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Bolten S, Ralyea RD, Lott TT, Orsi RH, Martin NH, Wiedmann M, Trmcic A. Utilizing whole genome sequencing to characterize Listeria spp. persistence and transmission patterns in a farmstead dairy processing facility and its associated farm environment. J Dairy Sci 2024:S0022-0302(24)00995-0. [PMID: 39004131 DOI: 10.3168/jds.2024-24789] [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: 02/15/2024] [Accepted: 06/14/2024] [Indexed: 07/16/2024]
Abstract
Farmstead dairy processing facilities may be particularly susceptible to Listeria spp. contamination due to the close physical proximity of their processing environments (PE) to associated dairy farm environments (FE). In this case study, we supported the implementation of interventions focused on improving (i) cleaning and sanitation efficacy, (ii) hygienic zoning, and (iii) sanitary equipment/facility design and maintenance in a farmstead dairy processing facility, and evaluated their impact on Listeria spp. detection in the farmstead's PE over 1 year. Detection of Listeria spp. in the farmstead's PE was numerically reduced from 50% to 7.5% after 1 year of intervention implementation, suggesting that these interventions were effective at improving Listeria spp. control. In addition, environmental samples were also collected from the farmstead's FE to evaluate the risk of the FE as a potential source of Listeria spp. in the PE. Overall, detection of Listeria spp. was higher in samples collected from the FE (75%, 27/36) compared with samples collected from the PE (24%, 29/120). Whole genome sequencing (WGS) performed on select isolates collected from the PE and FE supported the identification of 6 clusters (range of 3 to 15 isolates per cluster) that showed ≤ 50 high quality single nucleotide polymorphism (hqSNP) differences. Of these 6 clusters, 3 (i.e., clusters 2, 4, and 5) contained isolates that were collected from both the PE and FE, suggesting that transmission between these 2 environments was likely. Moreover, all cluster 2 isolates represented a clonal complex (CC) of L. monocytogenes commonly associated with dairy farm environmental reservoirs (i.e., CC666), which may support that the farmstead's FE represented an upstream source of the cluster 2 isolates that were found in the PE. Overall, our data underscore that, while the FE can represent a potential upstream source of Listeria spp. contamination in a farmstead dairy processing facility, implementation of targeted interventions can help effectively minimize Listeria spp. contamination in the PE.
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Affiliation(s)
- Samantha Bolten
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY, 14853; Food Safety Laboratory, Department of Food Science, Cornell University, Ithaca, NY, 14853
| | - Robert D Ralyea
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY, 14853
| | - Timothy T Lott
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY, 14853
| | - Renato H Orsi
- Food Safety Laboratory, Department of Food Science, Cornell University, Ithaca, NY, 14853
| | - Nicole H Martin
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY, 14853
| | - Martin Wiedmann
- Food Safety Laboratory, Department of Food Science, Cornell University, Ithaca, NY, 14853
| | - Aljosa Trmcic
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY, 14853.
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2
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Li X, Zheng J, Zhao W, Wu Y. Prevalence of Listeria monocytogenes in Milk and Dairy Product Supply Chains: A Global Systematic Review and Meta-analysis. Foodborne Pathog Dis 2024. [PMID: 38904302 DOI: 10.1089/fpd.2024.0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2024] Open
Abstract
Listeria monocytogenes, one of the main foodborne pathogens, is commonly found in milk and dairy products. This study aimed to estimate the presence of L. monocytogenes in milk and dairy product supply chains using a meta-analysis based on PubMed, Embase, Web of Science, and Scopus databases. A total of 173 studies were included in this meta-analysis. The pooled prevalence in the supply chain environment was 8.69% (95% confidence interval [CI]: 5.30%-12.78%), which was higher than that in dairy products (4.60%, 95% CI: 1.72%-8.60%) and milk products (2.93%, 95% CI: 2.14%-3.82%). Subgroup analysis showed that L. monocytogenes prevalence in raw milk (3.44%, 95% CI: 2.61%-4.28%) was significantly higher than in pasteurized milk (0.60%, 95% CI: 0.00%-2.06%). The highest prevalence of L. monocytogenes in milk and dairy products was observed in North America (5.27%, 95% CI: 2.19%-8.35%) and South America (13.54%, 95% CI: 3.71%-23.37%). In addition, studies using culture and molecular methods (5.17%, 95% CI: 2.29%-8.06%) had higher prevalence than other detection methods. Serogroup 1/2a and 3a (45.34%, 95% CI: 28.74%-62.37%), serogroup 1/2b and 3b (14.23%, 95% CI: 6.05%-24.24%), and serogroup 4b/4e (13.71%, 95% CI: 6.18%-22.83%) were dominant in these studies. The results of this study provide a better understanding of the prevalence of L. monocytogenes in milk and dairy product supply chains and suggest a potential foodborne pathogen burden.
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Affiliation(s)
- Xin Li
- Quality Management Department, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jingying Zheng
- Department of Epidemiology and Health Statistics, School of Public Health, Jilin University, Changchun, China
| | - Wei Zhao
- Institute of Microbiology, Jilin Center for Disease Prevention and Control, Changchun, China
| | - Yafang Wu
- Quality Management Department, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
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3
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Koutsoumanis K, Allende A, Bolton D, Bover‐Cid S, Chemaly M, De Cesare A, Herman L, Hilbert F, Lindqvist R, Nauta M, Nonno R, Peixe L, Ru G, Simmons M, Skandamis P, Suffredini E, Fox E, Gosling R(B, Gil BM, Møretrø T, Stessl B, da Silva Felício MT, Messens W, Simon AC, Alvarez‐Ordóñez A. Persistence of microbiological hazards in food and feed production and processing environments. EFSA J 2024; 22:e8521. [PMID: 38250499 PMCID: PMC10797485 DOI: 10.2903/j.efsa.2024.8521] [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] [Indexed: 01/23/2024] Open
Abstract
Listeria monocytogenes (in the meat, fish and seafood, dairy and fruit and vegetable sectors), Salmonella enterica (in the feed, meat, egg and low moisture food sectors) and Cronobacter sakazakii (in the low moisture food sector) were identified as the bacterial food safety hazards most relevant to public health that are associated with persistence in the food and feed processing environment (FFPE). There is a wide range of subtypes of these hazards involved in persistence in the FFPE. While some specific subtypes are more commonly reported as persistent, it is currently not possible to identify universal markers (i.e. genetic determinants) for this trait. Common risk factors for persistence in the FFPE are inadequate zoning and hygiene barriers; lack of hygienic design of equipment and machines; and inadequate cleaning and disinfection. A well-designed environmental sampling and testing programme is the most effective strategy to identify contamination sources and detect potentially persistent hazards. The establishment of hygienic barriers and measures within the food safety management system, during implementation of hazard analysis and critical control points, is key to prevent and/or control bacterial persistence in the FFPE. Once persistence is suspected in a plant, a 'seek-and-destroy' approach is frequently recommended, including intensified monitoring, the introduction of control measures and the continuation of the intensified monitoring. Successful actions triggered by persistence of L. monocytogenes are described, as well as interventions with direct bactericidal activity. These interventions could be efficient if properly validated, correctly applied and verified under industrial conditions. Perspectives are provided for performing a risk assessment for relevant combinations of hazard and food sector to assess the relative public health risk that can be associated with persistence, based on bottom-up and top-down approaches. Knowledge gaps related to bacterial food safety hazards associated with persistence in the FFPE and priorities for future research are provided.
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4
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Bonilla-Luque OM, Possas A, Cabo ML, Rodríguez-López P, Valero A. Tracking microbial quality, safety and environmental contamination sources in artisanal goat cheesemaking factories. Food Microbiol 2023; 114:104301. [PMID: 37290877 DOI: 10.1016/j.fm.2023.104301] [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: 12/15/2022] [Revised: 04/26/2023] [Accepted: 04/27/2023] [Indexed: 06/10/2023]
Abstract
A harmonised microbiological survey was performed in two artisanal factories of raw goat milk cheeses (A and B) located in the Andalusian region (Spain). A total of 165 different control points or samples (raw materials, final products, food-contact surfaces [FCS], and air) were examined as microbial and pathogen sources of contamination of artisanal goat raw milk cheeses. For raw milk samples analysed from both producers, the concentrations of aerobic-mesophilic bacteria (AMB), total coliforms, coagulase-positive Staphylococcus spp. (CPS), lactic-acid bacteria (LAB) and moulds and yeasts ranged between 3.48 and 8.59, 2.45-5.48, 3.42-4.81, 4.99-8.59 and 3.35-6.85 log cfu/mL respectively. For the same microbial groups, the analysis of raw milk cheeses revealed concentrations ranging from 7.82 to 8.88, 2.00-6.82, 2.00-5.28, 8.11-9.57 and 2.00-5.76 log cfu/g, respectively. Although the raw material analysed from producer A presented higher microbial loads and between-batch variability, it was B the producer with the most loaded final products. Regarding the microbial air quality, the fermentation area, storage room, milk reception and packaging room were the most AMB loaded places, while the ripening chamber was the area with higher fungal loads in bioareosol from both producers. Conveyor belts, cutting machine, storage boxes and brine tank were highlighted as the most contaminated FCS evaluated. Staphylococcus aureus was the only pathogen detected within the set of 51 isolates from samples as revealed by MALDI-TOF and molecular PCR, with a prevalence of 12.5% for samples from the producer B. The public health risk attributed to the consumption of artisanal goat cheese should not be neglected, and may consider the whole cheesemaking processing chain, from microbiological quality of raw milk to the ready-to-eat final product, especially concerning the presence of S. aureus.
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Affiliation(s)
- Olga María Bonilla-Luque
- Department of Food Science and Technology, UIC Zoonosis y Enfermedades Emergentes (ENZOEM), CeiA3, Universidad de Córdoba, Campus Rabanales, 14014, Córdoba, Spain.
| | - Arícia Possas
- Department of Food Science and Technology, UIC Zoonosis y Enfermedades Emergentes (ENZOEM), CeiA3, Universidad de Córdoba, Campus Rabanales, 14014, Córdoba, Spain.
| | - Marta L Cabo
- Laboratory of Microbiology and Technology of Marine Products (MICROTEC), Instituto de Investigacións Mariñas, CSIC, Eduardo Cabello, 6, 36208, Vigo, Spain.
| | - Pedro Rodríguez-López
- Laboratory of Microbiology and Technology of Marine Products (MICROTEC), Instituto de Investigacións Mariñas, CSIC, Eduardo Cabello, 6, 36208, Vigo, Spain; Department of Animal and Food Science, Faculty of Veterinary Medicine, Universitat Autònoma de Barcelona, Travessera Dels Turons S/n, 08193, Bellaterra, Cerdanyola Del Vallès, Spain.
| | - Antonio Valero
- Department of Food Science and Technology, UIC Zoonosis y Enfermedades Emergentes (ENZOEM), CeiA3, Universidad de Córdoba, Campus Rabanales, 14014, Córdoba, Spain.
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5
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Pyz-Łukasik R, Paszkiewicz W, Kiełbus M, Ziomek M, Gondek M, Domaradzki P, Michalak K, Pietras-Ożga D. Genetic Diversity and Potential Virulence of Listeria monocytogenes Isolates Originating from Polish Artisanal Cheeses. Foods 2022; 11:foods11182805. [PMID: 36140933 PMCID: PMC9497517 DOI: 10.3390/foods11182805] [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: 07/20/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 11/16/2022] Open
Abstract
Artisanal cheeses can be sources of Listeria monocytogenes and cause disease in humans. This bacterial pathogen is a species of diverse genotypic and phenotypic characteristics. The aim of the study was to characterize 32 isolates of L. monocytogenes isolated in 2014-2018 from artisanal cheeses. The isolates were characterized using whole genome sequencing and bioinformatics analysis. The artisanal cheese isolates resolved to four molecular groups: 46.9% of them to IIa (1/2a-3a), 31.2% to IVb (4ab-4b-4d-4e), 12.5% to IIc (1/2c-3c), and 9.4% to IIb (1/2b-3b-7). Two evolutionary lineages emerged: lineage II having 59.4% of the isolates and lineage I having 40.6%. The sequence types (ST) totaled 18: ST6 (15.6% of the isolates), ST2, ST20, ST26, and ST199 (each 9.4%), ST7 and ST9 (each 6.3%), and ST1, ST3, ST8, ST16, ST87, ST91, ST121, ST122, ST195, ST217, and ST580 (each 3.1%). There were 15 detected clonal complexes (CC): CC6 (15.6% of isolates), CC9 (12.5%), CC2, CC20, CC26, and CC199 (each 9.4%), CC7 and CC8 (each 6.3%), and CC1, CC3, CC14, CC87, CC121, CC195, and CC217 (each 3.1%). The isolates were varied in their virulence genes and the differences concerned: inl, actA, LIPI-3, ami, gtcA, aut, vip, and lntA.
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Affiliation(s)
- Renata Pyz-Łukasik
- Department of Food Hygiene of Animal Origin, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Akademicka 12, 20-033 Lublin, Poland
- Correspondence:
| | - Waldemar Paszkiewicz
- Department of Food Hygiene of Animal Origin, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Akademicka 12, 20-033 Lublin, Poland
| | - Michał Kiełbus
- Department of Experimental Hematooncology, Medical University of Lublin, Chodźki 1, 20-093 Lublin, Poland
| | - Monika Ziomek
- Department of Food Hygiene of Animal Origin, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Akademicka 12, 20-033 Lublin, Poland
| | - Michał Gondek
- Department of Food Hygiene of Animal Origin, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Akademicka 12, 20-033 Lublin, Poland
| | - Piotr Domaradzki
- Department of Quality Assessment and Processing of Animal Products, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland
| | - Katarzyna Michalak
- Department of Epizootiology and Clinic of Infectious Diseases, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Głęboka 30, 20-612 Lublin, Poland
| | - Dorota Pietras-Ożga
- Department of Epizootiology and Clinic of Infectious Diseases, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Głęboka 30, 20-612 Lublin, Poland
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6
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Listeria monocytogenes survives better at lower storage temperatures in regular and low-salt soft and cured cheeses. Food Microbiol 2022; 104:103979. [DOI: 10.1016/j.fm.2022.103979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 01/11/2022] [Accepted: 01/11/2022] [Indexed: 11/24/2022]
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7
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Campagnollo FB, Pedrosa GT, Kamimura BA, Furtado MM, Baptista RC, Nascimento HM, Alvarenga VO, Magnani M, Sant’Ana AS. Growth potential of three strains of Listeria monocytogenes and Salmonella enterica in Frescal and semi-hard artisanal Minas microcheeses: Impact of the addition of lactic acid bacteria with antimicrobial activity. Lebensm Wiss Technol 2022. [DOI: 10.1016/j.lwt.2022.113169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Yao J, Gao J, Guo J, Wang H, Zhang EN, Lin Y, Chen Z, Li S, Tao S. Characterization of Bacteria and Antibiotic Resistance in Commercially Produced Cheeses Sold in China. J Food Prot 2022; 85:484-493. [PMID: 34855936 DOI: 10.4315/jfp-21-198] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 11/28/2021] [Indexed: 11/11/2022]
Abstract
ABSTRACT The consumption of cheese in the People's Republic of China is increasing rapidly. Little is known about the microbiota, the presence of antibiotic-resistant bacteria, or the distribution of antibiotic resistance genes (ARGs) in commercially produced cheeses sold in China. This information is important for evaluating quality and safety. This study was conducted using 16S rRNA gene sequencing to assess the metagenomics of 15 types of cheese. Fourteen bacterial genera were detected, and Lactococcus, Lactobacillus, and Streptococcus were dominant based on number of sequence reads. Multidrug-resistant lactic acid bacteria (i.e., resistant to two or more types of antibiotic) were isolated from most of the types of cheese. Of these isolates, 100 and 91.7% were resistant to streptomycin and sulfamethoxazole, respectively, and genes involved in acquired resistance to streptomycin (strB) and sulfonamides (sul2) were detected with high frequency. To analyze the distribution of ARGs in the cheeses overall, 309 ARGs from eight categories and nine transposase genes were profiled. A total of 169 ARGs were detected in the 15 cheeses; their occurrence and abundance varied significantly between cheeses. Our study revealed diverse bacteria and ARGs in cheeses sold in China. The risks associated with multidrug resistance among dominant lactic acid bacteria are of great concern. HIGHLIGHTS
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Affiliation(s)
- Jinghui Yao
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, People's Republic of China 200240.,Shanghai Municipal Veterinary Key Laboratory, Shanghai, People's Republic of China 200240
| | - Jing Gao
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, People's Republic of China 200240.,Shanghai Municipal Veterinary Key Laboratory, Shanghai, People's Republic of China 200240
| | - Jianming Guo
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, People's Republic of China 200240.,Shanghai Municipal Veterinary Key Laboratory, Shanghai, People's Republic of China 200240
| | - Hengan Wang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, People's Republic of China 200240.,Shanghai Municipal Veterinary Key Laboratory, Shanghai, People's Republic of China 200240
| | - E N Zhang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, People's Republic of China 200240.,Shanghai Municipal Veterinary Key Laboratory, Shanghai, People's Republic of China 200240
| | - Yingzheng Lin
- Technical Center for Animal, Plant and Food Inspection and Quarantine of Shanghai Customs, Shanghai, People's Republic of China 200135
| | - Zhifei Chen
- Technical Center for Animal, Plant and Food Inspection and Quarantine of Shanghai Customs, Shanghai, People's Republic of China 200135
| | - Shuqing Li
- Technical Center for Animal, Plant and Food Inspection and Quarantine of Shanghai Customs, Shanghai, People's Republic of China 200135
| | - Sun Tao
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, People's Republic of China 200240.,Shanghai Municipal Veterinary Key Laboratory, Shanghai, People's Republic of China 200240
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Monitoring by a Sensitive Liquid-Based Sampling Strategy Reveals a Considerable Reduction of Listeria monocytogenes in Smeared Cheese Production over 10 Years of Testing in Austria. Foods 2021; 10:foods10091977. [PMID: 34574086 PMCID: PMC8471813 DOI: 10.3390/foods10091977] [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: 07/21/2021] [Revised: 08/19/2021] [Accepted: 08/19/2021] [Indexed: 11/16/2022] Open
Abstract
Most Austrian dairies and cheese manufacturers participated in a Listeria monitoring program, which was established after the first reports of dairy product-associated listeriosis outbreaks more than thirty years ago. Within the Listeria monitoring program, up to 800 mL of product-associated liquids such as cheese smear or brine are processed in a semi-quantitative approach to increase epidemiological sensitivity. A sampling strategy within cheese production, which detects environmental contamination before it results in problematic food contamination, has benefits for food safety management. The liquid-based sampling strategy was implemented by both industrial cheese makers and small-scale dairies located in the mountainous region of Western Austria. This report considers more than 12,000 Listeria spp. examinations of liquid-based samples in the 2009 to 2018 timeframe. Overall, the occurrence of L. monocytogenes in smear liquid samples was 1.29% and 1.55% (n = 5043 and n = 7194 tested samples) for small and industrial cheese enterprises, respectively. The liquid-based sampling strategy for Listeria monitoring at the plant level appears to be superior to solid surface monitoring. Cheese smear liquids seem to have good utility as an index of the contamination of cheese up to that point in production. A modelling or validation process should be performed for the new semi-quantitative approach to estimate the true impact of the method in terms of reducing Listeria contamination at the cheese plant level.
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10
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Flynn BT, Kozak SM, Lawton MR, Alcaine SD. Lactose oxidase: An enzymatic approach to inhibit Listeria monocytogenes in milk. J Dairy Sci 2021; 104:10594-10608. [PMID: 34334205 DOI: 10.3168/jds.2021-20450] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 06/16/2021] [Indexed: 12/18/2022]
Abstract
Listeria monocytogenes is a ubiquitous pathogen that can cause morbidity and mortality in immunocompromised individuals. Growth of L. monocytogenes is possible at refrigeration temperatures due to its psychrotrophic nature. The use of antimicrobials in dairy products is a potential way to control L. monocytogenes growth in processes with no thermal kill step, thereby enhancing the safety of such products. Microbial-based enzymes offer a clean-label approach for control of L. monocytogenes outgrowth. Lactose oxidase (LO) is a microbial-derived enzyme with antimicrobial properties. It oxidizes lactose into lactobionic acid and reduces oxygen, generating H2O2. This study investigated the effects of LO in UHT skim milk using different L. monocytogenes contamination scenarios. These LO treatments were then applied to raw milk with various modifications; higher levels of LO as well as supplementation with thiocyanate were added to activate the lactoperoxidase system, a natural antimicrobial system present in milk. In UHT skim milk, concentrations of 0.0060, 0.012, and 0.12 g/L LO each reduced L. monocytogenes counts to below the limit of detection between 14 and 21 d of refrigerated storage, dependent on the concentration of LO. In the 48-h trials in UHT skim milk, LO treatments were effective in a concentration-dependent fashion. The highest concentration of LO in the 21-d trials, 0.12 g/L, did not show great inhibition over 48 h, so concentrations were increased for these experiments. In the lower inoculum, after 48 h, a 12 g/L LO treatment reached levels of 1.7 log cfu/mL, a reduction of 1.3 log cfu/mL from the initial inoculum, whereas the control grew out to approximately 4 log cfu/mL, an increase of 1 log cfu/mL from the inoculum on d 0. When a higher challenge inoculum of 5 log cfu/mL was used, the 0.12 g/L and 1.2 g/L treatments reduced the levels by 0.2 to 0.3 log cfu/mL below the initial inoculum and the 12 g/L treatment by >1 log cfu/mL below the initial inoculum by hour 48 of storage at refrigeration temperatures. After the efficacy of LO was determined in UHT skim milk, LO treatments were applied to raw milk. Concentrations of LO were increased, and the addition of thiocyanate was investigated to supplement the effect of the lactoperoxidase system against L. monocytogenes. When raw milk was inoculated with 2 log cfu/mL, 1.2 g/L LO alone and combined with sodium thiocyanate reduced ~0.8 log cfu/mL from the initial inoculum on d 7 of storage, whereas the control grew out to >1 log cfu/mL from the initial inoculum. Furthermore, in the higher inoculum, 1.2 g/L LO combined with sodium thiocyanate reduced L. monocytogenes counts from the initial inoculum by >1 log cfu/mL, whereas the control grew out 2 log cfu/mL from the initial inoculum. Results from this study suggest that LO is inhibitory against L. monocytogenes in UHT skim milk and in raw milk. Therefore, LO may be an effective treatment to prevent L. monocytogenes outgrowth, increase the safety of raw milk, and be used as an effective agent to prevent L. monocytogenes proliferation in fresh cheese and other dairy products. This enzymatic approach is a novel application to control the foodborne pathogen L. monocytogenes in dairy products.
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Affiliation(s)
- Brenna T Flynn
- Department of Food Science, Cornell University, Ithaca, NY 14853
| | - Sarah M Kozak
- Department of Food Science, Cornell University, Ithaca, NY 14853
| | - Marie R Lawton
- Department of Food Science, Cornell University, Ithaca, NY 14853
| | - Samuel D Alcaine
- Department of Food Science, Cornell University, Ithaca, NY 14853.
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11
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Exploring Listeria monocytogenes perceptions in small and medium sized food manufacturers: Technical leaders' perceptions of risk, control and responsibility. Food Control 2021. [DOI: 10.1016/j.foodcont.2021.108078] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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12
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Occurrence of Listeria monocytogenes in Artisanal Cheeses from Poland and Its Identification by MALDI-TOF MS. Pathogens 2021; 10:pathogens10060632. [PMID: 34064133 PMCID: PMC8224308 DOI: 10.3390/pathogens10060632] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/11/2021] [Accepted: 05/18/2021] [Indexed: 11/16/2022] Open
Abstract
Listeria monocytogenes is a foodborne pathogen. A source of infection can be artisanal cheeses. Identification of the Listeria species is important for the protection of public health and the food industry. This study aimed to examine artisanal cheeses for the presence of L. monocytogenes and the effectiveness of the MALDI-TOF MS method in the identification of the L. monocytogenes isolates. A total of 370 samples of artisanal cheeses were examined. L. monocytogenes was found in 23 cheese samples (6.2%). The reliability of L. monocytogenes identification achieved by MALDI-TOF MS was varied, and the vast majority of the isolates (27/32) were identified only to the secure genus, probable species level. This study showed that (i) the occurrence of L. monocytogenes in the artisanal cheeses was at a higher level than that in the other EU countries, (ii) the standard of species identification of L. monocytogenes isolates from artisanal cheeses achieved by MALDI-TOF MS was not satisfactory and (iii) the presence of L. monocytogenes in artisanal cheeses remains a problem with regard to the food safety criterion and a potential public health risk.
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