Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

VPH > PH4-5: Food Microbiology > Flashcards

PH4-5: Food Microbiology Flashcards

1
Q

What are the main food-borne bacterial pathogens?

A

Campylobacter, Salmonella, E.coli, Listeria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the main food-borne viruses?

A

Hepatitis A, Heptatis E, Norovirus, Enterovirus, Adenovirus, Rotavirus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define the microbiological criteria for foodstuffs?

A

Defined limits on presence or number of microbes or metabolites in food

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Who is responsible for microbiological criteria for foodstuffs?

A

FBO is responsible to ensure product meets the requirements

Competent authority (ie OV) responsible for compliance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the three areas where microbiological criteria for foodstuffs are defined?

A

Process hygiene criteria, food safety criteria, meat and working surface testing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the purpose of testing against the process criteria?

A

It is not to assess the fitness of individual carcases or processed meat for human consumption but rather to provide an indication of performance and control of the slaughter, dressing, and production hygienic process at the time of sampling.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the requirements for process hygiene criteria?

A
  • Aerobic colony count and Enterobacteriaceae on cattle, sheep, goats, horses, and pig carcases
  • Salmonella on cattle, sheep, goats, horses, pig, broiler, and turkey carcases
  • Aerobic colony count and E. coli in minced meat and mechanically separated meat
  • E. coli in meat preparations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the purpose of the food safety criteria?

A

That the food safety criteria applicable throughout the shelf-life of the products can be met under reasonably foreseeable conditions of distribution, storage, and use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

For what products have food safety criteria been set?

A

Poultry meat, minced meat, meat preparations, meat products, mechanically separated meat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the food safety criteria regarding Salmonella?

A

Salmonella must be absent in:

  • Minced meat and meat preparations intended to be eaten raw
  • Minced meat and meat preparations intended to be eaten cooked
  • Mechanically separated meat (MSM)
  • Meat products intended to be eaten raw
  • Meat products made from poultry meat intended to be eaten cooked
  • fresh poultry meat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the food safety criteria regarding Listeria?

A

The absence of L. monocytogenes in:

  • RTE foods intended for infants
  • RTE able to support the growth of L. monocytogenes other than those intended for infants
  • RTE unable to support the growth of L. Monocytogenes other than those intended for infants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the criteria for selecting a test?

A
  • Sensitivity (proportion of true-positives identified as positive by the test)
  • Specificity (proportion of true-negatives identified as negative by the test)
  • Limits of detection for enumeration tests
  • Take taken to carry out the test
  • Ease-of-use of the test
  • Cost of test
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What should you keep in mind when interpreting test results?

A
  • The accuracy of the test: determined by sensitivity and specificity
  • Result is only valid for one specific point in time
  • Failure to detect specific organisms does not mean that metabolites or toxins of that organism are not present
  • Results are only valid for the sample tested, bacteria may not be evenly distributed throughout a batch of product
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the different methods of rapid detection?

A

IMS (Immunomagnetic separation)

HGMF (Hydrophobic grid membrane filter)

DEFT (Direct Epifluorescence Technique)

ELISA (Enzyme Linked Immunosorbent Assay)

PCR

Serum Agglutination

Whole Genome Sequencing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does HGMF work? What is it used for?

A
  1. Filter sample to remove particular matter
  2. Filter through HGMF to trap organisms
  3. 1600 grid squares on membrane
  4. Transfer to agar plate for culture

Used for detection and enumeration of bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does IMS work? What is it used for?

A

Used to separate and concentrate target organism

  1. Specific antibody fixed on magnetic beads added to broth
  2. Binding of pathogen to antibody
  3. Magnet used to immobilise pathogen
  4. Pathogen then subject to other tests
17
Q

How does DEFT work? What is it used for? Any drawbacks?

A

Useful for rapid counting of bacteria in samples

  1. Used in conjunction with membrane filter
  2. Stain filter membrane acridine orange, wash and dry
  3. Observe under epifluorescence microscope
  4. ssDNA and RNA fluoresces red with bacteria; dsDNA fluoresces green with eukaryotic cells

Test only indicated the general presence of bacteria but does not identify individual species?

18
Q

How does an ELISA test work? What is it used for?

A

Rapid detection of specific organisms and toxins

  1. Test plate coated with specific primary antibody to organism of interest
  2. Organism in sample binds to antibody
  3. Washing to remove non-target organisms
  4. Secondary antibody then added - labelled with horseradish peroxidise
  5. Further wash step
  6. Substrate for enzyme then added
  7. If target organism is present it will be bound by primary antibody - secondary antibody with enzyme attached in turn will bind to target; addition of substrate will then result in colour change
19
Q

How does PCR work? What is it used for? Any drawbacks?

A

ID for single pathogen strain

PCR identifies both viable and non-viable organisms as well as DNA in dead cells

20
Q

Define thinning. How does it impact food safety?

A

When a producer is going to the poultry shed and pick out any birds that are not growing well and may have other problems

Going into the shed halfway through the production shed increases that chance that you are bringing in diseases

21
Q

What are the two types of salmonellosis?

A

Enteric and typhoidal

22
Q

What are the different pathotypes of E. coli?

A

Entertoxigenic - ETEC

Enteropathogenic - EPEC

Enteroaggregative - EAEC

Enteroinvasive - EIEC

Diffusely adherent - DAEC

Enterohaemorrhagic/Shiga-toxigenic/verotoxigenic - EHEC/STEC/VTEC

23
Q

What is the most important control measure for STEC at the abattoir?

A

Only send clean cattle for slaughter.

24
Q

Describe the relationship between viruses and food.

A

Viruses do not multiply and do not produce toxins in foods, food items merely act as vehicles for their transfer

As such, they are not zoonotic. Viral foodborne infections are limited to the recycling of human viruses back to humans.

25
Q

What are the two separate entities of hepatitis? What is the difference between them?

A

Infectious: faecal-oral route transmission or “enteric” hepatitis

Serum: parenterally transmitted

26
Q

What are the advantages and disadvantages of conventional culture?

A

Advantages

  • Developed and validated over long period of time
  • Considered gold standard tests
  • Standardised methods
  • Relatively cheap
  • Easy to perform with minimal training

Disadvantages

  • Slow
27
Q

What are the different types of bacteriological agar?

A

Luria-Bertani Agar/Nutrient Agar

MacConkey Agar

Xylose Lysine Deoxycholate (XLD) Agar

Blood agar

Selective for E. coli

Charcoal-cefoperazone-desoxycholate agar (CCDA)

28
Q

What grows on nutrient agar? What do bacteria look like on this agar?

A

It is non-selective, non-chromogenic

Most bacteria appear similar

29
Q

What grows on MacConkey agar? What do bacteria look like on this agar?

A

Selective for enterobacteriacaea

Lactose fermenters appear pink/red (E. coli)

Non-fermenters appear white (Salmonella)

30
Q

What grows on XLD agar? What do bacteria look like on this agar?

A

Selective for Salmonella and Shigella

Salmonella can metabolise thiosulphate to produce hydrogen sulphite and turn black in the center

31
Q

What grows on Blood agar? What do bacteria look like on this agar?

A

Non-selective

Used for assessment of haemolysis, especially for staph and strep

32
Q

What grows on CCDA agar? What do bacteria look like on this agar?

A

Selective for Campylobacter

VPH (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions