The document describes a study that evaluated a new combined method for detecting Listeria species in environmental and food samples. The method involves enriching samples for 20-26 hours in ActeroTM Listeria Enrichment Media followed by detection of Listeria using the DuPontTM BAX® System Real-Time PCR assay. The study found that this new combined method performed equally well or better than standard reference methods for detecting Listeria in stainless steel, plastic, sealed concrete, frankfurters, spinach, cheese, shrimp and salmon samples. The new method provided results in about half the time as reference methods, offering an improved solution for rapid Listeria monitoring in the food industry.
A comparative study of procedures for binding of aflatoxin M1 to 1 Lactobacil...Jean Claude Assaf
Several strains of Lactic Acid Bacteria (LAB), frequently used in food fermentation and 20 preservation, have been reported to bind different types of toxins in liquid media. This study 21 was carried out to investigate the effect of different concentrations of Lactobacillus 22 rhamnosus GG (ATCC 53103) to bind aflatoxin M1 (AFM1) in liquid media. AFM1 binding 23 was tested following repetitive washes or filtration procedures in combination with additional 24 treatments as heat, pipetting, and centrifugation. The mixture of L. rhamnosus GG and AFM1 25 was incubated for 18 hours at 37 °C and the unbound AFM1 was quantified by HPLC. The 26 stability of the bacteria-AFM1 complex for both viable and heat treated bacteria was tested. 27 Depending on the bacterial concentration and procedure used, the percentages of bound AFM1 28 by L. rhamnosus GG varied from as low as undetectable to as high as 63%. The highest 29 reduction in the level of unbound AFM1 was recorded for the five washes procedure that 30 involved heat and pipetting treatments. Results also showed that binding was partially 31 reversible and AFM1 was released after repeated washes. These findings highlight the effect 32 of different treatments on the binding of L. rhamnosus GG to AFM1 in liquid matrix.
Preservative potentials of crude bacteriocins produced by Lactobacillus tucce...iosrjce
IOSR Journal of Biotechnology and Biochemistry (IOSR-JBB) covers studies of the chemical processes in living organisms, structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules, chemical properties of important biological molecules, like proteins, in particular the chemistry of enzyme-catalyzed reactions, genetic code (DNA, RNA), protein synthesis, cell membrane transport, and signal transduction. IOSR-JBB is privileged to focus on a wide range of biotechnology as well as high quality articles on genetic engineering, cell and tissue culture technologies, genetics, microbiology, molecular biology, biochemistry, embryology, cell biology, chemical engineering, bioprocess engineering, information technology, biorobotics.
Effect of Some Disinfectants on Antibiotic Resistance Staphylococcus Isolated...iosrjce
IOSR Journal of Agriculture and Veterinary Science (IOSR-JAVS) is a double blind peer reviewed International Journal edited by the International Organization of Scientific Research (IOSR). The journal provides a common forum where all aspects of Agricultural and Veterinary Sciences are presented. The journal invites original papers, review articles, technical reports and short communications containing new insight into any aspect Agricultural and Veterinary Sciences that are not published or not being considered for publication elsewhere.
A comparative study of procedures for binding of aflatoxin M1 to 1 Lactobacil...Jean Claude Assaf
Several strains of Lactic Acid Bacteria (LAB), frequently used in food fermentation and 20 preservation, have been reported to bind different types of toxins in liquid media. This study 21 was carried out to investigate the effect of different concentrations of Lactobacillus 22 rhamnosus GG (ATCC 53103) to bind aflatoxin M1 (AFM1) in liquid media. AFM1 binding 23 was tested following repetitive washes or filtration procedures in combination with additional 24 treatments as heat, pipetting, and centrifugation. The mixture of L. rhamnosus GG and AFM1 25 was incubated for 18 hours at 37 °C and the unbound AFM1 was quantified by HPLC. The 26 stability of the bacteria-AFM1 complex for both viable and heat treated bacteria was tested. 27 Depending on the bacterial concentration and procedure used, the percentages of bound AFM1 28 by L. rhamnosus GG varied from as low as undetectable to as high as 63%. The highest 29 reduction in the level of unbound AFM1 was recorded for the five washes procedure that 30 involved heat and pipetting treatments. Results also showed that binding was partially 31 reversible and AFM1 was released after repeated washes. These findings highlight the effect 32 of different treatments on the binding of L. rhamnosus GG to AFM1 in liquid matrix.
Preservative potentials of crude bacteriocins produced by Lactobacillus tucce...iosrjce
IOSR Journal of Biotechnology and Biochemistry (IOSR-JBB) covers studies of the chemical processes in living organisms, structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules, chemical properties of important biological molecules, like proteins, in particular the chemistry of enzyme-catalyzed reactions, genetic code (DNA, RNA), protein synthesis, cell membrane transport, and signal transduction. IOSR-JBB is privileged to focus on a wide range of biotechnology as well as high quality articles on genetic engineering, cell and tissue culture technologies, genetics, microbiology, molecular biology, biochemistry, embryology, cell biology, chemical engineering, bioprocess engineering, information technology, biorobotics.
Effect of Some Disinfectants on Antibiotic Resistance Staphylococcus Isolated...iosrjce
IOSR Journal of Agriculture and Veterinary Science (IOSR-JAVS) is a double blind peer reviewed International Journal edited by the International Organization of Scientific Research (IOSR). The journal provides a common forum where all aspects of Agricultural and Veterinary Sciences are presented. The journal invites original papers, review articles, technical reports and short communications containing new insight into any aspect Agricultural and Veterinary Sciences that are not published or not being considered for publication elsewhere.
2.6.12. microbiological examination of non sterile products (total viable aer...Guide_Consulting
Salah Satu Referensi Yang Digunakan Dalam One Day Seminar "Preservative Effectiveness Validation"
04 Desember 2014. Bogor
Detail : info@traininglaboratorium.com
Journal of Bacteriology and Mycology is a peer-reviewed, open access journal published by Austin Publishers. It provides easy access to high quality manuscripts in all related aspects of two major sub branches of Microbiology namely Bacteriology: the study of Bacterial Mycology& the study of fungus. The Journal focuses upon the identification, classification, characterization of bacterial/fungal species and the infections and health issues caused by these dreadful bacteria and fungus.
Austin Publishing Group is a successful host of more than hundred peer reviewed journals, open access journals in various fields of science and technology with intent to bridge the gap between academic and research access.
Journal of Bacteriology and Mycology journal accepts original research articles, review articles, case reports, mini reviews, rapid communication, opinions and editorials in all related aspects of Bacterial Mycology & Fungal Species.
Evaluation of mancozeb activity towards various plant fungal pathogen agents ...UPL
Tests were carried out in petri dishes and concern the evaluation of conidial germination of different pathogen populations of Alternaria spp., V. inaequalis and S. vesicarium (for these last two fungi were analyzed two type of strains: sensitive e resistant to strobilurins according to our previous results (Collina et al, 2007 and Fiaccadori et al, 2011). Mancozeb was used as formulated product (solo) dissolved in sterile distillate water.
Microbiological inspection of mineral water by redox-potential measurement Olivér Reichart
MicroTester as a validated method is suitable for rapid microbiological testing of mineral water, carbonated water, tank and running drinking water and other types of water. The time needed for a reliable detection of microorganisms is of key importance: in water industry the real-time (or at least as fast as possible) monitoring of the microbiological properties of the production is indispensable; in public water supply the essential basis of the epidemiological and public health measures is the fast and reliable result of the microbiological inspection. Beside the most important and most widely inspected microbiological contaminants the most relevant disturbing flora was involved to the validation process as well.
Antibacterial Resistance in the Muscles of Chicken, Pig and Beef IJERA Editor
Though antibiotic drugs are known to improve the health and welfare of food animals , there is parallel risk due
to the development of resistant microorganisms in the body of target animals. Seven meat samples were
procured from wet market in Old Town,Petaling Jaya, Malaysia and assessed for the presence of antibiotic
residues. The samples chosen were chicken parts (skin, muscle and liver) , pig parts (liver, muscle and
intestine) and beef muscle. The results indicated that chicken skin had high level of antibioticresidues which
positively resisted the presence of gram positive, Staphylococcus aureus, S. epidermidisand B. cereus as known
by the zone of inhibition.The beef muscle also held residue which resisted S. aureusChosenbacteriaalong with
the extracts of chicken skin, pig intestine and beef muscle were observed to be resistant totetracycline
hydrochloride, ciprofloxacin hydrochloride monohydrate and their combinations when tested at a concentration
of 1 percent
International Journal of Pharmaceutical Science Invention (IJPSI)inventionjournals
International Journal of Pharmaceutical Science Invention (IJPSI) is an international journal intended for professionals and researchers in all fields of Pahrmaceutical Science. IJPSI publishes research articles and reviews within the whole field Pharmacy and Pharmaceutical Science, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Detection techniques for microorganisms in food of animalMANJEET RATHOUR
The detection and enumeration of microorganisms in food are an essential
part of any quality control or food safety plan. Traditional methods of detecting foodborne pathogenic bacteria are often time-consuming because of the need for growth
in culture media, followed by isolation, biochemical and/or serological identifi cation,
and in some cases, subspecifi c characterization. Advances in technology have made
detection and identifi cation faster, more sensitive, more specifi c, and more convenient than traditional assays. These new methods include for the most part antibodyand DNA-based tests, and modifi cations of conventional tests made to speed up
analysis and reduce handling.
2.6.12. microbiological examination of non sterile products (total viable aer...Guide_Consulting
Salah Satu Referensi Yang Digunakan Dalam One Day Seminar "Preservative Effectiveness Validation"
04 Desember 2014. Bogor
Detail : info@traininglaboratorium.com
Journal of Bacteriology and Mycology is a peer-reviewed, open access journal published by Austin Publishers. It provides easy access to high quality manuscripts in all related aspects of two major sub branches of Microbiology namely Bacteriology: the study of Bacterial Mycology& the study of fungus. The Journal focuses upon the identification, classification, characterization of bacterial/fungal species and the infections and health issues caused by these dreadful bacteria and fungus.
Austin Publishing Group is a successful host of more than hundred peer reviewed journals, open access journals in various fields of science and technology with intent to bridge the gap between academic and research access.
Journal of Bacteriology and Mycology journal accepts original research articles, review articles, case reports, mini reviews, rapid communication, opinions and editorials in all related aspects of Bacterial Mycology & Fungal Species.
Evaluation of mancozeb activity towards various plant fungal pathogen agents ...UPL
Tests were carried out in petri dishes and concern the evaluation of conidial germination of different pathogen populations of Alternaria spp., V. inaequalis and S. vesicarium (for these last two fungi were analyzed two type of strains: sensitive e resistant to strobilurins according to our previous results (Collina et al, 2007 and Fiaccadori et al, 2011). Mancozeb was used as formulated product (solo) dissolved in sterile distillate water.
Microbiological inspection of mineral water by redox-potential measurement Olivér Reichart
MicroTester as a validated method is suitable for rapid microbiological testing of mineral water, carbonated water, tank and running drinking water and other types of water. The time needed for a reliable detection of microorganisms is of key importance: in water industry the real-time (or at least as fast as possible) monitoring of the microbiological properties of the production is indispensable; in public water supply the essential basis of the epidemiological and public health measures is the fast and reliable result of the microbiological inspection. Beside the most important and most widely inspected microbiological contaminants the most relevant disturbing flora was involved to the validation process as well.
Antibacterial Resistance in the Muscles of Chicken, Pig and Beef IJERA Editor
Though antibiotic drugs are known to improve the health and welfare of food animals , there is parallel risk due
to the development of resistant microorganisms in the body of target animals. Seven meat samples were
procured from wet market in Old Town,Petaling Jaya, Malaysia and assessed for the presence of antibiotic
residues. The samples chosen were chicken parts (skin, muscle and liver) , pig parts (liver, muscle and
intestine) and beef muscle. The results indicated that chicken skin had high level of antibioticresidues which
positively resisted the presence of gram positive, Staphylococcus aureus, S. epidermidisand B. cereus as known
by the zone of inhibition.The beef muscle also held residue which resisted S. aureusChosenbacteriaalong with
the extracts of chicken skin, pig intestine and beef muscle were observed to be resistant totetracycline
hydrochloride, ciprofloxacin hydrochloride monohydrate and their combinations when tested at a concentration
of 1 percent
International Journal of Pharmaceutical Science Invention (IJPSI)inventionjournals
International Journal of Pharmaceutical Science Invention (IJPSI) is an international journal intended for professionals and researchers in all fields of Pahrmaceutical Science. IJPSI publishes research articles and reviews within the whole field Pharmacy and Pharmaceutical Science, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Detection techniques for microorganisms in food of animalMANJEET RATHOUR
The detection and enumeration of microorganisms in food are an essential
part of any quality control or food safety plan. Traditional methods of detecting foodborne pathogenic bacteria are often time-consuming because of the need for growth
in culture media, followed by isolation, biochemical and/or serological identifi cation,
and in some cases, subspecifi c characterization. Advances in technology have made
detection and identifi cation faster, more sensitive, more specifi c, and more convenient than traditional assays. These new methods include for the most part antibodyand DNA-based tests, and modifi cations of conventional tests made to speed up
analysis and reduce handling.
People in a big city as Antananarivo, capital of Madagascar, have leads to take street foods for their daily nutritional needs. This food habits may be a risk for consumers due to contaminations from street environment and bad practices related to hygiene. This study aimed to examine the quality and safety of street vended foods in Antananarivo, on January 2016 to December 2017.Six hundred and sixty two samples including 126samples of melting salads, 70 beef skewers, 54 chicken skewers, and typical Malagasy foods as : mofoanana (67 samples), mofogasy (64 samples), ramanonaka (64), makasaoka (66), mofoakondro (62) and kobandravina(89);were randomly collected from the streetvendors in Antananarivo marketsto evaluate their bacteriological quality.International Methods (ISO) was adopted for to find the load of Total Aerobic Bacteria andEnterobateriaceae,Escherichia coli and to search pathogen bacteria as Salmonella, Campylobacter jejuni, Escherichia coli O157H7 and Bacillus cereus in these foods.The results revealed that the mean values ofthe Total Aerobic Bacteria count was 0.1x106- 4.8x106cfu/g. Enterobacteriaceaecount range from 0.4x102 to 1.9x102cfu/g. Escherichia coli count range from 0.04x102cfu/g. to 0.19 x102cfu/g.Salmonellawas only present in melting salads, beef skewers and chicken skewers samples. Bacillus cereus count range from 0,1x102 to 1,5x102cfu/g. Campylobacter jejuniwas only present in samples of ramanonaka and kobandravina. Two strains of presumptive Eschercichia coli O157 H7 (βglucuronidase -) were isolated. PCR method was used to confirm the identity of these two isolates. A high contamination above 106 cfu/g food and the presence of potential pathogens bacteria could be hazardous. Systematic inspections and training of food vendors on food hygiene and application of hazard analysis critical control point (HACCP) has been recognised as measures to guarantee improvement of the quality of street foods.
Bioprocess development for enhanced spore production in shake flask and pilot...iosrjce
Bacillus thuringiensis subsp. Israelensis (Bti), has proven to be a safe and effective larvicide for controlling
mosquito and black fly larvae. The effect of cultivation and bioprocess development on Bti growth and sporulation was
investigated in shake flask level and batch cultivation in the semi-industrial scale 16-L stirred tank bioreactor. For
industrial production of biocontrol microorganism, it is necessary to obtain high cell mass and spore production in a short
time with low cost cultivation media. In this study, the new composition of production media was optimized which composed
of (g L
-1
): glucose, 10; yeast extract, 30; KH2PO4, 5; K2HPO4, 5; MgSO4. 7H20, 0.005; MnSO4.H2O, 0.03; FeSO4, 0.01;
CaCl2.7 H2O, 0.05; NaH2PO4, 1.5; NH4H2PO4, 1.5. The maximal cell dry mass and spore production, Sporemax for shake
flask study were 4.26 gL-1
at 36 h and 3.29106
spore mL-1
, respectively. Furthermore, studies of the cultivation conditions
under controlled and uncontrolled pH in the 16L-bioreactor was performed. The growth of Bti under uncontrolled pH
cultivation showing decreased of glucose and total protein concentration in the media was correlated with the vegetative cell
growth and sporulation. The maximal cell dry mass and Sporemax for uncontrolled pH bioreactor were 4.14 gL-1
at 36h and
3.7106
spore mL-1
, respectively. The maximal cell dry mass and spore production, Sporemax for controlled pH bioreactor
were 3.36 gL-1
at 26 h and 3.23 106
spore mL-1
, respectively. In conclusion, batch cultivation in 16-L bioreactor with the
new optimized production medium under uncontrolled pH condition increased of the cell dry mass and number of spores up to 23 % and 47 % , respectively
Antimicrobial activity of Lactobacillus spp. especially (L. planetarium and L. acidophilus) against S. aureus were tested using agar-plug, agar well diffusion methods to select the best isolate that could inhibit the growth of multidrug resistance isolates. Further identification for the presence of bacteriocin was done using ELISA kit. Results showed that Lactobacillus spp isolates were bacteriocin producers with different degrees and that L. planetarium (L7) was the most efficient in bacteriocin production. Therefore, L. planetarium (L7) was selected for purification using 70% saturated ammonium sulfate and gel chromatography. The effect of purified bacteriocin was tested on 16 bacterial isolates using micro-titer plate method and well diffusion method. The results showed the ability of the bacteriocin to inhibit bacteria only at concentrations 1866U/ml (50%), 3732U/ml (100%) with a diameter of inhibition zones ranges between (11-23 mm) respectively. The anti-biofilm activity of purified bacteriocin at concentration 100% was investigated and the results showed that biofilm formation was reduced by 100% in the presence of bacteriocin.
Presentation based on a research article published in the journal scientific reports in 2017, entitled as "A Novel Pathogen Capturing Device for Removal and Detection"
ABSTRACT- Live microorganisms, have beneficial effects on their host’s health, are called as probiotics. There are various possible sources to isolate
these bacteria. In this studyp harmaceutical probiotic sachet is used as isolation source. The purpose of this study is to search the potentiality of
probiotic bacteria and investigate the probiotic properties of isolates.9 different samples of 3 brands of sachet were used for isolation of bacteria.
Isolates were examined according to their probiotic properties. The probiotic characteristics like pH and Bile tolerance, Antagonistic activity and
Antibiotic susceptibility of isolated bacteria Such as Lactobacillus acidophilus, Lactobacillus rhamnosus and Bifidobacterium bifidum was done. Bile
Tolerance and pH tolerance was determined with the help of the help of coefficient of growth inhibition if their coefficient of growth inhibition is less
than 0.5 the organism was considered as the pH and Bile tolerance. The Strains of Lactobacillus acidophilus and Lactobacillus rhamnosus and Bifidobacterium
bifidum show best result at the pH Acidic to Neutral (5 to 7) and show a bile tolerance from 1-4 % bile. All the isolated bacteria show
the maximum inhibition against Staphyloccocus aureus and minimum against Salmonella typhi by Lactobacillus Strains but Bifidobacterium show
minimum against Escheria coli. Most isolates show resistance toward antibiotics. From this study it can be concluded that pharmaceutical probiotic
products used in the study were showing satisfactory quality and potential probiotic strain.
Key words- Probiotic, Lactobacillus, Bifidobacterium, Sachet
Campylobacter (curved rod in Greek) may have been discovered in the late nineteenth century (1886) by Theodor Escherich from an infant who died of cholera and called the disease “cholera infantum”
In the last 30 years, Campylobacter has been recognized as a leading pathogen causing diseases in both animals and humans and considered a zoonotic pathogen
Campylobacters (formerly Vibrio fetus) were first associated with diseases of cattle and sheep at the beginning of 20th century
Detection of Slime-Producing Staphylococcus aureus Strains Isolated from Food...Agriculture Journal IJOEAR
Abstract— The contamination of food with pathogenic microorganisms producing biofilm, implies a high cost for the food industry and represents a serious risk for the health of consumers. The antibacterial activity of organic extracts of Azorella trifurcata and Mulinum echegarayii was evaluated against 4 Staphylococcus aureus slime-producing strains isolated from bakery foods and against S. aureus ATCC 35556 slime-producing strain and S. aureus ATCC 25923 non slime-producing strain. The plant extracts showed antibacterial effectiveness against all the strains of S. aureus tested with minimum inhibitory concentration (MIC) between 500 and 8000 µg/ml. M. echegarayii 30:70% AcOEt:HEX showed the best activity: five strains of S. aureus showed MIC of 1000 μg/ml and S. aureus ATCC 25923 was inhibited at doses of 500 μg/ml. The values of minimum bactericidal concentration (MBC) of the extracts assayed were one or two times higher than corresponding MIC values. This study showed that extracts of Azorella trifurcata and Mulinum echegarayii are promising for future natural therapy against slime-producing S. aureus. Plant extracts with activity against slime producing S. aureus strains could provide benefits for of food technology and public health.
Enterocin 55 produced by non rabbit-derived strain Enterococcus faecium EF55 ...Agriculture Journal IJOEAR
— Ent55 is produced by poultry strain Enterococcus faecium EF55. It is substance which can be allotted to Class II enterocins; thermo-stable, small peptide. Because producer strain has shown beneficial effect in poultry and broiler rabbits as well, we decided to apply Ent55 in broiler rabbit husbandry. Ent55 showed antimicrobial activity in broiler rabbits by reduction of staphylococci, Clostridiae, pseudomonads and coliforms. Its beneficial effect was demonstrated by stimulation of phagocytic activity as well as by reduction of Eimeria spp. oocysts. GPx values were lower; it means, no oxidative stress was evoked. Moreover, it has not negative influence on growth performance and biochemical parameters. Our results indicated that enterocin produced by not-autochtonous strain can also have protective and beneficial effect in broiler rabbits.
IOSR Journal of Pharmacy and Biological Sciences(IOSR-JPBS) is an open access international journal that provides rapid publication (within a month) of articles in all areas of Pharmacy and Biological Science. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Pharmacy and Biological Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Similar to FoodChek_White Paper_Combined Method BAX Listeria Genus Actero Listeria (20)
FoodChek_White Paper_Combined Method BAX Listeria Genus Actero Listeria
1. A New Combined Method forSimple and
Rapid Detection of Listeria spp. in
Environmental and Food Samples
Method Comparison Study
2. A New Combined Method for Simple and Rapid Detection of Listeria spp. in
Environmental and Food Samples
The food safety regulations have tended to adopt a zero tolerance attitude for the presence of Listeria
monocytogenes in ready-to-eat foods. Therefore, detection of L. monocytogenes in foods and food processing
environment is one of the key elements to a food safety strategy. Furthermore, detection of any Listeria
species in environmental samples is considered as an indication of a potential risk to find L. monocytogenes in
manufactured food.
A collaboration between FoodChek Systems Inc. (Canada) and DuPont Nutrition & Health (USA) has
resulted in the development of one of the fastest methods of Listeria detection available in the food industry.
This method combines a 20-26 hour single-step enrichment of environmental and food samples in Actero™
Listeria Enrichment Media (Actero™ Listeria medium) followed by two hours of sample preparation and
processing with the DuPont™ BAX® System Real-Time PCR assay for Genus Listeria (BAX® System assay).
The main advantage of the Actero™ Listeria medium is the ability to provide the ideal growing environment
for sub lethally injured Listeria to allow for accelerated, reliable and faster detection. The BAX® System assay
is a next-generation test, which combines shorter, simpler sample preparation and faster real-time processing
without sacrificing accuracy or reliability. Combining the improved technology of the new BAX® System
assay with the optimized Actero™ Listeria medium undoubtedly affords one of the best solutions for rapid
and effective monitoring of Listeria in the food industry.
A series of internal laboratory validation studies were completed for submission to the AOAC-Research
Institute that compared the new combined method of Listeria spp. detection to the USDA-FSIS MLG 8.09
and the US FDA BAM 10 reference methods. Environmental sponge samples collected from food contact
(stainless steel and plastic) and non-food contact (sealed concrete) surfaces were tested in the presence of
high levels of competing background flora. Food sample type tested in the studies included frankfurters, fresh
bagged spinach, soft Mexican style cheese, frozen cooked shrimps and cold smoked salmon.
The independent laboratory validation studies were performed for stainless steel samples (Q Laboratories,
Inc., Cincinnati, USA) and for soft Mexican style cheese samples (Food Microbiology, Agriculture and Food
Laboratory, University of Guelph, Guelph, Canada).
The samples artificially inoculated with different Listeria spp. were enriched with the Actero™ Listeria
followed by the detection of Listeria spp. using the BAX® System assay.
The results of the study demonstrated that performance of the candidate method is statistically
equivalent or superior to the reference culture methods for detecting Listeria spp. in environmental
and food samples.
The time to detect Listeria spp. was significantly reduced when single-step enrichment in Actero™
Listeria was combined with the detection using the BAX® System assay.
The high accuracy and reliability of the method were confirmed by the independent laboratory
validation studies.
3. Methodology
Equipment, reagents and supplies
Actero™ Listeria Enrichment Media
Dehydrated formats: FCM-011 – 500 g, FCM-022 – 2 kg, FCM-192 – 1 L MediaPouch, FCM-193 – 10 liter
MediaPouch.
Ready to use liquid formats: FCM-045 – 5 L MediaBox, FCM-046: 10 L MediaBox.
DuPont™ BAX® System Real-Time PCR Assay Genus Listeria. Kit #D15131113
BAX® System standard equipment and supplies
Buffered Listeria enrichment broth (BLEB)
UVM enrichment broth
MOPS – Buffered Listeria enrichment broth (MOPS-BLEB)
Modified Oxoid (MOX) agar plates
Trypticase Soy broth with 0.6% yeast extract (TSA-YE)
Horse blood overlay agar (HL)
Biochemical test panel Listeria API® system
Sample inoculation
The strains of Listeria spp. were selected from FoodChek Laboratories Inc. Collection to artificially inoculate
environmental surfaces and food matrices. One strain of Pseudomonas aeruginosa and one strain of Enterococcus
faecalis were also selected to represent competing flora. For independent laboratory validation study carried
out with stainless steel samples, well-characterized ATCC target and non-target strains were used (see Table
1).
A pure culture of each Listeria strain was grown overnight in TSB-YE at 35 °C, then diluted in 10% non-fat
dry milk (for environmental samples) or in PBS (for food samples) to levels expected to produce fractional
positive results. The selected competing flora strains were diluted to a level approximately 10-fold higher than
the Listeria strain dilutions.
Artificially contaminated food samples were stabilized at 2-8 °C for 48-72 hours (for frankfurters, fresh
bagged spinach, soft Mexican style cheese and cold smoked salmon) or at -20 °C for 14 days (for frozen
cooked shrimps) prior to testing.
For each type of environmental samples, decontaminated surfaces of 100 cm2 were spread evenly with 250 µL
of mixed culture of the target and competitor bacteria. The surfaces were dried at room temperature for 18-
20 hours to stress the target bacterium, and then swabbed using non-bactericidal sampling sponges pre-
hydrated with 10 mL D/E neutralizing broth by performing five vertical swabs (up and down) and five
horizontal swabs (side to side). Sponges were held at room temperature for at least two hours before testing.
4. Table 1. Bacterial strains selected for environmental surface and food matrix contamination
Matrix type Inoculating organism Strain ID Strain source
Stainless steel
L. monocytogenes 1/2c
P. aeruginosa
MSR0119 MSR0132
Food-ready-to-eat
Field isolate
Stainless steel1
L. monocytogenes 1/2c
P. aeruginosa
ATCC 7644
ATCC 15442
Human
Animal room water
bottle
Plastic
L. seeligeri
P. aeruginosa
MSR0460
MSR0132
Raw milk
Field isolate
Sealed concrete
L. welshimeri
E. faecalis
MSR0461
MSR0118
Chicken drip
N/D
Frankfurters L. monocytogenes 1/2a MSR0453 Milk
Fresh bagged spinach L. monocytogenes 1/2a MSR0437 Lettuce
Soft Mexican style
cheese2
L. innocua MSR0127 Manure (soil)
Frozen cooked shrimps L. seeligeri MSR0458 Field water
Cold smoked salmon L. innocua MSR0433
Turkey/ham/cheese
stick
Notes: 1Independent laboratory validation study. 2The same L. innocua strain was used for internal and independent
laboratory validation studies.
Sample Enrichment
BAX® System method – Environmental sponge samples were stomached for 30 seconds with 90 mL of pre-
warmed to 35°C Actero™ Listeria and incubated at 35°C for 20 hours.
Frankfurter samples (125 g) were stomached for 30 seconds with 750 mL of pre-warmed to 35°C Actero™
Listeria and incubated at 35°C for 26 hours.
Fresh bagged spinach, soft Mexican style cheese, frozen cooked shrimp and cold smoked salmon samples (25
g) were stomached for 30 seconds with 150 mL of pre-warmed to 35°C Actero™ Listeria and incubated at
35°C for 22 hours.
5. USDA-FSIS MLG 8.09 method – Environmental sponge samples were stomached for two minutes with
225 mL of pre-warmed to 30°C UVM and incubated at 30°C for 24 hours. Frankfurter samples (125 g) were
stomached for two minutes with 1125 mL of pre-warmed to 30°C UVM and incubated at 30°C for 24 hours.
For each sample, 100 µL aliquot of the primary UVM enrichment was transferred to 9.9 mL of MOPS-BLEB
and then incubated at 35°C for an additional 24 hours.
US FDA BAM 10 method – Fresh bagged spinach, soft Mexican style cheese, frozen cooked shrimp and cold
smoked salmon samples (25 g) were stomached for two minutes with 225 mL of pre-warmed to 30°C BLEB
without selective supplements and incubated at 30°C for 4 hours. After the pre-enrichment phase, the
selective supplements acriflavin, nalidixic acid and cycloheximide were added, and the samples were incubated
at 30°C for a total time of 48 hours.
Listeria spp. Detection and Confirmation
BAX® System method – Lysis reagent was prepared by adding 150 µL protease and 200 µL of lysing agent 2 to
12 ml of lysis buffer. For each sample, 5 µL enriched sample was added to 200 µL prepared lysis reagent in
cluster tubes. Tubes were heated for 30 minutes at 55°C and 10 minutes at 95°C, and then cooled for at least
5 minutes at 4°C. PCR tablets were hydrated with 30 µL lysate and a full process was run in the BAX®
System Q7 instrument.
All results obtained with the BAX® System method were confirmed according to the USDA-FSIS MLG 8.09
or US FDA BAM 10 reference methods.
USDA-FSIS MLG 8.09 method – After secondary enrichment, 10 µL aliquot of each sample was streaked onto
MOX agar plate. The plates were checked for typical Listeria colonies after 24-48 hours of incubation at 35°C.
Typical colonies were then picked and confirmed using biochemical test panel Listeria API® system.
US FDA BAM 10 method – At the end of the each enrichment period (after 24 and 48 hours of incubation),
the samples were directly streaked onto MOX agar plates. The plates were incubated at 35 °C for 24 to
48 hours. Typical colonies were then picked and confirmed using biochemical test panel Listeria API®
system.
Data Analysis
Probability of detection (POD) statistical model was used to evaluate the differences between presumptive
and confirmed results as well as between the alternative and the reference methods. All the data are presented
in summary tables of POD values, dPOD values, and confidence intervals by matrix and concentration.
Results
No interference effects of the Actero™ Listeria medium on detection of Listeria spp. by RT-PCR BAX®
assay in environmental and food samples were found.
The results for environmental samples tested are summarized in Tables 2-3 below. For plastic and stainless
steel (independent laboratory validation study) samples, POD analysis didn’t show any significant differences
(the 95% confidence interval of the dPODs contains zero) in the method performance between the BAX®
System and the USDA-FSIS MLG 8.09 methods. However, according to the POD statistical model,
6. significantly superior method performance was observed for fractionally inoculated stainless steel (internal
validation study) and sealed concrete samples tested using the BAX® System method as compared to the
USDA-FSIS MLG 8.09 method.
No false positive results have been observed. No more than one false negative outcome (stainless steel) was
detected for the all environmental samples tested.
The results for food samples tested are summarized in Tables 4-5. For fresh bagged spinach, soft Mexican
style cheese (independent laboratory validation study), frozen cooked shrimps and cold smoked salmon
samples, POD analysis didn’t show any significant differences (the 95% confidence interval of the dPODs
contains zero) in the method performance between the BAX® System and the US FDA BAM 10 methods.
Frankfurter and soft Mexican style cheese (internal validation study) samples analysed according to the
BAX® System method demonstrated significantly superior method performance as compared to the USDA-
FSIS MLG 8.09 (for frankfurters) or US FDA BAM 10 (for soft Mexican style cheese) reference methods.
No false positive or false negative results have been observed for the all food samples tested.
Conclusions
The results of the study demonstrated that performance of the BAX® System method to detect Listeria spp.
in environmental and food samples enriched with Actero™ Listeria medium is equivalent or superior to the
reference methods.