scholarly journals Retail Survey of Brazilian Milk and Minas Frescal Cheese and a Contaminated Dairy Plant To Establish Prevalence, Relatedness, and Sources of Listeria monocytogenes Isolates

2008 ◽  
Vol 74 (15) ◽  
pp. 4954-4961 ◽  
Author(s):  
J. Renaldi F. Brito ◽  
Emilia M. P. Santos ◽  
Edna F. Arcuri ◽  
Carla C. Lange ◽  
Maria A. V. P. Brito ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Environmental Samples ◽  
Minas Gerais ◽  
Processing Plant ◽  
Contamination Source ◽  
Milk Samples ◽  
Dairy Processing ◽  
Processing Plants ◽  
Serotype 1 ◽  
Dairy Plant

ABSTRACT A study was designed to recover Listeria monocytogenes from pasteurized milk and Minas frescal cheese (MFC) sampled at retail establishments (REs) and to identify the contamination source(s) of these products in the corresponding dairy processing plant. Fifty milk samples (9 brands) and 55 MFC samples (10 brands) were tested from REs located in Juiz de Fora, Minas Gerais, Brazil. All milk samples and 45 samples from 9 of 10 MFC brands tested negative for L. monocytogenes; however, “brand F” of MFC obtained from REs 119 and 159 tested positive. Thus, the farm/plant that produced brand F MFC was sampled; all samples from the milking parlor tested negative for L. monocytogenes, whereas several sites within the processing plant and the MFC samples tested positive. All 344 isolates recovered from retail MFC, plant F MFC, and plant F environmental samples were serotype 1/2a and displayed the same AscI or ApaI fingerprints. Since these results established that the storage coolers served as the contamination source of the MFC, plant F was closed so that corrective renovations could be made. Following renovation, samples from sites that previously tested positive for the pathogen were collected from the processing environment and from MFC on multiple visits; all tested negative for L. monocytogenes. In addition, on subsequent visits to REs 159 and 119, all MFC samples tested negative for the pathogen. Studies are ongoing to quantify the prevalence, levels, and types of L. monocytogenes in MFC and associated processing plants to lessen the likelihood of listeriosis in Brazil.

Biological Aerosols: A Review of Airborne Contamination and its Measurement in Dairy Processing Plants

1989 ◽  
Vol 52 (7) ◽  
pp. 512-524 ◽  
Author(s):  
YOUNG-JAE KANG ◽  
JOSEPH F. FRANK
Keyword(s):  
Control Point ◽  
Additional Stress ◽  
Processing Plant ◽  
Selective Media ◽  
Critical Control Point ◽  
Biological Aerosols ◽  
Dairy Processing ◽  
Airborne Contamination ◽  
Processing Plants ◽  
Dairy Plant

Processing plant air is a source of post-pasteurization contamination of dairy products. Little is known about the extent to which biological aerosols contaminate pasteurized products, however evidence indicates that air within a packaging area is a critical control point for both pathogens and spoilage microorganisms. Consequently, it is important to understand the characteristics of biological aerosols, learn how to control their occurrence, and discover practical and valid monitoring methods. Methods used for monitoring viable particles in air include the use of sedimentation plates, impingers, slit and sieve impactors, filters, and centrifugal samplers. Each of these methods has limitations on its usefulness for dairy plant air monitoring. Microorganisms are often injured due to the stresses of the aerosolized state and consequently may not grow on selective media. Sampling methods such as impingement and filtration which subject the organisms to additional stress may cause sufficient injury to prevent growth on non-selective media. However, gentler collection methods such as centrifugal samplers may not generate enough force to collect the smallest viable particles. Aerosols are generated within the dairy plant by worker activity, sink and floor drains, water spraying, and air conditioning systems. Environmental sanitation, air filtration, air flow control, and control over personnel cleanliness and activity are useful control measures. The adoption of “clean room” design principles for a packaging area will aid in controlling biological aerosols in new dairy processing plants.

Prevalence and Genetic Diversity of Listeria monocytogenes in Vacuum-Packaged Ready-to-Eat Meat Products at Retail Markets in Latvia

2009 ◽  
Vol 72 (6) ◽  
pp. 1283-1287 ◽  
Author(s):  
AIVARS BĒRZIŅŠ ◽  
MARGARITA TERENTJEVA ◽  
HANNU KORKEALA
Keyword(s):  
Listeria Monocytogenes ◽  
Shelf Life ◽  
Meat Products ◽  
Processing Plant ◽  
Meat Processing ◽  
Pork Products ◽  
Beef Products ◽  
Processing Plants ◽  
Serotype 1 ◽  
Packaged Beef

Nine groups of different retail ready-to-eat vacuum-packaged meat products from 10 Baltic meat processing plants were analyzed for presence and numbers of Listeria monocytogenes at the end of shelf life. A total of 38 (18%) of 211 samples tested positive for L. monocytogenes serotype 1/2a (88%) or 1/2c (12%). The prevalence of L. monocytogenes in cold-smoked, sliced, vacuum-packaged beef and pork products (42%) was significantly higher than in cooked, sliced, vacuum-packaged meat products (0.8%) (P < 0.001). Enumeration of L. monocytogenes showed that 84% of the positive samples contained <100 CFU/g upon expiry of product shelf life. The numbers of L. monocytogenes exceeded 100 CFU/g only in cold-smoked, sliced, vacuum-packaged beef products. Identical pulsed-field gel electrophoresis types were recovered from different production lots of cold-smoked vacuum-packaged beef and pork products produced by the same meat processing plant, demonstrating L. monocytogenes contamination as a recurrent problem within one meat processing plant.

Application of Automated Ribotyping To Support the Evaluation of Listeria monocytogenes Sources in a Taleggio Cheese Producing Plant

2007 ◽  
Vol 70 (5) ◽  
pp. 1116-1121 ◽  
Author(s):  
A. DE CESARE ◽  
G. MANFREDA ◽  
M. MACRÌ ◽  
C. CANTONI
Keyword(s):  
Listeria Monocytogenes ◽  
Molecular Typing ◽  
Environmental Samples ◽  
Processing Plant ◽  
Significant Incidence ◽  
Serotype 1 ◽  
Automated Ribotyping

In March 2005, Listeria monocytogenes was detected on the rinds of Taleggio cheeses produced in an Italian plant. To identify the pathogen source, 154 rinds of cheeses that had been manually and automatically salinated and 52 environmental swabs collected from salting equipment, ripening cloths, and ripening boxes were tested for L. monocytogenes. Twenty-seven strains isolated from cheese samples and 16 strains isolated from environmental samples were genotyped by EcoRI and PvuII automated ribotyping. The microbiological results revealed a significant incidence of contamination of cheeses that were automatically salinated and contamination on the salting equipment, ripening cloths, and boxes. All cheese and environmental strains had the same EcoRI and PvuII ribotyping profiles, designated 153-204-S5 and 153-210-S-2, respectively. The only exception were three Taleggio strains, isolated from the same lot of product, that had EcoRI and PvuII ribotyping profiles designated 153-289-S6 and 153-214-S-5, respectively. Strains with EcoRI profile 153-204-S5 were classified as DUP-ID 1045 and serotype 1/2a, whereas strains with EcoRI profile 153-289-S6 were classified as DUP-ID 1034 and serotype 1/2b. The microbiological and molecular typing data collected in this study suggest that the source of the L. monocytogenes contamination in the Taleggio plant under study was the automated salting equipment. The isolate DUP-IDs were used to trace the introduction of potentially dangerous strains, such as those characterized as DUP-ID 1034, in the processing plant.

Listeria monocytogenes Contamination Patterns for the Smoked Fish Processing Environment and for Raw Fish

2003 ◽  
Vol 66 (1) ◽  
pp. 52-60 ◽  
Author(s):  
ADAM D. HOFFMAN ◽  
KENNETH L. GALL ◽  
DAWN M. NORTON ◽  
MARTIN WIEDMANN
Keyword(s):  
Listeria Monocytogenes ◽  
Environmental Contamination ◽  
West Coast ◽  
Environmental Samples ◽  
Raw Materials ◽  
Processing Plant ◽  
Fish Processing ◽  
Smoked Fish ◽  
Fish Samples ◽  
Raw Fish

Reliable data on the sources of Listeria monocytogenes contamination in cold-smoked fish processing are crucial in designing effective intervention strategies. Environmental samples (n = 512) and raw fish samples (n = 315) from two smoked fish processing facilities were screened for L. monocytogenes, and all isolates were subtyped by automated ribotyping to examine the relationship between L. monocytogenes contamination from raw materials and that from environmental sites. Samples were collected over two 8-week periods in early spring and summer. The five types of raw fish tested included lake whitefish, sablefish, farm-raised Norwegian salmon, farm-raised Chilean salmon, and feral (wild-caught) salmon from the U.S. West Coast. One hundred fifteen environmental samples and 46 raw fish samples tested positive for L. monocytogenes. Prevalence values for environmental samples varied significantly (P < 0.0001) between the two plants; plant A had a prevalence value of 43.8% (112 of 256 samples), and plant B had a value of 1.2% (3 of 256 samples). For plant A, 62.5% of drain samples tested positive for L. monocytogenes, compared with 32.3% of samples collected from other environmental sites and 3.1% of samples collected from food contact surfaces. Ribotyping identified 11 subtypes present in the plant environments. Multiple subtypes, including four subtypes not found on any raw fish, were found to persist in plant A throughout the study. Contamination prevalence values for raw fish varied from 3.6% (sablefish) to 29.5% (U.S. West Coast salmon), with an average overall prevalence of 14.6%. Sixteen separate L. monocytogenes subtypes were present on raw fish, including nine that were not found in the plant environment. Our results indicate a disparity between the subtypes found on raw fish and those found in the processing environment. We thus conclude that environmental contamination is largely separate from that of incoming raw materials and includes strains persisting, possibly for years, within the plant. Operational and sanitation procedures appear to have a significant impact on environmental contamination, with both plants having similar prevalence values for raw materials but disparate contamination prevalence values for the environmental sites. We also conclude that regular L. monocytogenes testing of drains, combined with molecular subtyping of the isolates obtained, allows for efficient monitoring of persistent L. monocytogenes contamination in a processing plant.

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.

Prevalence of Listeria monocytogenes in Broilers at the Abattoir, Processing Plant, and Retail Level

2001 ◽  
Vol 64 (7) ◽  
pp. 994-999 ◽  
Author(s):  
MARIA K. MIETTINEN ◽  
LIISA PALMU ◽  
K. JOHANNA BJÖRKROTH ◽  
HANNU KORKEALA
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Conveyor Belt ◽  
Pulsed Field Gel Electrophoresis ◽  
Contamination Level ◽  
Contamination Rate ◽  
Processing Plant ◽  
Broiler Meat ◽  
Pulsed Field ◽  
Processing Plants

The environment and products from two broiler abattoirs and processing plants and raw broiler pieces at the retail level were sampled for Listeria monocytogenes in order to evaluate the contamination level of the broiler carcasses and products. Sampling started in the slaughtering process and finished with raw broiler meat or ready-to-eat cooked product. Sampling sites positive for L. monocytogenes at the broiler abattoir were the air chiller, the skin-removing machine, and the conveyor belt leading to the packaging area. The L. monocytogenes contamination rate varied from 1 to 19% between the two plants studied. Furthermore, 62% (38 of 61) of the raw broiler pieces, bought from retail stores, were positive for L. monocytogenes. Altogether, 136 L. monocytogenes isolates were obtained for serotyping and pulsed-field gel electrophoresis(PFGE) characterization performed with two rare-cutting enzymes (ApaI and AscI). Altogether three serotypes (1/2a, 1/2c, and 4b) and 14 different PFGE types were obtained using information provided from both ApaI and AscI patterns for discrimination basis. The two broiler abattoirs studied did not share the same PFGE types. However, the same PFGE types found in the raw broiler pieces at the retail level were also found in the broiler abattoirs where the broilers had been slaughtered.

Prediction of Persistence of Listeria monocytogenes ST451 in a Rabbit Meat Processing Plant in the Czech Republic

2019 ◽  
Vol 82 (8) ◽  
pp. 1350-1356
Author(s):  
TEREZA GELBÍČOVÁ ◽  
MARTINA FLORIANOVÁ ◽  
ZUZANA TOMÁŠTÍKOVÁ ◽  
LUCIE POSPÍŠILOVÁ ◽  
IVANA KOLÁČKOVÁ ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Core Genome ◽  
Sequence Type ◽  
Processing Plant ◽  
Meat Processing ◽  
Sequencing Method ◽  
Serotype 1 ◽  
Rabbit Meat ◽  
Meat Samples

ABSTRACT This study was focused on characterization of the genetic diversity of Listeria monocytogenes isolated from packed fresh rabbit meat obtained from one producer via retail outlets. The partial aim was to compare the characteristics of a suspect persistent strain with strains from human cases. The occurrence of L. monocytogenes in vacuum-packed rabbit meat was monitored during 2013 to 2016. All strains were characterized by serotyping, pulsed-field gel electrophoresis, and multilocus sequence typing (MLST). Selected strains, which represented each year, were analyzed using the whole genome sequencing method. L. monocytogenes was detected in 21 (38%) of 56 originally packed rabbit meat samples from one food producer during the whole monitored period. All strains showed the identical serotype (1/2a), AscI/ApaI pulsotype (735/2), and sequence type (ST451). The clonal similarity of strains from rabbit meat was also confirmed on the basis of core genome MLST (on 1,701 loci). This fact suggests the occurrence of a suspect persistent strain in the meat processing plant. Results of core genome MLST enabled us to unambiguously exclude rabbit meat as a source of listeriosis in humans caused by the indistinguishable AscI/ApaI pulsotype and sequence type, although all strains carried all genes important for the virulence of L. monocytogenes. No specific genes that may be associated with its persistence in the food processing environment were detected among the tested strains of ST451. HIGHLIGHTS

Prevalence and Typing of Listeria monocytogenes in Raw Catfish Fillets†

2006 ◽  
Vol 69 (4) ◽  
pp. 815-819 ◽  
Author(s):  
CHUNG-HSI CHOU ◽  
JUAN L. SILVA ◽  
CHINLING WANG
Keyword(s):  
Listeria Monocytogenes ◽  
Repetitive Element ◽  
Group Method ◽  
Processing Plant ◽  
Natural Habitats ◽  
Listeria Species ◽  
Pair Group ◽  
Catfish Fillets ◽  
Processing Plants ◽  
Different Seasons

Raw channel catfish fillets collected from three processing plants during four time periods were tested for the presence of Listeria species. Listeria monocytogenes was the predominant Listeria species found in these catfish fillets, with 25 to 47% prevalence. Other Listeria species, such as L. welshimeri, L. innocua, L. ivanovii, L. grayi, and L. seeligeri, were also found. L. monocytogenes isolates were further fingerprinted by a repetitive element PCR. Forty distinctive electrophoretic types (ETs) and three genetic clusters were determined by Dice coefficient analysis and UPGMA (unweighted pair group method using arithmetic averages). Twenty of 40 ETs were represented by a single isolate, and the other 20 ETs were represented by 2 to 11 isolates. Thirty-five ETs, represented by 76 isolates, were found in processing plant A, B, or C and designated plant-specific types. The remaining five ETs, represented by 21 isolates, were found in multiple plants and designated nonplant-specific types. In addition, 10 ETs from 52 isolates were found repeatedly during different seasons. Plant-specific and nonplant-specific L. monocytogenes coexisted in processed catfish fillets. Some isolates were persistently found in processed fillets, suggesting that either the current sanitation procedures used by these plants are inadequate or that these isolates originated from the natural habitats of the catfish. The results also suggest that the repetitive element PCR is a useful tool for differentiating L. monocytogenes subtypes and can be used for tracing the source of a contamination.

Evaluation of Air Samplers for Recovery of Biological Aerosols in Dairy Processing Plants

1989 ◽  
Vol 52 (9) ◽  
pp. 655-659 ◽  
Author(s):  
YOUNG-JAE KANG ◽  
JOSEPH F. FRANK
Keyword(s):  
Membrane Filter ◽  
Ice Cream ◽  
Processing Plant ◽  
Milk Processing ◽  
Air Sampler ◽  
Biological Aerosols ◽  
Dairy Processing ◽  
Processing Plants ◽  
Stage 1 ◽  
Number Of Particles

An All Glass Impinger-30 (AGI-30), Andersen 6-stage Sieve Air Sampler (Andersen impactor), Reuter centrifugal air sampler (RCS sampler), and the Millipore open type membrane filter sampler (Filter sampler) were evaluated for viable particle recovery in three dairy processing plant environments. There were two size distribution peaks for viable particles, at stage 1 (>7.0 μm) and stage 3 (3.3–4.7 μm). About 10–12% of the particles were smaller than 2.1 μm in size and were mostly non-molds. During milk processing, the highest number of particles were >7.0 μm in size. But, during ice cream processing and in the idle ice cream room, the highest number of particles were 3.3–4.7 μm in size and were mostly molds. Mean viable particle recovery decreased in the order of AGI-30, Andersen impactor, RCS sampler, and Filter sampler for each of the three sampling environments. These results contrast to those obtained using laboratory-generated aerosols where both the AGI-30 and RCS sampler exhibited low recovery. The increased aerosol recovery by AGI-30 in processing plant compared to laboratory-generated aerosols indicates the presence of carrier and passenger type aerosol particles which disintegrate upon impingement. A comparison of the percent of non-mold cfu recovered by the RCS sampler vs. Andersen impactor indicates that the RCS sampler has a bias toward the detection of non-mold containing particles at all three of the locations tested. The Andersen impactor proved to be the most reliable sampler for recovering biological aerosols from dairy processing plant air.

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.

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