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Monte DFM, Nethery MA, Barrangou R, Landgraf M, Fedorka-Cray PJ. Whole-genome sequencing analysis and CRISPR genotyping of rare antibiotic-resistant Salmonella enterica serovars isolated from food and related sources. Food Microbiol 2020; 93:103601. [PMID: 32912589 DOI: 10.1016/j.fm.2020.103601] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 07/17/2020] [Accepted: 07/21/2020] [Indexed: 11/25/2022]
Abstract
For decades, Salmonella Typhimurium and Salmonella Enteritidis have prevailed in several countries as agents of salmonellosis outbreaks. In Brazil, the largest exporter of poultry meat, relatively little attention has been paid to infrequent serovars. Here, we report the emergence and characterization of rare serovars isolated from food and related sources collected between 2014 and 2016 in Brazil. Twenty-two Salmonella enterica isolates were analyzed through the use of whole-genome sequencing (WGS) and clustered regularly interspaced short palindromic repeats (CRISPR) genotyping. These isolates were classified into 10 infrequent serovars, including S. Abony, S. Isangi, S. Rochdale, S. Saphra, S. Orion, S. Ouakam, S. Grumpensis, S. Carrau, S. Abaetetuba, and S. Idikan. The presence of six antimicrobial resistance (AMR) genes, qnrB19, blaCMY-2, tetA, aac(6')-Iaa, sul2 and fosA7, which encode resistance to quinolones, third-generation cephalosporin, tetracycline, aminoglycoside, sulfonamide and fosfomycin, respectively, were confirmed by WGS. All S. Isangi harbored qnrB19 with conserved genomic context across strains, while S. Abony harbored blaCMY-2. Twelve (54.5%) strains displayed chromosomal mutations in parC (Thr57→Ser). Most serovars were classified as independent lineages, except S. Abony and S. Abaetetuba, which phylogenetically nested with Salmonella strains from different countries. CRISPR analysis revealed that the spacer content was strongly correlated with serovar and multi-locus sequence type for all strains, independently confirming the observed phylogenetic patterns, and highlighting the value of CRISPR-based genotyping for Salmonella. These findings add valuable information to the epidemiology of S. enterica in Brazil, where the emergency of antibiotic-resistant Salmonella continues to evolve.
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Affiliation(s)
- Daniel F M Monte
- Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, Food Research Center, University of São Paulo, Brazil; Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, NC, USA.
| | - Matthew A Nethery
- Genomic Sciences Graduate Program, North Carolina State University, Raleigh, NC, USA; Department of Food, Bioprocessing & Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
| | - Rodolphe Barrangou
- Genomic Sciences Graduate Program, North Carolina State University, Raleigh, NC, USA; Department of Food, Bioprocessing & Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
| | - Mariza Landgraf
- Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, Food Research Center, University of São Paulo, Brazil
| | - Paula J Fedorka-Cray
- Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, NC, USA.
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2
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Mba-Jonas A, Culpepper W, Hill T, Cantu V, Loera J, Borders J, Saathoff-Huber L, Nsubuga J, Zambrana I, Dalton S, Williams I, Neil KP. A Multistate Outbreak of Human Salmonella Agona Infections Associated With Consumption of Fresh, Whole Papayas Imported From Mexico-United States, 2011. Clin Infect Dis 2019; 66:1756-1761. [PMID: 29471372 DOI: 10.1093/cid/cix1094] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 12/17/2017] [Indexed: 11/13/2022] Open
Abstract
Background Nontyphoidal Salmonella causes ~1 million food-borne infections annually in the United States. We began investigating a multistate outbreak of Salmonella serotype Agona infections in April 2011. Methods A case was defined as infection with the outbreak strain of Salmonella Agona occurring between 1 January and 25 August 2011. We developed hypotheses through iterative interviews. Product distribution analyses and traceback investigations were conducted. The Food and Drug Administration (FDA) tested papayas from Mexico for Salmonella. Results We identified 106 case patients from 25 states. Their median age was 21 years (range, 1-91). Thirty-nine of 61 case patients (64%) reported Hispanic/Latino ethnicity; 11 of 65 (17%) travelled to Mexico before illness. Thirty-two of 56 case patients (57%) reported papaya consumption. Distribution analyses revealed that three firms, including Distributor A, distributed papaya to geographic areas that aligned with both the location and timing of illnesses. Traceback of papayas purchased by ill persons in four states identified Distributor A as the common supplier. FDA testing isolated the outbreak strain from a papaya sample collected at distributor A and from another sample collected at the US-Mexico border, destined for distributor A. FDA isolated Salmonella species from 62 of 388 papaya import samples (16%). The investigation led to a recall of fresh, whole papayas from Distributor A and an FDA import alert for all papayas from Mexico. Conclusions This is the first reported Salmonella outbreak in the United States linked to fresh, whole papayas. The outbreak highlights important issues regarding the safety of imported produce.
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Affiliation(s)
- Adamma Mba-Jonas
- Epidemic Intelligence Service, Scientific Education and Professional Development Program Office, Atlanta, Georgia.,Outbreak Response and Prevention Branch, Division of Foodborne, Waterborne, and Environmental Diseases (DFWED), National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Centers for Disease Control and Prevention (CDC), Atlanta, Georgia
| | - Wright Culpepper
- Outbreak Response and Prevention Branch, Division of Foodborne, Waterborne, and Environmental Diseases (DFWED), National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Centers for Disease Control and Prevention (CDC), Atlanta, Georgia
| | - Thomas Hill
- Food and Drug Administration, Atlanta, Georgia
| | | | - Julie Loera
- Texas Department of State Health Services, Austin
| | | | | | | | | | - Shannon Dalton
- Enteric Diseases Laboratory Branch, DFWED, NCEZID, CDC, Atlanta, Georgia
| | - Ian Williams
- Outbreak Response and Prevention Branch, Division of Foodborne, Waterborne, and Environmental Diseases (DFWED), National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Centers for Disease Control and Prevention (CDC), Atlanta, Georgia
| | - Karen P Neil
- Outbreak Response and Prevention Branch, Division of Foodborne, Waterborne, and Environmental Diseases (DFWED), National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Centers for Disease Control and Prevention (CDC), Atlanta, Georgia
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3
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Machado-Moreira B, Richards K, Brennan F, Abram F, Burgess CM. Microbial Contamination of Fresh Produce: What, Where, and How? Compr Rev Food Sci Food Saf 2019; 18:1727-1750. [PMID: 33336968 DOI: 10.1111/1541-4337.12487] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 06/07/2019] [Accepted: 07/10/2019] [Indexed: 01/02/2023]
Abstract
Promotion of healthier lifestyles has led to an increase in consumption of fresh produce. Such foodstuffs may expose consumers to increased risk of foodborne disease, as often they are not subjected to processing steps to ensure effective removal or inactivation of pathogenic microorganisms before consumption. Consequently, reports of ready-to-eat fruit and vegetable related disease outbreak occurrences have increased substantially in recent years, and information regarding these events is often not readily available. Identifying the nature and source of microbial contamination of these foodstuffs is critical for developing appropriate mitigation measures to be implemented by food producers. This review aimed to identify the foodstuffs most susceptible to microbial contamination and the microorganisms responsible for disease outbreaks from information available in peer-reviewed scientific publications. A total of 571 outbreaks were identified from 1980 to 2016, accounting for 72,855 infections and 173 deaths. Contaminated leafy green vegetables were responsible for 51.7% of reported outbreaks. Contaminated soft fruits caused 27.8% of infections. Pathogenic strains of Escherichia coli and Salmonella, norovirus, and hepatitis A accounted for the majority of cases. Large outbreaks resulted in particular biases such as the observation that contaminated sprouted plants caused 31.8% of deaths. Where known, contamination mainly occurred via contaminated seeds, water, and contaminated food handlers. There is a critical need for standardized datasets regarding all aspects of disease outbreaks, including how foodstuffs are contaminated with pathogenic microorganisms. Providing food business operators with this knowledge will allow them to implement better strategies to improve safety and quality of fresh produce.
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Affiliation(s)
- Bernardino Machado-Moreira
- Teagasc Food Research Centre, Ashtown, Dublin, Ireland.,Functional Environmental Microbiology, National Univ. of Ireland Galway, Galway, Ireland
| | - Karl Richards
- Teagasc Johnstown Castle Environmental Research Centre, Wexford, Ireland
| | - Fiona Brennan
- Teagasc Johnstown Castle Environmental Research Centre, Wexford, Ireland
| | - Florence Abram
- Functional Environmental Microbiology, National Univ. of Ireland Galway, Galway, Ireland
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4
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Realpe-Delgado ME, Muñoz-Delgado ÁB, Donado-Godoy P, Rey-Ramírez LM, Díaz-Guevara PL, Arévalo- Mayorga SA. Epidemiología de Salmonella spp., Listeria monocytogenes y Campylobacter spp., en la cadena productiva avícola. IATREIA 2016. [DOI: 10.17533/udea.iatreia.v29n4a01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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5
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Micallef SA, Callahan MT, Pagadala S. Occurrence and Dispersal of Indicator Bacteria on Cucumbers Grown Horizontally or Vertically on Various Mulch Types. J Food Prot 2016; 79:1663-1672. [PMID: 28221845 DOI: 10.4315/0362-028x.jfp-16-106] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
No data exist on the impact of cultivation practices on food safety risks associated with cucumber. Cucumbers are typically grown horizontally over a mulch cover, with fruit touching the ground, but this vining plant grows well in vertical systems. To assess whether production system affects bacterial dispersal onto plants, field trials were conducted over 2 years. Cucumber cultivar 'Marketmore 76' was grown horizontally on plastic, straw, or bare ground or vertically on trellises installed on bare ground in soil previously amended with raw dairy manure. Fruit, flower, leaf, and soil samples were collected to quantify Escherichia coli , thermotolerant coliforms, and enterococci by direct plating. E. coli isolates were characterized by BOX-PCR to evaluate relatedness among strains. Although thermotolerant coliforms and enterococci were significantly less abundant on fruit in year 1 (P < 0.05), this result was not seen in year 2 when more rain was recorded. Instead, fruit from straw-mulched beds had higher levels of enterococci compared with fruit grown on bare ground (P < 0.05). Leaves on bare ground occasionally had more bacteria than did leaves on plastic mulch beds (P < 0.05). Production system did not impact flower-associated bacterial levels. E. coli isolates (n =127) were genotyped, generating 21 distinct fingerprints. Vertical production did not appear to be a barrier for E. coli dispersal to the crop, as suggested by numerous related isolates from soil and flowers on bare ground, straw-mulched, and trellised beds (subcluster B1). None of the isolates from soil and flowers in this subcluster were related to isolates recovered from fruit, showing that flower colonization does not necessarily lead to fruit colonization. One cluster of isolates contained those from flowers and fruits but not soil, indicating a source other than manure-amended soil. Straw may be a source of E. coli ; a number of closely related E. coli isolates were retrieved from soil and fruits from straw-mulched beds. Our approach revealed E. coli dispersal patterns and could be used to assess bacterial transmission in other production systems.
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Affiliation(s)
- Shirley A Micallef
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742, USA
| | - Mary Theresa Callahan
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742, USA
| | - Sivaranjani Pagadala
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742, USA
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6
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Shearer AEH, LeStrange K, Castañeda Saldaña R, Kniel KE. Transfer of Pathogens from Cantaloupe Rind to Preparation Surfaces and Edible Tissue as a Function of Cutting Method. J Food Prot 2016; 79:764-70. [PMID: 27296423 DOI: 10.4315/0362-028x.jfp-15-420] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Whole and cut cantaloupes have been implicated as vehicles in foodborne illness outbreaks of norovirus, salmonellosis, and listeriosis. Preparation methods that minimize pathogen transfer from external surfaces to the edible tissue are needed. Two preparation methods were compared for the transfer of Listeria monocytogenes, Salmonella enterica serovar Typhimurium LT2, murine norovirus, and Tulane virus from inoculated cantaloupe rinds to edible tissue and preparation surfaces. For the first method, cantaloupes were cut into eighths, and edible tissue was separated from the rind and cubed with the same knife used to open the cantaloupes. For the second method, cantaloupes were scored with a knife around the circumference sufficient to allow manual separation of the cantaloupes into halves. Edible tissue was scooped with a spoon and did not contact the preparation surface touched by the rind. Bacteria and virus were recovered from the rinds, preparation surfaces, and edible tissue and enumerated by culture methods and reverse transcription, quantitative PCR, respectively. Standard plate counts were determined throughout refrigerated storage of cantaloupe tissue. Cut method 2 yielded approximately 1 log lower recovery of L. monocytogenes and Salmonella Typhimurium from edible tissue, depending on the medium in which the bacteria were inoculated. A slight reduction was observed in murine norovirus recovered from edible tissue by cut method 2. The Tulane virus was detected in approximately half of the sampled cantaloupe tissue and only at very low levels. Aerobic mesophilic colony counts were lower through day 6 of storage for buffered peptone water-inoculated cantaloupes prepared by cut method 2. No differences were observed in environmental contamination as a function of cutting method. Although small reductions in contamination of edible tissue were observed for cut method 2, the extent of microbial transfer underscores the importance of preventing contamination of whole cantaloupes.
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Affiliation(s)
- Adrienne E H Shearer
- Department of Animal and Food Sciences, University of Delaware, Newark, Delaware 19716, USA
| | - Kyle LeStrange
- Department of Animal and Food Sciences, University of Delaware, Newark, Delaware 19716, USA; To-Jo Fresh Mushrooms Inc., 974 Penn Green Road, Avondale, PA 19311, USA
| | - Rafael Castañeda Saldaña
- Department of Animal and Food Sciences, University of Delaware, Newark, Delaware 19716, USA; Virginia Polytechnic Institute and State University, 301 Saunders Hall (0327), 490 West Campus Drive, Blacksburg, VA 24061, USA
| | - Kalmia E Kniel
- Department of Animal and Food Sciences, University of Delaware, Newark, Delaware 19716, USA.
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7
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Upadhyay A, Chen CH, Yin H, Upadhyaya I, Fancher S, Liu Y, Nair MS, Jankelunas L, Patel JR, Venkitanarayanan K. Inactivation of Listeria monocytogenes, Salmonella spp. and Escherichia coli O157:H7 on cantaloupes by octenidine dihydrochloride. Food Microbiol 2016; 58:121-7. [PMID: 27217367 DOI: 10.1016/j.fm.2016.04.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 04/21/2016] [Accepted: 04/24/2016] [Indexed: 11/24/2022]
Abstract
The efficacy of a new generation disinfectant, octenidine dihydrochloride (OH), as wash and coating treatments for reducing Listeria monocytogenes (LM), Salmonella spp. (SAL), and Escherichia coli O157:H7 (EC) on cantaloupe was investigated. Cantaloupe rind plugs inoculated separately with the three bacterial species (∼8 log CFU/cm(2)) were washed for 1, 3, 5 min at 25 °C in water, or chlorine (200 ppm), ethanol (1%), OH (0.01, 0.05, 0.1%) and surviving populations were measured after treatment. Additionally, inoculated cantaloupe rind plugs were coated with 2% chitosan or chitosan containing OH (0.01, 0.05, 0.1%) and sampled for surviving pathogens. Subsequently, the antimicrobial efficacy of OH wash and coating (0.1, 0.2%) on whole cantaloupes was determined. All OH wash reduced LM, SAL, and EC on cantaloupe rinds by > 5 log CFU/cm(2) by 2 min, and reduced populations to undetectable levels (below 2 log CFU/cm(2)) by 5 min (P < 0.05). Similarly, OH coating on cantaloupe rinds reduced the pathogens by 3-5 log /cm(2) (P < 0.05). Washing and coating whole cantaloupes with OH reduced the three pathogens by at least 5 log and 2 log CFU/cm(2), respectively (P < 0.05). Results suggest that OH could be used as antimicrobial wash and coating to reduce LM, SAL, and EC on cantaloupes.
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Affiliation(s)
- Abhinav Upadhyay
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
| | - Chi-Hung Chen
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
| | - Hsinbai Yin
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
| | - Indu Upadhyaya
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
| | - Samantha Fancher
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
| | - Yanyan Liu
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
| | | | - Leanne Jankelunas
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
| | - Jitendra R Patel
- Environmental Microbial & Food Safety Lab, USDA-ARS, 10300 Baltimore Avenue, Building 201 BARC-East, Room 101, Beltsville, MD 20705, USA
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8
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Glassner H, Zchori-Fein E, Compant S, Sessitsch A, Katzir N, Portnoy V, Yaron S. Characterization of endophytic bacteria from cucurbit fruits with potential benefits to agriculture in melons (Cucumis melo L.). FEMS Microbiol Ecol 2015; 91:fiv074. [PMID: 26183916 DOI: 10.1093/femsec/fiv074] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2015] [Indexed: 11/14/2022] Open
Abstract
Endophytes are microorganisms that mainly colonize vegetative parts, but are also found in reproductive and disseminating organs, and may have beneficial characteristics. To identify microorganisms associated with the agriculturally important family, Cucurbitaceae, endophytes were initially determined in fruits of Cucumis melo Reticulatus Group 'Dulce' by a cultivation-independent approach based on fluorescence in situ hybridization using double labeling of oligonucleotide probes. Alpha-, Beta-, Gammaproteobacteria, Firmicutes and Actinobacteria were localized inside the fruits. Culturable bacteria were further isolated and identified from fruit tissues of 'Dulce', from fruits of other cultivated and wild-field-grown Cucurbitaceae, and from wild fruits growing under natural conditions. Low densities of culturable bacteria were detected in the investigated fruits, especially in four out of the five wild species, regardless of their growing environment. Substantial differences were observed between the wild and cultivated cucurbit taxa in regard to the number of colonized fruits as well as the type of endophytes. Bacillus was the most dominant genus of endophytes colonizing fruits of Cucurbitaceae. The antagonistic effects of isolated endophytes were assessed against cucurbit disease agents in dual-culture assays. Several bacterial isolates exhibited antagonistic properties against the tested plant pathogens. The identified bacteria may be useful for protecting plants not only in the field, but also for post-harvest.
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Affiliation(s)
- Hanoch Glassner
- Faculty of Biotechnology and Food Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel ARO, Dept. of Entomology, Newe Ya'ar Research Center 30095, Israel
| | | | - Stéphane Compant
- AIT Austrian Institute of Technology GmbH, Department of Health & Environment, Bioresources Unit, Konrad-Lorenz-Strasse 24, A-3430, Tulln, Austria
| | - Angela Sessitsch
- AIT Austrian Institute of Technology GmbH, Department of Health & Environment, Bioresources Unit, Konrad-Lorenz-Strasse 24, A-3430, Tulln, Austria
| | - Nurit Katzir
- ARO, Agricultural Research Organization, Dept. of Vegetable Crops, Newe Ya'ar Research Center 30095, Israel
| | - Vitaly Portnoy
- ARO, Agricultural Research Organization, Dept. of Vegetable Crops, Newe Ya'ar Research Center 30095, Israel
| | - Sima Yaron
- Faculty of Biotechnology and Food Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel
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9
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Palekar MP, Taylor TM, Maxim JE, Castillo A. Reduction of Salmonella enterica serotype Poona and background microbiota on fresh-cut cantaloupe by electron beam irradiation. Int J Food Microbiol 2015; 202:66-72. [DOI: 10.1016/j.ijfoodmicro.2015.02.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 01/28/2015] [Accepted: 02/02/2015] [Indexed: 11/28/2022]
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10
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Efficacy of plant-derived compounds combined with hydrogen peroxide as antimicrobial wash and coating treatment for reducing Listeria monocytogenes on cantaloupes. Food Microbiol 2014; 44:47-53. [DOI: 10.1016/j.fm.2014.05.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 05/03/2014] [Accepted: 05/12/2014] [Indexed: 11/22/2022]
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Scientific Opinion on the risk posed by pathogens in food of non-animal origin. Part 2 (Salmonellain melons). EFSA J 2014. [DOI: 10.2903/j.efsa.2014.3831] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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12
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Strawn LK, Danyluk MD, Worobo RW, Wiedmann M. Distributions of Salmonella subtypes differ between two U.S. produce-growing regions. Appl Environ Microbiol 2014; 80:3982-91. [PMID: 24747908 PMCID: PMC4054229 DOI: 10.1128/aem.00348-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 04/16/2014] [Indexed: 11/20/2022] Open
Abstract
Salmonella accounts for approximately 50% of produce-associated outbreaks in the United States, several of which have been traced back to contamination in the produce production environment. To quantify Salmonella diversity and aid in identification of Salmonella contamination sources, we characterized Salmonella isolates from two geographically diverse produce-growing regions in the United States. Initially, we characterized the Salmonella serotype and subtype diversity associated with 1,677 samples collected from 33 produce farms in New York State (NYS). Among these 1,677 samples, 74 were Salmonella positive, yielding 80 unique isolates (from 147 total isolates), which represented 14 serovars and 23 different pulsed-field gel electrophoresis (PFGE) types. To explore regional Salmonella diversity associated with production environments, we collected a smaller set of samples (n = 65) from South Florida (SFL) production environments and compared the Salmonella diversity associated with these samples with the diversity found among NYS production environments. Among these 65 samples, 23 were Salmonella positive, yielding 32 unique isolates (from 81 total isolates), which represented 11 serovars and 17 different PFGE types. The most common serovars isolated in NYS were Salmonella enterica serovars Newport, Cerro, and Thompson, while common serovars isolated in SFL were Salmonella serovars Saphra and Newport and S. enterica subsp. diarizonae serovar 50:r:z. High PFGE type diversity (Simpson's diversity index, 0.90 ± 0.02) was observed among Salmonella isolates across both regions; only three PFGE types were shared between the two regions. The probability of three or fewer shared PFGE types was <0.000001; therefore, Salmonella isolates were considerably different between the two sampled regions. These findings suggest the potential for PFGE-based source tracking of Salmonella in production environments.
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Affiliation(s)
- Laura K Strawn
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Michelle D Danyluk
- Department of Food Science and Human Nutrition, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida, USA
| | - Randy W Worobo
- Department of Food Science, Cornell University, Ithaca, New York, USA
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, New York, USA
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13
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Hong YK, Yoon WB, Huang L, Yuk HG. Predictive modeling for growth of non- and cold-adapted Listeria monocytogenes on fresh-cut cantaloupe at different storage temperatures. J Food Sci 2014; 79:M1168-74. [PMID: 24754226 DOI: 10.1111/1750-3841.12468] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Accepted: 03/10/2014] [Indexed: 11/27/2022]
Abstract
UNLABELLED The aim of this study was to determine the growth kinetics of Listeria monocytogenes, with and without cold-adaption, on fresh-cut cantaloupe under different storage temperatures. Fresh-cut samples, spot inoculated with a 4-strain cocktail of L. monocytogenes (∼3.2 log CFU/g), were exposed to constant storage temperatures held at 10, 15, 20, 25, or 30 °C. All growth curves of L. monocytogenes were fitted to the Baranyi, modified Gompertz, and Huang models. Regardless of conditions under which cells grew, the time needed to reach 5 log CFU/g decreased with the elevated storage temperature. Experimental results showed that there were no significant differences (P > 0.05) in the maximum growth rate k (log CFU/g h(-1) ) and lag phase duration λ (h) between the cultures of L. monocytogenes with or without previous cold-adaption treatments. No distinct difference was observed in the growth pattern among 3 primary models at various storage temperatures. The growth curves of secondary modeling were fitted on an Arrhenius-type model for describing the relationship between k and temperature of the L. monocytogenes on fresh-cut cantaloupe from 10 to 30 °C. The root mean square error values of secondary models for non- and cold-adapted cells were 0.018, 0.021, and 0.024, and 0.039, 0.026, and 0.017 at the modified Gompertz, Baranyi, and Huang model, respectively, indicating that these 3 models presented the good statistical fit. This study may provide valuable information to predict the growth of L. monocytogenes on fresh-cut cantaloupes at different storage conditions. PRACTICAL APPLICATION Listeriosis has occurred and increased along with the increased demand of fresh and fresh-cut fruits and vegetables. This study was conducted to predict the growth of non- and cold-adapted L. monocytogenes on fresh-cut cantaloupe at different temperature using mathematical model. These results can be helpful for risk assessments of L. monocytogenes in fresh-cut cantaloupe. This study provides valuable information to food handlers to choose proper storage temperatures for extending the shelf-life of fresh-cut cantaloupe.
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Affiliation(s)
- Yoon-Ki Hong
- Dept. of Food Science and Biotechnology, College of Agriculture and Life Sciences, Kangwon Natl. Univ., Chuncheon, Gangwondo, 200-701, South Korea
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14
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The Impact of Imports. Food Saf (Tokyo) 2014. [DOI: 10.1128/9781555816186.ch14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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15
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Use of Bacteroidales microbial source tracking to monitor fecal contamination in fresh produce production. Appl Environ Microbiol 2013; 80:612-7. [PMID: 24212583 DOI: 10.1128/aem.02891-13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In recent decades, fresh and minimally processed produce items have been associated with an increasing proportion of food-borne illnesses. Most pathogens associated with fresh produce are enteric (fecal) in origin, and contamination can occur anywhere along the farm-to-fork chain. Microbial source tracking (MST) is a tool developed in the environmental microbiology field to identify and quantify the dominant source(s) of fecal contamination. This study investigated the utility of an MST method based on Bacteroidales 16S rRNA gene sequences as a means of identifying potential fecal contamination, and its source, in the fresh produce production environment. The method was applied to rinses of fresh produce, source and irrigation waters, and harvester hand rinses collected over the course of 1 year from nine farms (growing tomatoes, jalapeño peppers, and cantaloupe) in Northern Mexico. Of 174 samples, 39% were positive for a universal Bacteroidales marker (AllBac), including 66% of samples from cantaloupe farms (3.6 log10 genome equivalence copies [GEC]/100 ml), 31% of samples from tomato farms (1.7 log10 GEC/100 ml), and 18% of samples from jalapeño farms (1.5 log10 GEC/100 ml). Of 68 AllBac-positive samples, 46% were positive for one of three human-specific markers, and none were positive for a bovine-specific marker. There was no statistically significant correlation between Bacteroidales and generic Escherichia coli across all samples. This study provides evidence that Bacteroidales markers may serve as alternative indicators for fecal contamination in fresh produce production, allowing for determination of both general contamination and that derived from the human host.
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Narvaez-Bravo C, Miller MF, Jackson T, Jackson S, Rodas-Gonzalez A, Pond K, Echeverry A, Brashears MM. Salmonella and Escherichia coli O157:H7 prevalence in cattle and on carcasses in a vertically integrated feedlot and harvest plant in Mexico. J Food Prot 2013; 76:786-95. [PMID: 23643120 DOI: 10.4315/0362-028x.jfp-12-079] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
To determine the prevalence of Salmonella and Escherichia coli O157:H7 in cattle feedlots and the impact of subsequent contamination on carcasses in a Mexican Federal Inspection Type Standards harvest facility, 250 animals were tagged and sampled in each step of the slaughter process. Samples were taken from hides and fecal grabs, and composite samples were taken from three anatomical carcass sites (hindshank, foreshank, and inside round) during the slaughter process, at preevisceration (PE), prior to entering the hot box (PHB), and after 24 h of dry chilling (DC). Additionally, 250 fecal samples were collected from the feedlot (FL), holding pens (HP), and intestinal feces (IF), and water samples were taken from the HP area. E. coli O157:H7 and Salmonella detection were carried out with the BAX System, immunomagnetic separation, and conventional methods. Overall Salmonella prevalence was 52.5%. The highest prevalence (92.4%) was found on hides, followed by feces from the HP (91.0%), FL (55.56%), PE (49.0%), IF (46.8%), and PHB (24.8%), for all sampling periods combined. The lowest prevalence of 6.0% was found after DC. The overall prevalence of E. coli O157:H7 was as follows: 11.7% for hides, 5.2% for IF, 2.7% for FL, 2.0% for HP, 0.8% for PE, 0.4% for PHB, and 0.4% for the cooler. High prevalence of Salmonella in IF and on hides present a significant risk factor for contamination by Salmonella at the different processing steps. These results serve as a warning as to the risks of contamination in meats for these pathogens and the importance of following good manufacturing practices during beef production processes.
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Affiliation(s)
- C Narvaez-Bravo
- Department of Animal and Food Sciences, Texas Tech University, Box 42141, Lubbock, Texas 79409, USA
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Gu G, Cevallos-Cevallos JM, Vallad GE, van Bruggen AHC. Organically managed soils reduce internal colonization of tomato plants by Salmonella enterica serovar Typhimurium. PHYTOPATHOLOGY 2013; 103:381-388. [PMID: 23506364 DOI: 10.1094/phyto-04-12-0072-fi] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A two-phase experiment was conducted twice to investigate the effects of soil management on movement of Salmonella enterica Typhimurium in tomato plants. In the first phase, individual leaflets of 84 tomato plants grown in conventional or organic soils were dip inoculated two to four times before fruiting with either of two Salmonella Typhimurium strains (10(9) CFU/ml; 0.025% [vol/vol] Silwet L-77). Inoculated and adjacent leaflets were tested for Salmonella spp. densities for 30 days after each inoculation. Endophytic bacterial communities were characterized by polymerase chain reaction denaturing gradient gel electrophoresis before and after inoculation. Fruit and seed were examined for Salmonella spp. incidence. In phase 2, extracted seed were planted in conventional soil, and contamination of leaves and fruit of the second generation was checked. More Salmonella spp. survived in inoculated leaves on plants grown in conventional than in organic soil. The soil management effect on Salmonella spp. survival was confirmed for tomato plants grown in two additional pairs of soils. Endophytic bacterial diversities of tomato plants grown in conventional soils were significantly lower than those in organic soils. All contaminated fruit (1%) were from tomato plants grown in conventional soil. Approximately 5% of the seed from infested fruit were internally contaminated. No Salmonella sp. was detected in plants grown from contaminated seed.
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Affiliation(s)
- Ganyu Gu
- Department of Plant Pathology, University of Florida, Gainseville, FL, USA
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Fang T, Liu Y, Huang L. Growth kinetics of Listeria monocytogenes and spoilage microorganisms in fresh-cut cantaloupe. Food Microbiol 2012; 34:174-81. [PMID: 23498195 DOI: 10.1016/j.fm.2012.12.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 11/23/2012] [Accepted: 12/20/2012] [Indexed: 11/18/2022]
Abstract
The main objective of this study was to investigate the growth kinetics of Listeria monocytogenes and background microorganisms in fresh-cut cantaloupe. Fresh-cut cantaloupe samples, inoculated with three main serotypes (1/2a, 1/2b, and 4b) of L. monocytogenes, were incubated at different temperatures, ranging from 4 to 43 °C, to develop kinetic growth models. During storage studies, the population of both background microorganisms and L. monocytogenes began to increase almost immediately, with little or no lag phase for most growth curves. All growth curves, except for two growth curves of L. monocytogenes 1/2a at 4 °C, developed to full curves (containing exponential and stationary phases), and can be described by a 3-parameter logistic model. There was no significant difference (P = 0.28) in the growth behaviors and the specific growth rates of three different serotypes of L. monocytogenes inoculated to fresh-cut cantaloupe. The effect of temperature on the growth of L. monocytogenes and spoilage microorganisms was evaluated using three secondary models. For L. monocytogenes, the minimum and maximum growth temperatures were estimated by both the Ratkowsky square-root and Cardinal parameter models, and the optimum temperature and the optimum specific growth rate by the Cardinal parameter model. An Arrhenius-type model provided more accurate estimation of the specific growth rate of L. monocytogenes at temperatures <4 °C. The kinetic models developed in this study can be used by regulatory agencies and food processors for conducting risk assessment of L. monocytogenes in fresh-cut cantaloupe, and for estimating the shelf-life of fresh-cut products.
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Affiliation(s)
- Ting Fang
- Fujian Agriculture and Forestry University, College of Food Science, Fuzhou 350001, China
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Lopez-Velasco G, Sbodio A, Tomás-Callejas A, Wei P, Tan KH, Suslow TV. Assessment of root uptake and systemic vine-transport of Salmonella enterica sv. Typhimurium by melon (Cucumis melo) during field production. Int J Food Microbiol 2012; 158:65-72. [PMID: 22824339 DOI: 10.1016/j.ijfoodmicro.2012.07.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 07/02/2012] [Accepted: 07/05/2012] [Indexed: 10/28/2022]
Abstract
Among melons, cantaloupes are most frequently implicated in outbreaks and surveillance-based recalls due to Salmonella enterica. There is limited but compelling evidence that associates irrigation water quality as a significant risk of preharvest contamination of melons. However, the potential for root uptake from water and soil and subsequent systemic transport of Salmonella into melon fruit is uncharacterized. The aim of this work was to determine whether root uptake of S. enterica results in systemic transport to fruit at high doses of applied inoculum through sub-surface drip and furrow irrigation during field production of melons. Cantaloupe and honeydew were grown under field conditions, in a silt clay loam soil using standard agronomic practices for California. An attenuated S. enterica sv. Typhimurium strain was applied during furrow irrigation and, in separate plots, buried drip-emitter lines delivered the inoculum directly into the established root zone. Contamination of the water resulted in soil contamination within furrows however Salmonella was not detected on top of the beds or around melon roots of furrow-irrigated rows demonstrating absence of detectable lateral transfer across the soil profile. In contrast, positive detection of the applied isolate occurred in soil and the rhizosphere in drip injected plots; survival of Salmonella was at least 41 days. Despite high populations of the applied bacteria in the rhizosphere, after surface disinfection, internalized Salmonella was not detected in mature melon fruit (n=485). Contamination of the applied Salmonella was detected on the rind surface of melons if fruit developed in contact with soil on the sides of the inoculated furrows. Following an unusual and heavy rain event during fruit maturation, melons collected from the central area of the beds, were shown to harbor the furrow-applied Salmonella. Delivery of Salmonella directly into the peduncle, after minor puncture wounding, resulted in detection of applied Salmonella in the sub-rind tissue below the fruit abscission zone. Results indicate that Salmonella internalization from soil and vascular systemic transport to fruit is unlikely to occur from irrigation water in CA production regions, even if substantially above normal presumptive levels of contamination. Although contaminated irrigation water and subsequently soil in contact with fruit remains a concern for contamination of the external rind, results suggest an acceptable microbial indicator threshold and critical limit for the presence of Salmonella in applied water may be possible by defining appropriate microbiological standards for melon irrigation in California and regions with similar climate, soil texture, and crop management practices.
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Affiliation(s)
- Gabriela Lopez-Velasco
- Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA 95616, USA
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20
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Diarrhea and colitis in mice require the Salmonella pathogenicity island 2-encoded secretion function but not SifA or Spv effectors. Infect Immun 2012; 80:3360-70. [PMID: 22778101 DOI: 10.1128/iai.00404-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We investigated the roles of Salmonella pathogenicity island 2 (SPI-2) and two SPI-2 effectors in Salmonella colitis and diarrhea in genetically resistant BALB/c.D2(Slc11a1) congenic mice with the wild-type Nramp1 locus. Wild-type Salmonella enterica serovar Typhimurium 14028s caused a pan-colitis, and the infected mice developed frank diarrhea with a doubling of the fecal water content. An ssaV mutant caused only a 26% increase in fecal water content, without producing the pathological changes of colitis, and it did not cause weight loss over a 1-week period of observation. However, two SPI-2 effector mutants, the spvB and sifA mutants, and a double spvB sifA mutant caused diarrhea and colitis, even though the sifA mutant was sensitive to killing by bone marrow-derived macrophages from BALB/c.D2 mice and was severely impaired in extraintestinal growth but not in growth in the cecum. These results demonstrate that systemic S. enterica infection and diarrhea/colitis are distinct pathogenic processes and that only the former requires spvB and sifA.
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Loharikar A, Newton A, Rowley P, Wheeler C, Bruno T, Barillas H, Pruckler J, Theobald L, Lance S, Brown JM, Barzilay EJ, Arvelo W, Mintz E, Fagan R. Typhoid Fever Outbreak Associated With Frozen Mamey Pulp Imported From Guatemala to the Western United States, 2010. Clin Infect Dis 2012; 55:61-6. [DOI: 10.1093/cid/cis296] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Inactivation of Salmonella on whole cantaloupe by application of an antimicrobial coating containing chitosan and allyl isothiocyanate. Int J Food Microbiol 2012; 155:165-70. [PMID: 22361025 DOI: 10.1016/j.ijfoodmicro.2012.02.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 01/23/2012] [Accepted: 02/01/2012] [Indexed: 11/22/2022]
Abstract
This study investigated the antimicrobial effect of a chitosan coating+allyl isothiocyanate (AIT) and nisin against Salmonella on whole fresh cantaloupes. Cantaloupes were inoculated with a cocktail of three Salmonella strains and treated with chitosan, chitosan+AIT, chitosan+nisin, and chitosan+AIT+nisin coatings. With AIT concentrations increasing from 10 to 60 μl/ml, the antibacterial effects of coating treatments against Salmonella increased. Chitosan coatings with 60 μl/ml AIT (chitosan+60AIT) reduced more than 5 log₁₀ CFU/cm² of Salmonella. The addition of nisin to the chitosan-AIT coating synergistically increased the antibacterial effect; coatings with nisin (25 mg/ml or 25,000 IU/ml)+30 μl/ml AIT resulted in a 4.8 log₁₀ reduction of Salmonella. The chitosan+60AIT coating significantly (p<0.05) reduced populations of native bacteria on cantaloupes to ca. 2 log₁₀ CFU/cm² during the first 6 days and populations remained unchanged through day 14 at 10 °C. The same coating treatment completely inactivated mold and yeast on cantaloupe at day 1 and no regrowth occurred even up to 14 days of storage. Scanning electron microscopy revealed that cell membrane damage and leakage of intercellular components occurred as a result of the chitosan-AIT coating treatments. No visual changes in overall appearance and color of cantaloupe rind and flesh due to coating treatments were observed. These results indicate that the application of an antimicrobial coating may be an effective method for decontamination of cantaloupes.
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Gu G, Hu J, Cevallos-Cevallos JM, Richardson SM, Bartz JA, van Bruggen AHC. Internal colonization of Salmonella enterica serovar Typhimurium in tomato plants. PLoS One 2011; 6:e27340. [PMID: 22096553 PMCID: PMC3212569 DOI: 10.1371/journal.pone.0027340] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 10/14/2011] [Indexed: 01/04/2023] Open
Abstract
Several Salmonella enterica outbreaks have been traced back to contaminated tomatoes. In this study, the internalization of S. enterica Typhimurium via tomato leaves was investigated as affected by surfactants and bacterial rdar morphotype, which was reported to be important for the environmental persistence and attachment of Salmonella to plants. Surfactants, especially Silwet L-77, promoted ingress and survival of S. enterica Typhimurium in tomato leaves. In each of two experiments, 84 tomato plants were inoculated two to four times before fruiting with GFP-labeled S. enterica Typhimurium strain MAE110 (with rdar morphotype) or MAE119 (without rdar). For each inoculation, single leaflets were dipped in 10(9) CFU/ml Salmonella suspension with Silwet L-77. Inoculated and adjacent leaflets were tested for Salmonella survival for 3 weeks after each inoculation. The surface and pulp of ripe fruits produced on these plants were also examined for Salmonella. Populations of both Salmonella strains in inoculated leaflets decreased during 2 weeks after inoculation but remained unchanged (at about 10(4) CFU/g) in week 3. Populations of MAE110 were significantly higher (P<0.05) than those of MAE119 from day 3 after inoculation. In the first year, nine fruits collected from one of the 42 MAE119 inoculated plants were positive for S. enterica Typhimurium. In the second year, Salmonella was detected in adjacent non-inoculated leaves of eight tomato plants (five inoculated with strain MAE110). The pulp of 12 fruits from two plants inoculated with MAE110 was Salmonella positive (about 10(6) CFU/g). Internalization was confirmed by fluorescence and confocal laser microscopy. For the first time, convincing evidence is presented that S. enterica can move inside tomato plants grown in natural field soil and colonize fruits at high levels without inducing any symptoms, except for a slight reduction in plant growth.
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Affiliation(s)
- Ganyu Gu
- Emerging Pathogens Institute and Department of Plant Pathology, University of Florida, Gainesville, Florida, United States of America.
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25
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Shaw RK, Lasa I, García BM, Pallen MJ, Hinton JCD, Berger CN, Frankel G. Cellulose mediates attachment of Salmonella enterica Serovar Typhimurium to tomatoes. ENVIRONMENTAL MICROBIOLOGY REPORTS 2011; 3:569-573. [PMID: 23761337 DOI: 10.1111/j.1758-2229.2011.00263.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Fresh fruit and vegetables are important components of a healthy and balanced diet. However, they are increasingly being recognized as important vehicles for transmission of human pathogens that were traditionally classified as zoonotic. There is a significant gap in our knowledge and understanding of the mechanisms by which human pathogens colonize and survive on or in fruits and vegetables. In this study we investigated the binding of Salmonella enterica to tomato fruits (Solanum lycopersicum), which is becoming a major source of human infection. We report that Salmonella enterica serovars Typhimurium and Senftenberg bound to the surface of unripe tomatoes in an aggregative pattern, while serovar Thompson adhered diffusely. We found that while flagella did not have a role in binding, bcsC S. Typhimurim mutants, deficient in cellulose production, exhibited significantly reduced level of attachment to tomatoes. Trans complementation of the mutation restored adhesion to the wild-type level.
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Affiliation(s)
- Robert K Shaw
- Centre for Molecular Microbiology and Infection, Imperial College, London, UK Instituto de Agrobiotecnología, UPNA-CSIC-Gobierno de Navarra, Campus de Arrosadia, Pamplona, Spain Centre for Systems Biology, Department of Biosciences University of Birmingham, Birmingham, UK Department of Microbiology, School of Genetics and Microbiology, Trinity College, Dublin, Ireland
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Berger CN, Sodha SV, Shaw RK, Griffin PM, Pink D, Hand P, Frankel G. Fresh fruit and vegetables as vehicles for the transmission of human pathogens. Environ Microbiol 2010; 12:2385-97. [DOI: 10.1111/j.1462-2920.2010.02297.x] [Citation(s) in RCA: 581] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Alvarado-Casillas S, Ibarra-Sánchez LS, Martínez-Gonzáles NE, Rodríguez-García MO, Castillo A. Validation of a washing and sanitizing procedure for cantaloupes at a mexican packing facility. J Food Prot 2010; 73:362-5. [PMID: 20132684 DOI: 10.4315/0362-028x-73.2.362] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In-plant validation of an alternative washing and sanitizing method was conducted at a cantaloupe packing operation in Mexico. This method consisted of a spray water wash followed by spraying warm (55 to 60 degrees C) 2% (L)-lactic acid solution and was compared with the existing method of spray washing the melons with tap water followed by immersion in a chlorinated water tank. Surface samples (100 cm(2)) were collected from 160 melons subjected to each processing method and tested for counts of aerobic bacteria, coliforms, and Escherichia coli. The aerobic plate counts from cantaloupes washed in the dump tank ranged from 3.6 to 5.2 log CFU/cm(2) and were significantly higher (P < 0.05) than those from melons treated with the alternative spray method, which ranged from 1.8 to 2.6 log CFU/cm(2). Coliform counts for cantaloupes treated in the dump tank were 0.2 to 2.2 log CFU/cm(2) and were below the detection level (-6.0 log CFU/cm(2)) on cantaloupes treated by the spray method. Growth of E. coli was observed in 2.5% of the samples of cantaloupes treated in the dump tank and in none of the samples of cantaloupes treated by lactic acid spray (P < 0.05). These results support the elimination of dump tanks in cantaloupe packing operations established by the Mexican government for certification of firms exporting cantaloupes to the United States. When a sanitizer is to be applied to the product, lactic acid seems to be a viable option, at least for products such as cantaloupes whose quality is not affected by an acid wash.
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Affiliation(s)
- S Alvarado-Casillas
- Programa de Posgrado en Procesos Biotecnológicos, Universidad de Guadalajara, Guadalajara, Jalisco 44430, Mexico
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Nesbitt A, Majowicz S, Finley R, Marshall B, Pollari F, Sargeant J, Ribble C, Wilson J, Sittler N. High-risk food consumption and food safety practices in a Canadian community. J Food Prot 2009; 72:2575-86. [PMID: 20003742 DOI: 10.4315/0362-028x-72.12.2575] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Understanding consumers' high-risk food consumption patterns and food handling in the home is critical in reducing foodborne illness. This study was conducted to determine the prevalence of unsafe food practices of individuals in a Canadian-based population, specifically, high-risk food consumption and home food safety practices. During November 2005 to March 2006, a sample of 2,332 randomly selected residents of the Waterloo Region (Ontario, Canada) participated in a telephone survey of food consumption and food safety. Questions covered consumption of high-risk foods, hand washing practices, safe food handling knowledge, source of food safety education, meat thawing and cooking practices, cross-contamination after raw food preparation, and refrigeration temperatures. Certain high-risk food behaviors were common among respondents and were associated with demographic characteristics. In general, unsafe practices increased with increasing total annual household income level. Males were more likely to report engaging in risky practices than were females. Specific high-risk behaviors of public health concern were reported by elderly individuals (e.g., consuming undercooked eggs), children (e.g., consuming chicken nuggets), and rural residents (e.g., drinking unpasteurized milk). Respondents appeared to know proper food safety practices, but did not put them into practice. Thus, educational programs emphasizing specific practices to improve food safety should be directed to targeted audiences, and they should stress the importance of consumer behavior in the safety of foods prepared at home. Further investigation of consumer perceptions is needed to design such programs to effectively increase the implementation of safe food practices by consumers.
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Affiliation(s)
- Andrea Nesbitt
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 1P7.
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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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A multi-state outbreak of Salmonella Saintpaul in Australia associated with cantaloupe consumption. Epidemiol Infect 2009; 137:367-74. [PMID: 18559128 DOI: 10.1017/s0950268808000861] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
A multi-state outbreak of Salmonella enterica serovar Saintpaul infection occurred in Australia during October 2006. A case-control study conducted in three affected jurisdictions, New South Wales, Victoria and Australian Capital Territory, included 36 cases with the outbreak-specific strain of S. Saintpaul identified by multiple locus variable-number tandem repeat analysis (MLVA) in a faecal specimen and 106 controls. Consumption of cantaloupe (rockmelon) was strongly associated with illness (adjusted OR 23.9 95%, 95% CI 5.1-112.4). S. Saintpaul, with the outbreak MLVA profile, was detected on the skin of two cantaloupes obtained from an implicated retailer. Trace-back investigations did not identify the specific source of the outbreak strain of S. Saintpaul, but multiple Salmonella spp. were detected in environmental samples from farms and packing plants investigated during the trace-back operation. Cantaloupe production and processing practices pose a potential public health threat requiring regulatory and community educational interventions.
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Gallegos-Robles M, Morales-Loredo A, Álvarez-Ojeda G, Osuna-García J, Martínez I, Morales-Ramos L, Fratamico P. PCR Detection and Microbiological Isolation ofSalmonellaspp. from Fresh Beef and Cantaloupes. J Food Sci 2009; 74:M37-40. [DOI: 10.1111/j.1750-3841.2008.01006.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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32
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Molinos AC, Abriouel H, Ben Omar N, Lucas R, Valdivia E, Gálvez A. Inactivation of Listeria monocytogenes in raw fruits by enterocin AS-48. J Food Prot 2008; 71:2460-7. [PMID: 19244899 DOI: 10.4315/0362-028x-71.12.2460] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The purpose of this study was to determine the effect of enterocin AS-48 on Listeria monocytogenes CECT 4032 in fruits and fruit juice. Fruits were contaminated with a L. monocytogenes cell suspension, washed with enterocin AS-48 (25 microg/ml) or with sterile distilled water as control, and stored at different temperatures (-20, 6, 15, 22 degrees C). Washing treatments significantly inhibited or completely inactivated L. monocytogenes in strawberries, raspberries, and blackberries stored at 15 and 22 degrees C for up to 2 days and in blackberries and strawberries at 6 degrees C for up to 7 days. Washing treatments with enterocin AS-48 also reduced viable counts in sliced melon, watermelon, pear, and kiwi but did not avoid proliferation of survivors during storage at 15 and 22 degrees C. Added enterocin (25 microg/ml) completely inactivated L. monocytogenes in watermelon juice within 24 h. To enhance the antilisterial activity of treatments, enterocin AS-48 was tested in combination with other antimicrobial substances on sliced melon stored at 22 degrees C. The combinations of enterocin AS-48 and trisodium trimetaphosphate, sodium lactate, lactic acid, polyphosphoric acid, carvacrol, hydrocinnamic acid, p-hydroxybenzoic acid, n-propyl p-hydroxybenzoate, or 2-nitropropanol showed increased antilisterial activities compared with each antimicrobial tested separately. Washing treatments with enterocin AS-48 in combination with 12 mM carvacrol, as well as with 100 mM n-propyl p-hydroxybenzoate, avoided regrowth of Listeria during storage at 22 degrees C. Results from this study indicate that enterocin AS-48 alone or in combination with other preservatives could serve as an additional hurdle against L. monocytogenes in fruits and fruit juices.
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Affiliation(s)
- Antonio Cobo Molinos
- Area de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén, 23071-Jaén, Spain
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Reduction by gaseous ozone of Salmonella and microbial flora associated with fresh-cut cantaloupe. Food Microbiol 2008; 25:558-65. [DOI: 10.1016/j.fm.2008.02.006] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 02/21/2008] [Accepted: 02/23/2008] [Indexed: 11/21/2022]
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Mosqueda-Melgar J, Raybaudi-Massilia RM, Martín-Belloso O. Combination of high-intensity pulsed electric fields with natural antimicrobials to inactivate pathogenic microorganisms and extend the shelf-life of melon and watermelon juices. Food Microbiol 2008; 25:479-91. [DOI: 10.1016/j.fm.2008.01.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 01/09/2008] [Accepted: 01/13/2008] [Indexed: 10/22/2022]
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Effect of gaseous ozone and hot water on microbial and sensory quality of cantaloupe and potential transference of Escherichia coli O157:H7 during cutting. Food Microbiol 2008; 25:162-8. [DOI: 10.1016/j.fm.2007.06.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2006] [Revised: 05/21/2007] [Accepted: 06/10/2007] [Indexed: 11/19/2022]
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Abstract
We describe recent epidemiological changes in salmonellosis. Linking 1968-2000 National Salmonella Surveillance System to census data, we calculated population-based age- and sex-stratified rates of non-urinary salmonellosis for the top 30 non-typhoidal serotypes. Using 1996-1997, 1998-1999, and 2000-2001 population-based FoodNet surveys, we compared reported diarrhoea, medical visits, and stool cultures. Despite an overall female-to-male incidence rate ratio (FMRR) of 0.99, the sex-specific burden of salmonellosis varied by age (<5 years FMRR 0.92; 5-19 years 0.85; 20-39 years 1.09; 40-59 years 1.23, and 60 years 1.08) and serotype (FMRR range 0.87 for Mississippi to 1.25 for Senftenberg). Serotype-specific FMRRs and median age (range 2 years for Derby to 29 years for Senftenberg) were related (correlation 0.76, P<0.0001). Recently, the relative burden of salmonellosis in women has increased. FoodNet data suggest that this change is real rather than due to differential reporting. Excess salmonellosis in women may reflect differences in exposure or biological susceptibility.
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Barak JD, Jahn CE, Gibson DL, Charkowski AO. The role of cellulose and O-antigen capsule in the colonization of plants by Salmonella enterica. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:1083-91. [PMID: 17849711 DOI: 10.1094/mpmi-20-9-1083] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Numerous salmonellosis outbreaks have been associated with vegetables, in particular sprouted seed. Thin aggregative fimbriae (Tafi), a component of the extracellular matrix responsible for multicellular behavior, are important for Salmonella enterica attachment and colonization of plants. Here, we demonstrate that the other surface polymers composing the extracellular matrix, cellulose, and O-antigen capsule also play a role in colonization of plants. Mutations in bacterial cellulose synthesis (bcsA) and O-antigen capsule assembly and translocation (yihO) reduced the ability to attach to and colonize alfalfa sprouts. A colanic acid mutant was unaffected in plant attachment or colonization. Tafi, cellulose synthesis, and O-antigen capsule, all of which contribute to attachment and colonization of plants, are regulated by AgfD, suggesting that AgfD is a key regulator for survival outside of hosts of Salmonella spp. The cellulose biosynthesis regulator adrA mutant was not affected in the ability to attach to or colonize plants; however, promoter probe assays revealed expression by cells attached to alfalfa sprouts. Furthermore, quantitative reverse-transcriptase polymerase chain reaction revealed differential expression of agfD and adrA between planktonic and plant-attached cells. In addition, there was no correlation among mutants between biofilm formation in culture and attachment to plants. Outside of animal hosts, S. enterica appears to rely on an arsenal of adhesins to persist on plants, which can act as vectors and perpetuate public health concerns.
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Affiliation(s)
- Jeri D Barak
- Produce Safety and Microbiology Research Unit, United States Department of Agriculture-Agricultural Research Service, Albany, CA 94710, USA.
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Mosqueda-Melgar J, Raybaudi-Massilia RM, Martín-Belloso O. Influence of treatment time and pulse frequency on Salmonella Enteritidis, Escherichia coli and Listeria monocytogenes populations inoculated in melon and watermelon juices treated by pulsed electric fields. Int J Food Microbiol 2007; 117:192-200. [PMID: 17512997 DOI: 10.1016/j.ijfoodmicro.2007.04.009] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2006] [Revised: 03/23/2007] [Accepted: 04/13/2007] [Indexed: 11/24/2022]
Abstract
Consumption of unpasteurized melon and watermelon juices has caused several disease outbreaks by pathogenic microorganisms worldwide. Pulsed electric field (PEF) has been recognized as a technology that may inactivate those bacteria present in fluid food products at low temperatures. Hence, PEF treatment at 35 kV/cm, 4 mus pulse duration in bipolar mode and square shape were applied on Salmonella Enteritidis, E. coli and L. monocytogenes populations inoculated in melon and watermelon juices without exceeding 40 degrees C outlet temperatures. Different levels of treatment time and pulse frequency were applied to evaluate their effects on these microorganisms. Treatment time was more influential than pulse frequency (P</=0.05) on the PEF microbial reduction levels for both melon and watermelon juices. Populations of S. Enteritidis, E. coli and L. monocytogenes were experimentally reduced and validated in a single process up to 3.71+/-0.17, 3.7+/-0.3 and 3.56+/-0.26 log(10) units, respectively, in melon juice when 1440 micros and 217 Hz were used; whereas reductions up to 3.56+/-0.12, 3.6+/-0.4 and 3.41+/-0.13 log(10) units of those microorganisms, respectively, were reached in watermelon juice treated for 1727 micros at 188 Hz. Although PEF treatment reduced the populations of the three microorganisms, L. monocytogenes was more resistant to PEF than S. Enteritidis and E. coli in both juices when treated at the same processing conditions.
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Affiliation(s)
- Jonathan Mosqueda-Melgar
- Department of Food Technology, University of Lleida, UTPV-CeRTA, Av. Alcalde Rovira Roure, 191, 25198 Lleida, Spain
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Alvarado-Casillas S, Ibarra-Sánchez S, Rodríguez-García O, Martínez-Gonzáles N, Castillo A. Comparison of rinsing and sanitizing procedures for reducing bacterial pathogens on fresh cantaloupes and bell peppers. J Food Prot 2007; 70:655-60. [PMID: 17388055 DOI: 10.4315/0362-028x-70.3.655] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Increased consumption of fruits and vegetables is linked to health benefits but also to an increase in the number of outbreaks of foodborne illness. To determine the effectiveness of different sanitizing treatments for reducing bacterial pathogens on fresh produce, fresh cantaloupes and bell peppers were harvested and inoculated with suspensions of Salmonella Typhimurium and Escherichia coli O157:H7. The inoculated fruits were treated with water wash alone or were washed and then waxed or rinsed with 200 mg/liter hypochlorite, 10% Ca(OH)2, or 2% lactic acid solutions applied by dipping for 15 s or spraying for 15 s. Preliminary experiments with chlorine treatments indicated that spraying with a 200, 600, or 1,000 mg/liter hypochlorite solution reduced populations of both pathogens by 2.1 to 2.6 and 1.5 to 2.1 log CFU for Salmonella Typhimurium and E. coli O157:H7, respectively. In general, no differences were observed between chlorine solutions without pH adjustment (pH 9.2) and those with pH adjusted to 6.0. When different wash regimes were applied to inoculated cantaloupes or bell peppers, water wash alone produced significantly lower counts of both pathogens on bell peppers in comparison to untreated controls. However, this reduction was not observed on cantaloupes, indicating a possible surface effect. Application of 2% L-lactic acid by spray was the treatment that resulted in the lowest bacterial counts on both cantaloupes and bell peppers. This treatment did not produce any deleterious change in the sensorial characteristics of the products tested. None of the pathogens studied was able to grow during refrigerated storage (5 degrees C for cantaloupes and 10 degrees C for bell peppers), although numbers close to the detection limit of the counting method were found in randomly tested individual samples at days 14 and 28 of storage, indicating that these pathogens can survive for long periods on the produce surface. These results indicate that selected produce commodities could be sanitized at the packing facility. However, these interventions should not be applied as a replacement for but only as a complement to good hygiene practices.
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Affiliation(s)
- S Alvarado-Casillas
- 'Programa de Posgrado en Procesos Biotecnológicos, Universidad de Guadalajara, Guadalajara, Jalisco 44430, Mexico
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Materon LA, Martinez-Garcia M, McDonald V. Identification of sources of microbial pathogens on cantaloupe rinds from pre-harvest to post-harvest operations. World J Microbiol Biotechnol 2007. [DOI: 10.1007/s11274-007-9362-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Varma JK, Samuel MC, Marcus R, Hoekstra RM, Medus C, Segler S, Anderson BJ, Jones TF, Shiferaw B, Haubert N, Megginson M, McCarthy PV, Graves L, Gilder TV, Angulo FJ. Listeria monocytogenes infection from foods prepared in a commercial establishment: a case-control study of potential sources of sporadic illness in the United States. Clin Infect Dis 2007; 44:521-8. [PMID: 17243054 DOI: 10.1086/509920] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Accepted: 08/07/2006] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Listeria monocytogenes has been estimated to cause >2500 illnesses and 500 deaths annually in the United States. Efforts to reduce foodborne listeriosis have focused on foods frequently implicated in outbreaks. Potential sources for L. monocytogenes infection not associated with outbreaks remain poorly understood. METHODS The Foodborne Diseases Active Surveillance Network conducts surveillance for culture-confirmed listeriosis at clinical laboratories in 9 states. After excluding outbreak-associated cases, we attempted to enroll eligible case patients with L. monocytogenes infection in a case-control study from 2000 through 2003. Control subjects were recruited through health care providers and were matched to case patients by state, age, and immunosuppression status. Data were collected about exposures occurring in the 4 weeks before specimen collection from the case patients. RESULTS Of the 249 case patients with L. monocytogenes infection, only 12 (5%) had cases that were associated with outbreaks; 6 other patients were ineligible for other reasons. Of 231 eligible case patients, 169 (73%) were enrolled in the study. We classified 28 case patients as having pregnancy-associated cases. We enrolled 376 control subjects. In multivariable analysis, L. monocytogenes infection was associated with eating melons at a commercial establishment (odds ratio, 2.6; 95% confidence interval, 1.4-5.0) and eating hummus prepared in a commercial establishment (odds ratio, 5.7; 95% confidence interval, 1.7-19.1). CONCLUSIONS Most cases of L. monocytogenes infection were not associated with outbreaks. Reducing the burden of foodborne listeriosis may require interventions directed at retail environments and at foods, such as melons and hummus, that are not commonly recognized as high risk. Because of the severity of listeriosis, pregnant women and other persons at risk may wish to avoid eating these newly implicated foods.
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Affiliation(s)
- Jay K Varma
- Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
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Bowen A, Fry A, Richards G, Beuchat L. Infections associated with cantaloupe consumption: a public health concern. Epidemiol Infect 2006; 134:675-85. [PMID: 16318654 PMCID: PMC2870447 DOI: 10.1017/s0950268805005480] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2005] [Indexed: 11/06/2022] Open
Abstract
Fresh produce is an important part of a healthy diet and is consumed in greater quantity in the United States than ever before. Consumption of cantaloupe has recently been associated with several large outbreaks of infections in North America, highlighting the need for a better understanding of practices and processes that may contribute to contamination. We reviewed all cantaloupe-associated outbreaks that were reported to the Centers for Disease Control and Prevention (CDC) and published in the literature. Twenty-three outbreaks occurred between 1984 and 2002; 1434 people became ill, 42 were hospitalized, and two died in these outbreaks. Aetiological agents in the outbreaks included five serotypes of Salmonella enterica, Campylobacter jejuni, Escherichia coli O157:H7, and norovirus. We reviewed processes contributing to cantaloupe contamination, conditions affecting survival and growth of bacterial pathogens on melons, and potential methods for sanitization. For maximum safety, industry, federal, and international partners must collaborate to ensure that appropriate interventions are in place to minimize the risk of contamination and prevent the growth of pathogens during cantaloupe production, processing, storage, and preparation.
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Affiliation(s)
- A Bowen
- Centers for Disease Control and Prevention, National Center for Infectious Disease, Atlanta, GA 30333, USA.
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Lopman BA, Gallimore C, Gray JJ, Vipond IB, Andrews N, Sarangi J, Reacher MH, Brown DW. Linking healthcare associated norovirus outbreaks: a molecular epidemiologic method for investigating transmission. BMC Infect Dis 2006; 6:108. [PMID: 16834774 PMCID: PMC1539008 DOI: 10.1186/1471-2334-6-108] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Accepted: 07/11/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Noroviruses are highly infectious pathogens that cause gastroenteritis in the community and in semi-closed institutions such as hospitals. During outbreaks, multiple units within a hospital are often affected, and a major question for control programs is: are the affected units part of the same outbreak or are they unrelated transmission events? In practice, investigators often assume a transmission link based on epidemiological observations, rather than a systematic approach to tracing transmission.Here, we present a combined molecular and statistical method for assessing:1) whether observed clusters provide evidence of local transmission and2) the probability that anecdotally|linked outbreaks truly shared a transmission event. METHODS 76 healthcare associated outbreaks were observed in an active and prospective surveillance scheme of 15 hospitals in the county of Avon, England from April 2002 to March 2003. Viral RNA from 64 out of 76 specimens from distinct outbreaks was amplified by reverse transcription-PCR and was sequenced in the polymerase (ORF 1) and capsid (ORF 2) regions. The genetic diversity, at the nucleotide level, was analysed in relation to the epidemiological patterns. RESULTS Two out of four genetic and epidemiological clusters of outbreaks were unlikely to have occurred by chance alone, thus suggesting local transmission. There was anecdotal epidemiological evidence of a transmission link among 5 outbreaks pairs. By combining this epidemiological observation with viral sequence data, the evidence of a link remained convincing in 3 of these pairs. These results are sensitive to prior beliefs of the strength of epidemiological evidence especially when the outbreak strains are common in the background population. CONCLUSION The evidence suggests that transmission between hospitals units does occur. Using the proposed criteria, certain hypothesized transmission links between outbreaks were supported while others were refuted. The combined molecular/epidemiologic approach presented here could be applied to other viral populations and potentially to other pathogens for a more thorough view of transmission.
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Affiliation(s)
- Ben A Lopman
- Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | | | - Jim J Gray
- Centre for Infections, Health Protection Agency, London, UK
| | | | - Nick Andrews
- Centre for Infections, Health Protection Agency, London, UK
| | | | | | - David W Brown
- Centre for Infections, Health Protection Agency, London, UK
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45
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Espinoza-Medina IE, Rodríguez-Leyva FJ, Vargas-Arispuro I, Islas-Osuna MA, Acedo-Félix E, Martínez-Téllez MA. PCR identification of Salmonella: potential contamination sources from production and postharvest handling of cantaloupes. J Food Prot 2006; 69:1422-5. [PMID: 16786866 DOI: 10.4315/0362-028x-69.6.1422] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Salmonella is one of the most frequently reported etiological agents in outbreaks of foodborne diseases associated with the consumption of cantaloupes. Sensitive and reliable methods for detecting and identifying foodborne microorganisms are needed. The PCR can be used to amplify specific DNA fragments and thus to detect and identify pathogenic bacteria. In this study, a PCR method was used to evaluate the incidence of Salmonella at cantaloupe production, harvest, and packaging steps, and the results were compared with those of the standard method for detection of Salmonella in foods (Mexican NOM-114-SSA1-1994). Salmonella was detected by both standard and PCR methods in 23.5% of the irrigation water samples but only by the PCR method in 9.1% of the groundwater samples, 4.8% of the chlorinated water samples, 16.7% of samples from the hands of packing workers, 20.6% of samples from the packed cantaloupes, and 25.7% of samples from the in-field cantaloupes. With the standard method, Salmonella was found in 8.3% of the crop soil samples. Statistical analysis indicated a significant difference in sensitivity (P < 0.05) between the two methods; the PCR method was 4.3 times more sensitive than the standard method. Salmonella was found at seven of the eight pointsevaluated during the production and postharvest handling of cantaloupe melons.
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Affiliation(s)
- I E Espinoza-Medina
- Coordinación de Tecnología de Alimentos de Origen Vegetal, Centro de Investigación en Alimentación y Desarrollo, A.C., A.P. 1735, 83000 Hermosillo, Sonora, México
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46
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Lapidot A, Romling U, Yaron S. Biofilm formation and the survival of Salmonella Typhimurium on parsley. Int J Food Microbiol 2006; 109:229-33. [PMID: 16616389 DOI: 10.1016/j.ijfoodmicro.2006.01.012] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 11/03/2005] [Accepted: 01/05/2006] [Indexed: 11/20/2022]
Abstract
Although several studies provide evidence that the formation of biofilms by human pathogens on plant tissue is possible, to date there is no direct evidence that biofilms enhance the resistance of plant-associated pathogens to disinfectants or biocides. We hypothesized that biofilm formation would enhance the adhesion and survival of Salmonella on leafy vegetables. To test our hypothesis, we compared the adhesion and persistence of Salmonella Typhimurium and its biofilm-deficient isogenic mutant. Following inoculation of parsley and rinsing with water or chlorine solution, both strains had similar survival properties, and up to 3-log reduction were observed, depending on chlorine concentration. This indicates that the biofilm matrix of Salmonella likely does not play a significant role in initial adhesion and survival after disinfection. After a week of storage the biofilm producing strain survived chlorination significantly better than the biofilm-deficient mutant. However, the recovery of the mutant was still elevated, indicating that although the biofilm matrix has a role in persistence of Salmonella after chlorination treatment of parsley, this is not the most important mechanism, and other mechanisms, probably the ability to penetrate the plant tissue or the pre-existing biofilms, or production of different polysaccharides other than cellulose, provide the protection.
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Affiliation(s)
- Anat Lapidot
- Department of Biotechnology and Food Engineering, Technion, Haifa, Israel
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47
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Solomon EB, Huang L, Sites JE, Annous BA. Thermal Inactivation of Salmonella on Cantaloupes Using Hot Water. J Food Sci 2006. [DOI: 10.1111/j.1365-2621.2006.tb08903.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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48
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Palekar M, Cabrera-Diaz E, Kalbasi-Ashtari A, Maxim J, Miller R, Cisneros-Zevallos L, Castillo A. Effect of Electron Beam Irradiation on the Bacterial Load and Sensorial Quality of Sliced Cantaloupe. J Food Sci 2006. [DOI: 10.1111/j.1365-2621.2004.tb09941.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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49
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Sharma M, Adler BB, Harrison MD, Beuchat LR. Thermal tolerance of acid-adapted and unadapted Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in cantaloupe juice and watermelon juice. Lett Appl Microbiol 2005; 41:448-53. [PMID: 16305669 DOI: 10.1111/j.1472-765x.2005.01797.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS A study was performed to determine D values of acid-adapted and unadapted cells of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in cantaloupe juice and watermelon juice. METHODS AND RESULTS Salmonella enterica serotype Poona, S. enterica serotype Saphra, two strains of E. coli O157:H7, and two strains of L. monocytogenes were grown in tryptic soy broth (TSB) and TSB supplemented with 1% glucose for 24 h at 37 degrees C. Decimal reduction times (D values) of cells suspended in unpasteurized cantaloupe juice and watermelon juice were determined. Acid-adapted cells of Salmonella and E. coli O157:H7, but not L. monocytogenes, had increased thermal tolerance compared with cells that were not acid-adapted. There was no correlation between soluble solids content of the two types of juice and thermal resistance. CONCLUSIONS Growth of Salmonella and E. coli O157:H7 in cantaloupe juice, watermelon juice, or other acidic milieu, either in preharvest or postharvest environments, may result in cross protection to heat. The pasteurization conditions necessary to achieve elimination of pathogens from these juices would consequently have to be more severe if cells are habituated to acidic environments. SIGNIFICANCE AND IMPACT OF THE STUDY Insights from this study provide guidance to developing pasteurization processes to eliminate Salmonella, E. coli O157:H7, and L. monocytogenes in cantaloupe juice and watermelon juice.
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Affiliation(s)
- M Sharma
- Center for Food Safety and Department of Food Science and Technology, University of Georgia, Griffin, 30223, USA
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