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.

Tracking of Listeria monocytogenes in Smoked Fish Processing Plants†

2004 ◽  
Vol 67 (2) ◽  
pp. 328-341 ◽  
Author(s):  
JOANNE THIMOTHE ◽  
KENDRA KERR NIGHTINGALE ◽  
KEN GALL ◽  
VIRGINIA N. SCOTT ◽  
MARTIN WIEDMANN
Keyword(s):  
Listeria Monocytogenes ◽  
Environmental Samples ◽  
Control Strategies ◽  
Fish Processing ◽  
Smoked Fish ◽  
Plant Environment ◽  
Fish Samples ◽  
Processing Plants ◽  
Raw Fish ◽  
Contact Surfaces

Four smoked fish processing plants were used as a model system to characterize Listeria monocytogenes contamination patterns in ready-to-eat food production environments. Each of the four plants was sampled monthly for approximately 1 year. At each sampling, four to six raw fish and four to six finished product samples were collected from corresponding lots. In addition, 12 to 14 environmental sponge samples were collected several hours after the start of production at sites selected as being likely contamination sources. A total of 234 raw fish, 233 finished products, and 553 environmental samples were tested. Presumptive Listeria spp. were isolated from 16.7% of the raw fish samples, 9.0% of the finished product samples, and 27.3% of the environmental samples. L. monocytogenes was isolated from 3.8% of the raw fish samples (0 to 10%, depending on the plant), 1.3% of the finished product samples (0 to 3.3%), and 12.8% of the environmental samples (0 to 29.8%). Among the environmental samples, L. monocytogenes was found in 23.7% of the samples taken from drains, 4.8% of the samples taken from food contact surfaces, 10.4% of the samples taken from employee contact surfaces (aprons, hands, and door handles), and 12.3% of the samples taken from other nonfood contact surfaces. Listeria spp. were isolated from environmental samples in each of the four plants, whereas L. monocytogenes was not found in any of the environmental samples from one plant. Overall, the L. monocytogenes prevalence in the plant environment showed a statistically significant (P < 0.0001) positive relationship with the prevalence of this organism in finished product samples. Automated EcoRI ribotyping differentiated 15 ribotypes among the 83 L. monocytogenes isolates. For each of the three plants with L. monocytogenes–positive environmental samples, one or two ribotypes seemed to persist in the plant environment during the study period. In one plant, a specific L. monocytogenes ribotype represented 44% of the L. monocytogenes–positive environmental samples and was also responsible for one of the two finished product positives found in this plant. In another plant, a specific L. monocytogenes ribotype persisted in the raw fish handling area. However, this ribotype was never isolated from the finished product area in this plant, indicating that this operation has achieved effective separation of raw and finished product areas. Molecular subtyping methods can help identify plant-specific L. monocytogenes contamination routes and thus provide the knowledge needed to implement improved L. monocytogenes control strategies.

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).

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.

Detection of Listeria spp. Using ACTERO Listeria Enrichment Media

2014 ◽  
Vol 97 (4) ◽  
pp. 1127-1136
Author(s):  
David Claveau ◽  
Sergiy Olishevskyy ◽  
Michael Giuffre ◽  
Gabriela Martinez
Keyword(s):  
Stainless Steel ◽  
Environmental Samples ◽  
Incubation Temperature ◽  
Reference Method ◽  
Selective Medium ◽  
Single Step ◽  
Department Of Agriculture ◽  
Steel Surfaces ◽  
Inspection Service ◽  
The U.S

Abstract ACTERO™ Listeria Enrichment Media (ACTERO Listeria) is a selective medium developed for a single-step recovery and enrichment of Listeria spp. from environmental samples. Robustness testing of the ACTERO Listeria medium demonstrated good performance when minor changes were introduced to the incubation temperature and time. All 54 Listeria strains tested, representing the most frequently isolated Listeria species from food (L. monocytogenes, L. ivanovii, L. seeligeri, L. welshimeri, and L. grayi), were successfully enriched in ACTERO Listeria. None of the 30 nontarget strains tested in the exclusivity study was recovered after incubation in ACTERO Listeria. Recovery of Listeria was consistent across three independently produced lots of the ACTERO Listeria, and the prepared medium was stable for 45 days when stored at 4°C in the dark. Matrix studies performed with environmental sponge samples from plastic and stainless steel surfaces demonstrated similar recovery of Listeria spp. in a single-step enrichment using ACTERO Listeria from plastic, and significantly better recovery from stainless steel surfaces when compared to the U.S. Department of Agriculture-Food Safety and Inspection Service reference method. The results of this study prove that ACTERO Listeria Enrichment Media can be effectively used in replacement of the two-step enrichment suggested by the reference method without affecting the recovery of Listeria spp. from environmental samples.

Reveal®Listeria 2.0 Test for Detection of Listeria spp. in Foods and Environmental Samples

2012 ◽  
Vol 95 (2) ◽  
pp. 424-434 ◽  
Author(s):  
Susan Alles ◽  
Stephanie Curry ◽  
David Almy ◽  
Balamurugan Jagadeesan ◽  
Jennifer Rice ◽  
...  
Keyword(s):  
Environmental Samples ◽  
Test Sample ◽  
Growth Conditions ◽  
Sample Volume ◽  
Single Step ◽  
Department Of Agriculture ◽  
Environmental Surfaces ◽  
Inspection Service ◽  
The U.S ◽  
Culture Procedure

Abstract A Performance Tested MethodSM validation study was conducted for a new lateral flow immunoassay (Reveal®Listeria 2.0) for detection of Listeria spp. in foods and environmental samples. Results of inclusivity testing showed that the test detects all species of Listeria, with the exception of L. grayi. In exclusivity testing conducted under nonselective growth conditions, all non-listeriae tested produced negative Reveal assay results, except for three strains of Lactobacillus spp. However, these lactobacilli are inhibited by the selective Listeria Enrichment Single Step broth enrichment medium used with the Reveal method. Six foods were tested in parallel by the Reveal method and the U.S. Food and Drug Administration/Bacteriological Analytical Manual (FDA/BAM) reference culture procedure. Considering data from both internal and independent laboratory trials, overall sensitivity of the Reveal method relative to that of the FDA/BAM procedure was 101%. Four foods were tested in parallel by the Reveal method and the U.S. Department of Agriculture-Food Safety and Inspection Service (USDA-FSIS) reference culture procedure. Overall sensitivity of the Reveal method relative to that of the USDA-FSIS procedure was 98.2%. There were no statistically significant differences in the number of positives obtained by the Reveal and reference culture procedures in any food trials. In testing of swab or sponge samples from four types of environmental surfaces, sensitivity of Reveal relative to that of the USDA-FSIS reference culture procedure was 127%. For two surface types, differences in the number of positives obtained by the Reveal and reference methods were statistically significant, with more positives by the Reveal method in both cases. Specificity of the Reveal assay was 100%, as there were no unconfirmed positive results obtained in any phase of the testing. Results of ruggedness experiments showed that the Reveal assay is tolerant of modest deviations in test sample volume and device incubation time.

Evaluation of Enrichment and Plating Media for Isolating Listeria monocytogenes

1988 ◽  
Vol 71 (3) ◽  
pp. 664-668
Author(s):  
B Swaminathan ◽  
Peggy S Hayes ◽  
Vincent A Przybyszewski ◽  
Brian D Plikaytis
Keyword(s):  
Listeria Monocytogenes ◽  
Recovery Efficiency ◽  
Department Of Agriculture ◽  
Selective Enrichment ◽  
Colony Forming Units ◽  
Selective Plating ◽  
Inspection Service ◽  
The U.S ◽  
Better Than ◽  
Quantitative Recovery

Abstract We compared selective enrichment broths used by the U.S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA), Food Safety and Inspection Service, for their efficiency in the quantitative recovery of Listeria monocytogenes from a naturally contaminated Brie cheese that was obtained as part of an epidemic investigation. Quantitative recovery of Listeria in FDA broth (>2.4 x 10s colony forming units/mL) was significantly better than recovery in USDA broth (9.3 x 103 colony forming units/mL). When USDA broth was supplemented with i>glucose and Phytone (papaic digest of soy protein), its recovery efficiency improved but did not equal that of FDA broth for isolating L. monocytogenes from Brie cheese. A comparison of 4 selective plating media [modified McBride's agar, gum base nalidixic acid agar, lithium chloride-phenylethanol-moxalactam agar (LPM), and acriflavine-ceftazidime agar (AC)] showed that 3 L. monocytogenes strains belonging to serotype l/2a were partially or completely inhibited on LPM and AC agars. One strain of serotype l/2a formed microcolonies on modified McBride's agar after 48 h of incubation

Prevalence of Salmonella on Raw Poultry at Retail Markets in China

2011 ◽  
Vol 74 (10) ◽  
pp. 1724-1728 ◽  
Author(s):  
BAOWEI YANG ◽  
MEILI XI ◽  
XIN WANG ◽  
SHENGHUI CUI ◽  
TIANLI YUE ◽  
...  
Keyword(s):  
Hazard Analysis ◽  
Control Point ◽  
Agricultural Practices ◽  
Shaanxi Province ◽  
Poultry Production ◽  
Department Of Agriculture ◽  
Retail Markets ◽  
Critical Control Point ◽  
Inspection Service ◽  
Raw Poultry

Data regarding Salmonella on raw poultry are very limited in China. The objective of this study was to determine the prevalence of Salmonella on raw poultry at the retail level in six provinces and two national cities in China. Whole chicken carcasses (n = 1,152) were collected from three types of retail markets (large, small, and wet). All samples were analyzed for the presence of Salmonella by using the U.S. Department of Agriculture, Food Safety Inspection Service method. Of 1,152 chicken samples, overall Salmonella prevalence was 52.2%. The highest prevalence was observed in Guangxi Province (65.3%), next in Guangdong Province (64.6%), and then in Beijing (63.9%), Shaanxi Province (50.7%), Henan Province (47.9%), Shanghai (44.4%), and Fujian Province (42.4%), and lowest prevalence was observed in Sichuan Province (38.9%). Salmonella prevalence was significantly different among the six provinces and two national cities. Salmonella prevalence was highest in the wet markets (54.4%) compared with the large markets (50.3%) and the small markets (52.1%), but differences were not significant (P > 0.05). Good manufacturing practices, good agricultural practices, and hazard analysis critical control point systems for Salmonella control in poultry production at the farm, processing, and retail level should be implemented.

Environmental Sources of Listeria and Yersinia in Vermont Dairy Plants

1991 ◽  
Vol 54 (8) ◽  
pp. 607-611 ◽  
Author(s):  
RONA B. KLAUSNER ◽  
CATHERINE W. DONNELLY
Keyword(s):  
Environmental Samples ◽  
Microbial Contamination ◽  
Listeria Innocua ◽  
Manufacturing Plants ◽  
Yersinia Species ◽  
Dairy Processing ◽  
Processing Plants ◽  
Contact Surfaces ◽  
Area Of Concern ◽  
Additional Area

This survey was conducted to identify specific environmental sources of Listeria and Yersinia in Vermont dairy plants, and to further determine whether the type of plant and specific conditions existing within plants influenced the incidence of positive microbiological results. A total of 361 environmental samples, focusing on floors and other nonproduct contact surfaces, was taken from all of Vermont's 34 dairy processing plants. The incidence of Listeria monocytogenes (1.4%) was low compared to the incidence of Listeria innocua (16.1%). While only 2.5% yielded other Yersinia species, 10.5 % of the sites were positive for Yersinia enterocolitica. Sites positive for either Listeria or Yersinia were statistically more likely to produce a positive result for both (P<.05). Fluid plants had the highest incidence of both Listeria and Yersinia when compared to cheese plants or other types of dairy manufacturing plants. Areas associated with case washers in fluid plants had the highest incidence of microbial contamination. An additional area of concern for all types of plants was sanitizing floor mats and foot baths from which positive microbiological results were obtained. Contamination in wet areas was significantly greater than in dry areas of the plants (P<.05). Identification of the sources and conditions associated with these problematic bacterial pathogens is an important step in learning to control their incidence in dairy processing environments.

Contamination Revealed by Indicator Microorganism Levels during Veal Processing

2016 ◽  
Vol 79 (8) ◽  
pp. 1341-1347 ◽  
Author(s):  
JOSEPH M. BOSILEVAC ◽  
RONG WANG ◽  
BRANDON E. LUEDTKE ◽  
TOMMY L. WHEELER ◽  
MOHAMMAD KOOHMARAIE
Keyword(s):  
Escherichia Coli ◽  
Plate Count ◽  
Department Of Agriculture ◽  
E Coli ◽  
Veal Calves ◽  
Indicator Microorganism ◽  
Analysis Of Results ◽  
Aerobic Plate Count ◽  
Inspection Service ◽  
The U.S

ABSTRACT During site visits of veal processors, the U.S. Department of Agriculture, Food Safety Inspection Service (FSIS) has reported processing deficiencies that likely contribute to increased levels of veal contamination. Here, we report the results of measuring aerobic plate count bacteria (APC), Enterobacteriaceae, coliforms (CF), and Escherichia coli during eight sample collections at five veal processors to assess contamination during the harvest of bob veal and formula-fed veal before (n = 5 plants) and after (n = 3 plants) changes to interventions and processing practices. Hides of veal calves at each plant had mean log CFU/100 cm2 APC, Enterobacteriaceae, CF, and E. coli of 6.02 to 8.07, 2.95 to 5.24, 3.28 to 5.83, and 3.08 to 5.59, respectively. Preintervention carcasses had mean log CFU/100 cm2 APC, Enterobacteriaceae, CF, and E. coli of 3.08 to 5.22, 1.16 to 3.47, 0.21 to 3.06, and −0.07 to 3.10, respectively, before and 2.72 to 4.50, 0.99 to 2.76, 0.69 to 2.26, and 0.33 to 2.12, respectively, after changes were made to improve sanitary dressing procedures. Final veal carcasses had mean log CFU/100 cm2 APC, Enterobacteriaceae, CF, and E. coli of 0.36 to 2.84, −0.21 to 1.59, −0.23 to 1.59, and −0.38 to 1.45 before and 0.44 to 2.64, −0.16 to 1.33, −0.42 to 1.20, and −0.48 to 1.09 after changes were made to improve carcass-directed interventions. Whereas the improved dressing procedures resulted in improved carcass cleanliness, the changes to carcass-directed interventions were less successful, and veal processors are urged to use techniques that ensure uniform and consistent delivery of antimicrobials to carcasses. Analysis of results comparing bob veal to formula-fed veal found bob veal hides, preintervention carcasses, and final carcasses to have increased (P < 0.05) APC, Enterobacteriaceae, CF, and E. coli (with the exception of hide Enterobacteriaceae; P > 0.05) relative to formula fed veal. When both veal categories were harvested at the same plant on the same day, similar results were observed. Since identification by FSIS, the control of contamination during veal processing has started to improve, but challenges still persist.

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.

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