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Shirley A Micallef - One of the best experts on this subject based on the ideXlab platform.
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interactions between Salmonella enterica newport fusarium spp and melon cultivars
Foodborne Pathogens and Disease, 2020Co-Authors: Robert C Korir, Kathryne L Everts, Shirley A MicallefAbstract:Melons are perishable fruit of high food safety risk, grown in contact with soil and soil-borne organisms. To assess whether food safety risk could be augmented by the presence of soil-borne fungi, this study investigated the relationship between Fusarium spp. that were isolated from the surface of melon and the foodborne pathogen Salmonella enterica. In four repeated trials, rind discs from cultivars, Arava, Athena, Dulce Nectar, Jaune de Canaries, and Sivan fruit, grown in the field and in high tunnels in Maryland were inoculated separately with Fusarium isolates, F. oxysporum, F. fujikuroi, F. armeniacum, and F. proliferatum, with no Fusarium inoculation serving as a control and incubated at 25°C. Salmonella newport was inoculated onto melon discs 4 d post-Fusarium inoculation and recovered 24 h later. Melon cultivar impacted the retrieval of Salmonella newport. In all four replicated experiments, one or more of the netted varieties, Arava, Athena, and Sivan, yielded higher Salmonella newport counts than one or both smooth-rind melons, Jaune de Canaries and Dulce Nectar (p < 0.05). Fusarium inoculation did not have a marked impact on Salmonella retrieval. The average Salmonella count recovered was 5.0 log colony-forming unit (CFU)/mL for both Fusarium-inoculated and uninoculated melons. However, in one trial, Salmonella newport counts recovered from F. fujikuroi-inoculated melons were higher than all other treatments (8.6 log CFU/mL; p < 0.001), due to high levels of Salmonella recovered from Jaune de Canaries compared with other experiments. The food safety risk of melon did not appear to be enhanced by postharvest colonization with saprophytic Fusarium spp. However, melons with netted rinds appeared to favor Salmonella colonization compared with smooth melons. Choice of melon cultivar may be an important consideration in reducing Salmonella colonization risk in areas where Salmonella may be endemic in the environment.
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survival of Salmonella newport on whole and fresh cut cucumbers treated with lytic bacteriophages
Journal of Food Protection, 2017Co-Authors: Manan Sharma, Esmond Nyarko, Shirley A Micallef, Gwendolyn Dashiell, Eric T Handy, Cheryl East, Russell Reynnells, Chanelle White, Fawzy Hashem, Patricia D MillnerAbstract:ABSTRACT Salmonella enterica associated with consumption of cucumbers (Cucumis sativus) has led to foodborne outbreaks in the United States. Whole and fresh-cut cucumbers are susceptible to S. ente...
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soil type soil moisture and field slope influence the horizontal movement of Salmonella enterica and citrobacter freundii from floodwater through soil
Journal of Food Protection, 2017Co-Authors: Mary Theresa Callahan, Shirley A Micallef, Robert L BuchananAbstract:ABSTRACT Pathogens in soil are readily mobilized by infiltrating water to travel downward through the soil. However, limited data are available on the horizontal movement of pathogens across a field. This study used a model system to evaluate the influence of soil type, initial soil moisture content, and field slope on the movement of Salmonella enterica serovar newport across a horizontal plane of soil under flooding conditions. Three soil types of varying clay content were moistened to 40, 60, or 80% of their maximum water-holding capacities and flooded with water containing 6 log CFU/ml Salmonella newport and Citrobacter freundii, the latter being evaluated as a potential surrogate for S. enterica in future field trials. A two-phase linear regression was used to analyze the microbial populations recovered from soil with increasing distance from the flood. This model reflected the presence of lag distances followed by a quantifiable linear decrease in the population of bacteria as a function of the dist...
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Salmonella newport and typhimurium colonization of fruit differs from leaves in various tomato cultivars
Journal of Food Protection, 2014Co-Authors: Sanghyun Han, Shirley A MicallefAbstract:Several outbreaks of Salmonella enterica infections have been linked to tomatoes. One cost-effective way to complement on-farm preventive Good Agricultural Practices is to identify cultivars with inherent decreased susceptibility to Salmonella colonization. Fruit and leaves of 13 tomato cultivars with distinct phenotypes were screened to evaluate their susceptibility to Salmonella epiphytic colonization. Field-grown fruit or gnotobiotically grown seedling leaves were spot inoculated in replicate with either Salmonella Typhimurium LT2 or a tomato outbreak–associated strain of Salmonella newport. Initial loads of the Salmonella inocula were 2.5 log CFU per fruit and 3.5 or 7.0 log CFU per seedling. Salmonella cells were retrieved and enumerated using direct plating after 24 h of incubation at room temperature for fruit and 72 h at 26°C during the day and 18°C at night for seedling leaves. Epiphytic colonization of fruit by S. enterica was cultivar-dependent and serotype-specific, but did not necessarily cor...
Guojie Cao - One of the best experts on this subject based on the ideXlab platform.
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sequence analysis of inca c and inci1 plasmids isolated from multidrug resistant Salmonella newport using single molecule real time sequencing
Foodborne Pathogens and Disease, 2018Co-Authors: Guojie Cao, Marc W Allard, Shaohua Zhao, Maria Hoffmann, Tim Muruvanda, Yan Luo, Justin Payne, Kevin Meng, Patrick F McdermottAbstract:Abstract Multidrug-resistant (MDR) plasmids play an important role in disseminating antimicrobial resistance genes. To elucidate the antimicrobial resistance gene compositions in A/C incompatibility complex (IncA/C) plasmids carried by animal-derived MDR Salmonella newport, and to investigate the spread mechanism of IncA/C plasmids, this study characterizes the complete nucleotide sequences of IncA/C plasmids by comparative analysis. Complete nucleotide sequencing of plasmids and chromosomes of six MDR Salmonella newport strains was performed using PacBio RSII. Open reading frames were assigned using prokaryotic genome annotation pipeline (PGAP). To understand genomic diversity and evolutionary relationships among Salmonella newport IncA/C plasmids, we included three complete IncA/C plasmid sequences with similar backbones from Salmonella newport and Escherichia coli: pSN254, pAM04528, and peH4H, and additional 200 draft chromosomes. With the exception of canine isolate CVM22462, which contained an additi...
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genetic diversity of Salmonella pathogenicity islands spi 5 and spi 6 in Salmonella newport
Foodborne Pathogens and Disease, 2014Co-Authors: Guojie Cao, Marc W Allard, Errol Strain, Robert Stones, Shaohua Zhao, Eric W Brown, Jianghong MengAbstract:Abstract Salmonella enterica subspecies enterica serotype newport is one of the common serotypes causing foodborne salmonellosis outbreaks in the United States. Salmonella newport consists of three lineages exhibiting extensive genetic diversity. Due to the importance of Salmonella pathogenicity islands 5 and 6 (SPI-5 and SPI-6) in virulence of pathogenic Salmonella, the genetic diversity of these two SPIs may relate to different potentials of Salmonella newport pathogenicity. Most Salmonella newport strains from North America belong to Salmonella newport lineages II and III. A total 28 Salmonella newport strains of lineages II and III from diverse sources and geographic locations were analyzed, and 11 additional Salmonella genomes were used as outgroup in phylogenetic analyses. SPI-5 was identified in all Salmonella newport strains and 146 single nucleotide polymorphisms (SNPs) were detected. Thirty-nine lineage-defining SNPs were identified, including 18 nonsynonymous SNPs. Two 40-kb genomic islands (SP...
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phylogenetics and differentiation of Salmonella newport lineages by whole genome sequencing
PLOS ONE, 2013Co-Authors: Guojie Cao, Errol Strain, Robert Stones, Shaohua Zhao, Eric W Brown, Jianghong Meng, Patrick F Mcdermott, James B Pettengill, Marc W AllardAbstract:Salmonella newport has ranked in the top three Salmonella serotypes associated with foodborne outbreaks from 1995 to 2011 in the United States. In the current study, we selected 26 S. newport strains isolated from diverse sources and geographic locations and then conducted 454 shotgun pyrosequencing procedures to obtain 16–24 × coverage of high quality draft genomes for each strain. Comparative genomic analysis of 28 S. newport strains (including 2 reference genomes) and 15 outgroup genomes identified more than 140,000 informative SNPs. A resulting phylogenetic tree consisted of four sublineages and indicated that S. newport had a clear geographic structure. Strains from Asia were divergent from those from the Americas. Our findings demonstrated that analysis using whole genome sequencing data resulted in a more accurate picture of phylogeny compared to that using single genes or small sets of genes. We selected loci around the mutS gene of S. newport to differentiate distinct lineages, including those between invH and mutS genes at the 3′ end of Salmonella Pathogenicity Island 1 (SPI-1), ste fimbrial operon, and Clustered, Regularly Interspaced, Short Palindromic Repeats (CRISPR) associated-proteins (cas). These genes in the outgroup genomes held high similarity with either S. newport Lineage II or III at the same loci. S. newport Lineages II and III have different evolutionary histories in this region and our data demonstrated genetic flow and homologous recombination events around mutS. The findings suggested that S. newport Lineages II and III diverged early in the serotype evolution and have evolved largely independently. Moreover, we identified genes that could delineate sublineages within the phylogenetic tree and that could be used as potential biomarkers for trace-back investigations during outbreaks. Thus, whole genome sequencing data enabled us to better understand the genetic background of pathogenicity and evolutionary history of S. newport and also provided additional markers for epidemiological response.
Manan Sharma - One of the best experts on this subject based on the ideXlab platform.
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influence of poultry litter amendment type and irrigation events on survival and persistence of Salmonella newport
Journal of Food Protection, 2020Co-Authors: June Teichmann, Pushpinder Kaur Litt, Manan Sharma, Esmond Nyarko, Kalmia E KnielAbstract:ABSTRACT Salmonella enterica subsp. enterica serovar newport is a bacterial foodborne pathogen isolated from several environmental reservoirs on the Delmarva Peninsula and has been associated with several produce-related outbreaks. However, little is known about specific interactions between Salmonella newport and soil amendments used as fertilizers. The purpose of this study was to determine Salmonella newport persistence and resuscitation in raw poultry litter (PLR), a common biological soil amendment, and in soils containing poultry litter-based (heat-treated poultry pellets [HTPP]) or chemical fertilizer (urea [U]) amendments to provide equivalent levels of nitrogen to the soil. Inoculated samples were stored in a growth chamber and irrigated regularly over 4 weeks. Soil samples were collected every week for 4 weeks to determine moisture content and surviving Salmonella newport populations (log CFU per gram dry weight). Data were analyzed by using a one-way analysis of variance and Student's t test. The PLR supported significantly higher (5.07 log CFU/g dry weight [gdw]) populations of Salmonella newport than HTPP only (1.70 log CFU/gdw). However, PLR-amended (PRLA) soil (2.5 log CFU/gdw) samples had significantly (P < 0.05) lower Salmonella newport populations compared with HTPP-amended (4.5 log CFU/gdw) and U-amended (4.0 log CFU/gdw) soil samples. The effect of irrigation on Salmonella newport population levels in PRLA soils was significant, and in a comparative study, the overall increase in the pathogen levels in U-amended soil (mean = 1.12 log CFU/gdw) was significantly greater than that in PLRA soil (mean = 0.54 log CFU/gdw), whereas that in HTPP-amended soil (0.80 log CFU/gdw) was not significantly different from PLRA soil. HIGHLIGHTS
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survival and growth of wild type and rpos deficient Salmonella newport strains in soil extracts prepared with heat treated poultry pellets
Journal of Food Protection, 2019Co-Authors: Manoj K Shah, Esmond Nyarko, Rhodel Bradshaw, Patricia D Millner, Deborah A Neher, Thomas R Weicht, Teresa M Bergholz, Manan SharmaAbstract:Manure runoff can transfer pathogens to farmlands or to water sources, leading to subsequent contamination of produce. Untreated biological soil amendments, like manure, can be contaminated with foodborne pathogens, such as Salmonella newport, which may lead to transfer of the pathogen to fruits or vegetables. Studies have reported the occurrence and survival of Salmonella in manure or manure slurries. However, data on the survival and growth of Salmonella newport is lacking in matrices simulating runoff. We quantified the survival and growth of wild-type (WT) Salmonella newport and rpoS-deficient (Δ rpoS) strains in sterile and nonsterile soil extracts prepared with (amended) or without (unamended) heat-treated poultry pellets at 25°C. Salmonella newport WT and Δ rpoS populations reached a maximum cell density of 6 to 8 log CFU/mL in 24 to 30 h in amended and unamended soil extracts and remained in stationary phase for up to 4 days. Salmonella newport in amended soil extracts exhibited a decreased lag phase (λ , 2.87 ± 1.01 h) and greater maximum cell densities ( Nmax, 6.84 ± 1.25 CFU/mL) compared with λ (20.10 ± 9.53 h) and Nmax (5.22 ± 0.82 CFU/mL) in unamended soil extracts. In amended soil extract, the Δ rpoS strain had no measurable λ , similar growth rates (μmax) compared with WT, and a lower Nmax compared with the WT strain. Unamended, nonsterile soil extracts did not support the growth of Salmonella newport WT and led to a decline in populations for the Δ rpoS strain. Salmonella newport had lower cell densities in nonsterile soil extracts (5.94 ± 0.95 CFU/mL) than it did in sterile soil extracts (6.66 ± 1.50 CFU/mL), potentially indicating competition for nutrients between indigenous microbes and Salmonella newport. The most favorable growth conditions were provided by amended sterile and nonsterile soil extracts, followed by sterile, unamended soil extracts for both Salmonella newport strains. Salmonella newport may grow to greater densities in amended extracts, providing a route for increased Salmonella levels in the growing environments of produce.
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survival of Salmonella newport on whole and fresh cut cucumbers treated with lytic bacteriophages
Journal of Food Protection, 2017Co-Authors: Manan Sharma, Esmond Nyarko, Shirley A Micallef, Gwendolyn Dashiell, Eric T Handy, Cheryl East, Russell Reynnells, Chanelle White, Fawzy Hashem, Patricia D MillnerAbstract:ABSTRACT Salmonella enterica associated with consumption of cucumbers (Cucumis sativus) has led to foodborne outbreaks in the United States. Whole and fresh-cut cucumbers are susceptible to S. ente...
Jianghong Meng - One of the best experts on this subject based on the ideXlab platform.
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antimicrobial susceptibility virulence gene profiles and molecular subtypes of Salmonella newport isolated from humans and other sources
Infection Genetics and Evolution, 2015Co-Authors: Dai Kuang, Jianghong Meng, Xiaowei Yang, Huiming Jin, Weimin Shi, Haijian Pan, Ming Liao, Xianmin Shi, Jianmin ZhangAbstract:Salmonella newport (S. newport) is a major serotype associated with human salmonellosis. A total of 79 S. newport recovered from humans and other sources in China were characterized for antimicrobial susceptibility, virulence gene profiles and molecular subtypes using pulsed field gel electrophoresis (PFGE). Approximately 63.3% of the isolates were susceptible to all of 16 antimicrobials tested. Nearly one third of the isolates (31.6%) were resistant to sulfisoxazole, 20.3% to tetracycline and 13.9% to nalidixic acid. Twelve isolates (15.2%) were resistant to three or more antimicrobials. Among 10 virulence genes detected, Salmonella pathogenicity island genes avrA, ssaQ, mgtC, siiD, and sopB and fimbrial gene bcfC were present in most of the isolates (93.7% to 100%). Overall, we observed nine distinct virulence gene profiles, three of which (VP1, VP2 and VP3) were most common (86.1%). A total of 56 PFGE patterns were identified and mainly grouped into seven clusters (A to G) with 80% pattern similarity. Isolates from aquatic product shared a high similarity with those from humans in several clusters, highlighting a potential risk of aquatic product as a source of S. newport that infect humans. Furthermore, there was a strong association between certain PFGE clusters and virulence gene profiles, suggesting virulence subtyping can be a useful epidemiological tool to discriminate S. newport isolates.
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genetic diversity of Salmonella pathogenicity islands spi 5 and spi 6 in Salmonella newport
Foodborne Pathogens and Disease, 2014Co-Authors: Guojie Cao, Marc W Allard, Errol Strain, Robert Stones, Shaohua Zhao, Eric W Brown, Jianghong MengAbstract:Abstract Salmonella enterica subspecies enterica serotype newport is one of the common serotypes causing foodborne salmonellosis outbreaks in the United States. Salmonella newport consists of three lineages exhibiting extensive genetic diversity. Due to the importance of Salmonella pathogenicity islands 5 and 6 (SPI-5 and SPI-6) in virulence of pathogenic Salmonella, the genetic diversity of these two SPIs may relate to different potentials of Salmonella newport pathogenicity. Most Salmonella newport strains from North America belong to Salmonella newport lineages II and III. A total 28 Salmonella newport strains of lineages II and III from diverse sources and geographic locations were analyzed, and 11 additional Salmonella genomes were used as outgroup in phylogenetic analyses. SPI-5 was identified in all Salmonella newport strains and 146 single nucleotide polymorphisms (SNPs) were detected. Thirty-nine lineage-defining SNPs were identified, including 18 nonsynonymous SNPs. Two 40-kb genomic islands (SP...
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phylogenetics and differentiation of Salmonella newport lineages by whole genome sequencing
PLOS ONE, 2013Co-Authors: Guojie Cao, Errol Strain, Robert Stones, Shaohua Zhao, Eric W Brown, Jianghong Meng, Patrick F Mcdermott, James B Pettengill, Marc W AllardAbstract:Salmonella newport has ranked in the top three Salmonella serotypes associated with foodborne outbreaks from 1995 to 2011 in the United States. In the current study, we selected 26 S. newport strains isolated from diverse sources and geographic locations and then conducted 454 shotgun pyrosequencing procedures to obtain 16–24 × coverage of high quality draft genomes for each strain. Comparative genomic analysis of 28 S. newport strains (including 2 reference genomes) and 15 outgroup genomes identified more than 140,000 informative SNPs. A resulting phylogenetic tree consisted of four sublineages and indicated that S. newport had a clear geographic structure. Strains from Asia were divergent from those from the Americas. Our findings demonstrated that analysis using whole genome sequencing data resulted in a more accurate picture of phylogeny compared to that using single genes or small sets of genes. We selected loci around the mutS gene of S. newport to differentiate distinct lineages, including those between invH and mutS genes at the 3′ end of Salmonella Pathogenicity Island 1 (SPI-1), ste fimbrial operon, and Clustered, Regularly Interspaced, Short Palindromic Repeats (CRISPR) associated-proteins (cas). These genes in the outgroup genomes held high similarity with either S. newport Lineage II or III at the same loci. S. newport Lineages II and III have different evolutionary histories in this region and our data demonstrated genetic flow and homologous recombination events around mutS. The findings suggested that S. newport Lineages II and III diverged early in the serotype evolution and have evolved largely independently. Moreover, we identified genes that could delineate sublineages within the phylogenetic tree and that could be used as potential biomarkers for trace-back investigations during outbreaks. Thus, whole genome sequencing data enabled us to better understand the genetic background of pathogenicity and evolutionary history of S. newport and also provided additional markers for epidemiological response.
Patricia D Millner - One of the best experts on this subject based on the ideXlab platform.
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survival and growth of wild type and rpos deficient Salmonella newport strains in soil extracts prepared with heat treated poultry pellets
Journal of Food Protection, 2019Co-Authors: Manoj K Shah, Esmond Nyarko, Rhodel Bradshaw, Patricia D Millner, Deborah A Neher, Thomas R Weicht, Teresa M Bergholz, Manan SharmaAbstract:Manure runoff can transfer pathogens to farmlands or to water sources, leading to subsequent contamination of produce. Untreated biological soil amendments, like manure, can be contaminated with foodborne pathogens, such as Salmonella newport, which may lead to transfer of the pathogen to fruits or vegetables. Studies have reported the occurrence and survival of Salmonella in manure or manure slurries. However, data on the survival and growth of Salmonella newport is lacking in matrices simulating runoff. We quantified the survival and growth of wild-type (WT) Salmonella newport and rpoS-deficient (Δ rpoS) strains in sterile and nonsterile soil extracts prepared with (amended) or without (unamended) heat-treated poultry pellets at 25°C. Salmonella newport WT and Δ rpoS populations reached a maximum cell density of 6 to 8 log CFU/mL in 24 to 30 h in amended and unamended soil extracts and remained in stationary phase for up to 4 days. Salmonella newport in amended soil extracts exhibited a decreased lag phase (λ , 2.87 ± 1.01 h) and greater maximum cell densities ( Nmax, 6.84 ± 1.25 CFU/mL) compared with λ (20.10 ± 9.53 h) and Nmax (5.22 ± 0.82 CFU/mL) in unamended soil extracts. In amended soil extract, the Δ rpoS strain had no measurable λ , similar growth rates (μmax) compared with WT, and a lower Nmax compared with the WT strain. Unamended, nonsterile soil extracts did not support the growth of Salmonella newport WT and led to a decline in populations for the Δ rpoS strain. Salmonella newport had lower cell densities in nonsterile soil extracts (5.94 ± 0.95 CFU/mL) than it did in sterile soil extracts (6.66 ± 1.50 CFU/mL), potentially indicating competition for nutrients between indigenous microbes and Salmonella newport. The most favorable growth conditions were provided by amended sterile and nonsterile soil extracts, followed by sterile, unamended soil extracts for both Salmonella newport strains. Salmonella newport may grow to greater densities in amended extracts, providing a route for increased Salmonella levels in the growing environments of produce.
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survival of Salmonella newport on whole and fresh cut cucumbers treated with lytic bacteriophages
Journal of Food Protection, 2017Co-Authors: Manan Sharma, Esmond Nyarko, Shirley A Micallef, Gwendolyn Dashiell, Eric T Handy, Cheryl East, Russell Reynnells, Chanelle White, Fawzy Hashem, Patricia D MillnerAbstract:ABSTRACT Salmonella enterica associated with consumption of cucumbers (Cucumis sativus) has led to foodborne outbreaks in the United States. Whole and fresh-cut cucumbers are susceptible to S. ente...
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in situ evaluation of paenibacillus alvei in reducing carriage of Salmonella enterica serovar newport on whole tomato plants
Applied and Environmental Microbiology, 2014Co-Authors: Errol Strain, Eric W Brown, Patricia D Millner, Sarah M Allard, Alexander S Enurah, Steven L Rideout, Jie ZhengAbstract:Recently, tomatoes have been implicated as a primary vehicle in food-borne outbreaks of Salmonella enterica serovar newport and other Salmonella serovars. Long-term intervention measures to reduce Salmonella prevalence on tomatoes remain elusive for growing and postharvest environments. A naturally occurring bacterium identified by 16S rRNA gene sequencing as Paenibacillus alvei was isolated epiphytically from plants native to the Virginia Eastern Shore tomato-growing region. After initial antimicrobial activity screening against Salmonella and 10 other bacterial pathogens associated with the human food supply, strain TS-15 was further used to challenge an attenuated strain of S. newport on inoculated fruits, leaves, and blossoms of tomato plants in an insect-screened high tunnel with a split-plot design. Survival of Salmonella after inoculation was measured for groups with and those without the antagonist at days 0, 1, 2, and 3 and either day 5 for blossoms or day 6 for fruits and leaves. Strain TS-15 exhibited broad-range antimicrobial activity against both major food-borne pathogens and major bacterial phytopathogens of tomato. After P. alvei strain TS-15 was applied onto the fruits, leaves, and blossoms of tomato plants, the concentration of S. newport declined significantly (P ≤ 0.05) compared with controls. Astonishingly, >90% of the plants had no detectable levels of Salmonella by day 5 for blossoms. The naturally occurring antagonist strain TS-15 is highly effective in reducing the carriage of Salmonella newport on whole tomato plants. The application of P. alvei strain TS-15 is a promising approach for reducing the risk of Salmonella contamination during tomato production.
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effectiveness of cleaners and sanitizers in killing Salmonella newport in the gut of a free living nematode caenorhabditis elegans
Journal of Food Protection, 2004Co-Authors: Stephen J Kenney, Patricia D Millner, Gary L Anderson, Phillip L Williams, Larry R BeuchatAbstract:Caenorhabditis elegans, a free-living nematode found in soil, has been shown to ingest human enteric pathogens, thereby potentially serving as a vector for preharvest contamination of fruits and vegetables. A study was undertaken to evaluate the efficacy of cleaners and sanitizers in killing Salmonella enterica serotype newport in the gut of C. elegans. Adult worms were fed nalidixic acid-adapted cells of Escherichia coli OP50 (control) or Salmonella newport for 24 h, washed, placed on paper discs, and incubated at temperatures of 4 or 20 degrees C and relative humidities of 33 or 98% for 24 h. Two commercial cleaners (Enforce and K Foam Lo) and four sanitizers (2% acetic acid, 2% lactic acid, Sanova, and chlorine [50 and 200 microg/ml]) were applied to worms for 0, 2, or 10 min. Populations of E. coli and Salmonella newport (CFU per worm) in untreated and treated worms were determined by sonicating worms in 0.1% peptone and surface plating suspensions of released cells on tryptic soy agar containing nalidixic acid. Populations of Salmonella newport in worms exposed to 33 or 98% relative humidity at 4 degrees or 33% relative humidity at 20 degrees C were significantly (P < or = 0.05) lower than the number surviving exposure to 98% relative humidity at 20 degrees C. In general, treatment of desiccated worms with cleaners and sanitizers was effective in significantly (P < or = 0.05) reducing the number of ingested Salmonella newport. Results indicate that temperature and relative humidity influence the survival of Salmonella newport in the gut of C. elegans, and cleaners and sanitizers may not eliminate the pathogen.
