
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43
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La Ragione RM, Coles KE, Jørgensen F, Humphrey TJ, Woodward MJ. Virulence in the chick model and stress tolerance of Salmonella enterica serovar Orion var. 15+. Int J Med Microbiol 2001; 290:707-18. [PMID: 11310449 DOI: 10.1016/s1438-4221(01)80011-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Three Salmonella enterica serovar Orion var. 15+ isolates of distinct provenance were tested for survival in various stress assays. All were less able to survive desiccation than a virulent S. Enteritidis strain, with levels of survival similar to a rpoS mutant of the S. Enteritidis strain, whereas one isolate (F3720) was significantly more acid tolerant. The S. Orion var. 15+ isolates were motile by flagellae and elaborated type-1 and curli-like fimbriae; surface organelles that are considered virulence determinants in Salmonella pathogenesis. Each adhered and invaded HEp-2 tissue culture cells with similar proficiency to the S. Enteritidis control but were significantly less virulent than S. Enteritidis in the one-day-old and seven-day-old chick model. Given an oral dose of 1 x 10(3) cfu to one-day-old chicken, S. Orion var. 15+ isolates colonised 25% of liver and spleens examined at 24 h whereas S. Enteritidis colonised 100% of organs by the same with the same dose. Given an oral dose of 1 x 10(7) cfu at seven-day old, S. Orion var. 15+ failed to colonise livers and spleens in any bird examined at 24 h whereas S. Enteritidis colonised 50% of organs by the same with the same dose. Based on the number of internal organs colonised, one of the three S. Orion var. 15+ isolates tested (strain F3720) was significantly more invasive than the other two (B1 and B7). Also, strain F3720 was shed less than either B1 or B7 supporting the concept that there may be an inverse relationship between the ability to colonise deep tissues and to persist in the gut. These data are discussed in the light that S. Orion var. 15+ is associated with sporadic outbreaks of human infection rather than epidemics.
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Affiliation(s)
- R M La Ragione
- Department of Bacterial Diseases, Addlestone, Surrey, UK
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44
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Jørgensen F, Kronborg K. [Survey of vaccination complications]. Ugeskr Laeger 2001; 163:1294. [PMID: 11258257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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Niemeyer M, Hougaard C, Hoffmann E, Jørgensen F, Stutzin A, Sepúlveda F. K+ conductance activated by osmotic cell swelling or by leukotriene D4 in ehrlich cells. Comp Biochem Physiol A Mol Integr Physiol 2000. [DOI: 10.1016/s1095-6433(00)80268-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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46
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Mattick KL, Jørgensen F, Legan JD, Cole MB, Porter J, Lappin-Scott HM, Humphrey TJ. Survival and filamentation of Salmonella enterica serovar enteritidis PT4 and Salmonella enterica serovar typhimurium DT104 at low water activity. Appl Environ Microbiol 2000; 66:1274-9. [PMID: 10742199 PMCID: PMC91980 DOI: 10.1128/aem.66.4.1274-1279.2000] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/1999] [Accepted: 01/03/2000] [Indexed: 11/20/2022] Open
Abstract
In this study we investigated the long-term survival of and morphological changes in Salmonella strains at low water activity (a(w)). Salmonella enterica serovar Enteritidis PT4 and Salmonella enterica serovar Typhimurium DT104 survived at low a(w) for long periods, but minimum humectant concentrations of 8% NaCl (a(w), 0. 95), 96% sucrose (a(w), 0.94), and 32% glycerol (a(w), 0.92) were bactericidal under most conditions. Salmonella rpoS mutants were usually more sensitive to bactericidal levels of NaCl, sucrose, and glycerol. At a lethal a(w), incubation at 37 degrees C resulted in more rapid loss of viability than incubation at 21 degrees C. At a(w) values of 0.93 to 0.98, strains of S. enterica serovar Enteritidis and S. enterica serovar Typhimurium formed filaments, some of which were at least 200 microm long. Filamentation was independent of rpoS expression. When the preparations were returned to high-a(w) conditions, the filaments formed septa, and division was complete within approximately 2 to 3 h. The variable survival of Salmonella strains at low a(w) highlights the importance of strain choice when researchers produce modelling data to simulate worst-case scenarios or conduct risk assessments based on laboratory data. The continued increase in Salmonella biomass at low a(w) (without a concomitant increase in microbial count) would not have been detected by traditional microbiological enumeration tests if the tests had been performed immediately after low-a(w) storage. If Salmonella strains form filaments in food products that have low a(w) values (0.92 to 0.98), there are significant implications for public health and for designing methods for microbiological monitoring.
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Affiliation(s)
- K L Mattick
- PHLS Food Microbiology Research Unit, Heavitree, Exeter EX2 5AD, United Kingdom.
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47
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Abstract
The aim of the paper is to develop a model of drivers' behaviour particularly designed to analyse the safety and total driving cost implications of warning sign installations. One special feature of the model is that it makes a clear distinction between drivers' perceived risk values at certain speeds and their respective objective values. When focusing on a certain stretch of road only, the paper concludes that warning signs will increase safety and probably reduce total objective driving costs; that is the sum of time costs and objective expected accident costs. Since drivers' speed will reduce implying higher time costs per distance, the reduction in total objective driving costs will be lower than the reductions in accident costs. The analysis is then extended to comprise the whole road system and using warning signs prior to curves as an example. Besides the driving conditions in different curves, the analysis shows that the optimal number of signs is dependent on the road authorities' objectives for road traffic and on how drivers form their risk perceptions. Generally speaking, simulations indicate that the safety and economic benefits of warning sign installation are not very high. When considering the whole road system, warning signs seem, however, to have a greater positive impact on total driving costs than on accident costs.
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48
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Thoreson AC, Borre M, Andersen LP, Jørgensen F, Kiilerich S, Scheibel J, Rath J, Krogfelt KA. Helicobacter pylori detection in human biopsies: a competitive PCR assay with internal control reveals false results. FEMS Immunol Med Microbiol 1999; 24:201-8. [PMID: 10378421 DOI: 10.1111/j.1574-695x.1999.tb01283.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A polymerase chain reaction assay (PCR) for the diagnosis of Helicobacter pylori in human gastric biopsies was developed. To prevent false-negative results while performing PCR on human tissues, an internal control is necessary. Primer set ACT1-ACT2 which specifically amplifies a 542-bp fragment of the 16S rRNA gene of H. pylori was used. dUTP and hot-start were used to prevent false-positives from carryover of previous products and avoid non-specific extension products. A competitive internal control DNA fragment was constructed to detect the presence of inhibitors. Biopsies from 101 unselected patients with gastric symptoms were tested. PCR results were compared with results from microscopy of histological sections and conventional culturing for H. pylori. Forty-two percent of the biopsies were found to contain compounds inhibiting the PCR. The addition of the internal control assures the performance of the PCR assay and is an important quality control parameter.
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Affiliation(s)
- A C Thoreson
- Department of Gastrointestinal Infections, Statens Serum Institut, Copenhagen, Denmark
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49
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Humphrey TJ, Williams A, McAlpine K, Jørgensen F, O'Byrne C. Pathogenicity in isolates of Salmonella enterica serotype Enteritidis PT4 which differ in RpoS expression: effects of growth phase and low temperature. Epidemiol Infect 1998; 121:295-301. [PMID: 9825780 PMCID: PMC2809526 DOI: 10.1017/s0950268898001162] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Experiments with 2 wild type isolates of Salmonella enterica serotype Enteritidis PT4, which differed in RpoS expression, tolerance to certain hostile environments and pathogenicity, found that changes in in vitro acid, heat, or peroxide tolerance had no effect on the ability of the isolates to multiply in the spleens of C57/BL7/J mice infected orally. Thus, with the pathogenic RpoS-positive isolate, the infectivity of log phase chilled cells, which are profoundly acid-sensitive, was the same as that of non-chilled stationary phase cells which are acid-tolerant. Similarity the infectivity of the RpoS-negative, sensitive isolate, was not enhanced by increases in any tolerance. The ability to survive on surfaces, like infectivity, was also largely unaffected by either growth phase or cold exposure. These two attributes may thus be related and, given that the pathogenic PT4 isolate is capable of prolonged survival and the nonpathogenic isolate survives poorly, survival could serve as a potential marker of pathogenicity. Although the pathogenicity of the two isolates was very different, they showed an almost identical increase in acid tolerance following culture at pH 4.0 for up to 60 min.
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Affiliation(s)
- T J Humphrey
- PHLS Food Microbiology Research Unit, Exeter, Devon, UK
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Winson MK, Swift S, Fish L, Throup JP, Jørgensen F, Chhabra SR, Bycroft BW, Williams P, Stewart GS. Construction and analysis of luxCDABE-based plasmid sensors for investigating N-acyl homoserine lactone-mediated quorum sensing. FEMS Microbiol Lett 1998; 163:185-92. [PMID: 9673021 DOI: 10.1111/j.1574-6968.1998.tb13044.x] [Citation(s) in RCA: 423] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Plasmid reporter vectors have been constructed which respond to activation of LuxR and its homologues LasR and RhlR (VsmR) by N-acyl homoserine lactones (AHLs). The expression of luxCDABE from transcriptional fusions to PluxI, PlasI and PrhlI respectively, occurs in the presence of activating AHLs. A profile of structure/activity relationships is seen where the natural ligand is most potent. The characterisation of individual LuxR homologue/AHL combinations allows a comprehensive evaluation of quorum sensing signals from a test organism.
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Affiliation(s)
- M K Winson
- Food Microbiology Section, School of Biological Sciences, University of Nottingham, Leics, UK
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