Comparison of cold enrichment and U.S. Department of Agriculture methods for isolating Listeria monocytogenes from naturally contaminated foods. The Listeria Study Group

Hayes, Peggy S.; Graves, Lewis M.; Ajello, Gloria W.; Swaminathan, Bala; Weaver, Robert E.; Wenger, Jay D.; Schuchat, Anne; Broome, Claire V.

doi:10.1128/aem.57.8.2109-2113.1991

Cited by 60 publications

(16 citation statements)

References 29 publications

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“…Most other raw vegetable samples have shown similar low levels of Listeriu (Faber et a/. 1989), as processing progresses their numbers increase but the contamination on these crops does not appear to be the same extent as that found in this study with grass (Sizmur and Walker 1988;Hayes et al 1991). One reason for this difference may be that grass grows from the base of the plant and has a protective sheath of decaying tissue, which may act as an inoculum of Lzsteria, whereas the aerial of other plants which grow from the tip will not be exposed to this potential source of this Lzsteria.…”

Section: Discussionsupporting

confidence: 49%

The incidence and level of Listeria monocytogenes contamination of food sources at primary production and initial processing

Fenlon¹,

Wilson²,

Donachie³

1996

J Appl Microbiol

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1996. Listeria monocytogenes was isolated in low numbers from a variety of environmental samples associated with the primary production of food, including vegetation, faeces and meat. T h e organism was rarely detected on growing grass and vegetables prior to processing. The excretion of L. monocytogenes by farm animals was linked to their diet, with animals fed entirely on hay or manufactured diets not excreting detectable levels of Listeria (i.e. absence in 25 g). However, animals fed on silage, which is frequently contaminated with L. monocytogenes, commonly excreted the organism. Transport of live animals over long distances ( > 100 km) significantly increased the level of excretion of Listeria, but the contamination of carcasses of sheep and cattle was not high. Pigs and poultry faeces were free of Listeria prior to slaughter and pig carcasses were not found to have Listeria present. Frozen and chilled chicken did show detectable levels reflecting the greater potential for contamination during poultry processing. Samples of minced beef were tested and 21 of 23 samples were positive for L. monocytogenes, demonstrating that processing significantly increases the level of contamination compared to whole carcasses. Multilocus enzyme electrophoresis of a representative selection of the isolates showed that there was a wide range of electrophoretic types present in the primary production environment, relatively few of which have been linked to cases of human listeriosis. However, these types do arise on farms and occasional contamination of food raw material by potentially virulent strains may be sufficient to allow adaptable strains to become established in the processing environment and thus be responsible for more widespread contamination of the food available to the consumer.

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Section: Discussionsupporting

confidence: 49%

The incidence and level of Listeria monocytogenes contamination of food sources at primary production and initial processing

Fenlon¹,

Wilson²,

Donachie³

1996

J Appl Microbiol

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“…LSA was found to be more effective in isolating L. monocytogenes from artificially seeded clinical specimen such as faeces and vaginal swabs (Curtis et al, 1989) and from food (Tiwari and Aldenrath, 1990; Curtis and Lee, 1995) but less effective in isolating the bacteria from silage (Fernandez‐Garayzabal et al, 1992). Cold enrichment was also reported to be inefficient in isolating L. monocytogenes from food (Pini and Gilbert, 1988), faecal samples (Hayes et al, 1991) and autopsy material (Eld et al, 1993) when compared with liquid selective enrichment at higher temperatures. The variability between the isolation techniques and the failure of our attempts to isolate L. monocytogenes from faeces without exposure to cold storage led us to combine cold enrichment with selective enrichment and selective plating at higher temperature.…”

Section: Discussionmentioning

confidence: 99%

“…In conventional cold enrichment procedures a liquid medium (selective or non selective) has always been used (Gray and Killinger, 1966, Hayes et al, 1991). The use of saline, NB and LSEB as cold enrichment media failed to improve the frequency of isolation of L. monocytogenes from faeces when compared with the samples held at 4°C without any medium.…”

Section: Discussionmentioning

confidence: 99%

Optimization of a Culture Technique for the Isolation of Listeria monocytogenes from Faecal Samples

Erdoğan

Cripps

Morgan

2002

Journal of Veterinary Medicine, Series B

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A culture technique employing cold enrichment at 4 degrees C followed by selective enrichment and plating at higher temperatures (30 degrees C) was used to isolate Listeria monocytogenes from faecal samples. The samples were held at 4 degrees C for 15 weeks and cultured weekly to assess the sensitivity of the culture after cold storage for different lengths of time. No media, Listeria selective enrichment broth (LSEB), nutrient broth (NB) and saline were used as cold storage medium. Cold storage increased the frequency of Listeria positive samples. The sensitivity of the culture for Listeria spp. and L. monocytogenes was 72 and 94%, and 56 and 61% after third and seventh week of cold storage, respectively. When the results of third and seventh week of cold storage were combined, the sensitivity was 100% for Listeria spp. and 94% for L. monocytogenes. LSEB and NB as storage medium increased Listeria positive samples after the first week of cold storage but did not maintain the increase thereafter while saline had an adverse effect on the growth of the bacteria. However, samples held in no media in a pilot study involving monthly sampling of a herd revealed better results. Detection limit of the culture media was also investigated. The lowest concentration detected by culture media was 3.17 organisms/ml. This was seven organisms/g for known Listeria positive sample. The faecal samples spiked with 10-fold dilutions of L. monocytogenes and held at 4 degrees C revealed that the sample spiked with 3.17 x 10-1 cfu/ml organisms resulted in growth after the second week of cold storage. The results suggest that the culture technique employing cold enrichment followed by selective enrichment and plating is more sensitive, the storage of faecal samples in no media when compared with the samples in storage medium, LSEB, NB and saline, during cold enrichment is a better application and culture of faeces, immediately after collection, at third and seventh week of cold enrichment produce more satisfactory results.

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“…If antagonistic microflora are lacking, L. monocytogenes can grow up to >1000 CFU/g, constituting a primary public health problem [8,52,132]. The most frequent serogroups found in ripened fermented sausages are 1/2c, 1/2a, and 1/2b [52,84,85,91], while serogroup 4b is rare [133,134].…”

Section: Listeria Monocytogenes In Fermented Sausagesmentioning

confidence: 99%

High-Hydrostatic-Pressure (HHP) Processing Technology as a Novel Control Method for Listeria monocytogenes Occurrence in Mediterranean-Style Dry-Fermented Sausages

Meloni

2019

Foods

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Although conventional microbial control techniques are currently employed and largely successful, their major drawbacks are related to their effects on quality of processed food. In recent years, there has been a growing demand for high-quality foods that are microbially safe and retain most of their natural freshness. Therefore, several modern and innovative methods of microbial control in food processing have been developed. High-hydrostatic-pressure (HHP) processing technology has been mainly used to enhance the food safety of ready-to-eat (RTE) products as a new pre-/post-packaging, non-thermal purification method in the meat industry. Listeria monocytogenes is a pertinent target for microbiological safety and shelf-life; due to its capacity to multiply in a broad range of food environments, is extremely complicated to prevent in fermented-sausage-producing plants. The frequent detection of L. monocytogenes in final products emphasizes the necessity for the producers of fermented sausages to correctly overcome the hurdles of the technological process and to prevent the presence of L. monocytogenes by applying novel control techniques. This review discusses a collection of recent studies describing pressure-induced elimination of L. monocytogenes in fermented sausages produced in the Mediterranean area.

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Comparison of cold enrichment and U.S. Department of Agriculture methods for isolating Listeria monocytogenes from naturally contaminated foods. The Listeria Study Group

Cited by 60 publications

References 29 publications

The incidence and level of Listeria monocytogenes contamination of food sources at primary production and initial processing

The incidence and level of Listeria monocytogenes contamination of food sources at primary production and initial processing

Optimization of a Culture Technique for the Isolation of Listeria monocytogenes from Faecal Samples

High-Hydrostatic-Pressure (HHP) Processing Technology as a Novel Control Method for Listeria monocytogenes Occurrence in Mediterranean-Style Dry-Fermented Sausages

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