scholarly journals Behaviour of Listeria monocytogenes and Escherichia coli O157:H7 during the cheese making of traditional raw-milk cheeses from Italian Alps

2015 ◽  
Vol 4 (2) ◽  
Author(s):  
Elena Cosciani-Cunico ◽  
Elena Dalzini ◽  
Stefania Ducoli ◽  
Chiara Sfameni ◽  
Barbara Bertasi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Raw Milk ◽  
Starter Cultures ◽  
Cow Milk ◽  
Italian Alps ◽  
Cheese Making ◽  
E Coli ◽  
Food Borne ◽  
First Time

The behaviour of <em>Listeria monocytogenes</em> and <em>Escherichia coli</em> O157:H7 was studied during the manufacture and ripening of two traditional Italian Alps cheeses. Each cheese type was manufactured in a pilot plan from raw cow milk (without the addition of starter cultures) artificially inoculated with <em>L. monocytogenes</em> and <em>E. coli</em> O157:H7 to a final concentration of about 4 log CFU/mL. The pathogens were enumerated throughout the cheese making and ripening processes to study their behaviour. When the milk was inoculated with 4 Log CFU/mL, the pathogens counts increased in the first time during the manufacturing process and then remained constant, until the end of ripening, or decreased significantly. Results indicate that the environment and nature of food borne pathogens affected the concentration of the bacteria during the manufacturing and ripening process. Thus, the presence of low cells numbers of <em>L. monocytogenes</em> and <em>E. coli</em> O157:H7 in milk destined for the production of raw milk cheeses characterized by a cooking of the curd less than 48°C can constitute a hazard for the consumer.

scholarly journals Assessment of a multiplex detection method for Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes in cow milk

2019 ◽  
Vol 24 (1) ◽  
pp. 277-294
Author(s):  
Rocio Esperanza Patiño-Burbano ◽  
Ana Karina Carrascal ◽  
Jorge Luis Parra-Arango ◽  
José Luis Rodríguez-Bautista
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Detection Rate ◽  
Pathogenic Bacteria ◽  
Simultaneous Detection ◽  
Cow Milk ◽  
Escherichia Coli O157 ◽  
Salmonella Spp ◽  
E Coli ◽  
Microbiological Methods

Raw cow milk is considered one of the most important vehicles for pathogenic bacteria like Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes. These three bacteria are responsible for foodborne diseases. Routine microbiological methods to detect these microorganisms in cow milk can be complicated and time consuming. The aim of this work was to evaluate a method to simultaneously detect Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes in experimentally contaminated cow milk. The assessed method combined a standard microbiological culture step, using a pre-enrichment medium that favors the growth of the three focal microorganisms: SEL broth, followed by a single PCR assay. A total of 43 interference bacterial strains were used to evaluate the method’s specificity. The detection rate for the microbiological method with standard culture media was 10 UFC/mL, and that of the PCR detection, following pre-enrichment in SEL broth, was 10 UFC/mL for S. enterica and L. monocytogenes and between 1 and 5 UFC/mL for E. coli O157:H7. The PCR method showed specificity for the reference strains. Simultaneous detection by multiple PCR using SEL broth was successful for the detection of S. enterica, E. coli O157:H7, and L. monocytogenes in samples of experimentally contaminated cow milk, featuring both a high detection rate and a high specificity. This approach promises to be a feasible routine procedure when testing milk samples in industry and public health control setups.

Note: Behaviour of Escherichia Coli O157: H7, Listeria Monocytogenes 4b and Yersinia Enterocolitica O3 in Pasteurised and Non-pasteurised Kefir Fermented for One or Two Days

2003 ◽  
Vol 9 (5) ◽  
pp. 365-369 ◽  
Author(s):  
M. Gulmez ◽  
A. Guven
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Yersinia Enterocolitica ◽  
Cold Storage ◽  
Susceptible Strain ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Food Borne Pathogens ◽  
Food Borne

The behaviour of three selected food-borne pathogens, E. coli O157: H7, L. monocytogenes 4b and Y. enterocolitica O3, added to fermented and pasteurised kefir was monitored. Populations of the three strains increased in one-day-fermented kefir, but only E. coli O157: H7 increased in two-days-fermented kefir during fermentation. None of the strains grew during cold storage (4 1 C), although E. coli O157: H7 and L. monocytogenes 4b survived up to 21 days in all samples cold. Y. enterocolitica O3 was the most susceptible strain that was present in one-day-fermented kefir for at least 14 days. Twodaysfermented kefir samples were more acidic thanthose of one-day-fermented samples, but none of the samples was safe enough to create an environment to eliminate the pathogens.

scholarly journals Microbiological and physicochemical changes during ripening in Bulgarian white brined cheese made from raw cow milk

2020 ◽  
Vol 23 (4) ◽  
pp. 494-503
Author(s):  
D. Bangieva
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Titratable Acidity ◽  
Chloride Content ◽  
Raw Milk ◽  
Cow Milk ◽  
Microbiological Analysis ◽  
Physicochemical Changes ◽  
Raw Milk Cheese

The main microbiological hazards of raw milk cheese are associated with Listeria monocytogenes, Escherichia coli and Staphylococcus aureus. Due to its high nutritional value, cheese is an excellent medium for the growth of these pathogens. This study was aimed to observe microbial dynamics of Bulgarian white brined cheese during cheese production and ripening. Microbiological analysis included determination of Staphylococcus aureus, Listeria spp. and Escherichia coli counts. Some physicochemical parameters, such as total titratable acidity, sodium chloride content, water activity and pH were also examined. Results revealed statistically significant increase in bacterial counts after cheesemaking steps and decrease at the end of the ripening period. Listeria monocytogenes was not detected in any of the cheese samples. Raw milk cheese was of unsatisfactory quality that emphasises the need for applying and maintaining good hygiene practices along the food chain to prevent microbial contamination and growth

scholarly journals Contribution of natural milk culture to microbiota, safety and hygiene of raw milk cheese produced in alpine malga

2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Rosaria Lucchini ◽  
Barbara Cardazzo ◽  
Lisa Carraro ◽  
Michele Negrinotti ◽  
Stefania Balzan ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Safety Evaluation ◽  
Raw Milk ◽  
Starter Cultures ◽  
Salmonella Spp ◽  
E Coli ◽  
First Case ◽  
Bacterial Biodiversity ◽  
Natural Milk ◽  
Coagulase Positive Staphylococci

Processing of alpine milk in malga farms is carried out under conditions that can favor contamination by coliforms, coagulase-positive staphylococci, or pathogens such as Listeria monocytogenes. With the aim to improve the hygienic characteristics and safety of cheese produced in four malga farms the use of lyophilized Natural Milk Culture prepared with selected strains was tested. Two cheesemaking tests were carried out in the same day always starting from the same milk: in the first case following the malga recipe that uses either Natural Whey Culture or without the addition of a starter, in the second one using a Natural Milk Culture. Cheesemaking were carried out in four malga farms located in the west area of Trentino region within the same week. For hygienic and safety evaluation, aerobic colony count, coagulase-positive staphylococci, Escherichia coli, staphylococcal toxins, Listeria monocytogenes , and Salmonella spp, pH and aw were determined in raw milk from evening and morning milking, curd in vat, curd after extraction and two months-ripened cheese. Pathogens or toxins, high values of coagulase- positive staphylococci and E. coli were not found in cheese samples. However, in the curd coagulase-positive staphylococci reached values almost of 5 Log CFU/g in the two malga without starter cultures. The use of Natural Milk Culture reduced E. coli counts. In addition, DNA was extracted from cheese samples and from Natural Milk Culture and the composition of the microbial community determined by Next Generation Sequencing method. The determination of cheese microbial communities demonstrated that the use of Natural Milk Culture exerted different effects in the different malga, in any case preserving bacterial biodiversity.

scholarly journals Antilisterial activity of lactic acid bacteria against Listeria monocytogenes strains originating from different sources

2014 ◽  
Vol 32 (No. 2) ◽  
pp. 145-151 ◽  
Author(s):  
I. Složilová ◽  
S. Purkrtová ◽  
M. Kosová ◽  
M. Mihulová ◽  
E. Šviráková ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Starter Culture ◽  
Raw Milk ◽  
Starter Cultures ◽  
Cow Milk ◽  
Live Cells ◽  
Dairy Equipment ◽  
Different Sources

Eight individual bacteriocin-producing lactic acid bacteria (LAB) strains and three bacteriocin-non-producing cheese starter cultures were evaluated for their ability to inhibit the growth of six Listeria monocytogenes strains, originating from the guinea-pig lymph nodes, raw cow milk, and manufacturing dairy equipment. Results showed that either live cells or cell-free neutralised supernatant (CFNS) and/or heated CFNS of six individual LAB strains (Lcc. lactis subsp. lactis CCDM 416 and NIZO R5, Lbc. plantarum HV 11 and DC 1246, P. acidilactici HV 12, and Ent. mundtii CCM 1282) and one starter culture (DELVO-ADD<sup>&reg;</sup> 100-X DSF) were effective in the suppression of at least one listeria strain. Neither any individual LAB strain nor starter culture was antagonistic toward all studied L. monocytogenes strains, indicating diverse sensitivity/resistance among L. monocytogenes strains to antimicrobial compounds of LAB. The significant susceptibility of listerias isolated from raw milk and dairy equipment together with the strong antilisterial activity of DELVO-ADD<sup>&reg; </sup>100-X DSF could be applied in dairy technology, where commonly used starter cultures could play both the biopreservative and fermentation role. &nbsp;

scholarly journals Antimicrobial Effects of Mustard Flour and Acetic Acid against Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica Serovar Typhimurium

2003 ◽  
Vol 69 (5) ◽  
pp. 2959-2963 ◽  
Author(s):  
Min-Suk Rhee ◽  
Sun-Young Lee ◽  
Richard H. Dougherty ◽  
Dong-Hyun Kang
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Bacterial Resistance ◽  
Fixed Amount ◽  
E Coli ◽  
Food Borne ◽  
Serovar Typhimurium

ABSTRACT This study was designed to investigate the individual and combined effects of mustard flour and acetic acid in the inactivation of food-borne pathogenic bacteria stored at 5 and 22°C. Samples were prepared to achieve various concentrations by the addition of acetic acid (0, 0.5, or 1%) along with mustard flour (0, 10, or 20%) and 2% sodium chloride (fixed amount). Acid-adapted three-strain mixtures of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica serovar Typhimurium strains (106 to 107 CFU/ml) were inoculated separately into prepared mustard samples stored at 5 and 22°C, and samples were assayed periodically. The order of bacterial resistance, assessed by the time required for the nominated populations to be reduced to undetectable levels against prepared mustards at 5°C, was S. enterica serovar Typhimurium (1 day) < E. coli O157:H7 (3 days) < L. monocytogenes (9 days). The food-borne pathogens tested were reduced much more rapidly at 22°C than at 5°C. There was no synergistic effect with regard to the killing of the pathogens tested with the addition of 0.5% acetic acid to the mustard flour (10 or 20%). Mustard in combination with 0.5% acetic acid had less bactericidal activity against the pathogens tested than did mustard alone. The reduction of E. coli O157:H7 and L. monocytogenes among the combined treatments on the same storage day was generally differentiated as follows: control < mustard in combination with 0.5% acetic acid < mustard alone < mustard in combination with 1% acetic acid < acetic acid alone. Our study indicates that acidic products may limit microbial growth or survival and that the addition of small amounts of acetic acid (0.5%) to mustard can retard the reduction of E. coli O157:H7 and L. monocytogenes. These antagonistic effects may be changed if mustard is used alone or in combination with >1% acetic acid.

scholarly journals Epidemiological Investigation, Serotypes and Distribution of Verocytotoxigenic Escherichia coli (VTEC) in Raw Milk and Milk Products in Uyo, Nigeria

2020 ◽  
Vol 37 (1) ◽  
pp. 10-20
Author(s):  
O.J. Akinjogunla ◽  
B.C. Akaka ◽  
C.U. Inyang
Keyword(s):  
Escherichia Coli ◽  
Cold Water ◽  
Raw Milk ◽  
Epidemiological Investigation ◽  
Milk Products ◽  
E Coli ◽  
Percentage Occurrence ◽  
Unpasteurized Milk ◽  
Food Borne ◽  
Structured Questionnaire

Food borne diseases are of great concern globally especially in the developing countries where poor sanitation is applied during collection and processing of milk from animals. The epidemiological investigation, serotypes and distribution of verocytotoxin (VTI and VT2)- producing Escherichia coli in raw milk and milk products were determined using structured questionnaire, Cefixime tellurite-sorbitol MacConkey agar, agglutination kits and VTEC-RPLA Toxin detection Kit. Out of 27 milkers, 7.4 % had primary education, 22.2 % washed the milk utensils with cold water and soap, 11.1 % washed their hands before milking, while 7.4 % milkers washed the udder of the animals before milking. All the yoghurts had the product names; 85.7 % had NAFDAC numbers; 80.0% had Batch Numbers, while 71.4 % had Manufacturer s’ Addresses. The unpasteurized milk samples had E. coli 0157 and non 0157 E. coli counts (CFU.ml-1) ranging from 4.0 x 102 to 1.7 x 103 and 6.0 x 102 to 2.0 x 103 , respectively, while E. coli 0157 and non 0157 E. coli counts of milk products were between 1.0 x 102 and 1.0 x 103 CFU.ml-1. E. coli 0157 had the highest percentage occurrence (38.3%), while E. coli 0145 had the lowest percentage occurrence (2.1%). More than 38.3% of the E. coli serotypes produced VT2, while ≥ 12.8% were VT1 producers. The occurrence of VTEC in the unpasteurized milk shows that the milkers should be enlightened on the necessary sanitary practices to adopt during milking and also post-pasteurization contamination of milk products should be avoided. Key Words: Verotoxigenic, Escherichia coli, Milk, Yoghurt, Nono, Serotypes.

scholarly journals Antimicrobial and Immunomodulating Activities of Two Endemic Nepeta Species and Their Major Iridoids Isolated from Natural Sources

2021 ◽  
Vol 14 (5) ◽  
pp. 414
Author(s):  
Neda Aničić ◽  
Uroš Gašić ◽  
Feng Lu ◽  
Ana Ćirić ◽  
Marija Ivanov ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Food Industry ◽  
Balkan Peninsula ◽  
Antimicrobial Activities ◽  
Natural Sources ◽  
E Coli ◽  
Food Borne ◽  
Metabolite Profiles ◽  
Aspergillus Sp ◽  
First Time

Two Balkan Peninsula endemics, Nepeta rtanjensis and N. argolica subsp. argolica, both characterized by specialized metabolite profiles predominated by iridoids and phenolics, are differentiated according to the stereochemistry of major iridoid aglycone nepetalactone (NL). For the first time, the present study provides a comparative analysis of antimicrobial and immunomodulating activities of the two Nepeta species and their major iridoids isolated from natural sources—cis,trans-NL, trans,cis-NL, and 1,5,9-epideoxyloganic acid (1,5,9-eDLA), as well as of phenolic acid rosmarinic acid (RA). Methanol extracts and pure iridoids displayed excellent antimicrobial activity against eight strains of bacteria and seven strains of fungi. They were especially potent against food-borne pathogens such as L. monocytogenes, E. coli, S. aureus, Penicillium sp., and Aspergillus sp. Targeted iridoids were efficient agents in preventing biofilm formation of resistant P. aeruginosa strain, and they displayed additive antimicrobial interaction. Iridoids are, to a great extent, responsible for the prominent antimicrobial activities of the two Nepeta species, although are probably minor contributors to the moderate immunomodulatory effects. The analyzed iridoids and RA, individually or in mixtures, have the potential to be used in the pharmaceutical industry as potent antimicrobials, and in the food industry to increase the shelf life and safety of food products.

scholarly journals Characterization of Escherichia coli Strains Derived from Cow Milk of Subclinical and Clinical Cases of Mastitis

2021 ◽  
Vol 11 (2) ◽  
pp. 541
Author(s):  
Katarzyna Grudlewska-Buda ◽  
Krzysztof Skowron ◽  
Ewa Wałecka-Zacharska ◽  
Natalia Wiktorczyk-Kapischke ◽  
Jarosław Bystroń ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacterial Species ◽  
Subclinical Mastitis ◽  
Clinical Mastitis ◽  
Economic Problem ◽  
Cow Milk ◽  
P Value ◽  
Dairy Herds ◽  
E Coli ◽  
Bonferroni Test

Mastitis is a major economic problem in dairy herds, as it might decrease fertility, and negatively affect milk quality and milk yield. Out of over 150 bacterial species responsible for the udder inflammation, Escherichia coli is one of the most notable. This study aimed to assess antimicrobial susceptibility, resistance to dipping agents and biofilm formation of 150 E. coli strains isolated from milk of cows with subclinical and clinical mastitis. The strains came from three dairy herds located in Northern and Central Poland. The statistical analyses were performed with post-hoc Bonferroni test and chi-square test (including Yates correction). The data with a p value of <0.05 were considered significant. We found that the tested strains were mostly sensitive to antimicrobials and dipping agents. It was shown that 37.33% and 4.67% of strains were resistant and moderately resistant to at least one antimicrobial agent, respectively. No extended-spectrum beta-lactamases (ESBL)-producing E. coli were detected. The majority of strains did not possess the ability to form biofilm or formed a weak biofilm. The strong biofilm formers were found only among strains derived from cows with subclinical mastitis. The lowest bacteria number was noted for subclinical mastitis cows’ strains, after stabilization with iodine (3.77 log CFU × cm−2) and chlorhexidine (3.96 log CFU × cm−2) treatment. In the present study, no statistically significant differences in susceptibility to antibiotics and the ability to form biofilm were found among the strains isolated from cows with subclinical and clinical mastitis. Despite this, infections in dairy herds should be monitored. Limiting the spread of bacteria and characterizing the most common etiological factors would allow proper treatment.

scholarly journals ATIVIDADE ANTIMICROBIANA DE MICRORGANISMOS ISOLADOS DE GRÃOS DE KEFIR

2018 ◽  
Vol 19 (0) ◽  
Author(s):  
Priscila Alves Dias ◽  
Daiani Teixeira Silva ◽  
Cláudio Dias Timm
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Salmonella Enterica ◽  
Escherichia Coli O157 ◽  
E Coli

Resumo Kefir é o produto da fermentação do leite pelos grãos de kefir. Esses grãos contêm uma mistura simbiótica de bactérias e leveduras imersas em uma matriz composta de polissacarídeos e proteínas. Muitos benefícios à saúde humana têm sido atribuídos ao kefir, incluindo atividade antimicrobiana contra bactérias Gram positivas e Gram negativas. A atividade antimicrobiana de 60 microrganismos isolados de grãos de kefir, frente à Escherichia coli O157:H7, Salmonella enterica subsp. enterica sorotipos Typhimurium e Enteritidis, Staphylococcus aureus e Listeria monocytogenes, foi estudada através do teste do antagonismo. A ação antimicrobiana dos sobrenadantes das bactérias ácido-lácticas que apresentaram atividade no teste do antagonismo foi testada. O experimento foi repetido usando sobrenadantes com pH neutralizado. Salmonella Typhimurium e Enteritidis sobreviveram por 24 horas no kefir em fermentação. E. coli O157:H7, S. aureus e L. monocytogenes foram recuperados até 72 horas após o início da fermentação. Todos os isolados apresentaram atividade antimicrobiana contra pelo menos um dos patógenos usados no teste do antagonismo. Sobrenadantes de 25 isolados apresentaram atividade inibitória e três mantiveram essa atividade com pH neutralizado. As bactérias patogênicas estudadas sobreviveram por tempo superior àquele normalmente utilizado para a fermentação do kefir artesanal, o que caracteriza perigo em potencial para o consumidor quando a matéria-prima não apresentar segurança sanitária. Lactobacillus isolados de grãos de kefir apresentam atividade antimicrobiana contra cepas de E. coli O157:H7, Salmonella sorotipos Typhimurium e Enteritidis, S. aureus e L. monocytogenes além daquela exercida pela diminuição do pH.

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