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Pasquali F, Valero A, Possas A, Lucchi A, Crippa C, Gambi L, Manfreda G, De Cesare A. Variability in Physicochemical Parameters and Its Impact on Microbiological Quality and Occurrence of Foodborne Pathogens in Artisanal Italian Organic Salami. Foods 2023; 12:4086. [PMID: 38002143 PMCID: PMC10670534 DOI: 10.3390/foods12224086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 10/29/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
Artisanal salami is produced in small-scale production plants, where the lack of full automation might result in higher variability in food intrinsic properties. The aim of the present study was to evaluate the inter- and intra-batch variability in physicochemical parameters and its impact on microbial quality and occurrence of foodborne pathogens on 480 samples collected from six batches of an artisanal Italian production of organic salami. Relatively high total bacterial counts (TBC) were found on the surface of the table in the stuffing room (4.29 ± 0.40 log cfu/cm2). High loads of Enterobacteriaceae in the meat mixture of batch 2 and TBC in batch 5 were associated with a higher occurrence of bacterial pathogens. During ripening, water activity (aw) and pH failed to reach values lower than 0.86 and 5.3, respectively. Six Staphylococcus aureus and four Listeria monocytogenes isolates were collected from the salami meat mixture during ripening and the processing environment. A total of 126 isolates of Enterobacteriaceae were characterized at a species level, with Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Citrobacter freundii isolated from the final products. Results suggest the relevance of first steps of production in terms of the hygiene of raw materials and handling during stuffing procedures, especially when the physicochemical parameters of the final products do not reach values that represent hurdles for foodborne pathogens.
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Affiliation(s)
- Frédérique Pasquali
- Department of Agricultural and Food Sciences, Alma Mater Studiorum—University of Bologna, 40126 Bologna, Italy; (F.P.); (A.L.); (C.C.); (L.G.); (G.M.)
| | - Antonio Valero
- Department of Food Science and Technology, University of Cordoba, Agrifood Campus of International Excellence ceiA3, Campus Rabanales, 14014 Córdoba, Spain;
| | - Arícia Possas
- Department of Food Science and Technology, University of Cordoba, Agrifood Campus of International Excellence ceiA3, Campus Rabanales, 14014 Córdoba, Spain;
| | - Alex Lucchi
- Department of Agricultural and Food Sciences, Alma Mater Studiorum—University of Bologna, 40126 Bologna, Italy; (F.P.); (A.L.); (C.C.); (L.G.); (G.M.)
| | - Cecilia Crippa
- Department of Agricultural and Food Sciences, Alma Mater Studiorum—University of Bologna, 40126 Bologna, Italy; (F.P.); (A.L.); (C.C.); (L.G.); (G.M.)
| | - Lucia Gambi
- Department of Agricultural and Food Sciences, Alma Mater Studiorum—University of Bologna, 40126 Bologna, Italy; (F.P.); (A.L.); (C.C.); (L.G.); (G.M.)
| | - Gerardo Manfreda
- Department of Agricultural and Food Sciences, Alma Mater Studiorum—University of Bologna, 40126 Bologna, Italy; (F.P.); (A.L.); (C.C.); (L.G.); (G.M.)
| | - Alessandra De Cesare
- Department of Veterinary Medical Sciences, Alma Mater Studiorum—University of Bologna, 40126 Bologna, Italy;
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Gambi L, Crippa C, Lucchi A, Manfreda G, De Cesare A, Pasquali F. Investigation on the microbiological hazards in an artisanal salami produced in Northern Italy and its production environment in different seasonal periods. Ital J Food Saf 2023; 12:10831. [PMID: 37064520 PMCID: PMC10102968 DOI: 10.4081/ijfs.2023.10831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 01/23/2023] [Indexed: 03/10/2023] Open
Abstract
In the present study, the occurrence of Listeria monocytogenes, Staphylococcus aureus, Salmonella spp. and Escherichia coli VTEC was investigated in two batches of artisanal Italian salami tested in winter and summer. Moreover, enumerations of total bacterial count, lactic acid bacteria and Enterobacteriaceae were performed as well as monitoring of water activity and pH. Samples were taken from raw materials, production process environment, semi-finished product and finished products. The results revealed an overall increase of total bacterial count and lactic acid bacteria during the ripening period, along with a decrease of Enterobacteriaceae, pH and water activity. No significant difference was observed between the two batches. The enterobacterial load appeared to decrease during the maturation period mainly due to a decrease in pH and water activity below the limits that allow the growth of these bacteria. E. coli VTEC, Salmonella spp. or L. monocytogenes were not detected in both winter and summer batches. However, Klebsiella pneumoniae was detected in both summer and winter product. Except for one isolate, no biological hazards were detected in the finished salami, proving the efficacy of the ripening period in controlling the occurrence of microbiological hazard in ripened salami. Further studies are required to assess the virulence potential of the Klebsiella pneumoniae isolates.
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Pasquali F, Valero A, Possas A, Lucchi A, Crippa C, Gambi L, Manfreda G, De Cesare A. Occurrence of foodborne pathogens in Italian soft artisanal cheeses displaying different intra- and inter-batch variability of physicochemical and microbiological parameters. Front Microbiol 2022; 13:959648. [PMID: 36090085 PMCID: PMC9453248 DOI: 10.3389/fmicb.2022.959648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 07/26/2022] [Indexed: 11/13/2022] Open
Abstract
Artisanal cheeses are produced in small-scale production plants, where the lack of full automation and control of environmental and processing parameters suggests a potential risk of microbial contamination. The aim of this study was to perform a longitudinal survey in an Italian artisanal factory producing a spreadable soft cheese with no rind to evaluate the inter- and intra-batch variability of physicochemical and microbial parameters on a total of 720 environmental and cheese samples. Specifically on cheese samples, the evaluation was additionally performed on physicochemical parameters. Cheese samples were additionally collected during 15 days of storage at constant temperatures of 2 and 8°C, as well as a dynamic profile of 2°C for 5 days and 8°C for 10 days. Furthermore, Enterobacteriaceae isolates were identified at species level to have a better knowledge of the environmental and cheese microbiota potentially harboring human pathogens. High inter-batch variability was observed for lactic acid bacteria (LAB) and total bacteria count (TBC) in cheese at the end of production but not for pH and water activity. A temperature of 8°C was associated with a significantly higher load of Enterobacteriaceae in cheeses belonging to batch 6 at the end of storage, and this temperature also corresponded with the highest increase in LAB and TBC loads over cheese shelf life. Results from generalized linear mixed models (GLMMs) indicated that drains in the warm room and the packaging area were associated with higher levels of TBC and Enterobacteriaceae in cheese. Regarding foodborne pathogens, no sample was positive for verotoxigenic Escherichia coli (VTEC) or Listeria monocytogenes, whereas six Staphylococcus aureus and one Salmonella pullorum isolates were collected in cheese samples during storage and processing, respectively. Regarding Enterobacteriaceae, 166 isolates were identified at species level from all batches, with most isolates belonging to Klebsiella oxytoca and pneumoniae, Enterobacter cloacae, Hafnia alvei, and Citrobacter freundii evidencing the need to focus on standardizing the microbial quality of cow milk and on hygienic procedures for cleaning and disinfection especially in warm and maturation rooms. Further studies should be performed to investigate the potential pathogenicity and antimicrobial resistance of the identified Enterobacteriaceae species in artisanal cheeses.
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Affiliation(s)
- Frédérique Pasquali
- Department of Agricultural and Food Sciences, Alma Mater Studiorum - University of Bologna, Bologna, Italy
| | - Antonio Valero
- Department of Food Science and Technology, University of Córdoba, Agrifood Campus of International Excellence ceiA3, Córdoba, Spain
| | - Arícia Possas
- Department of Food Science and Technology, University of Córdoba, Agrifood Campus of International Excellence ceiA3, Córdoba, Spain
| | - Alex Lucchi
- Department of Agricultural and Food Sciences, Alma Mater Studiorum - University of Bologna, Bologna, Italy
| | - Cecilia Crippa
- Department of Agricultural and Food Sciences, Alma Mater Studiorum - University of Bologna, Bologna, Italy
| | - Lucia Gambi
- Department of Agricultural and Food Sciences, Alma Mater Studiorum - University of Bologna, Bologna, Italy
| | - Gerardo Manfreda
- Department of Agricultural and Food Sciences, Alma Mater Studiorum - University of Bologna, Bologna, Italy
| | - Alessandra De Cesare
- Department of Veterinary Medical Sciences, Alma Mater Studiorum - University of Bologna, Bologna, Italy
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Crippa C, Pasquali F, Lucchi A, Gambi L, De Cesare A. Investigation on the microbiological hazards in an artisanal soft cheese produced in northern Italy and its production environment in different seasonal periods. Ital J Food Saf 2022; 11:9983. [PMID: 35795464 PMCID: PMC9251870 DOI: 10.4081/ijfs.2022.9983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 01/10/2022] [Indexed: 11/23/2022] Open
Abstract
The present study aimed at assessing the occurrence of microbiological hazards (Listeria monocytogenes, Staphylococcus aureus, Salmonella spp. and Escherichia coli O157) in an artisanal soft cheese produced in northern Italy. In the same product total bacterial count, lactic acid bacteria and Enterobacteriaceae were enumerated, and pH and water activity measured in two batches sampled in summer and winter. Samples of raw materials, environmental swabs from the production processes and cheese during 15 days of storage at 2 and 8°C as well as dynamic temperature of 2°C for 5 days and 8°C for 10 days were collected and tested. The load of total bacterial count was significantly higher in the winter batch in comparison to the summer one, with a significant increase at the end of the storage period also noticed for lactic acid bacteria. Statistical higher values of pH were registered in raw materials and end of storage in winter batch. S. aureus was confirmed only in the winter batch within samples (n=4) of stored cheese. On plates used for E. coli O157 detection, colonies of Klebsiella pneumoniae and Klebsiella oxytoca were isolated. The results suggest that the highest bacterial population in the winter batch was associated to a higher pH in stored cheese and a higher number of biological hazards identified. Their isolation started in the maturation room suggesting this step as relevant for possible cheese contamination.
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Affiliation(s)
| | | | - Alex Lucchi
- Department of Agricultural and Food Sciences, and
| | - Lucia Gambi
- Department of Agricultural and Food Sciences, and
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Short Communication: Prevalence of Listeria monocytogenes in Raw Milk of Healthy Sheep and Goats. Vet Med Int 2022; 2022:3206172. [PMID: 35646303 PMCID: PMC9135515 DOI: 10.1155/2022/3206172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 03/30/2022] [Accepted: 04/08/2022] [Indexed: 11/29/2022] Open
Abstract
Listeria monocytogenes, one of the most important bacterial pathogens transmitted through milk, causes listeriosis in humans and animals. This study aimed to investigate the prevalence of L. monocytogenes in raw milk of healthy sheep and goats in the west of Iran (Lorestan Province) by touchdown PCR (TD-PCR). Listeria spp. were found in milk samples taken from 21 sheep (29.16%) and 3 goats (10.71%) whereas L. monocytogenes was isolated from milk samples taken from 4 sheep (5.55%) and 1 goat (3.75%). The results showed that there was a significant difference between sheep and goats in the prevalence of Listeria spp. in their raw milk (p < 0.05), but no significant difference was observed between them in the prevalence of L. monocytogenes. The study findings suggested that the raw milk of healthy sheep and goats was infected with L. monocytogenes and warned of the risk of human infection with listeriosis following consumption of raw and unpasteurized milk.
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Park E, Ha J, Oh H, Kim S, Choi Y, Lee Y, Kim Y, Seo Y, Kang J, Yoon Y. High Prevalence of Listeria monocytogenes in Smoked Duck: Antibiotic and Heat Resistance, Virulence, and Genetics of the Isolates. Food Sci Anim Resour 2021; 41:324-334. [PMID: 33987552 PMCID: PMC8115007 DOI: 10.5851/kosfa.2021.e2] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/24/2020] [Accepted: 01/18/2021] [Indexed: 11/21/2022] Open
Abstract
This study aimed at determining the genetic and virulence characteristics of the
Listeria monocytogenes from smoked ducks. L.
monocytogenes was isolated by plating, and the isolated colonies
were identified by PCR. All the obtained seven L. monocytogenes
isolates possessed the virulence genes (inlA,
inlB, plcB, and hlyA) and
a 385 bp actA amplicon. The L. monocytogenes
isolates (SMFM2018 SD 1-1, SMFM 2018 SD 4-1, SMFM 2018 SD 4-2, SMFM 2018 SD 5-2,
SMFM 2018 SD 5-3, SMFM 2018 SD 6-2, and SMFM 2018 SD 7-1) were inoculated in
tryptic soy broth (TSB) containing 0.6% yeast extract at 60°C,
followed by cell counting on tryptic soy agar (TSA) containing 0.6% yeast
extract at 0, 2, 5, 8, and 10 min. We identified five heat resistant isolates
compared to the standard strain (L. monocytogenes ATCC13932),
among which three exhibited the serotype 1/2b and D-values of 5.41, 6.48, and
6.71, respectively at 60°C. The optical densities of the cultures were
regulated to a 0.5 McFarland standard to assess resistance against nine
antibiotics after an incubation at 30°C for 24 h. All isolates were
penicillin G resistant, possessing the virulence genes (inlA,
inlB, plcB, and hlyA) and
the 385-bp actA amplicon, moreover, three isolates showed
clindamycin resistance. In conclusion, this study allowed us to characterize
L. monocytogenes isolates from smoked ducks, exhibiting
clindamycin and penicillin G resistance, along with the 385-bp
actA amplicon, representing higher invasion efficiency than
the 268-bp actA, and the higher heat resistance serotype
1/2b.
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Affiliation(s)
- Eunyoung Park
- Department of Food and Nutrition, Sookmyung Women's University, Seoul 04310, Korea
| | - Jimyeong Ha
- Risk Analysis Research Center, Sookmyung Women's University, Seoul 04310, Korea
| | - Hyemin Oh
- Department of Food and Nutrition, Sookmyung Women's University, Seoul 04310, Korea
| | - Sejeong Kim
- Risk Analysis Research Center, Sookmyung Women's University, Seoul 04310, Korea
| | - Yukyung Choi
- Risk Analysis Research Center, Sookmyung Women's University, Seoul 04310, Korea
| | - Yewon Lee
- Department of Food and Nutrition, Sookmyung Women's University, Seoul 04310, Korea
| | - Yujin Kim
- Department of Food and Nutrition, Sookmyung Women's University, Seoul 04310, Korea
| | - Yeongeun Seo
- Department of Food and Nutrition, Sookmyung Women's University, Seoul 04310, Korea
| | - Joohyun Kang
- Department of Food and Nutrition, Sookmyung Women's University, Seoul 04310, Korea
| | - Yohan Yoon
- Department of Food and Nutrition, Sookmyung Women's University, Seoul 04310, Korea
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Lee Y, Yoon Y, Seo Y, Kim S, Ha J, Lee J, Choi Y, Oh H, Kim Y, Kang J, Park E, Kim WI, Lee S. Combined Enrichment and Quantitative Polymerase Chain Reaction to Improve Sensitivity and Reduce Time of Detection of Listeria monocytogenes in Mushrooms. Foodborne Pathog Dis 2019; 17:276-283. [PMID: 31855070 DOI: 10.1089/fpd.2019.2688] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
This study evaluated a combined method for the detection of Listeria monocytogenes in mushrooms, involving enrichment and quantitative real-time polymerase chain reaction (qPCR), to improve sensitivity and reduce detection time. The growth of L. monocytogenes was evaluated in Listeria enrichment broth (LEB) with modified carbon and nitrogen sources, increasing sodium concentrations, and added micronutrients. Primers targeting the L. monocytogenes iap (iap1 and iap2), hlyA (hlyA1-hlyA6), and prfA (prfA1-prfA4) genes were developed and their sensitivity and specificity were evaluated. The greatest increase in L. monocytogenes cell count was observed after 6-h incubation at 30°C in LEB+2 × FAC (LEB plus 20 mL/L ferric ammonium citrate), where cell count increased by 1.4 log CFU (colony-forming unit)/mL, compared with 0.9 log CFU/mL in LEB (p < 0.05). iap2 primers targeting the iap gene showed high specificity and were the most sensitive among those tested, with a detection limit of 2 log CFU/mL in LEB medium, 3.1 log CFU/g in golden needle mushroom, and 3.5 log CFU/g in large oyster mushroom. When applied to detection in golden needle mushrooms, a combination of 3-h incubation in LEB+2 × FAC medium and qPCR analysis with iap2 primers permitted detection of L. monocytogenes, even at an inoculum of 1 log CFU/g. Similarly, in large oyster mushrooms, 10-h enrichment in LEB+2 × FAC medium resulted in a cell count of 3.7 log CFU/g. These results indicate that a combined detection method, using LEB+2 × FAC medium for enrichment followed by qPCR with iap2 primer pair, can reduce enrichment time and improve the sensitivity and specificity of L. monocytogenes detection in mushrooms.
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Affiliation(s)
- Yewon Lee
- Department of Food and Nutrition, Sookmyung Women's University, Seoul, Korea
| | - Yohan Yoon
- Department of Food and Nutrition, Sookmyung Women's University, Seoul, Korea
| | - Yeongeun Seo
- Department of Food and Nutrition, Sookmyung Women's University, Seoul, Korea
| | - Sejeong Kim
- Risk Analysis Research Center, Sookmyung Women's University, Seoul, Korea
| | - Jimyeong Ha
- Risk Analysis Research Center, Sookmyung Women's University, Seoul, Korea
| | - Jeeyeon Lee
- Risk Analysis Research Center, Sookmyung Women's University, Seoul, Korea
| | - Yukyung Choi
- Department of Food and Nutrition, Sookmyung Women's University, Seoul, Korea
| | - Hyemin Oh
- Department of Food and Nutrition, Sookmyung Women's University, Seoul, Korea
| | - Yujin Kim
- Department of Food and Nutrition, Sookmyung Women's University, Seoul, Korea
| | - Joohyun Kang
- Department of Food and Nutrition, Sookmyung Women's University, Seoul, Korea
| | - Eunyoung Park
- Department of Food and Nutrition, Sookmyung Women's University, Seoul, Korea
| | - Won-Il Kim
- Microbial Safety Team, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, Korea
| | - Soomin Lee
- Department of Food and Nutrition, Sookmyung Women's University, Seoul, Korea
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Oh H, Kim S, Lee S, Lee H, Ha J, Lee J, Choi Y, Choi KH, Yoon Y. Prevalence, Serotype Diversity, Genotype and Antibiotic Resistance of Listeria monocytogenes Isolated from Carcasses and Human in Korea. Korean J Food Sci Anim Resour 2018; 38:851-865. [PMID: 30479494 PMCID: PMC6238023 DOI: 10.5851/kosfa.2018.e5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 05/29/2018] [Accepted: 06/03/2018] [Indexed: 11/22/2022] Open
Abstract
This study investigated the prevalence of Listeria monocytogenes in slaughterhouses, and determined serovars and genotypes, and antibiotic resistance of the isolates obtained from slaughterhouses and humans in Korea. Two hundred ninety samples were collected from feces (n=136), carcasses [n=140 (cattle: n=61, swine: n=79)], and washing water (n=14) in nine slaughterhouses. Eleven human isolates were obtained from hospitals and the Korea Center for Disease Control and Prevention. Listeria monocytogenes was enriched and identified, using polymerase chain reaction (PCR) and 16S rRNA sequencing. Serovars and presence of virulence genes were determined, and genetic correlations among the isolates were evaluated by the restriction digest patterns of AscI. Antibiotic resistance of L. monocytogenes isolates were examined against 12 different antibiotics. Of 290 slaughterhouse samples, 15 (5.17%) carcass samples were L. monocytogenes positive. Most L. monocytogenes isolates possessed all the virulence genes, while polymorphisms in the actA gene were found between carcass and human isolates. Serovars 1/2a (33.3%) and 1/2b (46.7%) were the most frequent in carcass isolates. Genetic correlations among the isolates from carcass and clinical isolates were grouped within serotypes, but there were low geographical correlations. Most L. monocytogenes isolates were antibiotic resistant, and some strains showed resistance to more than four antibiotics. These results indicate that L. monocytogenes are isolated from carcass and human in Korea, and they showed high risk serotypes and antibiotic resistance. Therefore, intensive attentions are necessary to be aware for the risk of L. monocytogenes in Korea.
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Affiliation(s)
- Hyemin Oh
- Department of Food and Nutrition, Sookmyung
Women’s University, Seoul 04310,
Korea
- Risk Analysis Research Center, Sookmyung
Women’s University, Seoul 04310,
Korea
| | - Sejeong Kim
- Department of Food and Nutrition, Sookmyung
Women’s University, Seoul 04310,
Korea
- Risk Analysis Research Center, Sookmyung
Women’s University, Seoul 04310,
Korea
| | - Soomin Lee
- Department of Food and Nutrition, Sookmyung
Women’s University, Seoul 04310,
Korea
- Risk Analysis Research Center, Sookmyung
Women’s University, Seoul 04310,
Korea
| | - Heeyoung Lee
- Department of Food and Nutrition, Sookmyung
Women’s University, Seoul 04310,
Korea
- Risk Analysis Research Center, Sookmyung
Women’s University, Seoul 04310,
Korea
| | - Jimyeong Ha
- Department of Food and Nutrition, Sookmyung
Women’s University, Seoul 04310,
Korea
- Risk Analysis Research Center, Sookmyung
Women’s University, Seoul 04310,
Korea
| | - Jeeyeon Lee
- Department of Food and Nutrition, Sookmyung
Women’s University, Seoul 04310,
Korea
- Risk Analysis Research Center, Sookmyung
Women’s University, Seoul 04310,
Korea
| | - Yukyung Choi
- Department of Food and Nutrition, Sookmyung
Women’s University, Seoul 04310,
Korea
- Risk Analysis Research Center, Sookmyung
Women’s University, Seoul 04310,
Korea
| | - Kyoung-Hee Choi
- Department of Oral Microbiology, College of
Dentistry, Wonkwang University, Iksan 54538,
Korea
| | - Yohan Yoon
- Department of Food and Nutrition, Sookmyung
Women’s University, Seoul 04310,
Korea
- Risk Analysis Research Center, Sookmyung
Women’s University, Seoul 04310,
Korea
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De Cesare A, Doménech E, Comin D, Meluzzi A, Manfreda G. Impact of Cooking Procedures and Storage Practices at Home on Consumer Exposure to Listeria Monocytogenes and Salmonella Due to the Consumption of Pork Meat. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2018; 38:638-652. [PMID: 28846810 DOI: 10.1111/risa.12882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Revised: 07/05/2017] [Accepted: 07/11/2017] [Indexed: 06/07/2023]
Abstract
The objective of this research was to analyze the impact of different cooking procedures (i.e., gas hob and traditional static oven) and levels of cooking (i.e., rare, medium, and well-done) on inactivation of Listeria monocytogenes and Salmonella in pork loin chops. Moreover, the consumer's exposure to both microorganisms after simulation of meat leftover storage at home was assessed. The results showed that well-done cooking in a static oven was the only treatment able to inactivate the tested pathogens. The other cooking combinations allowed to reach in the product temperatures always ≥73.6 °C, decreasing both pathogens between 6 log10 cfu/g and 7 log10 cfu/g. However, according to simulation results, the few cells surviving cooking treatments can multiply during storage by consumers up to 1 log10 cfu/g, with probabilities of 0.059 (gas hob) and 0.035 (static oven) for L. monocytogenes and 0.049 (gas hob) and 0.031 (static oven) for Salmonella. The key factors affecting consumer exposure in relation to storage practices were probability of pathogen occurrence after cooking, doneness degree, time of storage, and time of storage at room temperature. The results of this study can be combined with prevalence data and dose-response models in risk assessment models and included in guidelines for consumers on practices to be followed to manage cooking of pork meat at home.
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Affiliation(s)
- Alessandra De Cesare
- Department of Agricultural and Food Sciences, Alma Mater Studiorum, University of Bologna, Ozzano dell'Emilia, Bologna, Italy
| | - Eva Doménech
- Institute of Food Engineering for Development (IUIAD), Food Technology Department (DTA), Universitat Politécnica de Valencia, Valencia, Spain
| | - Damiano Comin
- Istituto Zooprofilattico delle Venezie, Legnaro, Padua, Italy
| | - Adele Meluzzi
- Department of Agricultural and Food Sciences, Alma Mater Studiorum, University of Bologna, Ozzano dell'Emilia, Bologna, Italy
| | - Gerardo Manfreda
- Department of Agricultural and Food Sciences, Alma Mater Studiorum, University of Bologna, Ozzano dell'Emilia, Bologna, Italy
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Chen JQ, Healey S, Regan P, Laksanalamai P, Hu Z. PCR-based methodologies for detection and characterization of Listeria monocytogenes and Listeria ivanovii in foods and environmental sources. FOOD SCIENCE AND HUMAN WELLNESS 2017. [DOI: 10.1016/j.fshw.2017.03.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Tolerance to quaternary ammonium compound disinfectants may enhance growth of Listeria monocytogenes in the food industry. Int J Food Microbiol 2017; 241:215-224. [DOI: 10.1016/j.ijfoodmicro.2016.10.025] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 10/18/2016] [Accepted: 10/19/2016] [Indexed: 12/26/2022]
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Aras Z, Ardıç M. Occurrence and Antibiotic Susceptibility of Listeria Species in Turkey Meats. Korean J Food Sci Anim Resour 2015; 35:669-73. [PMID: 26761896 PMCID: PMC4670897 DOI: 10.5851/kosfa.2015.35.5.669] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 08/21/2015] [Accepted: 08/31/2015] [Indexed: 11/06/2022] Open
Abstract
The aims of this study were to investigate the occurrence of Listeria species in turkey meats and to check the antimicrobial susceptibility of the isolated strains. Hundred and fifteen raw turkey meat samples were randomly collected from the supermarkets, butchers and restaurants. Strain isolation and identification were made according to the ISO11290-1 method. Antimicrobial susceptibility was determined by the standard disc diffusion method. A total of 47 Listeria spp. were isolated from 115 (40.9%) raw turkey meat samples. The isolates were distributed between L. monocytogenes (25.53%), L. innocua (34.04%), L. grayi (31.91%) and L. welshimeri (8.51%). A total of 55.3 % of Listeria spp. isolates were multi-resistant to at least 3 of the antimicrobial agent tested. The level of multi-resistance was higher in L. monocytogenes strains (66.7%) than in L. innocua (62.5%) and L. grayi (53.3%). Listeria spp. isolates were highly resistant to ampicillin, cephalothin, penicillin, meticillin, oxacillin, and trimethoprime-sulfamethoxazole. The isolates particularly L. monocytogenes are increasingly resistant to one or more antibiotics and may represent a potential risk for public health because these antibiotics are common used in treatment of listeriosis. The correct and controlled use of antibiotics in veterinary medicine is important to the emergence of resistant strains.
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Affiliation(s)
- Zeki Aras
- Department of Microbiology, Faculty of Veterinary Medicine, Aksaray University, Aksaray 68100, Turkey
| | - Mustafa Ardıç
- Department of Food Engineering, Faculty of Engineering, Aksaray University, Aksaray 68100, Turkey
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Baysal AH. Comparison of conventional culture method and fluorescent in situ hybridization technique for detection of Listeria spp. in ground beef, turkey, and chicken breast fillets in İzmir, Turkey. J Food Prot 2014; 77:2021-30. [PMID: 25474046 DOI: 10.4315/0362-028x.jfp-14-034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The occurrence of Listeria species in refrigerated fresh chicken breast fillet, turkey breast fillet, and ground beef was evaluated, comparing the conventional culture method and fluorescent in situ hybridization (FISH). FISH uses hybridization of a nucleic acid sequence target of a microorganism with a specific DNA probe labeled with a fluorochrome and imaging by a fluorescence microscope. First, Listeria was inoculated in chicken breast fillet, turkey breast fillet, or ground beef, and the applicability of the FISH method was evaluated. Second, Listeria was detected in fresh chicken breast fillet, turkey breast fillet, and ground beef by culture and FISH methods. Listeria was isolated from 27 (37.4%) of 216 samples by the standard culture method, whereas FISH detected 25 (24.7%) preenriched samples. Of these isolates, 17 (63%) were L. innocua, 6 (22%) L. welshimeri, and 4 (14.8%) L. seeligeri. Overall, the prevalences of Listeria spp. found with the conventional culture method in chicken breast fillet, turkey breast fillet, and ground beef were 9.7, 6.9, and 20.8%, whereas with the FISH technique these values were 11.1, 6.9, and 16.7%, respectively. The molecular FISH technique appears to be a cheap, sensitive, and time-efficient procedure that could be used for routine detection of Listeria spp. in meat. This study showed that retail raw meats are potentially contaminated with Listeria spp. and are, thus, vehicles for transmitting diseases caused by foodborne pathogens, underlining the need for increased precautions, such as implementation of hazard analysis and critical control points and consumer food safety education.
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Affiliation(s)
- Ayse Handan Baysal
- Izmir Institute of Technology, Department of Food Engineering, 035430 a, Izmir, Turkey.
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Proposal of performance objectives and sampling schemes for Listeria monocytogenes in fresh meat intended to be eaten cooked under different storage practices. Int J Food Microbiol 2014; 184:50-4. [PMID: 24560104 DOI: 10.1016/j.ijfoodmicro.2014.01.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 01/20/2014] [Accepted: 01/21/2014] [Indexed: 11/27/2022]
Abstract
The goal of this study was to define a practical approach to derive risk management measures, such as performance objectives (POs), for Listeria monocytogenes in pork cuts intended to be eaten cooked. Moreover, sampling plans to verify the compliance of meat lots to such POs are presented. The POs were estimated as prevalence and/or concentration values that should not be exceeded at time of consumption. To derive possible POs for L. monocytogenes, ten lots of pork cuts, collected within the same slaughterhouse along a one-year period, were tested for the presence and concentration of the pathogen under four different scenarios through the product shelf life. Our results indicated that the median values of the prevalence distributions ranged between 0.41 and 0.68. The number of samples to be tested in order to verify lot compliance ranged between six, for samples tested immediately after packaging, and three, for samples tested at the end of the shelf life. The concentration values ranged between 2.02 log10 CFU/g, for samples tested immediately after packaging, up to 3.14 log10 CFU/g for samples tested after final storage at 14°C. The concentration of L. monocytogenes in the samples contaminated by less than 10 CFU/g was estimated between 7 CFU/10g to 7 CFU/g, after storage at retail and abuse temperature, respectively. Basing on the knowledge of log normal distributions, the maximum contamination level of the lots in order to achieve the suggested POs, was calculated. It was obtained that mean concentration estimated as PO should be between -0.43 and 0.48 log10 CFU/g. Other risk management options are further evaluated and discussed. These results would help food operators and authorities to establish safety targets and corrective actions regarding inhibition of L. monocytogenes in fresh pork meat.
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De Cesare A, Pasquali F, Lucchi A, Manfreda G. Relative Accuracy, Specificity and Sensitivity of a 5′ Nuclease Real-Time PCR Assay for Listeria monocytogenes Detection in Naturally Contaminated Pork Cuts. FOOD ANAL METHOD 2014. [DOI: 10.1007/s12161-014-9819-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Osman KM, Zolnikov TR, Samir A, Orabi A. Prevalence, pathogenic capability, virulence genes, biofilm formation, and antibiotic resistance of Listeria in goat and sheep milk confirms need of hygienic milking conditions. Pathog Glob Health 2014; 108:21-9. [PMID: 24548157 PMCID: PMC4083164 DOI: 10.1179/2047773213y.0000000115] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Goat and sheep milk is consumed by human populations throughout the world; as a result, it has been proposed as an alternative, nutrient-rich milk to feed infants allergic to cow's milk. Unfortunately, potentially harmful bacteria have not been thoroughly tested in goat or sheep milk. Listeria monocytogenes is a harmful bacterium that causes adverse health effects if ingested by humans. The purpose of this study was to estimate the prevalence and characterize the phenotype, genotype, virulence factors, biofilm formation, and antibiopotential of Listeria isolated from the milk of goat and sheep. Udder milk samples were collected from 107 goats and 102 sheep and screened for mastitis using the California mastitis test (CMT). Samples were then examined for the presence of pathogenic Listeria spp; if detected, the isolation of pathogenic Listeria (L. monocytogenes and Listeria ivanovii) was completed using isolation and identification techniques recommended by the International Organization for Standards (ISO 11290-1, 1996), in addition to serological, in vitro and in vivo pathogenicity tests. The isolates were subjected to PCR assay for virulence associated genes (hlyA, plcA, actA, and iap). Pathogenic Listeria spp. were isolated from 5·6% of goat and 3·9% sheep milk samples, with 33·3 and 25% of these selected samples respectively containing L. monocytogenes. The results of this study provide evidence of the low-likelihood of contamination leading to the presence of L. monocytogenes in raw goat and sheep milk; however, this study also confirmed a strong in vitro ability for biofilm formation and pathogenic capability of L. monocytogenes if discovered in the milk. L. monocytogenes may be present in goat and sheep milk and in order to reduce the exposure, hygienic milking conditions must be employed for the milk to be considered a safe alternative for human consumption.
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De Cesare A, Valero A, Lucchi A, Pasquali F, Manfreda G. Modeling growth kinetics of Listeria monocytogenes in pork cuts from packaging to fork under different storage practices. Food Control 2013. [DOI: 10.1016/j.foodcont.2013.04.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Ryu J, Park SH, Yeom YS, Shrivastav A, Lee SH, Kim YR, Kim HY. Simultaneous detection of Listeria species isolated from meat processed foods using multiplex PCR. Food Control 2013. [DOI: 10.1016/j.foodcont.2013.01.048] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Szymczak B, Szymczak M, Sawicki W, Dąbrowski W. Anthropogenic impact on the presence of L. monocytogenes in soil, fruits, and vegetables. Folia Microbiol (Praha) 2013; 59:23-9. [PMID: 23775320 PMCID: PMC3889501 DOI: 10.1007/s12223-013-0260-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 05/22/2013] [Indexed: 11/05/2022]
Abstract
The aim of this study was to determine the prevalence of Listeria sp. and Listeria monocytogenes in soil samples with reference to type of fertilizers (natural and artificial) and distance from places intensively exploited by men, as well as to determine the relationship between the presence of L. monocytogenes in the soil and in fruits and vegetables. The examined 1,000 soil samples originated from 15 different areas, whilst 140 samples of fruits and 210 samples of vegetables were collected from those areas. L. monocytogenes was isolated only from 5.5 % of all soil samples coming exclusively from meadows intensively grazed by cattle (27.8 %) and areas near food processing plants (25 %) and wild animal forests (24 %). Listeria sp. and L. monocytogenes were not present on artificially fertilized areas and wastelands. L. monocytogenes was detected in 10 % of samples of strawberry, 15 % of potato samples, and 5 % of parsley samples. Our data indicate that Listeria spp. and particularly L. monocytogenes were found in the soil from (1) arable lands fertilized with manure, (2) pasture (the land fertilized with feces of domestic animals), and (3) forests (again, the land fertilized with feces of animals, not domestic but wild). The bacteria were not detected in the soil samples collected at (1) artificially fertilized arable lands and (2) wastelands (the lands that were not fertilized with manure or animal feces). Moreover, a correlation was determined in the presence of L. monocytogenes between soil samples and samples of the examined fruits and vegetables.
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Affiliation(s)
- Barbara Szymczak
- Department of Microbiology and Applied Biotechnology, West Pomeranian University of Technology, Papieża Pawła VI 3, 71-459, Szczecin, Poland,
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Schirmer BC, Langsrud S, Møretrø T, Hagtvedt T, Heir E. Performance of two commercial rapid methods for sampling and detection of Listeria in small-scale cheese producing and salmon processing environments. J Microbiol Methods 2012; 91:295-300. [DOI: 10.1016/j.mimet.2012.08.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/27/2012] [Accepted: 08/27/2012] [Indexed: 11/15/2022]
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Dalmasso A, Rantsiou K, Cocolin L, Bottero MT. Development of a Biomolecular Assay for the Identification ofListeriaat Species Level. Foodborne Pathog Dis 2010; 7:565-71. [DOI: 10.1089/fpd.2009.0456] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Alessandra Dalmasso
- Department of Animal Pathology, Faculty of Veterinary Medicine, University of Turin, Grugliasco, Italy
| | - Kalliopi Rantsiou
- Di.Va.P.R.A., Faculty of Agriculture, University of Turin, Grugliasco, Italy
| | - Luca Cocolin
- Di.Va.P.R.A., Faculty of Agriculture, University of Turin, Grugliasco, Italy
| | - Maria Teresa Bottero
- Department of Animal Pathology, Faculty of Veterinary Medicine, University of Turin, Grugliasco, Italy
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AYAZ N, EROL I. RAPID DETECTION OFLISTERIA MONOCYTOGENESIN GROUND TURKEY BY IMMUNOMAGNETIC SEPARATION AND POLYMERASE CHAIN REACTION. ACTA ACUST UNITED AC 2009. [DOI: 10.1111/j.1745-4581.2009.00172.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Dutta V, Huff GR, Huff WE, Johnson MG, Nannapaneni R, Sayler RJ. The Effects of Stress on Respiratory Disease and Transient Colonization of Turkeys with Listeria monocytogenes Scott A. Avian Dis 2008; 52:581-9. [DOI: 10.1637/8299-032808-reg.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Bilir Ormanci F, Erol I, Ayaz N, Iseri O, Sariguzel D. Immunomagnetic separation and PCR detection ofListeria monocytogenesin turkey meat and antibiotic resistance of the isolates. Br Poult Sci 2008; 49:560-5. [DOI: 10.1080/00071660802298328] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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25
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Wesley IV, Larsen S, Hurd HS, McKean JD, Griffith R, Rivera F, Nannapaneni R, Cox M, Johnson M, Wagner D, de Martino M. Low prevalence of Listeria monocytogenes in cull sows and pork. J Food Prot 2008; 71:545-9. [PMID: 18389698 DOI: 10.4315/0362-028x-71.3.545] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The goal of this study was to determine the prevalence of Listeria monocytogenes in sows slaughtered at a single Midwestern plant on two occasions (trial 1, n = 179 sows; trial 2, n = 160 sows). Fecal samples collected antemortem (trial 1) as well as animal tissues, and carcass swabs collected at the abattoir (trials 1 and 2) were analyzed. Eight isolates of L. monocytogenes were recovered from five samples that represented 0.18% of the total samples (n = 2,775). In trial 1, L. monocytogenes was detected in a tonsil sample (0.6%; 1 positive of 181 tonsils), in a carcass (0.6%; 1 positive of 179 carcasses), which was sampled prior to the organic rinse, and in two chopped meat block samples (1.2%; 2 positive of 165 samples). In trial 2, L. monocytogenes was only detected in a single chopped meat block sample (0.15%; 1 positive of 688 total samples). These data indicate the low prevalence of L. monocytogenes in the cull sow.
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Affiliation(s)
- Irene V Wesley
- US Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa 50010, USA.
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Gasanov U, Hughes D, Hansbro PM. Methods for the isolation and identification of Listeria spp. and Listeria monocytogenes: a review. FEMS Microbiol Rev 2004; 29:851-75. [PMID: 16219509 DOI: 10.1016/j.femsre.2004.12.002] [Citation(s) in RCA: 216] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2004] [Revised: 10/07/2004] [Accepted: 12/10/2004] [Indexed: 11/18/2022] Open
Abstract
Listeria monocytogenes is an important food-borne pathogen and is widely tested for in food, environmental and clinical samples. Identification traditionally involved culture methods based on selective enrichment and plating followed by the characterization of Listeria spp. based on colony morphology, sugar fermentation and haemolytic properties. These methods are the gold standard; but they are lengthy and may not be suitable for testing of foods with short shelf lives. As a result more rapid tests were developed based on antibodies (ELISA) or molecular techniques (PCR or DNA hybridization). While these tests possess equal sensitivity, they are rapid and allow testing to be completed within 48 h. More recently, molecular methods were developed that target RNA rather than DNA, such as RT-PCR, real time PCR or nucleic acid based sequence amplification (NASBA). These tests not only provide a measure of cell viability but they can also be used for quantitative analysis. In addition, a variety of tests are available for sub-species characterization, which are particularly useful in epidemiological investigations. Early typing methods differentiated isolates based on phenotypic markers, such as multilocus enzyme electrophoresis, phage typing and serotyping. These phenotypic typing methods are being replaced by molecular tests, which reflect genetic relationships between isolates and are more accurate. These new methods are currently mainly used in research but their considerable potential for routine testing in the future cannot be overlooked.
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Affiliation(s)
- Uta Gasanov
- Immunology and Microbiology, Biomedical Sciences, Faculty of Health, The University of Newcastle, Australia; Vaccines, Immunology/Infection, Viruses and Asthma Group, The Hunter Medical Research Institute, Newcastle, Australia
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RodrÃguez-Lázaro D, Hernández M, Pla M. Simultaneous quantitative detection ofListeriaspp. andListeria monocytogenesusing a duplex real-time PCR-based assay. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09490.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Zhu M, Wesley IV, Nannapaneni R, Cox M, Mendonca A, Johnson MG, Ahn DU. The role of dietary vitamin E in experimental Listeria monocytogenes infections in turkeys. Poult Sci 2003; 82:1559-64. [PMID: 14601733 DOI: 10.1093/ps/82.10.1559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The current study was designed to determine if dietary vitamin E influenced either the gut clearance or levels of peripheral blood CD4+ and CD8+ T lymphocytes in adult turkeys experimentally infected with Listeria monocytogenes. Turkeys were fed vitamin E (0, 100, or 200 IU) from day of hatch to time of necropsy. After 6 wk on the experimental diet, turkeys were orally inoculated with L. monocytogenes (approximately 10(9) cfu). To monitor infection status, cloacal swabs were taken on selected days post-inoculation (DPI). At necropsy, samples of viscera, including liver, spleen, cecum, duodenum, ileum, and colon were collected and cultured for L. monocytogenes. In experiments 1 and 2, recovery of L. monocytogenes from cloacal swabs, tissues, and intestines from turkeys fed vitamin E was generally lower than that from turkeys fed the control diet, although these differences were not statistically significant. When data from both trials were combined, L. monocytogenes was cultured less frequently from cloacal swabs of the vitamin E-treated group (200 IU) on 2 and 3 DPI, when compared to controls (0 IU, P < 0.01). There were no changes in virulence characteristics of L. monocytogenes cells, as measured by in vitro killing of Ped-2E9 cells, recovered from cloacal swabs or tissues of experimentally infected turkeys fed the control or a vitamin E treatment diet. Flow cytometric analysis indicated that CD4+ and CD8+ peripheral blood T lymphocytes were elevated at 6 and 8 DPI in infected turkeys given 200 IU vitamin E.
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Affiliation(s)
- M Zhu
- Pre-Harvest Food Safety and Enteric Diseases Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, Iowa 50010, USA
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Somer L, Kashi Y. A PCR method based on 16S rRNA sequence for simultaneous detection of the genus Listeria and the species Listeria monocytogenes in food products. J Food Prot 2003; 66:1658-65. [PMID: 14503721 DOI: 10.4315/0362-028x-66.9.1658] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The genus Listeria comprises six closely related species, of which only Listeria monocytogenes is a human pathogen. The rapid and sensitive detection of L. monocytogenes is important in the food industry as well as in medical diagnosis. In this study, a PCR-based method for the rapid, specific, and sensitive detection of L. monocytogenes in food products was developed. The PCR is based on DNA sequences and primer pairs that are found within the 16S subunit of the rRNA gene and are specific to the Listeria genus and to L. monocytogenes within the Listeria genus. The primers for the Listeria genus and for L. monocytogenes were used in the same reaction mix for their simultaneous detection. In addition, a pair of bacterial primers universal to any bacterial DNA at the 16S subunit of the rRNA gene were developed as a positive control. For the detection of Listeria and L. monocytogenes in food products, the method includes selective enrichment for Listeria followed by DNA extraction and a specific PCR reaction. The method detects 1 to 5 CFU in a 25-g sample in < or = 24 h. It can be easily incorporated into the routine screening of diverse food products and readily adapted for clinical use.
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Affiliation(s)
- Lilach Somer
- Department of Food Engineering and Biotechnology, Technion--Israel Institute of Technology, Haifa 32000, Israel
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Kanuganti SR, Wesley IV, Reddy PG, McKean J, Hurd HS. Detection of Listeria monocytogenes in pigs and pork. J Food Prot 2002; 65:1470-4. [PMID: 12233860 DOI: 10.4315/0362-028x-65.9.1470] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this study, we surveyed hogs (n = 300) as well as pork products (ground pork and raw chitterlings) for Listeria monocytogenes. Pig specimens collected before (tonsil swabs) and after slaughter (tonsils, lymph nodes, carcass swabs, and rectal contents) were examined for L. monocytogenes by enrichment with conventional enrichment broths followed by subculturing to selective agar. A multiplex polymerase chain reaction assay targeting the highly conserved 16S rRNA gene of the Listeria species as well as the hlyA gene unique to L. monocytogenes was used to screen aliquots of the enrichment (method I) as well as to confirm presumptive Listeria colonies from Columbia agar with 0.05% glucose supplemented with polymyxin B-acriflavine-lithium chloride-ceftazidime-aesculin-mannitol (PALCAM; method II). Subculturing to PALCAM agar was the more sensitive of the two methods on the basis of the overall detection of Listeria. For hog tissues, method I detected L. monocytogenes (0.87% positive) and no other Listeria spp. in all samples (n = 1,849). In contrast, method II detected significantly more (P < 0.05) L. monocytogenes (2.38%) and Listeria spp. (0.38%) in these tissues. For small intestines (n = 300 raw chitterlings), L. monocytogenes was identified in 8.3% of enrichments with University of Vermont modified Listeria enrichment broth; plating to PALCAM slightly improved recovery (9%). Overall, ground pork samples (n = 340) harbored L. monocytogenes (45% positive) and other Listeria species (1.5% positive), as determined by method I. Subculturing to PALCAM significantly (P < 0.05) improved the detection of L. monocytogenes (50.2%) but not that of other Listeria species (1.7%). L. monocytogenes isolates (n = 243) were assigned to serotype 1 (53.5%), serotype 4 (25%), and serotypes other than 1 and 4 (21.4%).
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