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2. Multi-laboratory validation study of a real-time PCR method for detection of Salmonella in baby spinach

Author

Deng, Kaiping, primary, Wang, Shizhen Steven, additional, Kiener, Shannon, additional, Smith, Emily, additional, Chen, Kai-Shun, additional, Pamboukian, Ruiqing, additional, Laasri, Anna, additional, Pelaez, Catalina, additional, Ulaszek, Jodie, additional, Kmet, Matthew, additional, De Jesus, Antonio, additional, Hammack, Thomas, additional, Reddy, Ravinder, additional, and Wang, Hua, additional

Published
2023
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3. Survey of Foodborne Pathogens, Aerobic Plate Counts, Total Coliform Counts, and Escherichia coli Counts in Leafy Greens, Sprouts, and Melons Marketed in the United States

Author

Zhang, Guodong, primary, Chen, Yi, additional, Hu, Lijun, additional, Melka, David, additional, Wang, Hua, additional, Laasri, Anna, additional, Brown, Eric W., additional, Strain, Errol, additional, Allard, Marc, additional, Bunning, Vincent K., additional, Parish, Mickey, additional, Musser, Steven M., additional, and Hammack, Thomas S., additional

Published
2018
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5. Enumeration and characterization of Listeria monocytogenes in novelty ice cream samples manufactured on a specific production line linked to a listeriosis outbreak

Author

Burall, Laurel S., primary, Chen, Yi, additional, Macarisin, Dumitru, additional, Pouillot, Regis, additional, Strain, Errol, additional, De Jesus, Antonio J., additional, Laasri, Anna, additional, Wang, Hua, additional, Ali, Laila, additional, Tatavarthy, Aparna, additional, Zhang, Guodong, additional, Hu, Lijun, additional, Day, James, additional, Kang, Jihun, additional, Sahu, Surasri, additional, Grim, Christopher J., additional, Srinivasan, Devayani, additional, Parish, Mickey, additional, Evans, Peter S., additional, Brown, Eric W., additional, Hammack, Thomas S., additional, Zink, Don, additional, and Datta, Atin R., additional

Published
2017
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7. Prevalence of Salmonella in Cashews, Hazelnuts, Macadamia Nuts, Pecans, Pine Nuts, and Walnuts in the United States

Author

Zhang, Guodong, primary, Hu, Lijun, additional, Melka, David, additional, Wang, Hua, additional, Laasri, Anna, additional, Brown, Eric W., additional, Strain, Errol, additional, Allard, Marc, additional, Bunning, Vincent K., additional, Musser, Steven M., additional, Johnson, Rhoma, additional, Farakos, Sofia M.Santillana, additional, Scott, Virginia N., additional, Pouillot, Régis, additional, Van Doren, Jane M., additional, and Hammack, Thomas S., additional

Published
2017
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8. Comparative evaluation of direct plating and most probable number for enumeration of low levels of Listeria monocytogenes in naturally contaminated ice cream products

Author

Chen, Yi, primary, Pouillot, Régis, additional, S. Burall, Laurel, additional, Strain, Errol A., additional, Van Doren, Jane M., additional, De Jesus, Antonio J., additional, Laasri, Anna, additional, Wang, Hua, additional, Ali, Laila, additional, Tatavarthy, Aparna, additional, Zhang, Guodong, additional, Hu, Lijun, additional, Day, James, additional, Sheth, Ishani, additional, Kang, Jihun, additional, Sahu, Surasri, additional, Srinivasan, Devayani, additional, Brown, Eric W., additional, Parish, Mickey, additional, Zink, Donald L., additional, Datta, Atin R., additional, Hammack, Thomas S., additional, and Macarisin, Dumitru, additional

Published
2017
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9. Listeria monocytogenes in Stone Fruits Linked to a Multistate Outbreak: Enumeration of Cells and Whole-Genome Sequencing

Author

Chen, Yi, primary, Burall, Laurel S., additional, Luo, Yan, additional, Timme, Ruth, additional, Melka, David, additional, Muruvanda, Tim, additional, Payne, Justin, additional, Wang, Charles, additional, Kastanis, George, additional, Maounounen-Laasri, Anna, additional, De Jesus, Antonio J., additional, Curry, Phillip E., additional, Stones, Robert, additional, K'Aluoch, Okumu, additional, Liu, Eileen, additional, Salter, Monique, additional, Hammack, Thomas S., additional, Evans, Peter S., additional, Parish, Mickey, additional, Allard, Marc W., additional, Datta, Atin, additional, Strain, Errol A., additional, and Brown, Eric W., additional

Published
2016
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10. Prevalence and Level of Listeria monocytogenes in Ice Cream Linked to a Listeriosis Outbreak in the United States

Author

Chen, Yi, primary, Burall, Laurel S., additional, MaCarisin, Dumitru, additional, Pouillot, Régis, additional, Strain, Errol, additional, De Jesus, Antonio J., additional, Laasri, Anna, additional, Wang, Hua, additional, Ali, Laila, additional, Tatavarthy, Aparna, additional, Zhang, Guodong, additional, Hu, Lijun, additional, Day, James, additional, Kang, Jihun, additional, Sahu, Surasri, additional, Srinivasan, Devayani, additional, Klontz, Karl, additional, Parish, Mickey, additional, Evans, Peter S., additional, Brown, Eric W., additional, Hammack, Thomas S., additional, Zink, Donald L., additional, and Datta, Atin R., additional

Published
2016
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14. Survey of Foodborne Pathogens, Aerobic Plate Counts, Total Coliform Counts, and Escherichia coli Counts in Leafy Greens, Sprouts, and Melons Marketed in the United States.

Author

GUODONG ZHANG, YI CHEN, LIJUN HU, DAVID MELKA, HUAWANG, LAASRI, ANNA, BROWN, ERIC W., STRAIN, ERROL, ALLARD, MARC, BUNNING, VINCENT K., PARISH, MICKEY, MUSSER, STEVEN M., and HAMMACK, THOMAS S.

Subjects
FOOD pathogens, COLIFORMS, ESCHERICHIA coli, SPROUTS, VEROCYTOTOXINS
Abstract

The objective of this research was to assess the microbiological status of leafy greens, sprouts, and melons from U.S. markets. A total of 14,183 samples of leafy greens, 2,652 samples of sprouts, and 3,411 samples of melons were collected throughout the United States from 2009 to 2014. The samples were analyzed for aerobic plate counts, total coliform counts, Escherichia coli counts, and the presence and levels of Salmonella, Shigella, Listeria monocytogenes, and Shiga toxin--producing E. coli (STEC), depending on the year and type of produce. Among the leafy greens, no E. coli O157:H7 or non-O157 STEC were detected from iceberg lettuce samples. The overall prevalences of Salmonella, E. coli O157:H7, non-O157 STEC, and L. monocytogenes in the 14,183 samples of leafy greens were 0.05, 0.01, 0.07, and 0.11%, respectively. Among sprout samples, no Salmonella or E. coli O157:H7 was detected, and the overall prevalences of non-O157 STEC and L. monocytogenes were 0.04 and 0.11%, respectively. Among melon samples, no Salmonella was detected from cucumbers, no L. monocytogenes was detected from cantaloupes, and the overall prevalences of Salmonella and L. monocytogenes were 0.12 and 0.23%, respectively. L. monocytogenes levels were 0.4 to 1,470 most probable number (MPN)/g in leafy greens, 0.36 to 1,100 MPN/g in sprouts, and <0.03 to 150 MPN/g in melons, and most positive samples had low levels of these pathogens. The isolates from these foods were very diverse genetically. Foodborne pathogens, including Salmonella, STEC, and L. monocytogenes, had relatively low prevalences in the produce surveyed. Because these foods are usually consumed raw, measures should be taken to significantly minimize the presence and levels of human pathogens. [ABSTRACT FROM AUTHOR]

Published
2018
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15. Complete Genome Sequence of Salmonella enterica subsp. enterica serovarMinnesota Strain.

Author

Hua Wang, Hoffmann, Maria, Laasri, Anna, Jacobson, Andrew P., Melka, David, Curry, Phillip E., Hammack, Thomas S., and Jie Zheng

Subjects
FOOD pathogens, SALMONELLA enterica, MANGO, NUCLEOTIDE sequencing, BACTERIAL genomes
Abstract

Mango has been implicated as food vehicle in several Salmonella-causing foodborne outbreaks. Here, Salmonella enterica subsp. enterica serovarMinnesotawas isolated fromfresh mango fruit imported fromMexico in 2014. The complete genome sequence of S. Minnesota CFSAN017963 was sequenced using single-molecule real-time DNA sequencing. Distinct prophage regions, Salmonella pathogenicity islands, and fimbrial gene clusters were observed in comparative genomic analysis on S. Minnesota CFSAN017963with other phylogenetically closely related Salmonella serovars. Core genomemultilocus sequencing typing analysis of all the S.Minnesota isolates in theGenbank and Enterobase also revealed a high genomic diversity among the genomes analyzed. [ABSTRACT FROM AUTHOR]

Published
2017
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16. Draft Genome Sequence of Salmonella enterica subsp. enterica Serovar Give, Isolated from an Imported Chili Powder Product

Author

Wang, Hua, primary, Chen, Yi, additional, Ayers, Sherry, additional, Melka, David, additional, Laasri, Anna, additional, Payne, Justin S., additional, Zheng, Jie, additional, Son, Insook, additional, Timme, Ruth, additional, Kastanis, George, additional, Hammack, Thomas S., additional, Strain, Errol, additional, Allard, Marc W., additional, Evans, Peter S., additional, and Brown, Eric W., additional

Published
2015
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18. Prevalence and Level of Listeria monocytogenes in Ice Cream Linked to a Listeriosis Outbreak in the United States.

Author

YI CHEN, BURALL, LAUREL S., MACARISIN, DUMITRU, POUILLOT, RÉGIS, STRAIN, ERROL, DE JESUS, ANTONIO J., LAASRI, ANNA, HUA WANG, ALI, LAILA, TATAVARTHY, APARNA, GUODONG ZHANG, LIJUN HU, DAY, JAMES, JIHUN KANG, SAHU, SURASRI, SRINIVASAN, DEVAYANI, KLONTZ, KARL, PARISH, MICKEY, EVANS, PETER S., and BROWN, ERIC W.

Subjects
ICE cream, ices, etc., FOOD contamination, FOODBORNE diseases, LISTERIA monocytogenes, FOOD pathogens, PUBLIC health, DISEASE risk factors
Abstract

A most-probable-number (MPN) method was used to enumerate Listeria monocytogenes in 2,320 commercial ice cream scoops manufactured on a production line that was implicated in a 2015 listeriosis outbreak in the United States. The analyzed samples were collected from seven lots produced in November 2014, December 2014, January 2015, and March 2015. L. monocytogenes was detected in 99% (2,307 of 2,320) of the tested samples (lower limit of detection, 0.03 MPN/g), 92% of which were contaminated at <20 MPN/g. The levels of L. monocytogenes in these samples had a geometric mean per lot of 0.15 to 7.1 MPN/g. The prevalence and enumeration data from an unprecedented large number of naturally contaminated ice cream products linked to a listeriosis outbreak provided a unique data set for further understanding the risk associated with L. monocytogenes contamination for highly susceptible populations. [ABSTRACT FROM AUTHOR]

Published
2016
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20. Survey of Foodborne Pathogens, Aerobic Plate Counts, Total Coliform Counts, and Escherichia coliCounts in Leafy Greens, Sprouts, and Melons Marketed in the United States

Author

Zhang, Guodong, Chen, Yi, Hu, Lijun, Melka, David, Wang, Hua, Laasri, Anna, Brown, Eric W., Strain, Errol, Allard, Marc, Bunning, Vincent K., Parish, Mickey, Musser, Steven M., and Hammack, Thomas S.

Abstract

The objective of this research was to assess the microbiological status of leafy greens, sprouts, and melons from U.S. markets. A total of 14,183 samples of leafy greens, 2,652 samples of sprouts, and 3,411 samples of melons were collected throughout the United States from 2009 to 2014. The samples were analyzed for aerobic plate counts, total coliform counts, Escherichia colicounts, and the presence and levels of Salmonella, Shigella, Listeria monocytogenes,and Shiga toxin–producing E. coli(STEC), depending on the year and type of produce. Among the leafy greens, no E. coliO157:H7 or non-O157 STEC were detected from iceberg lettuce samples. The overall prevalences of Salmonella, E. coliO157:H7, non-O157 STEC, and L. monocytogenesin the 14,183 samples of leafy greens were 0.05, 0.01, 0.07, and 0.11%, respectively. Among sprout samples, no Salmonellaor E. coliO157:H7 was detected, and the overall prevalences of non-O157 STEC and L. monocytogeneswere 0.04 and 0.11%, respectively. Among melon samples, no Salmonellawas detected from cucumbers, no L. monocytogeneswas detected from cantaloupes, and the overall prevalences of Salmonellaand L. monocytogeneswere 0.12 and 0.23%, respectively. L. monocytogeneslevels were 0.4 to 1,470 most probable number (MPN)/g in leafy greens, 0.36 to 1,100 MPN/g in sprouts, and <0.03 to 150 MPN/g in melons, and most positive samples had low levels of these pathogens. The isolates from these foods were very diverse genetically. Foodborne pathogens, including Salmonella,STEC, and L. monocytogenes,had relatively low prevalences in the produce surveyed. Because these foods are usually consumed raw, measures should be taken to significantly minimize the presence and levels of human pathogens.

Published
2018
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22. Recovery and Growth Potential of Listeria monocytogenes in Temperature Abused Milkshakes Prepared from Naturally Contaminated Ice Cream Linked to a Listeriosis Outbreak.

Author

Yi Chen, Allard, Emma, Wooten, Anna, Hur, Minji, Sheth, Ishani, Laasri, Anna, Hammack, Thomas S., Macarisin, Dumitru, Valero, Antonio, and Lianou, Alexandra

Subjects
BACTERIAL growth, LISTERIA monocytogenes, MILKSHAKES
Abstract

The recovery and growth potential of Listeria monocytogenes was evaluated in three flavors of milkshakes (vanilla, strawberry, and chocolate) that were prepared from naturally contaminated ice cream linked to a listeriosis outbreak in the U.S. in 2015, and were subsequently held at room temperature for 14 h. The average lag phase duration of L. monocytogenes was 9.05 h; the average generation time was 1.67 h; and the average population level increase per sample at 14 h was 1.14 log CFU/g. Milkshake flavors did not significantly affect these parameters. The average lag phase duration of L. monocytogenes in milkshakes with initial contamination levels 3 CFU/g (9.50 h) was significantly longer (P < 0.01) than that with initial contamination levels > 3 CFU/g (8.60 h). The results highlight the value of using samples that are contaminated with very low levels of L. monocytogenes for recovery and growth evaluations. The behavior of L. monocytogenes populations in milkshakes prepared from naturally contaminated ice cream linked to the listeriosis outbreak should be taken into account when performing risk based analysis using this outbreak as a case study. [ABSTRACT FROM AUTHOR]

Published
2016
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24. Prevalence of Salmonellain Cashews, Hazelnuts, Macadamia Nuts, Pecans, Pine Nuts, and Walnuts in the United States

Author

Zhang, Guodong, Hu, Lijun, Melka, David, Wang, Hua, Laasri, Anna, Brown, Eric W., Strain, Errol, Allard, Marc, Bunning, Vincent K., Musser, Steven M., Johnson, Rhoma, Farakos, Sofia M.Santillana, Scott, Virginia N., Pouillot, Régis, Van Doren, Jane M., and Hammack, Thomas S.

Abstract

Nuts have been identified as a vector for salmonellosis. The objective of this project was to estimate the prevalence and contamination level of Salmonellain raw tree nuts (cashews, pecans, hazelnuts, macadamia nuts, pine nuts, and walnuts) at retail markets in the United States. A total of 3,656 samples of six types of tree nuts were collected from different types of retail stores and markets nationwide between October 2014 and October 2015. These samples were analyzed using a modified version of the Salmonellaculture method from the U.S. Food and Drug Administration's Bacteriological Analytical Manual. Of the 3,656 samples collected and tested, 32 were culturally confirmed as containing Salmonella. These isolates represented 25 serotypes. Salmonellawas not detected in pecans and in-shell hazelnuts. Salmonellaprevalence estimates (and 95% confidence intervals) in cashews, shelled hazelnuts, pine nuts, walnuts, and macadamia nuts were 0.55% [0.15, 1.40], 0.35% [0.04, 1.20], 0.48% [0.10, 1.40], 1.20% [0.53, 2.40], and 4.20% [2.40, 6.90], respectively. The rates of Salmonellaisolation from major or big chain supermarkets, small chain supermarkets, discount, variety, or drug stores, and online were 0.64% [0.38, 1.00], 1.60% [0.80, 2.90], 0.00% [0.00, 2.40], and 13.64% [2.90, 35.00], respectively (Cochran-Mantel-Haenszel test: P= 0.02). The rates of Salmonellaisolation for conventional and organic nuts were not significantly different. Of the samples containing Salmonella,60.7% had levels less than 0.003 most probable number (MPN)/g. The highest contamination level observed was 0.092 MPN/g. The prevalence and levels of Salmonellain these tree nut samples were comparable to those previously reported for similar foods.

Published
2017
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25. Prevalence and Level of Listeria monocytogenesin Ice Cream Linked to a Listeriosis Outbreak in the United States

Author

Chen, Yi, Burall, Laurel S., MaCarisin, Dumitru, Pouillot, Régis, Strain, Errol, De Jesus, Antonio J., Laasri, Anna, Wang, Hua, Ali, Laila, Tatavarthy, Aparna, Zhang, Guodong, Hu, Lijun, Day, James, Kang, Jihun, Sahu, Surasri, Srinivasan, Devayani, Klontz, Karl, Parish, Mickey, Evans, Peter S., Brown, Eric W., Hammack, Thomas S., Zink, Donald L., and Datta, Atin R.

Abstract

A most-probable-number (MPN) method was used to enumerate Listeria monocytogenesin 2,320 commercial ice cream scoops manufactured on a production line that was implicated in a 2015 listeriosis outbreak in the United States. The analyzed samples were collected from seven lots produced in November 2014, December 2014, January 2015, and March 2015. L. monocytogeneswas detected in 99% (2,307 of 2,320) of the tested samples (lower limit of detection, 0.03 MPN/g), 92% of which were contaminated at <20 MPN/g. The levels of L. monocytogenesin these samples had a geometric mean per lot of 0.15 to 7.1 MPN/g. The prevalence and enumeration data from an unprecedented large number of naturally contaminated ice cream products linked to a listeriosis outbreak provided a unique data set for further understanding the risk associated with L. monocytogenescontamination for highly susceptible populations.

Published
2016
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26. Rapid Identification of Shiga Toxin–Producing Escherichia coliO Serogroups from Fresh Produce and Raw Milk Enrichment Cultures by Luminex Bead–Based Suspension Array

Author

Kase, Julie A., Maounounen-Laasri, Anna, and Lin, Andrew

Abstract

The U.S. Food and Drug Administration's Bacteriological Analytical Manual(BAM) Chapter 4a describes a Luminex microbead–based suspension array used to screen colonies for 11 clinically relevant Shiga toxin–producing Escherichia coli(STEC) serogroups: O26, O45, O91, O103, O104, O111, O113, O121, O128, O145, and O157. We evaluated the usefulness of this method to identify STEC-positive enrichment samples before agar plating. Twelve E. colistrains were added to three types of fresh produce (bagged baby spinach, alfalfa sprouts, and cilantro) at levels near the detection limit of the test. A subset of these strains (six O serogroups) was similarly evaluated in raw milk. For comparison, portions of each of the 168 enrichment cultures were analyzed for serogroup by a real-time PCR assay and a Bio-Plex 200 assay with the bead-based suspensions. No false-positive results were obtained. Of the 112 samples with a reported cycle threshold (CT) value, 101 undiluted, diluted, or extracted enrichment cultures also produced ratios above 5.0 in the Bio-Plex assay. When PCR CTvalues approached or were greater than 35, Bio-Plex detection became less reliable. Using undiluted or extracted enrichment cultures resulted in a significantly larger number of positive results. With the same enrichment material prepared for real-time PCR analysis as described in the BAM Chapter 4a, the STEC microbead-based suspension array can accurately screen food enrichment cultures.

Published
2016
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27. Listeria monocytogenes in Stone Fruits Linked to a Multistate Outbreak: Enumeration of Cells and Whole-Genome Sequencing.

Author

Yi Chen, Burall, Laurel S., Yan Luo, Timme, Ruth, Melka, David, Tim Muruvanda, Payne, Justin, Wang, Charles, Kastanis, George, Maounounen-Laasri, Anna, De Jesus, Antonio J., Curry, Phillip E., Stones, Robert, K'Aluoch, Okumu, Liu, Eileen, Salter, Monique, Hammack, Thomas S., Evans, Peter S., Parish, Mickey, and Allard, Marc W.

Subjects
*LISTERIA monocytogenes, *STONE fruit, *NUCLEOTIDE sequencing, *SINGLE nucleotide polymorphisms, *PULSED-field gel electrophoresis
Abstract

In 2014, the identification of stone fruits contaminated with Listeria monocytogenes led to the subsequent identification of a multistate outbreak. Simultaneous detection and enumeration of L. monocytogenes were performed on 105 fruits, each weighing 127 to 145 g, collected from 7 contaminated lots. The results showed that 53.3% of the fruits yielded L. monocytogenes (lower limit of detection, 5 CFU/fruit), and the levels ranged from 5 to 2,850 CFU/fruit, with a geometric mean of 11.3 CFU/fruit (0.1 CFU/g of fruit). Two serotypes, IVb-v1 and 1/2b, were identified by a combination of PCR- and antiserum-based serotyping among isolates from fruits and their packing environment; certain fruits contained a mixture of both serotypes. Single nucleotide polymorphism (SNP)-based whole-genome sequencing (WGS) analysis clustered isolates from two case-patients with the serotype IVb-v1 isolates and distinguished outbreak-associated isolates from pulsed-field gel electrophoresis (PFGE)-matched, but epidemiologically unrelated, clinical isolates. The outbreak-associated isolates differed by up to 42 SNPs. All but one serotype 1/2b isolate formed another WGS cluster and differed by up to 17 SNPs. Fully closed genomes of isolates from the stone fruits were used as references to maximize the resolution and to increase our confidence in prophage analysis. Putative prophages were conserved among isolates of each WGS cluster. All serotype IVb-v1 isolates belonged to singleton sequence type 382 (ST382); all but one serotype 1/2b isolate belonged to clonal complex 5. [ABSTRACT FROM AUTHOR]

Published
2016
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