Quantitative Comparison of Two Enrichment Methods for Isolating Listeria monocytogenes from Inoculated Ice Cream

1989 ◽  
Vol 52 (12) ◽  
pp. 898-900 ◽  
Author(s):  
ANTHONY D. HITCHINS
Keyword(s):  
Listeria Monocytogenes ◽  
Ice Cream ◽  
Quantitative Comparison ◽  
Portion Size ◽  
Alkali Pretreatment ◽  
Department Of Agriculture ◽  
Test Portion ◽  
Order Of Magnitude ◽  
The U.S ◽  
Enrichment Methods

Two enrichment methods for isolating Listeria monocytogenes (the Lovett method, formerly used by the U.S. Food and Drug Administration, and the revised method for the U. S. Department of Agriculture) were compared using 25 g test portions of spiked vanilla ice cream. Both methods were found to be equally sensitive. Prolonging the enrichments to 7 d and the use of alkali pretreatment had no significant effect on the results. Reduction of the test portion size from 25 to 1 g in the revised USDA method decreased the level of sensitivity by an order of magnitude, as expected.

Quantitative Comparison of Two Enrichment Methods for Isolating Listeria monocytogenes from Seafoods

1991 ◽  
Vol 54 (1) ◽  
pp. 7-11 ◽  
Author(s):  
JOSEPH LOVETT ◽  
DAVID W. FRANCIS ◽  
JAMES T. PEELER ◽  
ROBERT M. TWEDT
Keyword(s):  
Listeria Monocytogenes ◽  
Drug Administration ◽  
Clinical Sample ◽  
Quantitative Comparison ◽  
Plate Count ◽  
Department Of Agriculture ◽  
Standard Procedures ◽  
Aerobic Plate Count ◽  
The U.S ◽  
Enrichment Methods

Two enrichment methods that had been used as standard procedures by the U.S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA) were quantitatively compared for their ability to isolate Listeria monocytogenes from seafoods. Cultures of a clinical sample and a seafood isolate were inoculated into raw and cooked shrimp; cultures heated at 57.8°C for 5 min were added to surimi, cooked crabmeat, and cooked shrimp. With the FDA procedure, which used enrichment intervals of 24 h, 48 h, and 7 d, KOH culture treatment and enrichment for 24 h provided no advantage for Listeria recovery. The FDA procedure isolated heated L. monocytogenes from seafoods at a lower level than the USDA method; however, the two methods isolated unheated cells equally well. The greater selectivity of the USDA procedure may offer an advantage for isolating nonheat-stressed Listeria when the aerobic plate count of the product is high.

Comparison of Three Selective Enrichment Methods for the Isolation of Listeria monocytogenes from Naturally Contaminated Foods

1992 ◽  
Vol 55 (12) ◽  
pp. 952-959 ◽  
Author(s):  
PEGGY S. HAYES ◽  
LEWIS M. GRAVES ◽  
B. SWAMINATHAN ◽  
GLORIA W. AJELLO ◽  
GEORGIA B. MALCOLM ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
The Netherlands ◽  
Department Of Agriculture ◽  
Selective Enrichment ◽  
Negative Results ◽  
Sporadic Cases ◽  
Inspection Service ◽  
The U.S ◽  
Enrichment Methods ◽  
Better Than

Three selective enrichment procedures—the U.S. Food and Drug Administration (FDA) method, the U.S. Department of Agriculture (USDA) method, and the Netherlands Government Food Inspection Service (NGFIS) method—were compared for isolating Listeria monocytogenes from contaminated foods. The foods were obtained from the refrigerators of patients with culture-proven listeriosis who were identified through multistate active surveillance in a U.S. population of 19 million. The study was designed to identify foods that may be important in transmission of L. monocytogenes in sporadic cases of human listeriosis. Of 899 foods analyzed by all three methods, 121 were positive for L. monocytogenes by at least one method. The three enrichment methods detected L. monocytogenes in 65% (FDA), 74% (USDA), and 74% (NGFIS) of the foods shown to contain L. monocytogenes. The differences among the three methods were not statistically significant. However, the recovery of L. monocytogenes by a combination of any two methods (USDA-FDA 88%, USDA-NGFIS 91%, FDA-NGFIS 87%) was significantly better than that by one method alone (p < 0.02). The differences among the combinations of methods were not statistically significant. These results suggest that at least two enrichment methods must be used in combination to recover L. monocytogenes from contaminated foods with a success rate near 90%. Correlations were observed between negative results and low (<0.3 CFU/g) level of L. monocytogenes contamination for the USDA (p << 0.001) and NGFIS (p << 0.001) methods. A similar but somewhat weaker association was observed for the FDA method (p < 0.06).

Thermal Inactivation of Listeria monocytogenes in Chicken Gravy

1992 ◽  
Vol 55 (7) ◽  
pp. 492-496 ◽  
Author(s):  
I-PING D. HUANG ◽  
AHMED E. YOUSEF ◽  
ELMER H. MARTH ◽  
M. EILEEN MATTHEWS
Keyword(s):  
Heat Treatment ◽  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Thermal Inactivation ◽  
Refrigerated Storage ◽  
Department Of Agriculture ◽  
Large Numbers ◽  
Z Value ◽  
D Values ◽  
The U.S

Heat resistance of Listeria monocytogenes strains V7 and Scott A in chicken gravy and changes in heat resistance during refrigerated storage were studied. After chicken gravy was made, it was cooled to 40°C, inoculated with 105 CFU L. monocytogenes per ml of gravy, and then stored at 7°C for 10 d. Gravy was heated at 50, 55, 60, and 65°C immediately after inoculation and after 1, 3, 5, and 10 d of refrigerated storage. The D values for strains Scott A and V7 in gravy heated at 50°C at day 0 were 119 and 195 min and at day 10 they were 115 and 119 min, respectively, whereas at 65°C comparable values at day 0 were 0.48 and 0.19 min and at day 10 they were 0.014 and 0.007 min. Heat resistance (expressed as D values) was greater at day 0 than at the end of refrigerated storage. The z values ranged from 3.41 to 6.10°C and were highest at the early stages of chill storage and then decreased at the later stages. Strain V7 was more heat resistant than Scott A at 50°C. Strain Scott A always had a higher z value than did strain V7 at the same storage interval. A heat treatment greater than the 4-D process recommended by the U.S. Department of Agriculture was required to inactivate the large numbers of L. monocytogenes that developed in chicken gravy during refrigerated storage.

Crystal Diagnostics Xpress S Kit for the Rapid Detection of Salmonellaspp. in Selected Food Matrixes

2017 ◽  
Vol 100 (4) ◽  
pp. 1038-1050 ◽  
Author(s):  
Brian Bullard ◽  
Curtis H Stumpf ◽  
Weidong Zhao ◽  
Stephanie Kuzenko ◽  
Gary D Niehaus
Keyword(s):  
Liquid Crystal ◽  
Rapid Detection ◽  
Portion Size ◽  
Third Party ◽  
Rapid Screening ◽  
Salmonella Spp ◽  
Screening Assay ◽  
Department Of Agriculture ◽  
Single Use ◽  
The U.S

Abstract The Crystal Diagnostics (CDx) Xpress S Kit is a rapid-screening assay for Salmonella spp. in whole raw tomatoes, whole chicken carcasses, raw ground beef, raw beef trim, and whole liquid pasteurized eggs with citric acid when present at levels of 1 CFU/portion size. The Xpress S system comprises an automatic CDx Xpress Reader and a single-use CDx BioCassette that incorporates antibody-coupled microspheres and liquid crystal for the selective identification of the intended microbe. In internal evaluations, the CDx Xpress S Kit detected all 142 Salmonella strains tested, including non-enterica subspecies, and excluded all non-Salmonella species assayed. Method-developer studies, as well as a third-party evaluation, demonstrated that 15 h single-stage enrichment permits rapid detection equivalent to the U.S. Department of Agriculture and U.S. Food and Drug Administration reference methods. The results demonstrate that the CDx Xpress S Kit is one of the fastest, most sensitive, and most accurate methods for detecting Salmonella in food matrixes.

Prevalence, Types, and Geographical Distribution of Listeria monocytogenes from a Survey of Retail Queso Fresco and Associated Cheese Processing Plants and Dairy Farms in Sonora, Mexico†

2007 ◽  
Vol 70 (11) ◽  
pp. 2596-2601 ◽  
Author(s):  
R. I. MORENO-ENRIQUEZ ◽  
A. GARCIA-GALAZ ◽  
E. ACEDO-FELIX ◽  
H. GONZALEZ-RIOS ◽  
J. E. CALL ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Environmental Samples ◽  
Northern Region ◽  
Pulsed Field Gel Electrophoresis ◽  
Department Of Agriculture ◽  
Retail Markets ◽  
Processing Plants ◽  
Contact Surfaces ◽  
Inspection Service ◽  
The U.S

In the first part of this study, samples were collected from farms, cheese processing plants (CPPs), and retail markets located in various geographical areas of Sonora, Mexico, over a 12-month period during the summer of 2004 and winter of 2005. Four (all Queso Fresco [QF] from retail markets) of 349 total samples tested positive for Listeria monocytogenes (Lm). Of these four positive samples, three were collected in the northern region and one in the southern region of Sonora. Additionally, two were collected during the winter months, and two were collected during the summer months. For the second part of the study, a total of 39 samples from a farm, a CPP, and retail markets were collected and processed according to a combination of the Norma Oficial Mexicana NOM-143-SSA1-1995.10 method (NOM) and the U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual method, and 27 samples from these same locations were collected and processed according to the U.S. Department of Agriculture Food Safety and Inspection Service method (USDA-FSIS). The NOM-FDA method recovered the pathogen from 6 (15%) of 39 samples (one cheese and five product contact surfaces), while the USDA-FSIS method recovered the pathogen from 5 (18.5%) of 27 samples (all product contact surfaces). In addition, the 40 isolates recovered from the 15 total samples that tested positive for Lm grouped into five distinct pulsotypes that were ca. 60% related, as determined by pulsed-field gel electrophoresis analysis. The results of this study confirmed a 3.4% prevalence of Lm in QF collected from retail markets located in Sonora and no appreciable difference in the effectiveness of either the NOM-FDA or USDA-FSIS method to recover the pathogen from cheese or environmental samples.

scholarly journals Survival of Listeria monocytogenes during Storage of Ready-to-Eat Meat Products Processed by Drying, Fermentation, and/or Smoking

2004 ◽  
Vol 67 (12) ◽  
pp. 2698-2702 ◽  
Author(s):  
STEVEN C. INGHAM ◽  
DENNIS R. BUEGE ◽  
BRENDA K. DROPP ◽  
JILL A. LOSINSKI
Keyword(s):  
Listeria Monocytogenes ◽  
Water Activity ◽  
Room Temperature ◽  
Meat Products ◽  
Department Of Agriculture ◽  
Poultry Products ◽  
Beef Jerky ◽  
The U.S

The survival of Listeria monocytogenes was evaluated on 15 ready-to-eat meat products made using drying, fermentation, and/or smoking. The products were obtained from six processors and included summer sausage, smoked cured beef, beef jerky, snack stick, and pork rind and crackling products. The water activity of the products ranged from 0.27 (pork rinds and cracklings) to 0.98 (smoked cured beef slices). Products were inoculated with a five-strain cocktail of L. monocytogenes, repackaged under either vacuum or air, and then stored either at room temperature (21°C) or under refrigeration (5°C) for 4 to 11 weeks. Numbers of L. monocytogenes fell for all products during storage, ranging from a decrease of 0.8 log CFU on smoked cured beef slices during 11 weeks under vacuum at 5°C to a decrease of 3.3 log CFU on a pork rind product stored 5 weeks under air at 21°C. All of the products tested could be produced under alternative 2 of the U.S. Department of Agriculture regulations mandating control of L. monocytogenes on ready-to-eat meat and poultry products. For many of the products, 1 week of postprocessing storage prior to shipment would act as an effective postlethality treatment and would allow processors to operate under alternative 1 of these regulations.

Recovery of Heat-Stressed Listeria monocytogenes from Experimentally and Naturally Contaminated Shrimp

1990 ◽  
Vol 53 (1) ◽  
pp. 22-25 ◽  
Author(s):  
SUSAN A. McCARTHY ◽  
MILES L. MOTES ◽  
R. MERRILL McPHEARSON
Keyword(s):  
Listeria Monocytogenes ◽  
Drug Administration ◽  
Food And Drug Administration ◽  
New Method ◽  
Department Of Agriculture ◽  
The U.S ◽  
Thermally Stressed

A method was developed to enhance recovery of thermally stressed Listeria monocytogenes from internally contaminated shrimp. Shrimp tail meat was inoculated with 105 L. monocytogenes cells/g and boiled for 1–5 min. Thermally stressed L. monocytogenes cells were recovered following cold enrichment for 3 d without broth. Methods of the Food and Drug Administration and the U.S. Department of Agriculture for isolating L. monocytogenes permitted recovery of the organism from shrimp boiled for 1 min: however, with the new method, L. monocytogenes cells were recovered from shrimp boiled up to 5 min. No Listeria spp. were recovered from naturally contaminated, frozen, imported shrimp after 1 min of boiling.

Effect of Inhibitory Extracts Derived from Liquid Smoke Combined with Postprocess Pasteurization for Control of Listeria monocytogenes on Ready-to-Eat Meats†

2007 ◽  
Vol 70 (12) ◽  
pp. 2749-2756 ◽  
Author(s):  
SARITHA GEDELA ◽  
RACHEL K. GAMBLE ◽  
SUNITA MACWANA ◽  
JOSEPH R. ESCOUBAS ◽  
PETER M. MURIANA
Keyword(s):  
Listeria Monocytogenes ◽  
Shelf Life ◽  
Meat Products ◽  
Radiant Heat ◽  
Department Of Agriculture ◽  
Log Reduction ◽  
Liquid Smoke ◽  
Heat Pasteurization ◽  
Inspection Service ◽  
The U.S

Surface pasteurization was examined in combination with low-phenolic antimicrobial extracts derived from liquid smoke to inhibit and prevent the growth of Listeria monocytogenes during the shelf life of ready-to-eat meats. In preliminary trials with retail frankfurters, one smoke derivative (2-min dip) produced a 0.3-log reduction of L. monocytogenes and a 1-min inbag pasteurization (73.9°C) produced a 2.9-log reduction, whereas a combination of the two treatments produced a 5.3-log reduction that resulted in no detectable Listeria by week 3 under accelerated shelf-life conditions (10°C). In trials with frankfurters manufactured without lactate or diacetate that were treated with a shortened 1-s dip, this smoke extract and one with reduced smoke flavor and color both produced a >4.5-log reduction of L. monocytogenes on frankfurters when heated at 73.9°C for 1 min, with no recoverable Listeria detected for 10 weeks when stored at 6.1°C. When deli turkey breast chubs manufactured without lactate, diacetate, or nitrite were treated with a 1-s dip in combination with radiant-heat pasteurization (270°C), growth of L. monocytogenes was retarded but not prevented. However, in a similar study in which smoke extract treatment of deli turkey breast was combined with in-bag postpackage pasteurization (water submersion at 93.3°C), a 60-, 45-, or even 30-s heat treatment resulted in a 2- to 3-log reduction of L. monocytogenes, with no growth on the meat during 10 weeks of storage at 6.1°C. These findings indicate that reduced-acid low-phenolic antimicrobial liquid smoke derivatives combined with surface pasteurization are capable of reducing or preventing growth of L. monocytogenes to meet the criteria for the U.S. Department of Agriculture Food Safety and Inspection Service Alternative 1 process for ready-to-eat deli meat products manufactured without lactate or diacetate.

Atlas® Listeria monocytogenes LmG2 Detection Assay Using Transcription Mediated Amplification to Detect Listeria monocytogenes in Selected Foods and Stainless Steel Surface

2014 ◽  
Vol 97 (5) ◽  
pp. 1343-1358 ◽  
Author(s):  
Vanessa Bres ◽  
Hua Yang ◽  
Ernie Hsu ◽  
Yan Ren ◽  
Ying Cheng ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Ice Cream ◽  
Food Samples ◽  
Steel Grade ◽  
Stainless Steel Surface ◽  
Dilution Ratio ◽  
Reference Methods ◽  
Detection Assay ◽  
The U.S

Abstract The Atlas Listeria monocytogenes LmG2 Detection Assay, developed by Roka Bioscience Inc., was compared to a reference culture method for seven food types (hot dogs, cured ham, deli turkey, chicken salad, vanilla ice cream, frozen chocolate cream pie, and frozen cheese pizza) and one surface (stainless steel, grade 316). A 125 g portion of deli turkey was tested using a 1:4 food:media dilution ratio, and a 25 g portion for all other foods was tested using 1:9 food:media dilution ratio. The enrichment time and media for Roka's method was 24 to 28 h for 25 g food samples and environmental surfaces, and 44 to 48 h for 125 g at 35 ± 2°C in PALCAM broth containing 0.02 g/L nalidixic acid. Comparison of the Atlas Listeria monocytogenes LmG2 Detection Assay to the reference method required an unpaired approach. For each matrix, 20 samples inoculated at a fractional level and five samples inoculated at a high level with a different strain of Listeria monocytogenes were tested by each method. The Atlas Listeria monocytogenes LmG2 Detection Assay was compared to the Official Methods of Analysis of AOAC INTERNATIONAL 993.12 method for dairy products, the U.S. Department of Agriculture, Food Safety and Inspection Service, Microbiology Laboratory Guidebook 8.08 method for ready-to-eat meat and environmental samples, and the U.S. Food and Drug Administration Bacteriological Analytical Manual, Chapter 10 method for frozen foods. In the method developer studies, Roka's method, at 24 h (or 44 h for 125 g food samples), had 126 positives out of 200 total inoculated samples, compared to 102 positives for the reference methods at 48 h. In the independent laboratory studies, vanilla ice cream, deli turkey and stainless steel grade 316 were evaluated. Roka's method, at 24 h (or 44 h for 125 g food samples), had 64 positives out of 75 total inoculated samples compared to 54 positives for the reference methods at 48 h. The Atlas Listeria monocytogenes LmG2 Detection Assay detected all 50 L. monocytogenes strains that encompassed 13 serotypes across the various lineages and none of the 30 exclusive organisms, including seven other Listeria species. The product consistency and kit stability studies revealed no statistical differences between the three lots tested or to the term of the shelf life. Finally, the robustness study demonstrated no statistical differences when samples were incubated at 33 ± 2°C or 37 ± 2°C, when enrichment aliquots were 1.3 mL or 1.7 mL, or when the samples were analyzed the same day or five days later. Overall the Atlas Listeria monocytogenes LmG2 Detection Assay is statistically equivalent to or better than the reference methods and is robust to the tested variations.

Historical Perspectives on Methodology to Detect Listeria monocytogenes

1988 ◽  
Vol 71 (3) ◽  
pp. 644-646 ◽  
Author(s):  
Catherine W Donnelly
Keyword(s):  
Listeria Monocytogenes ◽  
Meat Products ◽  
Federal Agencies ◽  
Department Of Agriculture ◽  
Historical Perspectives ◽  
Clinical Procedures ◽  
Future Challenges ◽  
Historical Developments ◽  
The U.S

Abstract While recognized as a causative agent of illness in animals and humans for some time, the foodborne role of Listeria monocytogenes is a new and emerging one. This review briefly summarizes the historical developments in methodology used to detect the presence of L. monocytogenes. Although clinical procedures exist, these procedures do not consider isolation of Listeria from heavily contaminated environments. Federal agencies such as the U.S. Food and Drug Administration and the U.S. Department of Agriculture have defined protocols for the isolation of Listeria from dairy and meat products, respectively. Each of these protocols, and current problems common to all methods for the isolation of Listeria from food products, are discussed. Finally, future challenges with respect to improvement in our abilities to recognize, isolate, and rapidly identify Listeria in foods are presented

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