• Journal of Food Hygiene and Safety
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• v.10 no.2
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• pp.89-95
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• 1995

Highly lethal Listeria monocytogenes, causing bromatoxism through vegetables, dairy products, meat products and shellfish etc, was examined for possible contamination in market beef. USDA, FDA, Malthus and Modified Cold Enrichment methods were used for the detection of Listeria spp.. Samples of domestic and imported market beef were collected from local meat shopsat Seoul, Korea. Total two hundreds and six of Listeria spp. were isolated and identified from beef. Among 206 isolates, the number of L. welshimeri was one hundred and twenty-one(44.8%). The numbers of isolated L. innocua, L. murrayi, L. monocytogenes, L. grayi, L. seeligeri, and L. ivanovii were 49(18.1%), 14(5.2%), 12(4.4%), 6(2.2%), 2(0.7%), and 2(0.7%), respectively. Detection rates of Listeria spp. varied among four methods. The highest detection rate of Listeria spp. in market beef was found at USDA method and that of L. monocytogenes was found at Malthus method.

• Food Science of Animal Resources
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• v.39 no.1
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• pp.84-92
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• 2019

Listeria monocytogenes is a major cause of serious foodborne illness in the dairy foods. Although Caenorhabditis elegans model is well established as a virulence model of pathogenic bacteria, its application on L. monocytogenes is critically unclear. The objective of this study was to carry out an evaluation of L. monocytogenes toxicity using C. elegans nematode as a simple host model. We found that C. elegans nematodes have high susceptibility to L. monocytogenes infection, as a consequence of accumulation of bacteria in the worms' intestine. However, L. innocua, which is known to be non-toxic, is not accumulate in the intestine of worms and is not toxic similarly to Escherichia coli OP50 known as the normal feed source of C. elegans. Importantly, immune-associated genes of C. elegans were intensely upregulated more than 3.0-fold when they exposed to L. monocytogenes. In conclusion, we established that C. elegans is an effective model for studying the toxicity of L. monocytogenes and we anticipate that this system will result in the discovery of many potential anti-listeria agents for dairy foods.

• Food Science of Animal Resources
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• v.28 no.5
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• pp.616-622
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• 2008

Listeria monocytogenes is a foodborne pathogen inducing listeriosis in human. We compared two different culture methods for detection of L. monocytogenes and validated two commercial kits, $VIDAS^{(R)}$ and $REVEAL^{(R)}$ for Listeria. L. monocytogenes was inoculated into various food samples to generate partial positive samples. The inoculated samples were enriched in half-Fraser broth for 48 hr at $30^{\circ}C$. The enriched samples were streaked onto Oxford agar at 24 and 48 hr postincubation followed by biochemical confirmation and concurrently analyzed by using the two commercial kits for comparison. When the enrichment period was extended from 24 to 48 hr, the numbers of positive samples were dramatically increased from 6 to 52 out of 80 samples tested using the culture method. With the commercial kits, the numbers of positive samples were also significantly increased from 10 to 18 and 1 to 18, respectively, when the enrichment period was extended from 48 to 72 hr. There was no statistical difference between the 24 hr culture method and $VIDAS^{(R)}$ or $Reveal^{(R)}$ with 48 hr enrichment. In conclusion, the 24 hr for the culture method was insufficient to detect L. monocytogenes in various foods. The commercial kits could be adequate means for presumptive screening of L. monocytogenes in food.

• Neonatal Medicine
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• v.16 no.1
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• pp.94-98
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• 2009

Listeria monocytogenes (L. monocytogenes) is a foodborne anaerobic gram-positive rod and the third most common pathogen for neonatal meningitis. Although the mortality and morbidity of L. monocytogenes infections are high, thus causing serious problems in Western populations, neonatal listeriosis is relatively rare in Eastern countries, including Korea. Possible routes for intrauterine infection or vertical transmission of L. monocytogenes include infected placentas and the reproductive tract. Intrauterine infections may cause chorioamnionitis, preterm labor, spontaneous abortion, stillbirth, or neonatal infection. A high index of suspicion and early empirical antibiotic treatment are critical to achieve a favorable prognosis for neonatal listeriosis. We managed a case of L. monocytogenes sepsis and pneumonia in a premature neonate born at 26 weeks of gestational age from an asymptomatic mother with culture-proven placental infection. The neonate was successively treated with ampicillin and gentamicin.

• Food Science of Animal Resources
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• v.34 no.5
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• pp.665-673
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• 2014

We compared standard culture methods as well as conventional PCR and real-time PCR for the detection of Listeria monocytogenes (L. monocytogenes) in milk, cheese, fresh-cut vegetables, and raw beef that have different levels of background microflora. No statistical differences were observed in sensitivity between the two selective media in all foods. In total, real-time PCR assay exhibited statistically excellent detection sensitivity (p<0.05) and was less time consuming and laborious as compared with standard culture methods. Conventional culture methods showed poor performance in detecting L. monocytogenes in food with high levels of background microflora, generating numerous false negative results. While the detection of L. monocytogenes in fresh cut vegetable by culture methods was hindered only by L. innocua, various background microflora, such as L. innocua, L. welshimeri, L. grayi, and Enterococcus faecalis appeared on the two selective media as presumptive positive colonies in raw beef indicating the necessity of improvement of current selective media. It appears that real-time PCR is an effective and sensitive presumptive screening tool for L. monocytogenes in various types of foods, especially foods samples with high levels of background microflora, thus complementing standard culture methodologies.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.495-502
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• 2020

Processing fresh produce into fresh-cut products increases the risk of bacterial growth and contamination by breaking the exterior barrier of produce. Our objective in this study was to develop predictive models of Listeria monocytogenes in the fresh-cut salad, fresh-cut pineapple, and frozen mango. Predictive growth and survival models were developed to predict the change of L. monocytogenes populations in the fresh-cut salad (4, 10, 12, 13, 17, 25, and 36℃), fresh-cut pineapple (4, 10, 17, 25, 30, and 36℃), and frozen mango (-2, -10 and -18℃) as a function of temperature. The growth of L. monocytogenes in fresh-cut salad and pineapple was observed at above 13℃ and 10℃, respectively. The growth of L. monocytogenes in pineapple was faster than in salad. The delta value of L. monocytogenes in frozen mango increased as the storage temperature decreased. The results indicate that L. monocytogenes behave differently according to the physicochemical properties of fresh-cut fruits and vegetables. Since L. monocytogenes grow and survive well in refrigerated and frozen conditions, management programs and preventive controls for the processing of fresh-cut produce should be effectively implemented to enhance the safety of fresh-cut fruits and vegetables at retail markets.

• Journal of Veterinary Clinics
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• v.5 no.1
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• pp.53-59
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• 1988

한국 재래산양에 대한 L. monocytogenes균의 감염원을 조사하기 위하여 총 459개의 재래산양 분변, 비즙, 장기, 사료 및 토양재료로부터 균분리를 시도하였으며, 분리균의 항균성 물질에 대한 감수성 및 인공 감염시의 L. monocytogenes의 침입장기를 조사하였던 결과는 다음과 같다. L. monocytogenes는 분변에서만 분리되었으며 (분리율 8.2%) 분변이 본균의 주요 감염원으로 인정되었다. 가검재료로부터 L. monocytogenes의 분리방법으로는 유제화 재료를 혈액배지로써 37에서 24～48시간 동안 호기배양함이 우수하였다. 분리된 L. monocytogenes 8주 중 100%의 균주가 amikacin, colistin, tanamycin, neomycin에 내성을 나타내었으며, clinmycin, gentamicin, lincomycin, methicillin 및 refampin에 87.5%, ampicillin및 oles-ndomycin에 75.0%, Chloramphenico에 62.5%, tetracycline에 50.0% 및 cephalot hin에 37.5%의 균주가 내성이었다. Nitrofurantoin에는 전 균주가 감수성을 나타내었다. L. monocytogenes를 재래산양에 경구 및 정맥내로 접종하였을때 패혈증이 인정되었으며 대부분의 실질장기가 이 균의 침입부위인 것으로 관찰되었다.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.469-473
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• 2013

Livestock manure is a valuable source of nutrients and organic matter for plant. Thus, livestock manure compost is commonly used fertilizer in organic vegetable and fruit production in many countries. However, contaminated or inadequate manure compost can give negative effect to soil microorganisms. This study was conducted to investigate the survival difference of Salmonella enterica and Listeria monocytogenes in chicken and pig manure compost under the selected environmental conditions. Commercially available manure compost (pig, chicken) was inoculated with S. enterica and L. monocytogenes. Manure compost was incubated at $25^{\circ}C$ and consistent moisture content. Samples had been collected during 200 days depending on the given conditions. S. enterica survived for 130 days in pig manure compost and over 200 days in chicken manure compost, respectively. L. monocytogenes persisted for 120 days in pig manure compost and over 200 days in chicken manure compost, respectively. It is noted that the number of S. enterica and L. monocytogenes gradually decreased over time. The results indicate that S. enterica survived longer than L. monocytogenes in manure compost at $25^{\circ}C$. S. enterica and L. monocytogenes survived longer in chicken manure compost than in pig manure compost. Increased knowledge of pathogen behavior in agricultural environments is a valuable part of future work on improving risk evaluations and, in a longer perspective, in providing data for guidelines regarding safe handling of pathogen-contaminated manure compost and soil.

• Korean Journal of Veterinary Research
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• v.42 no.3
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• pp.327-333
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• 2002

The study was carried out to examine the distribution and survival rate of Listeria monocytogenes (L monocytogenes) from various source of waters using improved isolation method. In comparision of enrichment media for isolation of L monocytogenes from water, the isolation rate and 50% detection limit of the pathogen were higher in UVM modified Listeria enrichment broth (UVM) than Listeria enrichment broth (LEB). On the other hand, when compared the selective media for isolation of the pathogen from water, the isolation rate was highest in culture at Oxford agar followed by Fraser agar, and LEB agar. In order to improve enrichment method, 100 ml of water samples with 0.1 CFU/ml of L monocytogenes was inoculated into 10 ml of UVM concentrated at 10-fold, and incubated for 24 h at $36^{\circ}C$. Isolated frequency of the pathogens in improved enrichment method completely corresponded with common (filter) method. Of a total mumber of 147 water samples from river, lake and sea, the pathogen was isolated from 1 of 39 (2.6%) river water samples and 1 of 75 (1.3%) sea water samples, but no pathogen was isolated from 33 lake water samples. Serotypes of 2 isolates were identified as type 1. L monocytogenes decreased in number from 7.2-7.4 to 4.2-4.7 log CFU/ml for 1 week poststorage (5 and $20^{\circ}C$), but the pathogens were able to be detected in river and sea water until 8 weeks after storage. However, in tap water, L monocytogenes were decreased to undetectable level after 2 weeks of storage.

• Korean Journal of Food Science and Technology
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• v.33 no.2
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• pp.271-277
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• 2001

Ethanol extracts from Mallotus japonicus Muell exhibited strong antimicrobial activities by paper disc diffusion method on the five strains of Listeria monocytogenes(ATCC 19111, ATCC 19112, ATCC 19113, ATCC 19114 and ATCC 15313). Ethanol extract from Mallotus japonicus Muell was subsequently fractionated by n-hexane, chloroform, ethyl acetate and water. n-Hexane fraction of Mallotus japonicus Muell showed strong growth inhibition at concentrations as low as 20 ppm level in broth culture medium on the five strains of L. monocytogenes for 72 hr at $30^{\circ}C$. Single substance(M34-4-4) was isolated from n-hexane fraction of Mallotus japonicus Muell. M34-4-4 showed a bactericidal activity against L. monocytogenes at a concentration of 50 ppm level. The purified M34-4-4 was identified as linolenic acid by $^1H-NMR,\;DEPT-135\;and\;^{13}C-NMR$.