rapid test for the detection of pathogens in dairy products · rapid test for the detection of...
TRANSCRIPT
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June 13, 2013
Bioq. Mariano Veltri
Product Manager for BioMonitoring
Rapid Test for the Detection of Pathogens in Dairy Products
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Content
From classical culture to rapid testing
Overview Merck Millipore rapid detection solutions
General principle of real-time PCR
Overview Merck Millipore real-time PCR solutions
Pathogenic E.coli testing from ground beef using RapidCultTM
Other Pathogens in Food:
- Salmonella
- Listeria
- Bacillus Cereus and Cronobacter Sakazakii
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Food Pathogens
Cultivation Rapid Enrichment Microorganisms Identification
RTU RTU
DCM
Bactident
Lateral Flow
RT PCR
Salmonella
Cronobacter
Listeria
E. coli O157
Bac. cereus
Staph. aureus
Campylobacter
Enterococci
Enterobacteriaceae
Vibrio
Pseudo. aerug
Immunology
Singlepath
Real Time PCR
Foodproof MMB
DCM DCM
RTU
24-48 h 20-90 min 24-48 h 24-48 h
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Food & Beverage / Enrichment media Food & - Key products for QC Lab
1.07228. Buffered Peptone Water ( Salmonella)
1.10266. Lauryl Sulphate Broth ( Coliforms in Water)
1.10398. FRASER Broth ( Listeria)
1.10549. LEB (antibiotics incl.); ( Listeria)
1.14582. mEC Broth /mTSB ( Enterohemorrhagic E.coli)
1.07661. Lactose Broth ( Salmonella)
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Food & Beverage / Plating Agar Key products – for QC Lab
1.05463. Plate Count Agar ( Total Count)
1.05463 Chromocult Coliform Agar ( Coliforms & E.coli)
1.01406. VRB Agar ( Coliforms & E.coli)
1.16000. YGC Agar ( Yeasts)
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ISO 11133
ISO 11133-1
Microbiology of food and animal
feeding stuffs —
Guidelines on preparation and
production of culture media
- Part 1
ISO 11133-2
Microbiology of food and animal
feeding stuffs –
Practical guidelines on performance
testing of culture media - Part 2
This new standard describes for the first time in history
of Microbiology the definition of quality control for
commercial culture media.
Quantitative testing and reporting of results (CoA)
with recovery rates is the new preferred testing
method
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Quality Control of Plating Agar
> 70% for non selective media
> 50% for selective media
Productivity
Selectivity
Most important change !
ISO 11133 – Part 2 Practical Guideline on Performance testing of culture media - Certificate of Analysis
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Quality Control of Selective Liquid Media
10*6 to 10*8 c.f.u per ml
below 10*4 c.f.u per ml
Target bacteria
Unwanted
Extremely important to
avoid false-negative results
Methods for use in performance testing of culture media
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RVS / TTn / Selenite Cystine broth
Methods for use in performance testing of culture media
Quality control Minimum level must
be 10*5 c.f.u
Test strains Inoculum Growth after
24 hours
Escherichia coli
ATCC 25922
Approx. 99 % < 10 %
Salmonella typhimurium
ATCC 14028
Approx. 1 % > 90 %
Quality Control of Selective Liquid Media
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more than 70 % Recovery Rate for each test strain used
Specification of Tryptic Soy Agar Merck COA in
Compliance with ISO 11133
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From classical culture to rapid testing
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Classical Culture + ID
Culture + ELISA
Culture +PCR/
REAL TIME PCR
BIOCHIP
3 4 5 1 2 DAYS
log10 cfu
1
2
3
4
5
6
7
6 7
REAL TIME
TEST
SHORTENED
CULTURE
RAPID TESTING
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• All rapid testing methods are fully
dependent on the quality of the
corresponding non/selective enrichment
media
• If an enrichment medium does not allow
growth of a minimum level of bacteria
necessary for detection, a false-negative
results will occur !
• Minimum levels PCR: 103 -104 CFU / ml
• Minimum levels Immunoassays: 105 CFU / ml
Pre-Conditions for Using Rapid Tests
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Content
From classical culture to rapid testing
Overview Merck Millipore rapid detection solutions
General principle of real-time PCR
Overview Merck Millipore real-time PCR solutions
Pathogenic E.coli testing from ground beef using RapidCultTM
Other Pathogens in Food:
- Salmonella
- Listeria
- Bacillus Cereus and Cronobacter Sakazakii
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Overview rapid detection solutions
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Superior Granulated Dehydrated
Culture Media
Innovative Immunoassays – Lateral FlowTests
- Singlepath® and Duopath®
Broad range of preparation & detection kits
for real-time PCR
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Safe Minimizes air-borne toxins, allergens and workplace contaminations
Accurate Prevents component separation and clumping
Fast Dissolves rapidly in water
Easy Ensure easier handling by superior flow properties & non-sticking media
Reliable Homogenous distribution of ingredients assures high reproducibility
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Superior Granulated Culture Media
No dust
vs Powder Granulated media
No clumping
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3 BLENDING 2 ADD SAMPLE 1 ADD MEDIUM 4 INCUBATE 5 PIPETTE
SAMPLE
6 PLACE
SAMPLE
NEGATIVE
POSITIVE
Read
after
20 -25
min
General Application of Lateral Flow Tests
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Innovative Immunoassays – Lateral Flow Tests
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Immunochromatographic principle:
Antibody-linked colloidal gold particles react
with its complimentary antigenic determinant
to provide a visual reaction read-out
Fast
Definite results within 20–30 minutes
Easy to use
Clear yes/no results after simple sample
application
Safe
Positive control and specially adapted
enrichment media for precise, reliable
results
Economic
Rapid results save operating costs
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Principle of Lateral Flow Test
bacterium gold particle
antibody
membrane
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1. Control reaction in-built in LFT.
No need for separate reaction to demonstrate proper function,
as necessary for ELISA.
Can save costs esp. when low numbers of samples to be tested
2. LFT’s are 1-step tests.
After application of test sample to sample port, NO further pipetting
steps necessary.
No separate color reaction for LFT’s necessary to make reactions
visible.
3. LFT are provide results faster than ELISA
Only incubate test on lab bench for 20 – 30 min and read result.
Advantages of Lat. Flow tests vs. ELISA
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Merck‘s Lateral Flow Test Portfolio
Listeria: Salmonella: E. coli O157&VTEC: Campylobacter: Bacillus cereus: Legionella:
LEB Tetrathionate mEC + n Bolton Broth M.Y.P. Agar CYE Agar Base
Fraser Rappaport.-Vas. mTSB + n CCD Agar CGY Broth BCYE Suppl.
UVM Selenit Cystin CT-SMAC BHI GVPC Suppl.
PALCAM Salmosyst SMAC CYE-Plates
OXFORD M Broth BHI GVPC-Plates
Chromocult® XLT4 , XLD, CAYE Anaerocult® C
Listeria Agar Rambach®
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Content
From classical culture to rapid testing
Overview Merck Millipore rapid detection solutions
General principle of real-time PCR
Overview Merck Millipore real-time PCR solutions
Pathogenic E.coli testing from ground beef using RapidCultTM
- Other Pathogens in Food:
- Salmonella
- Listeria
- Bacillus Cereus and Cronobacter Sakazakii
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Presentation title in footer | 00 Month 0000 23
What is real-time PCR?
PCR = Polymerase Chain Reaction
Specific amplification of DNA fragments from
bacteria, viruses, human, animal or plant cells
&
the simultaneous automated detection of this
amplified DNA on the computer monitor by
fluorescence measurement = real-time
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PCR: Polymerase Chain Reaction
Invented by Karl Mullis, 1979
Nobel Price in Chemistry,1993
Specific amplification of DNA fragments
from bacteria, viruses, human, animal
or plant cells
&
simultaneous automated detection
of these amplified DNA by fluorescence
measurement
Real-Time PCR
©www.forensic-science.org
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Basic principle T T T T T A A A C C C C C
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PCR – Principle of Amplification
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Detection formats
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Hybridisation Probes
Probes remain intact
TaqMan Probes (5‘Nuclease)
Probes get destroyed
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Real-time PCR: Online data measurement
Agarose gel electrophoresis
Staining
Photography
Classical PCR Real-Time PCR
Ct-value
Threshold Cycle (Ct) value
Advantage
High specifity
Low risk of “false positive“ results
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PCR workflow
Start 20 min 40 min 130 min
90-120 min
PCR Set-up PCR run Sample
preparation
Enrichment,
Culture or
Single Colony
Detection
& Analysis
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Real Time PCR – Sample preparation
From manual to full automated handling
<30 min
ShortPrep SamplePrep RoboPrep
<60 min
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Content
From classical culture to rapid testing
Overview Merck Millipore rapid detection solutions
General principle of real-time PCR
Overview Merck Millipore real-time PCR solutions
Pathogenic E.coli testing from ground beef using RapidCultTM
Other Pathogens in Food: - -
- Salmonella -
- Listeria
- Bacillus Cereus and Cronobacter Sakazakii
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Corbett/QIAGEN
Rotor-Gene 3000
Broad range of real-time thermal cycler
Agilent/Stratagene Mx3000p
BioRad IQ5
Roche LightCycler 1.5 Roche LightCycler 2.0
ABI 7700
Cepheid SmartCycler
Eppendorf realplex
ABI 7000
Roche LC480
ABI 7500
BioRad myiQ
ABI 7900
ABI StepOne System
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Test for several bacteria in 1 PCR run
Salmonella
L. mono., L. Genus
E. coli O157
Campylobacter Quant.
GMO screening
RR Soya Quant.
Identical Thermoycler conditions
PCR Setup at room temperature
96 well plate
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Benefits of Real-Time PCR: Saving of labour / time
Applying real-time PCR, all samples are read by just one mouse-click
Clear results, no hidden colonies in the background
Objective results; no personal influence of lab manager who reads the plates
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Presence/absence tests of pathogenic bacteria
Quantitative investigation of pathogenic bacteria
Large scale identification of spoilage organisms
Detection and quantification of gene modified organisms
Real-time PCR product portfolio – Foodproof & MMB detection kits
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Foodproof Detection Kits: For Roche LightCycler 1.x, 2.0
Salmonella
Listeria monocytogenes
Listeria Genus
E. coli 0157
Campylobacter
Enterobacteriaceae plus E. sakazakii
E. sakazakii
E. coli and Shigella
Beer Screening bacteria
Saccharomyces cerevisiae var. diastaticus
GMO Maize Quantification
GMO Soya Quantification
GMO Screening
Hybridization Probes Kits
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Salmonella spp.
Listeria monocytogenes
Listeria Genus
E. coli O157
Campylobacter quantitatively
Enterobacteriaceae + E. sakazakii
Brucella
Dekkera (= Brettanomyces: Wine spoilage)
Alicyclobacillus
GMO Screening (4 events multiplexed!!!)
GMO Soya Quantification
GMO Maize Quantification
Foodproof 5‘Nuclease Kits: For TaqMan Instruments & LC 480
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Foodproof Sample Preparation Modules I
Rapid & Convenient Kits
foodproof ShortPrep I Kit (for Salmonella kits)
foodproof ShortPrep II Kit (for E. coli O157, Campylobacter & Listeria)
foodproof ShortPrep III Kit (for beer screening kit)
Kits for difficult matrices
foodproof Sample Preparation Kit I (Gram-neg. bacteria in raw & processed foods)
foodproof Sample Preparation Kit II (Gram-pos. bacteria in raw & processed foods)
foodproof GMO Sample Preparation Kit
Rapid Kits (with bulk reagents) = Value for Money
foodproof StarPrep One Kit (for all Enterobacteriaceae)
foodproof StarPrep Two Kit (for Gram-positive bacteria) Available Q1 / 2013
foodproof StarPrep Four Kit (for yeasts)
foodproof Magnetic Separation Kit I (for Gram-negative bacteria)
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39 39
Foodproof products from Merck for various instruments
• Brand label: foodproof®
• Lightcycler (Roche): foodproof® Salmonella Detection Kit
- Hybridization Probes (LC 1.x, 2.0) -
• TaqMan-Instruments: foodproof® Salmonella Detection Kit
- 5‘Nuclease -
NO kit based on SYBR Green from Merck !!!!
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All foodproof real-time PCR kits contain:
Internal Amplification Control (IAC) present in every capillary / well and every test
PCR run positive control (PC) as a separate reaction. Target DNA from kit added.
PCR Negative control (NC) as a separate reaction. Ultra-pure H2O from kit added.
Taq / UNG enzyme Mix present in every capillary / well and every test
Highest Quality Assurance with foodproof real-time PCR kits
No false-negative results
from food matrix
No false-negative
results from defective kit
No false-positive results
due to contaminated kit
No false-positive results
due to carry-over
contamination
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Prevention of Carry-over Contamination
Mechanism of Uracil N Glycosylase
a au uaa a u a aau aaau aa u a aa uu aua
t t a at t t a t t ta t t t a t t a t t t aa tat
Uracil-N-Glycosylase
a au uaa a u a aau aaau aa u a aa uu aua
PCR mit Thymin
a a t taa a t a aa t aaa t aa t a aa t t ata
a a t taa a t a aa t aaa t aa t a aa t t atat t a at t t a t t t a t t t a t t at t t aa tat
a a t taa a t a aa t aaa t aa t a aa t t atat t a at t t a t t t a t t t a t t a t t t aa tat
t t a at t t a t t ta t t t a t t a t t t aa tat
DNA-Matrix DNA-Matrix
a a t taa a t a aa t aaa t aa t a aa t t ata a a t taa a t a aa t aaa t aa t a aa t t ata
u ua auu u a u uua uuua uu a u uu aa uau
u ua auu u a u uua uuua uu a u uu aa uau
t t a a t t t a t t t a t t t a t t a t t t aa tat
PCR with uracil PCR with thymine
Native DNA Amplified DNA
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Prevention of Carry-over Contamination
Necessary Kit component UNG
Sample Enrichment
DNA Extraction Purification
PCR
Detection no false positive results possible
due to lab contamination
UNG degrades ONLY „old“ amplified GAUC-DNA
UNG cannot degrade native GATC-DNA
UNG is inactivated before „new“ PCR starts
(during initial denaturation of DNA)
UNG - Glycosylase step
Contamination by “old“
amplified GAUC-DNA
possible
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43
Content
From classical culture to rapid testing
Overview Merck Millipore rapid detection solutions
General principle of real-time PCR
Overview Merck Millipore real-time PCR solutions
Pathogenic E.coli testing from ground beef using RapidCultTM
Other Pathogens in Food: - -
- Salmonella -
- Listeria
- Bacillus Cereus and Cronobacter Sakazakii
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EHEC‘s: Emerging Pathogens
44
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EHEC‘s: Emerging Pathogens Highly pathogenic enterohaemorrhagic E. coli (EHEC) strains like
verotoxin (= shiga-toxin)– producing (VTEC/STEC) strains gain importance
Serovars: O157:H7, O26, O103, O111, O145 and other strains are of
interest
Production of verotoxins is the most common criteria for detection:
Verotoxin 1 (VT1, SLT1, Stx1) and 2 (VT2, SLT2, Stx2)
EHEC strains produce either VT1 or VT2 only or even both
VT2 is causative agent for severe diseases, like hemolytic uremic
syndrome (HUS)
Infection with E. coli O157 are known as “Hamburger Disease”
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Fast
Reduced time to result – from more than 18 down to 8-12 hours
Flexible
Incubation for 12 or less up to 22 hours to fit with optimal workflow
Efficient
Pooled samples: 25 g and 375 g are validated
High yield
Increased growth of all E. coli due to special composition
Reliable
Validation with Singlepath® E.coli 0157 & foodproof ® E. coli O157 Detection Kit
consistent with USDA-FSIS guidance
High-quality
Comprehensive inclusivity study: superior growth of all E .coli strains tested
Granulated medium meet ISO 11133 guidelines
46
Features of Rapidcult™ E. coli
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Confirmation by culture and biochemical tests required
Day
1
Day
2
Day
3
25 g/ml TEST SAMPLE
225 ml m-EC or m-TSB
37 °C FOR 24 h
CT-SMAC Agar 37°C / 24 h Fluorocult E.coli 0157 Agar
Sorbitol (+)
are non
pathogenic
E.coli
ISO Standard for testing of E.coli 0157 in Food
Caution: Some E.c. O157 are
Sorbitol (+) -> false-neg. result
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One broth detects all EHEC strains Enrichment*
25g/375g in pre-warm Rapidcult 8-22h/42°C
Classical culture media Lateral Flow Test* Real-time PCR* Post-enrichment
160 µl in Sample Port
Result: 8h 20 min
After immunoconcentration streak out on
CT-SMAC Agar
Incubation: 24h/35-37°C
Conformation e.g. Fluorocult E.coli 0157
48
DNA Extraction
StarPrep One Kit
PCR
foodproof E.coli 0157 Detection Kit
Result: 48 h Result: 10 h
CAYE Broth & supplement
Screening
Duopath ® Verotoxin
Result: 14 h
* USDA FIS validated
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Rapidcult™ results with real-time PCR
Sensitive screening for most important virulence genes: eae, stx 1 and stx 2 with
new foodproof® STEC Screening Kit – prototype version
After 8h enrichment using Rapidcult E.coli
The virulence patterns of more than 50 STEC strains were identified correctly
strains included: O26 (n=11), O103 (n=3), O111 (n=3), O121 (n=1), O145
(n=3), O157 (n=14) and others (n=15).
O104 as the cause of the severe outbreak in Germany in 2011 included
8h enrichment for 25g of ground beef
shown for E. coli O157, O26, O103, O111 and O104 compared to the
Microbiology Laboratory Guidebook USDA-FSIS,(MLG 5.05B ) and ISO/PRF TS
13136
Tests for O45, O121 and O45 ongoing
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Rapidcult™ results with real-time PCR
50
Real-time PCR detection of important virulence genes from E. coli 0157:H-
after 8 h RapidCult incubation
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Content
From classical culture to rapid testing
Overview Merck Millipore rapid detection solutions
General principle of real-time PCR
Overview Merck Millipore real-time PCR solutions
Pathogenic E.coli testing from ground beef using RapidCultTM
Other Pathogens in Food:
- Salmonella
- Listeria
- Bacillus Cereus and Cronobacter Sakazakii
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From presence/absence to quantitative risk assessment
Bacillus cereus © CDC Public Health Image Library Cronobacter Sakazakii
Salmonella Listeria
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Salmonella in Food
53
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Interpretating of Growth on Plates
Day
1
Day
2
Day
3
Day
4
Day
5
Day
6
For confirmation take 5 suspected colonies from each plate
and streak onto Nutrient agar 18 - 24 h / 35 - 37 °C
Biochemical / Serological Confirmation Tests
TSI / Urea / Lysin / -Gal / VP / Indol
25 g/ml test sample
in 225 ml BPW
16 - 20 h / 35 - 37 °C
1 ml BPW to
10 ml MKTTn Broth
24 h at 37°C
0.1 ml BPW to
10 ml RVS Broth
24 h at 41.5°C h
XLD Agar
24 h / 35-37°C
1 plate 14 cm /
2 plates 9 cm
Any other
Salmonella Agar
1 plate 14 cm /
2 plates 9 cm
3 days
11 media
XLD Agar
24 h / 35-37°C
1 plate 14 cm /
2 plates 9 cm
Any other
Salmonella Agar
1 plate 14 cm /
2 plates 9 cm
ISO Standard 6579 for Detection of Salmonella
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Cultural reference method ISO 6579:2002 Annex D
Non-selective pre-enrichment
Selective plating on XLD
Biochemical Identification
Selective enrichment
Confirmation
*Modified Semi-Solid
Rappaport-Vassiliadis Medium
25g/225ml BPW 18+2h/37°C
3 drops/0.1ml on MRSV* 24h/41,5°C
Negative plates: Further 24h incubation
Detection principle: Motility of Salmonellae to migrate into the semi-solid medium
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Day
1
Day
3
Day
4
25 g/ml TEST SAMPLE
In 225 ml Buff. Peptone Water
35 - 37°C for 16 - 20 h
Day
2
NO Salmonella
not present
0.1 ml BPW to 9.9 ml RVS Broth
42°C for 24 h
only 2 media
only 2 days
YES Salmonella
present
STREAK OUT
ONTO RAMBACH 37°C FOR 24 h
If positive, confirmation by culture and
biochemical tests required
Rapid Testing Singlepath® Salmonella - Screening
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Detection of Salmonella by RT-PCR: Within ONLY 24 h and only BPW
Conventional
Non-selective enrichment
in BPW 16 – 20h
Selective enrichment
24h
1. Solid media
24h
2. Solid Media
24h
Isolation/Incubation
24h
Biochemical
verification 4h
Serological
verification 4h
Non-selective
enrichment in BPW
16 – 24h
Sample preparation
0.5h
Amplification/Detection
1h
PCR
Time savings: neg. result > 2 d
pos. result > 4 d
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Real-time PCR-Analysis
Dilute possible PCR inhibitiors
Non-selective pre-enrichment
25g/225ml BPW 18+2h/37°C
Selective plating on XLD
Biochemical Identification
Selective enrichment
Confirmation
3 drops/0.1ml on MRSV* 24h/41,5°C
Negative plates: Further 24h incubation
0.5 ml BPW in 5 ml prewarmed BHI* 3h/37°C
Subcultivation 1:10
* Brain Heart Infusion
DNA extraction
StarPrep One Kit
PCR
Time: 3-5 days Time: 1.5 days
foodproof Salmonella Kit
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Results on Milk
Positive control
Negative control
Samples 1c 18 h / 18+3 h
Amplification Plots LC480II spiked with 12,9 cfu
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Listeria in Food
60
Milk and milk products: Soft cheese, raw milk, pasteurized milk, ice cream, fresh cream
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Day
1
Day
3-6
25 g/ml TEST SAMPLE
IN 225 ml 1/2 STRENGTH FRASER
30°C FOR 24h
STREAK OUT
ON ALOA® + PALCAM
37°C FOR 24 - 48h
Day
3-4
ISO Standard 11290-2004 for testing of Listeria
in Food and Animal feeds
Day
4-7
0.1 ml IN 10 ml FRASER
35 OR 37°C FOR 48h
All colonies showing a blue-green color with opaque halo / grey-green color with a black zone are
presumptive L. monocytogenes colonies (typical colonies) and counted as such. Suspect colonies
must be confirmed.
STREAK OUT
ON ALOA® +
PALCAM
37°C FOR 24 - 48h
BIOCHEMICAL CONFIRMATION: GRAM (+), CATALASE (+), MOTILITY (+),
CAMP (+), HAEMOLYSIS (+), GLUCOSE (+), RHAMNOSE (+), XYLOSE (-)
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Appearance of L. monocytogenes on Chromocult®:
• blue-green colonies = -D-glucosidase activity
• opaque halo = phosphatidylinosit-phospholipase C activity
Listeria spp. Listeria monocytogenes
Chromocult® Listeria Selective Agar
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Chromocult® Listeria Selective Agar complies with Agar Listeria
according to Ottaviani and Agosti (ALOA®) in line with the
recommendations of ISO 11290 (2004) and FDA / BAM (2003)
1.00427 Chromocult®
Listeria Selective Agar Base
1.00432 Chromocult®
Listeria Selective Supplement Contains 4 different antibiotics
1.00439 Chromocult®
Listeria Enrichment Supplement Contains L-α- phosphatidylinositol
Chromocult® Listeria Selective Agar
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Rapid Testing Singlepath® Listeria
Lateral Flow Test for the SPECIFIC detection of all Listeria species
For screening of environmental and food samples.
Very useful for screening in food plants acc HACCP guidelines
US-food companies screen for Listeria spp.
For the confirmation of presumptive Listeria spp. positive colonies
on Listeria selective agars like Chromocult® Listeria Agar
ALOA®) PALCAM, Oxford
Enrichment media used: Fraser, LEB, UVM
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Rapid Testing Singlepath® L’ mono
Worldwide first Lateral Flow Test for the SPECIFIC detection of
Listeria monocytogenes
For screening of environmental and food samples
Very useful for screening in food plants acc HACCP guidelines
European food companies screen for Listeria monocytogenes
For the confirmation of presumptive positive colonies
on Listeria selective agars like Chromocult® Listeria Agar
ALOA®) PALCAM, Oxford
Enrichment media used: Fraser, LEB, UVM
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Day
1
Day
3
0,1 ml IN 10 ml LEB or
Full Fraser OR UVM
30° / 37°C FOR 21 - 24 h
ALOA®
37°C for 24 - 48h
Day
2
L. monocytogenes
present
Singlepath® L’ mono / Singlepath Listeria - Screening
L. monocytogenes
not present
160µl
25 g/ml TEST SAMPLE
IN 225 ml 1/2 STRENGTH FRASER
30°C FOR 24h
Confirmation
Listeria spp.
not present
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suspend 1 - 3 presumptive colonies in 250 µl BHI or
CASO or Fraser or PALCAM Broth
L. monocytogenes
confirmed
PALCAM Agar OXFORD Agar ALOA® Agar
L. monocytogenes
not confirmed
Singlepath® L’ mono - Confirmation
150 µl
1 h at 37°C
• Confirmation within 1,5 h
• Fastest confirmation assay available on the market
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Detection of Listeria spp. & L. monocytogenes by real-time PCR:
Within ONLY 24 h
Conventional
Non-selective enrichment
½ Fraser 24 h
Selective
enrichment
Full Fraser 24 – 48 h
1. Solid media
24 h
Isolation/Incubation
24 h
Biochemical
verification 4 h
Serological
verification 4 h
Non-selective enrichment
½ Fraser 24 h
Sample preparation 0.5 h
Amplification/Detection 1 h
PCR
by foodproof Listeria Genus
or
by foodproof Listeria monocytogenes
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Cronobacter spp.
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Rapid Detection of Cronobacter spp.
Enterobacter sakazakii is renamed since 2008
New name is: Cronobacter spp. nov.
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Considered as a clear species since 1980. Renamed in
2008 due to pheno-and genotypic diversity.
C. spp. is an opportunistic pathogen.
High risk for newborns, especially low-birth weight infants.
Causes severe neonatal sepsis, meningitis
Powdered infant formula (PIF) is major vehicle and cause
of Cronobacter spp. illness.
Very resistant to osmotic & dry stress. Can survive >2
years in PIF
Cronobacter spp. (formerly E. sakazakii)
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Cronobacter spp.
EC Regulation 2073
Absence of Enterobacter sakazakii in 10 g sample Milk
powder
Mandatory for all infant formula producer
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Dr. A. Bubert, Merck KGaA 73
1. pre-enrichment in BPW
2. enrichment in EE broth,
3. plating + isolation on violet red bile glucose agar (VRBGA)
4. biochemical identification of typical colonies
is time consuming and requires up to 7 days
Cronobacter spp.: Current FDA method
FDA method only yielded 26% positive results
in a comparative study with old ISO draft (40%)
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Day
1
Day
3
Test sample
in BPW (1:10)
37°C for 16 - 20 h
10 ml Modified LST Broth – Vancomycin Medium
45°C for 22 - 26 h
Day
2
Streak onto
Enterobacter sakazakii Isolation Agar
44°C for 22 - 26 h
Biochemical Confirmation
ISO TS 22964 for isolation of E. sakazakii
Day
4
0,1 ml
Bottleneck: Not all E. sak.
can grow under
these conditions
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75
foodproof Enterobact. plus E. sakazakii Kit
Features
Unique real-time PCR kit for detection of all Enterobacteria
AND Cronobacter spp. simultaneously with ONLY 1 reaction
Highest reliability for Cronobacter Screening in powdered
Infant Formula and other babyfoods
Very useful for Hygiene Monitoring of Enterobacteriaceae
Kit is designed according to latest ISO standards for real-
time PCR to prevent false-positive and false-negative results
Kit does NOT require mLST enrichment step
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Conventional (ISO 22964:2006)
Enrichment
22 - 26 h
Isolation
22 - 26 h
Biochemical
Identification
44 - 48 h
Pre-Enrichment
16 – 20 h
PCR
Subcultivation
in BPW 3 h
DNA Isolation
0.5 h
Amplification/Detection
1 h
Pre-Enrichment
in BPW for 18 h
Cronobacter spp. – PCR vs. Conventional Detection
Time to result : 1 day only
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77
Detection of Enterobacteriaceae /
Cronobacter spp. by RT-PCR
PCR 1
Enterobacteriaceae/Cronobacter
Enrichment
20-24 h
DNA-Extraction
Internal Pos.
Control
Enterobacteriaceae Cronobacter
Positive Result
PCR 2
Salmonella
Negative Result
Enterobacteriaceae neg.
Cronobacter neg. E. coli neg.
Salmonella neg. Coliforms neg.
Positive
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78
Reagent D for dead-live discrimination
Reagent D efficiently eliminates amplification of DNA from
dead bacteria.
Mechanism: Reagent D invades ONLY into dead bacteria
and binds to DNA. DNA is not amplifiable any more.
Reagent D is a light sensitive substance. Exposure to visible light leads to
covalent binding of this substance to DNA and prevents the DNA from being
amplified via PCR.
Works until 106 dead bacteria / gram food
Currently validated for Enterobacteriaeceae only
Only Merck offers Reagent D for dead-live discrimination
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79
No false-positive results even at high Entero-
bacteriaceae concentrations using Reagent D
with Reagent D
Without Reagent D
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80
Advantages of foodproof® Enterobacteriaceae
plus E. sakazakii Detection Kit
• Unique 5 – in - 1 Test:
- Negative result of Enterobacteriaceae reaction means:
No Enterobacteriaceae
No Cronobacter spp. (formerly E. sakazakii)
No Salmonella
No E. coli
No Coliforms
• Unique kit which can discriminate between live and dead bacteria
• Unique kit which give no false-positive results for Enterobacteriaceae
These unique features save time and costs
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81
• Sybr green real-time PCR System:
- Only for the detection of E. sakazakii
- Disadvantage: High rate of false-positive (due to SYBR Green) results
• foodproof Enterobacteriaceae plus E. sakazakii
- Detects ALL Cronobacter spp. strains
- Advantage: No false-positive or false-negative results
Foodproof kit is successfully validated by Nestlé, Switzerland!!
- Nestlé recommends their babyfood plants to use foodproof kit –
- ISO is working on a revision of C. sakazakii method because the existing method
works not very well. Up to now there is no improved method available.
foodproof® Enterobacteriaceae plus E. sakazakii
Detection Kit vs. Sybr green system
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MMB Food Pathogen System
MMB Food Pathogen Prep Kits MMB Food Pathogen Detection Kits
MMB Bacteria Prep Kit
MMB DNA/RNA Virus Prep Kit
V = VIC for Applied Biosystems, Agilent, Eppendorf, QIAGEN
R = ROX for BioRad Systems LC = For Lightcycler Systems
MMB Staphylococcus aureus (V), (R), (LC) Kit
MMB Legionella Screening (V), (R), (LC) Kit
MMB Vibrio cholerae (V), (R), (LC) Kit
MMB Legionella pneumophilia (V), (R), (LC) Kit
MMB Clostridium perfringens (V), (R), (LC) Kit
MMB Bacillus cereus (V), (R), (LC) Kit
MMB Norovirus (V),(R),(LC) Kit
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MMB Food Pathogen Prep Kits 2 x 50 extractions
Membrane filter technology
Content:
1 x Lysis Buffer
1 x Binding Buffer
1 x Wash Buffer
1 x Elution Buffer
2.0 ml Receiver tube for washing
1.5 ml Receiver tube for elution
Spin filter
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1. Preparation of food matrix – for example
2. DNA Isolation with MMB Food Pathogen Prep Kit
225 ml
Buffered Peptone Water
Wash Wash
again
Elute Sample
DNA
25 g
chocolate
MMB Food Pathogen Prep Kits procedure
Incubation
16-20
hours
in
Lysis
84
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Bacillus cereus detection General
Environmentally widespread Gram-positive, spore-forming, motile rod
Cause gastrointestinal (e.g. diarrhea) as well as non-gastrointestinal diseases
(e.g. septicemia,endocarditis, infections of the central nervous system)
Self-limiting and of short duration, relative low number of registered cases; < 1%
Contamination risk by meat and milk products, vegetables, soups, spices and
especially baby food
Ability to produce one or more toxins: Cytotoxic enterotoxins are produced by
almost 95% of isolates
Pre-enrichment : Tryptone soya broth (TSB)
PCR detection: B. cereus, B. mycoides, B. thuringiensis, B. anthracis
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86
Duopath® Cereus Enterotoxins
Worldwide first Lateral Flow Test for the SPECIFIC detection of Bacillus cereus via their enterotoxins
For screening of foods (tested with cream of wheat, spinach,
coffee white, egg powder, chocolate powder)
For confirmation of enterotoxin-producing presumptive
positive B. cereus colonies on M.Y.P. Agar
CGY Broth (+ 1% Glucose) for the enhancement of toxin production
~ 90% of B. cereus are NHE toxin positive;
~ 50% of B. cereus are HBL toxin positive
Advantage:
Broad coverage of nearly all B. cereus (except emetic strains) due to
detection of 2 enterotoxins
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87
Singlepath® Emetic Toxin MRK
Worldwide FIRST Rapid Test for detection of emetic Bacillus cereus
Singlepath does not detect Emetic toxin but a protein which is co-produced with
Emetic Toxin in B. cereus = Surrogate Marker.
For screening of foods (tested with soup, rice)
For confirmation of emetic B. cereus on agar plates
Test successfully evaluated by Kagawa Food Univ. Japan
NOW available !!!! Singlepath Emetic is already standard method
for testing UHT milk in Malaysia)
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88
Day
1
Day
2
20 ml CGY + 1% Glucose
Sensitive Screening
(>1 CFU / g)
Rapid Screening
(>100 CFU / g)
in 20 ml CGY + 1% Glucose
Test Protocols – Screening of B. cereus in foods
Duopath® Cereus Enterotoxins AND / OR
Singlepath® Emetic Toxin MRK
B. cereus
present
B. cereus
not present
NO YES 150 µl
18 – 24 h at 30°C
10 g/ml sample into
90 ml CGY Broth + 1% Glucose or
BHI
200 µl
200 µl
18 – 24 h at 30°C
6 h at 30 °C
150 µl
Emetic B. cereus
not present
Emetic B. cereus
present
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89
Day
1
suspend
1 - 3 presumptive colonies into 1
ml CGY Broth + 1% Glucose,
M.Y.P. Agar
B. cereus
present
B. cereus
not present
4 h at 30°C
150 µl
NO YES
B. cereus by Duopath® Cereus Enterotoxins
Emetic B. cereus by Singlepath Emetic TOX MRK
Confirmation:
Emetic B. cereus
not present
Emetic B. cereus
present
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90
Clostridium perfringens detection
General
Anaerobic, Gram-positive, spore-forming rod
Widely distributed in the environment and frequently in the intestines of humans and
domestic and feral animals
Spores persist in soil, sediments, and areas subject to human or animal fecal pollution -
heat resistant and not killed by ordinary cooking
Poisoning associated with temperature abuse of prepared foods
Growth in foods with high starch or protein content, such as cooked beans, meat
products, thick soups, and gravy
8–22 h after consumption of foods containing large numbers of bacteria capable of
producing food poisoning toxins
Pre-enrichment: Thioglycolate broth
PCR detection: Positive reference C. perfringens ATCC 13124
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Norovirus detection
General
Norovirus particles with diameter of ~ 35 nm, highly stable in environment
Capside & a single strand RNA, 7300 – 7700 nucleotides
Cause of 90 % of non bacterial gastroenteritis
Outbreaks in community facilities, e.g. hospitals, rest or nursery homes
Symptoms: vomiting, diarrhoea and nausea
Minimal infection dose is 10-100 virus particles
Food incl. shellfish (oysters, clams, mussels), salads, peeled fruits, cold meats,
sandwiches, dairy products, egg dishes, ice and fecally contaminated water or of surfaces
of foods and food preparation
Pre-enrichment: None, direct detection
RT-PCR detection: Genotypes of genogroup I & genogroup II, dominant in outbreaks
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92
Staphylococcus aureus detection General
Facultative anaerobic Gram-positive coccus, which is non-motile, catalase and coagulase
positive.
Some strains produce staphylococcal enterotoxins (SEs), the causative agents of food
poisoning.
Common symptoms: nausea, vomiting, retching, abdominal cramping, and diarrhe.a
Exist in air, dust, sewage, water, milk, and food, as well as on food equipment,
environmental surfaces, humans, and animals.
Able to grow in a wide range of temperatures (7–48.5°C, with an optimum of 30–37°C), pH
(4.2 to 9.3, with an optimum of 7–7.5) and sodium chloride concentrations (up to 15% NaCl)
Foods include meat and meat products, poultry and egg products, salads, bakery products
(e.g. cream-filled pastries, cream pies, and chocolate eclairs), sandwich fillings and milk and
dairy products
Pre-enrichement : Tryptone soya broth (TSB) / PCR detection : MRSA Typ I, II, III, IV, IVa,
IVb,IVc and other S. aureus species, not detection of other Staphylococci
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Vibrio cholerae detection
General
Gram-negative, asporogenous, motile rods, straight or comma-shaped
Strictly aqueous organism, brackish and marine waters are natural environments
Transmission is fecal-oral, indirectly via polluted water supplies or irrigation water or
contaminated shellfish that is raw or undercooked
Infection of the small intestines caused by cholera enterotoxin (CT) producing Vibrio
cholerae of serogroups O1 and O139
Mild symptoms, 10% of patients may experience classical cholera symptoms with profuse
watery diarrhea (“rice-water stool”) and often vomiting
Pre-enrichment: Alkaline peptone water with 2% sodium chloride (APW)
PCR detection: Positive reference V. cholerae Mop 413 & 415 - Mop – a putative
protease modulating virulence, no detection of other Vibrio species