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Leigh WJ, Zadoks RN, Costa JZ, Jaglarz A, Thompson KD. Development and evaluation of a quantitative polymerase chain reaction for aquatic Streptococcus agalactiae based on the groEL gene. J Appl Microbiol 2020; 129:63-74. [PMID: 31851413 DOI: 10.1111/jam.14556] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 11/23/2019] [Accepted: 12/08/2019] [Indexed: 01/19/2023]
Abstract
AIMS The aim of this study was to develop a TaqMan quantitative polymerase chain reaction (qPCR), based on the Streptococcus agalactiae groEL gene, to specifically quantify levels of bacteria within samples derived from aquatic sources, particularly aquaculture. Enumeration of bacteria by qPCR was compared with culture-based methods. METHODS AND RESULTS The qPCR was sensitive to 33 isolates of S. agalactiae, representing 11 clonal complexes from aquatic, bovine and human hosts. The specificity of the assay was 92·5% at a threshold Cq value of 35. No cross-reaction with Streptococcus iniae was noted and of the 22 comparator species screened to test assay specificity, Streptococcus porcinus had a Cq value of 33·7 S, while Streptococcus gallolyticus subsp. macedonicus and Streptococcus ictaluri had one replicate value above the Cq threshold of 35 (34·5 and 34·4 respectively), while only S. agalactiae were detected with a Cq value of 30. The limit of detection of the assay was 1·7 copies per µl at Cq 35. Discrepancies between molecular and culture-based methods of enumeration were noted. CONCLUSIONS The qPCR was able to detect a diverse range of S. agalactiae isolates from different clonal complexes (CCs) and could distinguish between S. agalactiae and closely related species, notably S. iniae. The results suggest that a Cq 30 would be a very meaningful cut-off, allowing the detection of infected fish while ruling out all false positives. SIGNIFICANCE AND IMPACT OF THE STUDY This rapid and sensitive qPCR assay is useful to quantify DNA copy number in the laboratory and could prove useful for detecting low levels of S. agalactiae in aquaculture systems, including Oreochromis niloticus culture.
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Affiliation(s)
- W J Leigh
- Moredun Research Institute, Pentlands Science Park, Penicuik, UK.,Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - R N Zadoks
- Moredun Research Institute, Pentlands Science Park, Penicuik, UK.,Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - J Z Costa
- Moredun Research Institute, Pentlands Science Park, Penicuik, UK
| | - A Jaglarz
- Moredun Research Institute, Pentlands Science Park, Penicuik, UK
| | - K D Thompson
- Moredun Research Institute, Pentlands Science Park, Penicuik, UK
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Gu G, Ottesen A, Bolten S, Wang L, Luo Y, Rideout S, Lyu S, Nou X. Impact of routine sanitation on the microbiomes in a fresh produce processing facility. Int J Food Microbiol 2019; 294:31-41. [DOI: 10.1016/j.ijfoodmicro.2019.02.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 12/18/2022]
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3
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Qiao M, Liu Q, Yong Y, Pardo Y, Worobo R, Liu Z, Jiang S, Ma M. Scalable and Rechargeable Antimicrobial Coating for Food Safety Applications. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:11441-11450. [PMID: 30296071 DOI: 10.1021/acs.jafc.8b03864] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Environmental surfaces are common avenues for microbial contamination and transmission in food-processing establishments. We recently synthesized a polymer that combines both N-halamine and dopamine functional groups to form a novel antimicrobial coating material. A series of chemical (titration) and biological ("sandwich" and anti-inhabitation) tests were designed to prove the stability and functionality of as-developed coating material. Halamine-dopamine polymer-coated stainless-steel surface inactivated 6 log10 CFU of both Staphylococcus aureus and Escherichia coli O157:H7 under experimental detection limit within 10 min of contact time. After three "discharge-recharge" cycles, the surface maintained the same antimicrobial effectiveness; 60% of the surface chlorine remained after 10 "discharge-recharge" cycles. In addition, the coating thickness and chlorine content could be further tuned through adjusting the formulation of the coating. We also demonstrated that this coating material could be easily scaled up to apply on real food equipment parts through a spray-coating method. Thus our polymer material has great potential to produce a high-performance, low-cost, and easy-to-apply coating on food-associated environmental surfaces for food safety preventive-control applications.
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Affiliation(s)
- Mingyu Qiao
- Department of Biological and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
| | - Qingsheng Liu
- Department of Biological and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
| | - You Yong
- Department of Biological and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
- Department of Chemical Engineering , Tsinghua University , Beijing 100084 , China
| | - Yudi Pardo
- Department of Biological and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
| | - Randy Worobo
- Department of Food Science , Cornell University , Ithaca , New York 14853 , United States
| | - Zheng Liu
- Department of Chemical Engineering , Tsinghua University , Beijing 100084 , China
| | - Shan Jiang
- Department of Materials Science and Engineering , Iowa State University of Science and Technology , Ames , Iowa 50011 , United States
| | - Minglin Ma
- Department of Biological and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
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Ceylan E, McMahon W, Garren DM. Thermal Inactivation of Listeria monocytogenes and Salmonella during Water and Steam Blanching of Vegetables. J Food Prot 2017; 80:1550-1556. [PMID: 28805458 DOI: 10.4315/0362-028x.jfp-16-517] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Thermal inactivation of Listeria monocytogenes and Salmonella was evaluated on peas, spinach, broccoli, potatoes, and carrots that were treated with hot water and steam. One gram-positive bacterium, L. monocytogenes, and one gram-negative bacterium, Salmonella, were selected as pertinent human pathogens for evaluation. Samples were inoculated with a composite of five strains each of L. monocytogenes and Salmonella to achieve approximately 108 to 109 CFU/g. Inoculated samples were treated with hot water at 85 and 87.8°C and with steam at 85 and 96.7°C for up to 3.5 min. A greater than 5-log reduction of L. monocytogenes and Salmonella was achieved on all products within 0.5 min by hot water blanching at 85 and 87.8°C. Steam blanching at 85°C reduced Salmonella populations by greater than 5 log on spinach and peas within 2 min and on carrots and broccoli within 3.5 min. Populations of Salmonella were reduced by more than 5 log within 1 min on carrot, spinach, and broccoli and within 2 min on peas by steam blanching at 96.7°C. Steam blanching at 85°C reduced L. monocytogenes populations by more than 5 log on carrots and spinach within 2 min and on broccoli and peas within 3.5 min. L. monocytogenes populations were reduced more than 5 log within 1 min on carrot, spinach, peas and broccoli by steam blanching at 96.7°C. Longer treatment times and higher temperatures were required for steam-blanched samples than for samples blanched with hot water. Results suggest that hot water and steam blanching practices commonly used by the frozen vegetable industry will achieve the desired 5-log lethality of L. monocytogenes and Salmonella and will enhance microbiological safety prior to freezing.
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Affiliation(s)
- Erdogan Ceylan
- 1 Mérieux NutriSciences, 3600 Eagle Nest Drive, Crete, Illinois 60417; and
| | - Wendy McMahon
- 1 Mérieux NutriSciences, 3600 Eagle Nest Drive, Crete, Illinois 60417; and
| | - Donna M Garren
- 2 American Frozen Food Institute, 2000 Corporate Ridge, Suite 1000, McLean, Virginia 22102, USA
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Tan MSF, Rahman S, Dykes GA. Sonication reduces the attachment of Salmonella Typhimurium ATCC 14028 cells to bacterial cellulose-based plant cell wall models and cut plant material. Food Microbiol 2017; 62:62-67. [PMID: 27889167 DOI: 10.1016/j.fm.2016.10.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 06/30/2016] [Accepted: 10/02/2016] [Indexed: 11/19/2022]
Abstract
This study investigated the removal of bacterial surface structures, particularly flagella, using sonication, and examined its effect on the attachment of Salmonella Typhimurium ATCC 14028 cells to plant cell walls. S. Typhimurium ATCC 14028 cells were subjected to sonication at 20 kHz to remove surface structures without affecting cell viability. Effective removal of flagella was determined by staining flagella of sonicated cells with Ryu's stain and enumerating the flagella remaining by direct microscopic counting. The attachment of sonicated S. Typhimurium cells to bacterial cellulose-based plant cell wall models and cut plant material (potato, apple, lettuce) was then evaluated. Varying concentrations of pectin and/or xyloglucan were used to produce a range of bacterial cellulose-based plant cell wall models. As compared to the non-sonicated controls, sonicated S. Typhimurium cells attached in significantly lower numbers (between 0.5 and 1.0 log CFU/cm2) to all surfaces except to the bacterial cellulose-only composite without pectin and xyloglucan. Since attachment of S. Typhimurium to the bacterial cellulose-only composite was not affected by sonication, this suggests that bacterial surface structures, particularly flagella, could have specific interactions with pectin and xyloglucan. This study indicates that sonication may have potential applications for reducing Salmonella attachment during the processing of fresh produce.
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Affiliation(s)
- Michelle S F Tan
- School of Science, Monash University, Jalan Lagoon Selatan, Bandar Sunway, 46150 Selangor, Malaysia
| | - Sadequr Rahman
- School of Science, Monash University, Jalan Lagoon Selatan, Bandar Sunway, 46150 Selangor, Malaysia
| | - Gary A Dykes
- School of Public Health, Curtin University, Perth, 6845 Western Australia, Australia.
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Castro-Ibáñez I, López-Gálvez F, Gil MI, Allende A. Identification of sampling points suitable for the detection of microbial contamination in fresh-cut processing lines. Food Control 2016. [DOI: 10.1016/j.foodcont.2015.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Feng Y, Li G, Lv X, Xu Y, Wu Q, Shi C, Li Q, Yang B, Wang X, Xi M, Xia X. Prevalence, Distribution, and Diversity ofEscherichia coli,Staphylococcus aureus, andSalmonellain Kiwifruit Orchards and Processing Plants. Foodborne Pathog Dis 2014; 11:782-90. [DOI: 10.1089/fpd.2014.1759] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Affiliation(s)
- Yuqing Feng
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
| | - Guanghui Li
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
| | - Xiaoying Lv
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
| | - Yunfeng Xu
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
| | - Qian Wu
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
| | - Chao Shi
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
| | - Qiong Li
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
| | - Baowei Yang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
| | - Xin Wang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
| | - Meili Xi
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
| | - Xiaodong Xia
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
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Tango CN, Choi NJ, Chung MS, Oh DH. Bacteriological quality of vegetables from organic and conventional production in different areas of Korea. J Food Prot 2014; 77:1411-7. [PMID: 25198606 DOI: 10.4315/0362-028x.jfp-13-514] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Foods grown in organic production systems have been described as representing an increased risk to public health compared with foods from conventional production. Leafy vegetables (spinach, romaine lettuce, and green sesame leaves) grown in organic and conventional systems were collected from various areas in Korea and examined using standard culture methods to compare the microbiological quality of the produce grown in the two agricultural systems. The 354 samples of these leafy vegetables were analyzed for levels of indicator bacteria (aerobic bacteria, coliforms, and Escherichia coli) and the prevalence of the pathogens Staphylococcus aureus, E. coli O157:H7, Listeria monocytogenes, Bacillus cereus, and Salmonella. Aerobic bacteria and coliforms were detected in all vegetable types, but nonpathogenic E. coli was below the limit of detection in all samples. B. cereus was the most prevalent pathogen, found on 7 (11.1%) of the 63 organic spinach samples. The prevalence of S. aureus was highest in organic sesame leaves; it was found on 5 (8.0%) of the 63 samples. The prevalence of L. monocytogenes was highest on organic romaine lettuce and spinach; it was found in 4 (6.4%) of 63 samples of each type of vegetable. E. coli O157:H7 found on only 1 (1.58%) of 55 conventional spinach samples. These results suggest that farming type at most only slightly affects the hygienic quality of leafy vegetables, and no effect was found for sample collection area. Salmonella was not isolated from any of the conventional or organic leafy vegetables. These results do not support the hypothesis that organic produce poses a substantially greater risk of pathogen contamination than does conventional produce.
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Affiliation(s)
- Charles Nkufi Tango
- Department of Food Science and Biotechnology, Kangwon National University, Chuncheon, Gangwon 200-701, Republic of Korea
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11
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Kaminski CN, Davidson GR, Ryser ET. Listeria monocytogenes transfer during mechanical dicing of celery and growth during subsequent storage. J Food Prot 2014; 77:765-71. [PMID: 24780331 DOI: 10.4315/0362-028x.jfp-13-382] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The transfer of Listeria monocytogenes to previously uncontaminated product during mechanical dicing of celery and its growth during storage at various temperatures were evaluated. In each of three trials, 275 g of retail celery stalks was immersed in an aqueous five-strain L. monocytogenes cocktail to obtain an average of 5.6 log CFU/g and then was diced using a hand-operated dicer, followed by sequential dicing of 15 identical 250-g batches of uninoculated celery using the same dicer. Each batch of diced celery was examined for numbers of Listeria initially and after 3 and 7 days of storage at 4, 7, and 10 °C. Additionally, the percentage by weight of inoculated product transferred to each of 15 batches of uninoculated celery was determined using inoculated red stems of Swiss chard as a surrogate. Listeria transfer to diced celery was also assessed after removing the Swiss chard. L. monocytogenes transferred from the initial batch of inoculated celery to all 15 batches of uninoculated celery during dicing, with populations decreasing from 5.2 to 2.0 log CFU/g on the day of processing. At 10 °C, Listeria reached an average population of 3.4 log CFU/g in all batches of uninoculated celery. Fewer batches of celery showed significant growth during storage at 4 and 7 °C (P < 0.05). Swiss chard pieces were recovered from all 15 batches of celery, with similar amounts seen in batches 2 to 15 (P > 0.05). L. monocytogenes was also recovered from each batch of uninoculated celery after the removal of Swiss chard, with populations decreasing from 4.7 to 1.7 log CFU/g. Storing the diced celery at 10 °C yielded a L. monocytogenes generation time of 0.87 days, with no significant growth observed during storage at 4 or 7 °C. Consequently, mitigation strategies during dicing and proper refrigeration are essential to minimizing potential health risks associated with diced celery.
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Affiliation(s)
- Chelsea N Kaminski
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824, USA; Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Gordon R Davidson
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824, USA; Department of Food Science and Technology, University of California, Davis, Davis, CA 95616, USA
| | - Elliot T Ryser
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824, USA.
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Mohapatra BR, La Duc MT. Detecting the dormant: a review of recent advances in molecular techniques for assessing the viability of bacterial endospores. Appl Microbiol Biotechnol 2013; 97:7963-75. [PMID: 23912118 DOI: 10.1007/s00253-013-5115-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 07/05/2013] [Accepted: 07/09/2013] [Indexed: 10/26/2022]
Abstract
Due to their contribution to gastrointestinal and pulmonary disease, their ability to produce various deadly exotoxins, and their resistance to extreme temperature, pressure, radiation, and common chemical disinfecting agents, bacterial endospores of the Firmicutes phylum are a major concern for public and environmental health. In addition, the hardy and dormant nature of endospores renders them a particularly significant threat to the integrity of robotic extraterrestrial life-detection investigations. To prevent the contamination of critical surfaces with seemingly ubiquitous bacterial endospores, clean rooms maintained at exceedingly stringent cleanliness levels (i.e., fewer than 100,000 airborne particles per ft(3)) are used for surgical procedures, pharmaceutical processing and packaging, and fabrication and assembly of medical devices and spacecraft components. However, numerous spore-forming bacterial species have been reported to withstand typical clean room bioreduction strategies (e.g., UV lights, maintained humidity, paucity of available nutrients), which highlights the need for rapid and reliable molecular methods for detecting, enumerating, and monitoring the incidence of viable endospores. Robust means of evaluating and tracking spore burden not only provide much needed information pertaining to endospore ecophysiology in different environmental niches but also empower decontamination and bioreduction strategies aimed at sustaining the reliability and integrity of clean room environments. An overview of recent molecular advances in detecting and enumerating viable endospores, as well as the expanding phylogenetic diversity of pathogenic and clean room-associated spore-forming bacteria, ensues.
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Affiliation(s)
- Bidyut R Mohapatra
- Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA.
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Liu NT, Lefcourt AM, Nou X, Shelton DR, Zhang G, Lo YM. Native microflora in fresh-cut produce processing plants and their potentials for biofilm formation. J Food Prot 2013; 76:827-32. [PMID: 23643124 DOI: 10.4315/0362-028x.jfp-12-433] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Representative food contact and nonfood contact surfaces in two mid-sized, fresh-cut processing facilities were sampled for microbiological analyses after routine daily sanitization. Mesophilic and psychrotrophic bacteria on the sampled surfaces were isolated by plating on nonselective bacterial media. Alternatively, bacteria were isolated after an incubation period that allowed the formation of heterogeneous biofilms on stainless steel beads. Of over 1,000 tested isolates, most were capable of forming biofilms, with approximately 30 % being strong or moderate biofilm formers. Selected isolates (117) were subjected to species identification by using the Biolog Gen III microbial identification system. They distributed among 23 genera, which included soil bacteria, plant-related bacteria, coliforms, and opportunistic plant- or human-pathogenic bacteria. The most commonly identified bacteria species were Pseudomonas fluorescens, Rahnella aquatilis, and Ralstonia insidiosa. The high prevalence of R. insidiosa, a strong biofilm former, and P. fluorescens, a moderate biofilm former, suggests that they were established residents in the sampled plants. These results suggest that native microflora capable of forming biofilms are widely distributed in fresh-produce processing environments.
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Affiliation(s)
- Nancy T Liu
- Department of Nutrition and Food Science, University of Maryland, College Park, Maryland 20740, USA
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Champagne VK, Helfritch DJ. A demonstration of the antimicrobial effectiveness of various copper surfaces. J Biol Eng 2013; 7:8. [PMID: 23537176 PMCID: PMC3621704 DOI: 10.1186/1754-1611-7-8] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 03/15/2013] [Indexed: 11/22/2022] Open
Abstract
Background Bacterial contamination on touch surfaces results in increased risk of infection. In the last few decades, work has been done on the antimicrobial properties of copper and its alloys against a range of micro-organisms threatening public health in food processing, healthcare and air conditioning applications; however, an optimum copper method of surface deposition and mass structure has not been identified. Results A proof-of-concept study of the disinfection effectiveness of three copper surfaces was performed. The surfaces were produced by the deposition of copper using three methods of thermal spray, namely, plasma spray, wire arc spray and cold spray The surfaces were then inoculated with meticillin-resistant Staphylococcus aureus (MRSA). After a two hour exposure to the surfaces, the surviving MRSA were assayed and the results compared. The differences in the copper depositions produced by the three thermal spray methods were examined in order to explain the mechanism that causes the observed differences in MRSA killing efficiencies. The cold spray deposition method was significantly more effective than the other methods. It was determined that work hardening caused by the high velocity particle impacts created by the cold spray technique results in a copper microstructure that enhances ionic diffusion, and copper ions are principally responsible for antimicrobial activity. Conclusions This test showed significant microbiologic differences between coatings produced by different spray techniques and demonstrates the importance of the copper application technique. The cold spray technique shows superior anti-microbial effectiveness caused by the high impact velocity imparted to the sprayed particles which results in high dislocation density and high ionic diffusivity.
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Buchholz AL, Davidson GR, Marks BP, Todd ECD, Ryser ET. Transfer of Escherichia coli O157:H7 from equipment surfaces to fresh-cut leafy greens during processing in a model pilot-plant production line with sanitizer-free water. J Food Prot 2012; 75:1920-9. [PMID: 23127700 DOI: 10.4315/0362-028x.jfp-11-558] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Escherichia coli O157:H7 contamination of fresh-cut leafy greens has become a public health concern as a result of several large outbreaks. The goal of this study was to generate baseline data for E. coli O157:H7 transfer from product-inoculated equipment surfaces to uninoculated lettuce during pilot-scale processing without a sanitizer. Uninoculated cored heads of iceberg and romaine lettuce (22.7 kg) were processed using a commercial shredder, step conveyor, 3.3-m flume tank with sanitizer-free tap water, shaker table, and centrifugal dryer, followed by 22.7 kg of product that had been dip inoculated to contain ∼10(6), 10(4), or 10(2) CFU/g of a four-strain avirulent, green fluorescent protein-labeled, ampicillin-resistant E. coli O157:H7 cocktail. After draining the flume tank and refilling the holding tank with tap water, 90.8 kg of uninoculated product was similarly processed and collected in ∼5-kg aliquots. After processing, 42 equipment surface samples and 46 iceberg or 36 romaine lettuce samples (25 g each) from the collection baskets were quantitatively examined for E. coli O157:H7 by direct plating or membrane filtration using tryptic soy agar containing 0.6% yeast extract and 100 ppm of ampicillin. Initially, the greatest E. coli O157:H7 transfer was seen from inoculated lettuce to the shredder and conveyor belt, with all equipment surface populations decreasing 90 to 99% after processing 90.8 kg of uncontaminated product. After processing lettuce containing 10(6) or 10(4) E. coli O157:H7 CFU/g followed by uninoculated lettuce, E. coli O157:H7 was quantifiable throughout the entire 90.8 kg of product. At an inoculation level of 10(2) CFU/g, E. coli O157:H7 was consistently detected in the first 21.2 kg of previously uninoculated lettuce at 2 to 3 log CFU/100 g and transferred to 78 kg of product. These baseline E. coli O157:H7 transfer results will help determine the degree of sanitizer efficacy required to better ensure the safety of fresh-cut leafy greens.
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Affiliation(s)
- Annemarie L Buchholz
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA
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Buchholz AL, Davidson GR, Marks BP, Todd ECD, Ryser ET. Quantitative transfer of Escherichia coli O157:H7 to equipment during small-scale production of fresh-cut leafy greens. J Food Prot 2012; 75:1184-97. [PMID: 22980000 DOI: 10.4315/0362-028x.jfp-11-489] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Postharvest contamination and subsequent spread of Escherichia coli O157:H7 can occur during shredding, conveying, fluming, and dewatering of fresh-cut leafy greens. This study quantified E. coli O157:H7 transfer from leafy greens to equipment surfaces during simulated small-scale commercial processing. Three to five batches (22.7 kg) of baby spinach, iceberg lettuce, and romaine lettuce were dip inoculated with a four-strain cocktail of avirulent, green fluorescent protein-labeled, ampicillinresistant E. coli O157:H7 to contain ∼10(6), 10(4), and 10(2) CFU/g, and then were processed after 1 h of draining at ∼23°C or 24 h of storage at 4°C. Lettuce was shredded using an Urschel TransSlicer at two different blade and belt speeds to obtain normal (5 by 5 cm) and more finely shredded (0.5 by 5 cm) lettuce. Thereafter, the lettuce was step conveyed to a flume tank and was washed and then dried using a shaker table and centrifugal dryer. Product (25-g) and water (40-ml) samples were collected at various points during processing. After processing, product contact surfaces (100 cm(2)) on the shredder (n = 14), conveyer (n = 8), flume tank (n = 11), shaker table (n = 9), and centrifugal dryer (n = 8) were sampled using one-ply composite tissues. Sample homogenates diluted in phosphate or neutralizing buffer were plated, with or without prior 0.45- m m membrane filtration, on Trypticase soy agar containing 0.6% yeast extract supplemented with 100 ppm of ampicillin to quantify green fluorescent protein-labeled E. coli O157:H7 under UV light. During leafy green processing, ∼90% of the E. coli O157:H7 inoculum transferred to the wash water. After processing, E. coli O157:H7 populations were highest on the conveyor and shredder (P<0.05), followed by the centrifugal dryer, flume tank, and shaker table, with ∼29% of the remaining product inoculum lost during centrifugal drying. Overall, less (P<0.05) of the inoculum remained on the product after centrifugally drying iceberg lettuce that was held for 1 h (8.13%) as opposed to 24 h (42.18%) before processing, with shred size not affecting the rate of E. coli O157:H7 transfer.
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Affiliation(s)
- Annemarie L Buchholz
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA
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Sudershan RV, Naveen Kumar R, Kashinath L, Bhaskar V, Polasa K. Microbiological hazard identification and exposure assessment of poultry products sold in various localities of Hyderabad, India. ScientificWorldJournal 2012; 2012:736040. [PMID: 22593705 PMCID: PMC3347783 DOI: 10.1100/2012/736040] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 01/05/2012] [Indexed: 11/17/2022] Open
Abstract
A study was carried out to identify microbiological hazards and assess their exposure associated with consumption of poultry based street food served in different localities of Hyderabad. The study indicated that chicken 65, chicken fried rice, chicken noodles, chicken Manchuria and chilly chicken are the most common recipes. A process flow diagram was developed to identify critical control points in the food item. After analysis of the samples at each level of preparation, it was observed that rice and noodles were kept at room temperature for about 5-6 hrs which was a critical control point. A total of 376 samples including chicken fried rice, chicken noodles, boiled noodles and boiled rice were collected from circle 1, 2, 3, 4, 5, 6, and 7 of Greater Hyderabad municipal corporation (GHMC) and analyzed for microbiological examination. The most prevalent pathogenic bacteria isolated were S. aureus (3.4 log 10 cfu/g) and B. cereus (3.4 log 10 cfu/g). Salmonella spp. was present in salads (3.2 log 10 cfu/g) and hand washings of the food handler (3.5 log 10 cfu/g). Salmonella contamination was found in salads served along with chicken fried rice and chicken noodles than in the food.
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Affiliation(s)
- Rao V Sudershan
- Food and Drug Toxicology Research Centre, National Institute of Nutrition (Indian Council of Medical Research), Jamai-Osmania, Hyderabad 500007, India.
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Holvoet K, Jacxsens L, Sampers I, Uyttendaele M. Insight into the prevalence and distribution of microbial contamination to evaluate water management in the fresh produce processing industry. J Food Prot 2012; 75:671-81. [PMID: 22488054 DOI: 10.4315/0362-028x.jfp-11-175] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study provided insight into the degree of microbial contamination in the processing chain of prepacked (bagged) lettuce in two Belgian fresh-cut produce processing companies. The pathogens Salmonella and Listeria monocytogenes were not detected. Total psychrotrophic aerobic bacterial counts (TPACs) in water samples, fresh produce, and environmental samples suggested that the TPAC is not a good indicator of overall quality and best manufacturing practices during production and processing. Because of the high TPACs in the harvested lettuce crops, the process water becomes quickly contaminated, and subsequent TPACs do not change much throughout the production process of a batch. The hygiene indicator Escherichia coli was used to assess the water management practices in these two companies in relation to food safety. Practices such as insufficient cleaning and disinfection of washing baths, irregular refilling of the produce wash baths with water of good microbial quality, and the use of high product/water ratios resulted in a rapid increase in E. coli in the processing water, with potential transfer to the end product (fresh-cut lettuce). The washing step in the production of fresh-cut lettuce was identified as a potential pathway for dispersion of microorganisms and introduction of E. coli to the end product via cross-contamination. An intervention step to reduce microbial contamination is needed, particularly when no sanitizers are used as is the case in some European Union countries. Thus, from a food safety point of view proper water management (and its validation) is a critical point in the fresh-cut produce processing industry.
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Affiliation(s)
- Kevin Holvoet
- Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
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19
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WU JIHGUAN, WANG PEIJIN, CHEN SHAUNC. ANTIOXIDANT AND ANTIMICROBIAL EFFECTIVENESS OF CATECHIN-IMPREGNATED PVA-STARCH FILM ON RED MEAT. J FOOD QUALITY 2010. [DOI: 10.1111/j.1745-4557.2010.00350.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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20
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Todd ECD, Michaels BS, Greig JD, Smith D, Bartleson CA. Outbreaks where food workers have been implicated in the spread of foodborne disease. Part 8. Gloves as barriers to prevent contamination of food by workers. J Food Prot 2010; 73:1762-73. [PMID: 20828485 DOI: 10.4315/0362-028x-73.9.1762] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The role played by food workers and other individuals in the contamination of food has been identified as an important contributing factor leading to foodborne outbreaks. To prevent direct bare hand contact with food and food surfaces, many jurisdictions have made glove use compulsory for food production and preparation. When properly used, gloves can substantially reduce opportunities for food contamination. However, gloves have limitations and may become a source of contamination if they are punctured or improperly used. Experiments conducted in clinical and dental settings have revealed pinhole leaks in gloves. Although such loss of glove integrity can lead to contamination of foods and surfaces, in the food industry improper use of gloves is more likely than leakage to lead to food contamination and outbreaks. Wearing jewelry (e.g., rings) and artificial nails is discouraged because these items can puncture gloves and allow accumulation of microbial populations under them. Occlusion of the skin during long-term glove use in food operations creates the warm, moist conditions necessary for microbial proliferation and can increase pathogen transfer onto foods through leaks or exposed skin or during glove removal. The most important issue is that glove use can create a false sense of security, resulting in more high-risk behaviors that can lead to cross-contamination when employees are not adequately trained.
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Affiliation(s)
- Ewen C D Todd
- Department of Advertising Public Relations and Retailing, Michigan State University, East Lansing, Michigan 48824, USA.
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Salmonellosis Outbreaks in the United States Due to Fresh Produce: Sources and Potential Intervention Measures. Foodborne Pathog Dis 2009; 6:635-48. [DOI: 10.1089/fpd.2008.0232] [Citation(s) in RCA: 295] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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22
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Page K, Wilson M, Parkin IP. Antimicrobial surfaces and their potential in reducing the role of the inanimate environment in the incidence of hospital-acquired infections. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b818698g] [Citation(s) in RCA: 401] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Tominaga T, Sekine M, Oyaizu H. Tracing the contamination origin of coliform bacteria in two small food-processing factories. J Food Prot 2008; 71:1910-4. [PMID: 18810877 DOI: 10.4315/0362-028x-71.9.1910] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The objective of this study was to trace contamination sources of coliform bacteria by comparing the types of coliforms between food samples and the processing environments in two small food-processing factories (factories A and B). Fermentation tests of five sugars enabled the successful classification of 16 representative type strains into eight distinct groups. The grouping procedure was then applied to comparison of the coliform flora between food products and various locations in their processing environments. The consistency between each food and the tested locations was evaluated using the Jaccard index. The air conditioner and refrigeration room floor in factory A showed an index of 1.00, while the shaping machine in factory B showed an index of 0.98, indicating that these locations could be contamination sources. The validity of our results was confirmed by randomly amplified polymorphic DNA, which showed 100% matched profiles between the air conditioner and the food in factory A, and highly matched profiles between the machine and the food in factory B. This method for comparing the coliform flora between food and environments has the potential to be a reliable tracing tool for various food industries.
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Affiliation(s)
- Tatsuya Tominaga
- Saitama Industrial Technology Center North Institute, 2-133 Suehiro, Kumagaya-shi, Saitama 360-0031, Japan.
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Affiliation(s)
- M P Doyle
- Centre for Food Safety, University of Georgia, Griffin, GA, USA.
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25
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Pappelbaum K, Grif K, Heller I, Wüirzner R, Hein I, Ellerbroek L, Wagner M. Monitoring hygiene on- and at-line is critical for controlling Listeria monocytogenes during produce processing. J Food Prot 2008; 71:735-41. [PMID: 18468027 DOI: 10.4315/0362-028x-71.4.735] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The prevalence of Listeria monocytogenes in different types of produce and on processing plant environments was investigated over a 4-year period in a large produce processing plant in Poland. Prevalence of L. monocytogenes was 46% in frozen vegetables and 41.3% in swab samples taken from the plant environment. Survival studies using artificial inocula demonstrated that the number of Listeria in frozen produce stored for 100 days did not significantly decrease in relation to the initial contamination level. A subset of 129 L. monocytogenes isolates originating from produce and the plant environment were typed by pulsed-field gel electrophoresis. Seventy-six of these isolates were retyped by ribo- and serotyping. Thirteen pulsotypes and 18 ribotypes were distinguished. Persistent Listeria isolates were found even when cleansing and sanitization was applied on a daily basis. Nine (69.2%) of 13 pulsotypes were recovered during a period of more than 2 years. L. monocytogenes of the same pulsotype was isolated from broccoli sampled directly before and after blanching, thus suggesting that blanching at 92 to 95 degrees C for 4 to 8 min did not result in a Listeria-free product, most likely due to massive recontamination. This finding is of importance since blanching is the only critical control point in produce processing. Cross-contamination between the two lines was demonstrated through isolating L. monocytogenes strains indistinguishable by pulsed-field gel electrophoresis from contaminated gloves and floor surfaces.
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Affiliation(s)
- Krystyna Pappelbaum
- Provincial Sanitary Epidemiology Unit, ul. Kujawska 4, 85-031 Bydgoszcz, Poland
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26
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Taulo S, Wetlesen A, Abrahamsen R, Kululanga G, Mkakosya R, Grimason A. Microbiological hazard identification and exposure assessment of food prepared and served in rural households of Lungwena, Malawi. Int J Food Microbiol 2008; 125:111-6. [PMID: 18558451 DOI: 10.1016/j.ijfoodmicro.2008.02.025] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Revised: 12/19/2007] [Accepted: 02/14/2008] [Indexed: 11/26/2022]
Abstract
The presence of food-borne pathogens, Escherichia coli 0157:H7, Staphylococcus aureus, Salmonella species, Campylobacter jejuni and non-pathogenic E. coli, in 132 home cooked food samples consisting of maize flour porridge (MFP), (n=41), fish (n=37), vegetables (n=28), beans (n=13) and "Others" (n=13), collected from 6 villages in Lungwena, Malawi was investigated. It was found that 35% of the food samples were contaminated with one or more pathogens; with 48%, 8%, 61% and 23% of the food samples being found to harbour E. coli, pathogenic E. coli 0157: H7, S aureus and Salmonella species, respectively. C. jejuni was not detected in any food sample. Using a 95% level of significance, pathogen concentration among food categories demonstrated a statistical difference (p=0.001). Distribution of pathogens among villages was also found to be significant (p=0.03). MFP was the most contaminated food. Practices that promote the spread of the pathogens in the rural household kitchens were investigated. Food was thought to be contaminated as a result of poor food handling, preparation and storage practices.
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Affiliation(s)
- Steven Taulo
- Department of Environmental Health, University of Malawi, The Polytechnic, P/B 303, Chichiri, Blantyre 3, Malawi.
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27
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Martin-Diana A, Rico D, Frias J, Mulcahy J, Henehan G, Barry-Ryan C. Whey permeate as a bio-preservative for shelf life maintenance of fresh-cut vegetables. INNOV FOOD SCI EMERG 2006. [DOI: 10.1016/j.ifset.2005.08.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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28
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DiPersio PA, Kendall PA, Yoon Y, Sofos JN. Influence of blanching treatments on Salmonella during home-type dehydration and storage of potato slices. J Food Prot 2005; 68:2587-93. [PMID: 16355830 DOI: 10.4315/0362-028x-68.12.2587] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Recommended drying treatments may not enhance destruction of pathogens that could be present on home-dried foods. In this study, the effects of traditional and modified treatments on Salmonella were evaluated during preparation, home-type dehydration (60 degrees C for 6 h), and storage of potato slices. Potato slices inoculated with five strains of Salmonella (8.4 log CFU/ g) were left untreated or were treated by steam blanching (88 degrees C for 10 min), water blanching (88 degrees C for 4 min), 0.105% citric acid blanching (88 degrees C for 4 min), or 0.210% citric acid blanching (88 degrees C for 4 min). Slices were then dried (6 h for 60 degrees C) and aerobically stored for up to 30 days at 25 +/- 3 degrees C. Cells were enumerated on tryptic soy agar with 0.1% pyruvate (TSAP) and on xylose lysine deoxycholate agar. Salmonella populations were reduced by 4.5 to 4.8 CFU/g and by >5.4 log CFU/g immediately following steam and water blanching, respectively. Populations were below the detection limit (0.80 log CFU/g) immediately following acid blanching, except for samples blanched in 0.105% citric acid and recovered on TSAP. After dehydration (6 h for 60 degrees C), Salmonella reductions on blanched potato slices (5.3 to 5.6 log CFU/g) were significantly greater (P < 0.05) than those on untreated samples (1.9 to 2.7 log CFU/g). Populations on all samples continued to decrease throughout 30 days of storage but still were 3.1 to 3.9 log CFU/g on untreated samples. In comparison, bacterial populations on blanched samples were undetectable by direct plating following 30 days of storage (regardless of blanching method). Blanching treatments used in this study improved the effectiveness of drying for inactivating Salmonella inoculated onto potato slices and, therefore, may enhance the safety of the product.
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Affiliation(s)
- Patricia A DiPersio
- Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, Colorado 80523, USA
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29
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Boehme S, Werner G, Klare I, Reissbrodt R, Witte W. Occurrence of antibiotic-resistant enterobacteria in agricultural foodstuffs. Mol Nutr Food Res 2004; 48:522-31. [PMID: 15538714 DOI: 10.1002/mnfr.200400030] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Antibiotic-resistant bacteria or their corresponding resistance determinants are known to spread from animals to humans via the food chain. We screened 20 vegetable foods for antibiotic-resistant coliform bacteria and enterococci. Isolates were directly selected on antibiotic-containing selective agar (color detection). Thirteen "common vegetables" (tomato, mushrooms, salad) possessed 10(4)-10(7) cfu/g vegetable of coliform bacteria including only few antibiotic-resistant variants (0-10(5) cfu/g). All seven sprout samples showed a some orders of magnitude higher contamination with coliform bacteria (10(7)-10(9) cfu/g) including a remarkable amount of resistant isolates (up to 10(7) cfu/g). Multiple resistances (up to 9) in single isolates were more common in sprout isolates. Resistant bacteria did not originate from sprout seeds. The most common genera among 92 isolates were: 25 Enterobacter spp. (19 E. cloacae), 22 Citrobacter spp. (8 C. freundii), and 21 Klebsiella spp. (9 K. pneumoniae). Most common resistance phenotypes were: tetracycline (43%), streptomycin (37%), kanamycin (26%), chloramphenicol (29%), co-trimoxazol (9%), and gentamicin (4%). The four gentamicin-resistant isolates were investigated in molecular details. Only three (chloramphenicol) resistant, typical plant-associated enterococci were isolated from overnight enrichment cultures. In conclusion, a contribution of sprouts contaminated with multiresistant, Gram-negative enterobacteria to a common gene pool among human commensal and pathogenic bacteria cannot be excluded.
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Affiliation(s)
- Sybille Boehme
- Robert Koch Institute, Wernigerode Branch, Wernigerode, Germany
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30
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Allende A, Aguayo E, Artés F. Microbial and sensory quality of commercial fresh processed red lettuce throughout the production chain and shelf life. Int J Food Microbiol 2004; 91:109-17. [PMID: 14996454 DOI: 10.1016/s0168-1605(03)00373-8] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2002] [Revised: 02/19/2003] [Accepted: 06/21/2003] [Indexed: 11/22/2022]
Abstract
Red pigmented 'Lollo Rosso' lettuce was processed under usual and controlled conditions in an industrial plant. At different steps of the production chain (reception, shredding, washing, draining, rinsing, centrifugation, and packaging), microbial counts were evaluated. Following industrial practices, processed lettuce was packaged at 5 degrees C in sealed polypropylene (PP) bags with an initial atmosphere containing 3 kPa O(2) and 5 kPa CO(2). The numbers of psychrotrophic bacteria, coliform and lactic acid bacteria (LAB) were influenced by all the studied steps of the production chain of the fresh processed 'Lollo Rosso' lettuce. Shredding, rinsing and centrifugation in particular increased bacterial counts. During a storage period of 7 days at 5 degrees C, sensory attributes (general appearance, texture, aroma, translucency, initial and persistent off-odors, leaves superficial browning, leaves edges browning, and decay) as well as microbial counts (psychrotrophic and mesophilic bacteria, coliforms and lactic acid bacteria) were monitored. Due to high microbial counts and off-odors evaluation, a shelf life shorter than 7 days should be considered for fresh processed 'Lollo Rosso' lettuce.
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Affiliation(s)
- A Allende
- Postharvest and Refrigeration Laboratory, Food Science and Technology Department, CEBAS-CSIC, Murcia, Spain.
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31
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de Vries YP, van der Voort M, Wijman J, van Schaik W, Hornstra LM, de Vos WM, Abee T. Progress in Food-related Research Focussing on Bacillus cereus. Microbes Environ 2004. [DOI: 10.1264/jsme2.19.265] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Ynte P. de Vries
- Wageningen Centre for Food Sciences
- Wageningen UR Laboratory of Food Microbiology
- Agrotechnology and Food Innovations A&F
| | - Menno van der Voort
- Wageningen Centre for Food Sciences
- Wageningen UR Laboratory of Food Microbiology
| | - Janneke Wijman
- Wageningen Centre for Food Sciences
- Wageningen UR Laboratory of Food Microbiology
| | - Willem van Schaik
- Wageningen Centre for Food Sciences
- Wageningen UR Laboratory of Food Microbiology
| | - Luc M. Hornstra
- Wageningen Centre for Food Sciences
- Agrotechnology and Food Innovations A&F
| | | | - Tjakko Abee
- Wageningen Centre for Food Sciences
- Wageningen UR Laboratory of Food Microbiology
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32
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Fang TJ, Wei QK, Liao CW, Hung MJ, Wang TH. Microbiological quality of 18 degrees C ready-to-eat food products sold in Taiwan. Int J Food Microbiol 2003; 80:241-50. [PMID: 12423926 DOI: 10.1016/s0168-1605(02)00172-1] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A total of 164 samples of 18 degrees C ready-to-eat (RTE) food products, purchased in 1999-2000 from convenience stores and supermarkets in central Taiwan, were examined to determine the microbiological quality of these products. The 18 degrees C RTE food products, manufactured by 16 factories, were divided into groups based on the type of food and their major ingredients. Aerobic plate count, coliforms, Escherichia coli, Bacillus cereus, Staphylococcus aureus and psychrotrophic Pseudomonas spp. were evaluated. The incidence of E. coli and coliforms in these 18 degrees C RTE food products was 7.9% and 75.0%, respectively, while 49.8% and 17.9% of the samples were found to contain B. cereus and S. aureus, respectively. Among the samples tested, 1.3% of the food products contained more than 10(5) CFU g(-1) of B. cereus and 0.7% contained more than 10(5) CFU g(-1) of S. aureus. The pH values of the samples were all below 7.0, except for cold noodles, which had pH values ranging from 5.18 to 8.20. Among the five types of 18 degrees C food products tested, the highest incidence of E. coli (16%) and Pseudomonas spp. (64.0%) were detected in hand-rolled sushi in a cone shape. On the other hand, the highest incidence rate of coliforms, B. cereus, and S. aureus were found in sandwiches (88%), cold noodles (66.7%) and rice balls rolled in seaweed (25.0%), respectively. Food products made of ham contained the highest incidence of coliforms (88.0%) and E. coli (16.0%), while food products containing meat and ham as the major ingredients had the highest incidence rates of B. cereus (62.5%) and S. aureus (26.1%), respectively. For coliforms, E. coli, B. cereus and S. aureus, the percentage of 18 degrees C RTE food products exceeding the microbiological standards for RTE food accepted by Republic of China was 75.0%, 7.9%, 49.8% and 17.9%, respectively.
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Affiliation(s)
- Tony J Fang
- Department of Food Science, National Chung Hsing University, 250 Kuokuang Road, Taichung 40227, Taiwan, ROC.
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Gagliardi JV, Millner PD, Lester G, Ingram D. On-farm and postharvest processing sources of bacterial contamination to melon rinds. J Food Prot 2003; 66:82-7. [PMID: 12540185 DOI: 10.4315/0362-028x-66.1.82] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Multistate and international foodborne illness outbreaks, particularly involving cantaloupe and often involving rare Salmonella spp., have increased dramatically over the past 13 years. This study assessed the sources and extent of melon rind contamination in production fields and at processing and packing facilities. In the spring of 1999, cantaloupe (Cucumis melo L. [reticulatus group] cv. Cruiser) sampled from two sites in the Rio Grande River Valley showed that postharvest-processed melon rinds often had greater plate counts of bacterial contaminants than field-fresh melons. Cantaloupe in the field had 2.5 to 3.5 log CFU g(-1) rind total coliforms by aerobic plate counts, whereas washed melons had 4.0 to 5.0 log CFU g(-1). In the fall of 1999, coliforms on honeydew melons (C. melo [inodorous group] cv. Honey Brew) ranged from 2.6 to 3.7 log CFU g(-1) after processing, and total and fecal coliforms and enterococci never fell below 2.5 log CFU g(-1). A hydrocooler at another site contaminated cantaloupe rinds with up to 3.4 log CFU g(-1) total and fecal enterococci; a secondary rinse with chlorinated water incompletely removed these bacteria. Sources of coliforms and enterococci were at high levels in melon production soils, especially in furrows that were flood irrigated, in standing water at one field, and in irrigation water at both sites. At one processing facility, wash water pumped from the Rio Grande River may not have been sufficiently disinfected prior to use. Because soil, irrigation water, and process water were potential sources of bacterial contamination, monitoring and management on-farm and at processing and packing facilities should focus on water quality as an important control point for growers and packers to reduce bacterial contamination on melon rinds.
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Affiliation(s)
- J V Gagliardi
- U.S. Department of Agriculture-Agricultural Research Service Animal Waste Pathogens Lab, 10300 Baltimore Avenue, Building 001, Room 140, BARC-West, Beltsville, Maryland 20705, USA.
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Thunberg RL, Tran TT, Bennett RW, Matthews RN, Belay N. Microbial evaluation of selected fresh produce obtained at retail markets. J Food Prot 2002; 65:677-82. [PMID: 11952219 DOI: 10.4315/0362-028x-65.4.677] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The microbial quality of five types of fresh produce obtained at the retail level was determined by standard quantitative techniques. These techniques included aerobic plate count (APC), total coliform counts, Escherichia coli counts, and yeast and mold counts. Three different methods were used to determine total coliform counts, which consisted of MacConkey agar plate counts, Colicomplete most probable number counts, and Petrifilm E. coli (EC) plate counts. The mean APCs for sprouts, lettuce, celery, cauliflower, and broccoli were 8.7, 8.6, 7.5, 7.4. and 6.3 log10 CFU/g, respectively. MacConkey agar counts indicated that 89 to 96% of the APCs consisted of gram-negative bacteria. Yeast and mold counts were in a range expected of fresh produce. Fresh produce was also analyzed for human pathogens. Samples were analyzed for Staphylococcus spp., Bacillus spp., Salmonella spp., Listeria spp., and Campylobacter spp. One isolate of Staphylococcus was found to be enterotoxigenic, and one species of Bacillus was also toxigenic. Neither Salmonella spp. nor Campylobacter spp. were detected in any of the produce samples. A variety of Listeria spp., including Listeria monocytogenes, were found in fresh produce.
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Affiliation(s)
- Richard L Thunberg
- US Food and Drug Administration, Center for Food Safety and Applied Nutrition, Washington, DC 20204, USA.
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35
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McGuire RG, Hagenmaier RD. Shellac formulations to reduce epiphytic survival of coliform bacteria on citrus fruit postharvest. J Food Prot 2001; 64:1756-60. [PMID: 11726155 DOI: 10.4315/0362-028x-64.11.1756] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Survival of the coliform bacteria Enterobacter aerogenes and Escherichia coli was monitored in a neutral carboxymethylcellulose formulation and in shellac formulations with various pH and concentrations of ethanol and the preservative paraben; populations were subsequently measured from the surface of citrus fruit coated with these formulations. Numbers of the two bacteria increased over 24 h from 10(6) CFU/ml to approximately 10(8) CFU/ml in the carboxymethylcellulose solution, but over this time numbers remained little changed in the neutral solution of shellac. The Enterobacter was more tolerant of alcohol over a 3-h period: although its numbers in a shellac solution with 10% ethanol dropped from more than 10(6) CFU/ml to just over 10(3) CFU/ml. E. coli and a third species. Klebsiella pneunoniae, declined toward the limit of detection (5 CFU/ ml) during this time. The addition of morpholine to increase the formulation pH to 9.0 caused numbers of bacteria to plummet to an undetectable level within 30 to 60 min. On Ruby Red grapefruit and Valencia oranges in storage at 13 degrees C numbers of E. aerogenes and E. coli declined over 2 weeks from 10(5) CFU/cm2 to less than 2.5 x 10(1), but most of the loss in numbers occurred within 1 day. Numbers remained significantly less on shellacked fruit compared with those applied in the carboxymethylcellulose coating, and a shellac coating prepared from a pH 9 solution was more toxic to these species than one in which 12% ethanol had been added to the neutral formulation. The addition of the preservative paraben in the basic shellac was further inhibitory.
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Affiliation(s)
- R G McGuire
- US Department Agriculture, Agricultural Research Service, Miami, Florida 33158, USA.
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Montville R, Chen Y, Schaffner DW. Glove barriers to bacterial cross-contamination between hands to food. J Food Prot 2001; 64:845-9. [PMID: 11403136 DOI: 10.4315/0362-028x-64.6.845] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Human hands are an important source of microbial contamination of foods. However, published data on the effectiveness of handwashing and glove use in a foodservice setting are limited. Bacterial transfer through foodservice quality gloves was quantified using nalidixic acid-resistant Enterobacter aerogenes (a nonpathogenic surrogate with attachment characteristics similar to Salmonella). Five transfer rates were determined: chicken to bare hand, chicken to hand through gloves, bare hand to lettuce, hand to lettuce through gloves (with low inoculum on hands), and hand to lettuce through gloves (with high inoculum on hands). At least 30 observations were made for each percent transfer rate using 30 individual volunteers. The logarithm of percent transfer data were then fit to distributions: chicken to bare hand, normal (0.71, 0.42); chicken to hand through gloves, gamma (5.91, 0.40, -5.00); bare hand to lettuce, logistic (1.16, 0.30); hand to lettuce through gloves (low inoculum), normal (0.35, 0.88); hand to lettuce through gloves (high inoculum), normal (-2.52, 0.61). A 0.01% transfer was observed from food to hands and from hands to food when subjects wore gloves and a 10% transfer was observed without a glove barrier. These results indicate that gloves are permeable to bacteria although transfer from hands to food through a glove barrier was less than without a glove barrier. Our results indicate that gloves may reduce both bacterial transfer from food to the hands of foodservice workers and in subsequent transfer from hands back to food.
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Affiliation(s)
- R Montville
- Food Risk Analysis Institute, Rutgers University, New Brunswick, New Jersey 08901-8520, USA
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Del Torre M, Della Corte M, Stecchini ML. Prevalence and behaviour of Bacillus cereus in a REPFED of Italian origin. Int J Food Microbiol 2001; 63:199-207. [PMID: 11246903 DOI: 10.1016/s0168-1605(00)00421-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This paper reports on the prevalence and behaviour of Bacillus cereus in gnocchi, a REPFED of Italian origin. A survey of gnocchi under varying storage conditions, revealed that, although B. cereus was found in 33% of the samples, the contamination level was lower than 10(2) CFU/g for the unstored and the refrigerated (8 degrees C) samples. Counts increased with increasing storage temperatures and prolonged storage times in samples prepared without sorbic acid. The effect of different formulations (sorbic, citric and lactic acid) and storage conditions (8, 12 and 20 degrees C) have been evaluated in a challenge testing with spores of B. cereus. Results indicate that the use of sorbic acid in association with citric or lactic acid to pH 5.0 is effective in inhibiting growth of B. cereus and the anticipated shelf life of the product is safe even if temperature abuse occurs. If sorbic acid is omitted, lactic acid can inhibit B. cereus growth during storage at 8 degrees C. On the contrary, when temperature abuse occurs (12 and 20 degrees C), lactic or citric acid are not able to prevent growth of B. cereus.
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Affiliation(s)
- M Del Torre
- Department of Food Science, University of Udine, Italy.
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