Assessing the genome level diversity of Listeria monocytogenes from contaminated ice cream and environmental samples linked to a listeriosis outbreak in the United States

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.

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The use of quantitative polymerase chain reaction for the detection and enumeration of the harmful algaAureococcus anophagefferensin environmental samples along the United States East Coast

Limnology and Oceanography Methods ◽

10.4319/lom.2003.1.92 ◽

2003 ◽

Vol 1 (1) ◽

pp. 92-102 ◽

Cited By ~ 21

Author(s):

Linda C. Popels ◽

S. Craig Cary ◽

David A. Hutchins ◽

Rachel Forbes ◽

Frances Pustizzi ◽

...

Keyword(s):

United States ◽

Polymerase Chain Reaction ◽

Environmental Samples ◽

East Coast ◽

Quantitative Polymerase Chain Reaction ◽

The United States ◽

Chain Reaction ◽

Polymerase Chain

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Listeria monocytogenes in Raw Milk: Detection, Incidence, and Pathogenicity

Journal of Food Protection ◽

10.4315/0362-028x-50.3.188 ◽

1987 ◽

Vol 50 (3) ◽

pp. 188-192 ◽

Cited By ~ 219

Author(s):

J. LOVETT ◽

D. W. FRANCIS ◽

J. M. HUNT

Keyword(s):

United States ◽

Listeria Monocytogenes ◽

Sampling Period ◽

Raw Milk ◽

The United States ◽

Isolation Method ◽

Listeria Species ◽

Adult Mice ◽

Listeria Ivanovii

To determine the incidence of Listeria monocytogenes in raw milk, an isolation method was evaluated and used to analyze milk from three areas of the United States. The incidence varied by area from 0% in California to 7% in Massachusetts, with an overall incidence of 4.2%. The highest incidence found in any area during a single sampling period was 12% in Massachusetts in March 1985. During that same sampling, the incidence for all Listeria species was 26%. Of the 27 L. monocytogenes strains isolated during the survey, 25 were pathogenic in adult mice. One of three Listeria ivanovii isolated was pathogenic. No other isolates demonstrated pathogenicity.

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Salmonella Contamination during Production of Cantaloupe: A Binational Study

Journal of Food Protection ◽

10.4315/0362-028x-67.4.713 ◽

2004 ◽

Vol 67 (4) ◽

pp. 713-720 ◽

Cited By ~ 58

Author(s):

A. CASTILLO ◽

I. MERCADO ◽

L. M. LUCIA ◽

Y. MARTÍNEZ-RUIZ ◽

J. PONCE de LEÓN ◽

...

Keyword(s):

United States ◽

Water Samples ◽

Environmental Samples ◽

Rio Grande Valley ◽

The United States ◽

South Texas ◽

Pcr Analysis ◽

E Coli ◽

Binational Study ◽

Valley Area

Six cantaloupe farms and packing plants in South Texas (950 cantaloupe, 140 water, and 45 environmental samples), including the Rio Grande Valley area, and three farms in Colima State, Mexico (300 cantaloupe, 45 water, and 15 environmental samples), were sampled to evaluate cantaloupe contamination with Salmonella and Escherichia coli during production and processing. Samples collected from external surfaces of cantaloupes, water, and the environments of packing sheds on cantaloupe farms were examined for the presence of Salmonella and E. coli. Of a total of 1,735 samples collected, 31 (1.8%) tested positive for Salmonella. Fifteen Salmonella serotypes were isolated from samples collected in Texas, and nine from samples collected in Colima. Two serotypes (Poona and Oranienburg) that have been associated with three large Salmonella outbreaks in the United States and Canada linked to the consumption of contaminated cantaloupe were found in water samples collected at four farms (three from the United States). Susceptibility of Salmonella isolates to 10 antimicrobials was evaluated by disk diffusion. Eighty-eight percent of the isolates from the United States and Mexico were pansusceptible to the antimicrobials tested; eight isolates from the United States demonstrated an intermediate susceptibility to streptomycin and only two isolates were resistant to the same antimicrobial. From Mexico, four isolates showed an intermediate susceptibility to streptomycin and one isolate was resistant to nalidixic acid and streptomycin. Repetitive sequence-based PCR analysis of Salmonella isolates helped to trace potential sources of Salmonella contamination in source water and in subsequent water samples obtained after the filtration systems of U.S. and Mexican cantaloupe farms. No differences could be seen between the levels of Salmonella contamination in melons from both countries.

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Pulsed-field gel electrophoresis applied for comparing Listeria monocytogenes strains involved in outbreaks

Canadian Journal of Microbiology ◽

10.1139/m93-058 ◽

1993 ◽

Vol 39 (4) ◽

pp. 395-401 ◽

Cited By ~ 80

Author(s):

C. Buchrieser ◽

R. Brosch ◽

B. Catimel ◽

J. Rocourt

Keyword(s):

United States ◽

Listeria Monocytogenes ◽

Gel Electrophoresis ◽

The United States ◽

Pulsed Field Gel Electrophoresis ◽

Chromosomal Dna ◽

Restriction Patterns ◽

Pulsed Field ◽

Dna Restriction Fragments ◽

Dna Restriction

Recent food-borne outbreaks of human listeriosis as well as numerous sporadic cases have been mainly caused by Listeria monocytogenes serovar 4b strains. Thus, it was of interest to find out whether a certain clone or a certain few clones were responsible for these cases and especially for outbreaks., We used pulsed-field gel electrophoresis of large chromosomal DNA restriction fragments generated by ApaI, SmaI, or NotI to analyse 75 L. monocytogenes strains isolated during six major and eight smaller recent listeriosis outbreaks. These strains could be divided into 20 different genomic varieties. Thirteen of 14 strains isolated during major epidemics in Switzerland (1983–1987), the United States (California, 1985) and Denmark (1985–1987) demonstrated indistinguishable DNA restriction patterns. In contrast, strains responsible for the outbreaks in Canada (Nova Scotia, 1981), the United States (Massachusetts, 1983), France (Anjou, 1975–1976), New Zealand (1969), and Austria (1986) and some smaller outbreaks in France (1987, 1988, 1989) were each characterized by particular combinations of DNA restriction patterns. Seventy-seven percent of the tested strains could be classified into the previously described ApaI group A (Brosch et al. 1991), demonstrating a very close genomic relatedness. Because 49% of the epidemic strains selected for this study belonged to phagovar 2389/2425/3274/2671/47/108/340 or 2389/47/108/340, fifty-six additional strains of these phagovars, isolated from various origins, were also typed to determine whether differences in DNA restriction profiles between epidemic and randomly selected strains of the same phagovars could be pointed out. Variations in DNA patterns appeared more frequently within randomly selected strains than within epidemic strains.Key words: Listeria monocytogenes, listeriosis, typing, pulsed-field gel electrophoresis, epidemic.

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Analysis of clinical and food-borne isolates of Listeria monocytogenes in the United States by multilocus enzyme electrophoresis and application of the method to epidemiologic investigations.

Applied and Environmental Microbiology ◽

10.1128/aem.56.7.2133-2141.1990 ◽

1990 ◽

Vol 56 (7) ◽

pp. 2133-2141 ◽

Cited By ~ 95

Author(s):

W F Bibb ◽

B G Gellin ◽

R Weaver ◽

B Schwartz ◽

B D Plikaytis ◽

...

Keyword(s):

United States ◽

Listeria Monocytogenes ◽

The United States ◽

Enzyme Electrophoresis ◽

Multilocus Enzyme Electrophoresis ◽

Food Borne

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Bacillus amyloliquefaciens ALB65 Inhibits the Growth of Listeria monocytogenes on Cantaloupe Melons

Applied and Environmental Microbiology ◽

10.1128/aem.01926-20 ◽

2020 ◽

Vol 87 (1) ◽

Author(s):

Thao D. Tran ◽

Celia Del Cid ◽

Robert Hnasko ◽

Lisa Gorski ◽

Jeffery A. McGarvey

Keyword(s):

United States ◽

Biological Control ◽

Listeria Monocytogenes ◽

Bacillus Amyloliquefaciens ◽

Biological Control Agent ◽

Gene Clusters ◽

The United States ◽

Control Agent ◽

Content Type

ABSTRACT Listeria monocytogenes is a foodborne pathogen that causes high rates of hospitalization and mortality in people infected. Contamination of fresh, ready to eat produce by this pathogen is especially troubling because of the ability of this bacterium to grow on produce under refrigeration temperatures. In this study, we created a library of over 8,000 plant phyllosphere-associated bacteria and screened them for the ability to inhibit the growth of L. monocytogenes in an in vitro fluorescence-based assay. One isolate, later identified as Bacillus amyloliquefaciens ALB65, was able to inhibit the fluorescence of L. monocytogenes by >30-fold in vitro. B. amyloliquefaciens ALB65 was also able to grow, persist, and reduce the growth of L. monocytogenes by >1.5 log CFU on cantaloupe melon rinds inoculated with 5 × 103 CFU at 30°C and was able to completely inhibit its growth at temperatures below 8°C. DNA sequence analysis of the B. amyloliquefaciens ALB65 genome revealed six gene clusters that are predicted to encode genes for antibiotic production; however, no plant or human virulence factors were identified. These data suggest that B. amyloliquefaciens ALB65 is an effective and safe biological control agent for the reduction of L. monocytogenes growth on intact cantaloupe melons and possibly other types of produce. IMPORTANCE Listeria monocytogenes is estimated by the Centers for Disease Control and Prevention and the U.S. Food and Drug Administration to cause disease in approximately 1,600 to 2,500 people in the United States every year. The largest known outbreak of listeriosis in the United States was associated with intact cantaloupe melons in 2011, resulting in 147 hospitalizations and 33 deaths. In this study, we demonstrated that Bacillus amyloliquefaciens ALB65 is an effective biological control agent for the reduction of L. monocytogenes growth on intact cantaloupe melons under both pre- and postharvest conditions. Furthermore, we demonstrated that B. amyloliquefaciens ALB65 can completely inhibit the growth of L. monocytogenes during cold storage (<8°C).

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Comprehensive Survey of Pasteurized Fluid Milk Produced in the United States Reveals a Low Prevalence of Listeria monocytogenes

Journal of Food Protection ◽

10.4315/0362-028x-68.5.973 ◽

2005 ◽

Vol 68 (5) ◽

pp. 973-979 ◽

Cited By ~ 27

Author(s):

CARY FRYE ◽

CATHERINE W. DONNELLY

Keyword(s):

United States ◽

Listeria Monocytogenes ◽

The United States ◽

Assay Method ◽

Chocolate Milk ◽

Milk Samples ◽

Nonfat Milk ◽

Whole Milk ◽

Comprehensive Survey ◽

Fluid Milk

A comprehensive survey was undertaken to generate contemporary data on the prevalence of Listeria monocytogenes in pasteurized fluid milk produced in the United States. Samples (5,519) near the sell-by expiration date were purchased at retail outlets over a 5-week period and analyzed for presence of L. monocytogenes. Products consisted of whole milk, nonfat milk, and chocolate milk packaged in gallon, half gallon, quart, pint, and half-pint containers. Samples were collected from both large and small retail stores in urban and suburban locations in four FoodNet cities (Baltimore, Md., Atlanta, Ga., St. Paul/Minneapolis, Minn., and San Francisco, Calif.). Samples were prescreened for L. monocytogenes by the AOAC-approved rapid Vitek immunodiagnostic assay system, enzyme-linked fluorescent assay method. Positive prescreening samples were cultured according to the Bacteriological Analytical Manual, enumerated for L. monocytogenes with a nine-tube most-probable-number (MPN) procedure, and confirmed by biochemical characterization. The frequency of isolation of L. monocytogenes in these products was 0% (0 of 1,897) in whole milk, 0.05% (1 of 1,846) in nonfat milk, 0% (0 of 1,669) in chocolate milk, and 0% (0 of 107) in other (reduced fat and low fat) milk samples. Overall, L. monocytogenes was confirmed in only 0.018% of pasteurized milk samples (1 of 5,519). Enumeration of the single confirmed positive nonfat milk sample revealed low-level contamination (<0.3 MPN/g), even when sampled 5 days past the expiration of the sell-by date. The results confirm the low frequency of contamination of pasteurized fluid milk products by L. monocytogenes for products sold in the United States and reaffirm the reduction of contamination frequency of fluid milk by L. monocytogenes when compared with earlier estimates from the U.S. Food and Drug Administration Dairy Safety Initiatives Program.

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Evaluation of avocados as a possible source of Listeria monocytogenes infections, United States, 2016–2019

Journal of Food Protection ◽

10.4315/jfp-20-419 ◽

2021 ◽

Author(s):

Mary Pomeroy ◽

Amanda Conrad ◽

James B. Pettengill ◽

Monica McClure ◽

Allison A. Wellman ◽

...

Keyword(s):

United States ◽

Listeria Monocytogenes ◽

Retrospective Review ◽

Odds Ratio ◽

Epidemiological Data ◽

The United States ◽

National Database ◽

Food History ◽

Limited Evidence ◽

History Data

Outbreaks of Listeria monocytogenes (L. monocytogenes) infections have historically been associated with contaminated deli meats, but recent outbreaks have been linked to produce. To date, avocados have not been identified as the source of any outbreaks of L. monocytogenes infections in the United States, but avocado samples have yielded strains that were closely related genetically to clinical L. monocytogenes isolates. To determine whether avocados have been a source of listeriosis, we conducted a retrospective review of epidemiological data for clinical isolates that were genetically related to isolates from avocados. Using a national database, we identified clusters containing clinical and at least one avocado isolate. We then selected clusters based upon isolation dates, cluster and composition size, and available food history data. For each cluster, we assessed whether (1) avocado consumption was higher among case-patients in the cluster than among those with sporadic illnesses, and (2) whether the only food isolates within the cluster were from avocados. If both conditions were met, the link was considered “likely,” if one condition was met the link was considered “possible,” and if neither condition was met evidence was “limited.” Five of fifteen clusters met criteria for assessment. Of these, two were classified as having “limited” evidence for a link to avocados, two as “possible,” and one as “likely.” For the cluster considered “likely”, avocado consumption was significantly higher among case-patients in the cluster compared to sporadic illnesses (Odds ratio: 8.5, 95% CI 1.5-86.5). We identified three clusters that were likely or possibly linked to avocados, suggesting avocados could be a source of listeriosis in the United States. Messaging on safe handling might be warranted for groups at higher risk, but further research is first needed to better characterize the ecology of pathogens on avocados and likelihood of internalization of L. monocytogenes.

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