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Y2S1_FST2110 - Microbiology and fermentation > Lect 6 : Foodborne Pathogens Pt 3 > Flashcards

Lect 6 : Foodborne Pathogens Pt 3 Flashcards

Foodborne toxin producers and foodborne virus

1
Q

What 2 factors need to be considered before the MOs (bacterial strains) produces toxins?

A
  1. Presence of toxin genes
  2. Whether genes are EXPRESSED under the specific growth conditions (food/stomach)
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2
Q

What are the 3 main species of bacteria that produces toxins?

A
  1. Staphylococcus Aureus
  2. Bacillus Cereus
  3. Clostridium Botulinium
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3
Q

What are the characteristics of Staphylococcus Aureus?

Gram?
Spore-forming?
Aerobic / anaerobic / facultative anaerobic?

A

Gram positive
Non-sporeforming
Facultative anaerobe

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4
Q

How to prevent growth of Staphylococcus Aerus?

A

Good Manufacturing Practices

Maintaining suitable temperatures – cannot grow below 7°C, and dont abuse temperature (10-45°C)

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5
Q

What kinds of foods does Staphylococcus Aureus like?

A

Proteinaeous foods

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6
Q

Low numbers of Staphylococcus Aureus can be tolerated. What is the range of number of CFU/g that can be tolerated?

A

100-1000 CFU/g

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7
Q

What is the name of the toxin produced by Staphylococcus Aureus?

A

Emetic toxin

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8
Q

Emetic toxin produced by Staphylococcus Aureus is heat resistant. Partial damage is done by heating food for ___ min at ___ deg cel

A

30,100

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9
Q

What is the dosage of emetic toxin by Staphylococcus Aureus to cause sickness?

A

100ng

(produced when Staphylococcus Aureus counts reach 10^5 CFU/g

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10
Q

How can you detect the bacteria Staphylococcus Aureus? What indicator is used?

A

Coagulase production –> indicator of possible toxin production

Coagulase : protein enzyme produced by several MOs

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11
Q

How can you detect toxin produced by Staphylococcus Aureus ? [1]

A

Using Ready-to-use-kits based on Immunochemical methods, aka ready-to-use immunological kits

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12
Q

What are the characteristics of Staphylococcus Aureus?

Gram?
Spore-forming?
Aerobic / anaerobic / facultative anaerobic?

A

Gram positive
Non spore-forming
Facultative anaerobe

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13
Q

What kinds of foods do Bacillus Cereus love?

A

Starchy products such as boiled/fried rice etc

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14
Q

What is one main feature of Bacillus Cereus ?

A

It is able to survive and form biofilms on food products such as animal meat (also raw milk), as well as vegetables

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15
Q

Bacillus Cereus and Staphylococcus Aureus is omnipresent (can be commonly found everywhere). True or False?

A

True

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16
Q

What is the tolerable range of Bacillus Cereus?

A

100-1000 CFU/g

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17
Q

Toxin production of Bacillus Cereus starts at how many CFU/g?

A

10^5

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18
Q

What 2 kinds of foodborne illness can Bacillus Cereus cause and what are the associated toxins with each kind of illness?

A
  1. Toxico-infection : Diarrhea toxin
  2. Intoxication : Emetic toxin
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19
Q

The diarrhea toxin of Bacillus Cereus is heat labile (likely to be altered/degraded) when heated for ____ min at ____°C

A

5, 56

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20
Q

What are the 3 main symptoms of Diarrhea toxin?

A
  1. Abdominal pain
  2. Cramps
  3. WATERY diarrhea

(ocassionally nausea)

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21
Q

What are the 3 ways to detect Bacillus Cereus diarrhea toxin?

[not so impt]

A
  1. PCR detection of toxin-genes
  2. Available immunological detection kits
  3. Cytotoxicity
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22
Q

The B. Cereus emetic toxin is heat resistant. True or False?

A

True

It is heat resistant even at 121°C, for 90 mins of heating

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23
Q

What is the intoxication dose of B. Cereus emetic toxin?

A

8 micrograms / kg body weight

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24
Q

What are the 4 symptoms of intoxication from the B. Cereus emetic toxin?

[not so impt]

A
  1. Nausea
  2. Vomiting
  3. Malaise
  4. Fatal liver failure
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25
Q

What are the 4 ways that can be used to detect B. Cereus emetic toxin?

[not so impt]

A
  1. Boar-semen bio-assay
  2. Liquid Chromatography-Mass Spectrometry (LC-MS)
  3. Cytotoxicity
  4. Cereulide related genes by PCR
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26
Q

What are the characteristics of Clostridium Botulinium?

Gram?
Spore-forming?
Aerobic / anaerobic / facultative anaerobic?

A

Gram positive
Spore forming
STRICTLY anaerobic

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27
Q

Clostridium Botulinium is omni present in which environment/

A

soil, but may also be present in the sea

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28
Q

What type of Clostridium Botulinium is found in :

  1. Vegetables [1]
  2. Meat and meat products [3]
  3. Fish [1]
A
  1. type A (vegetAbles)
  2. type B, A, F [FAB]
  3. type E
29
Q

What is the name of the toxin produced by Botulinium Clotridium?

A

BoNT - Botulinium Neurotoxin

30
Q

Under what heating conditions are BoNTs (Botulinium Neurotoxins) labile (degrade)?

A

heating for 2 minutes at 75-80°C

but dependent on the type of toxin produced by different types of C.B.

31
Q

Intoxication by Botulinium Neurotoxins may lead to classical food borne botulism. Why is this disease a cause for concern though it has a low incidence rate/

A

it has a high mortality rate

32
Q

Why cant honey be given to infants less than 12 months old?

A

Honey may contain Clostridium Botulinium spores, which can produce toxin in-situ (in the existing place), which causes infant botulism

  • Infants also cannot consume Clostridium Botulinium bacteria though adults can tolerate low amounts, because their digestive system is not fully developed yet.
33
Q

How can we detect Botulinium Neurotoxins? [3]

[not so impt]

A
  1. ELISA
  2. BoNT related genes
  3. Mouse-bio assay

A mice bioassay is literally using a mouse to determine how safe a food is. We make an extract from the food and inject that directly into a mouse, and if the mouse survives, the food is safe, and if the mouse dies, the food is unsafe.

34
Q

What are the characteristics of mould?

Aerobic?
Sporeforming?

A

STRICTLY aerobic

spore-forming

35
Q

** What are the 2 genus names of moulds that produce mycotoxins?

A

Aspergillus

Penicillum

36
Q

What are the names of the 3 kinds of mycotoxins produced by moulds, and state if Aspergillus / Penicillum produces each of these mycotoxins.

A
  1. Aflatoxins
    - produced by Aspergillus (A and A)
  2. Ochratoxins
    - produced by Aspergillus AND Penicillum
  3. Patulin
    * - produced by Penicillum, Aspergillus

(in summary table, said only Penicillum but at slide 24, said produced by species of Penicillum, Aspergillus and Byssochylamys

37
Q

What are the important crops that produce Aflatoxins and what kind of products are Aflatoxins typically found in?

A
  • Corn, Peanuts and Soybeans
  • Aflatoxins usually found in oil (cooking oils)
38
Q

What 2 factors can cause aflatoxins to be produced in plants?

A
  1. Damage/stress in plants, leading to invasion of aflatoxins
  2. Poor STORAGE of food products after harvest
39
Q

How can we control the growth of aflatoxins? [3]

A
  1. Screening and sorting of products
  2. Usage of chemical treatments
  3. keeping moisture low during storage (since mould love humid, moist envt)

(moulds like to grow in humid envt – high moisture)

40
Q

Which organ does Aflatoxins target in humans and animals?

What kinds of diseases can result from aflatoxins?

A

Liver

Diseases :
1. accute liver damage (rare)
2. Liver cirrhosis (scarring of liver, flesh replaced by fiber)
3. tumour induction in liver of ANIMALS

41
Q

What are the regulatory limits imposed for aflatoxins B1 in peanuts and peanut products?

A

5-20 µg (micrograms) / kg

42
Q

What kinds of foods are orchratoxins usually found in?

A

Dried foods such as nuts, beans, dried fruits/meat/fish

43
Q

Penicillium verrucosum is only found in grain from Scandinavia and Canada, or meat from Europe.

What is the best growth temperature for Penicillium verrucosum?

A

Low temperature at 0°C

44
Q

What is the target organ for orchratoxins

What are the effects of ingesting orchatoxins[2] ?

A

Kidneys

Effects
1. Leads to acute and chronic lesions in kidney

  1. possibly causes cancer in humans (human carcinogen)
45
Q

Patulin is also regarded as an antibiotic. True or False?

A

True

46
Q

What kinds of disease can patulin cause in humans?

A

No chronic toxicity found in humans, thus not many diseases and small presence in foods is of little concern.

47
Q

What kind of food products is patulin usually found in?

A

Mouldy fruit, especially apple and pears

48
Q

Patulin is an important indicator for …?

A

It is an important indicator for telling you that the fruit used to make juices is of low-quality

49
Q

FOODBORNE VIRUS!! IMPT!! MEMORISE!!

What are the 3 important kinds of foodborne viruses?

A
  1. Norovirus
  2. Hepatitis A
  3. Hepatitis E
50
Q

How was norovirus discovered?

A

Through electron microscopy in 1972

51
Q

What is the size of the norovirus?

Genome :
1. What is it made up of? (RNA?DNA? strands)

  1. How long is the genome (base pairs of nucleotides)

[not so impt]

A

size : ~20nm

Genome
- Single (positive) stranded RNA
- 7.5 kb, including poly A tail (7.5kb = 7.5 kilo bases = 7.5 x 1000 base pairs)

52
Q

What is the virus capsid for norovirus made out of and does the norovirus have a lipid envelope?

[not so impt]

A

Virus capside : 180 copies of polyprotein which shows ISOCAHEDRAL symmetry
- isocahedral : solid figure w 20 sodes made of equilateral triangles

No lipid envelope, thus it is highly stable

53
Q

Norovirus : illness

What is the :

  1. Infectious dose?
  2. Number of particles shedded per g?
  3. incubation period?
  4. the 4 main symptoms?
A
  1. 10-100 virus particles
  2. up to 10^10 virus particles / g in faeces / vomit
  3. 12-48h
  4. Fever, diarrhoea, nausea, vomiting (‘stomach flu’)
54
Q

How to treat illness from norovirus?

A

Self-limiting, no treatment required other than oral fluid

55
Q

** What is the difference in transmission route for norovirus compared to other bacterial infection transmission routes?

A

For bacterial infections : sources of contamination can originate from animals themselves

  • can be transmitted from animals to human

For norovirus : all sources of contamination originate from human

it is only passed from one person to another, not from animal to human (animal meat are indirect carriers —> bc sick person handle meat etc)

  • norovirus can be transmitted through contaminated food and water
  • contaminated food :
    • A person with norovirus touches food with their bare hands.
    • Food is placed on a counter or surface that has poop or vomit particles on it.
    • Tiny drops of vomit from a person with norovirus spray through the air and land on the food.
    • Food is grown with contaminated water, such as oysters, or fruit and vegetables are watered with contaminated water in the field.
      [thus norovirus is not directly transmitted from animals to humans, its bc of the contaminated water used to grow food, and the contaminated water used for irrigation comes from filtering sewage water, and the sewage water contains faeces of infected individuals, and virus may pass through filters, never get filtered out)
56
Q

What is the family of Hepatitis A?

A

Picornaviridae (pico = small –> small RNA viruses)

57
Q

[NOT IMPT, FYI]
What does hepatitis mean?

A

Inflammation of the liver

58
Q

Which Hepatitis A genotypes are infectious to humans?

A

I, II, III, VII

(1,2,3,7)

59
Q

What is the genome of hepatitis A like?

  • DNA/RNA? Strand?
  • how long?
A
  • single stranded RNA molecule
  • 7.5kb
60
Q

What is the virus capsid in Hepatitis A made of ? Does it have a lipid envelope?

A

Virus capsid is made up of only 1 polyprotein and has no lipid envelope (thus high stability)

61
Q

Hepatitis A : What is the

  1. Infectious dose
  2. Incubation period
  3. the 2 hosts that Hep A infects
  4. Symptoms [4]

??

A
  1. Infectious dose : 10-100 HAV (Hepatits A Virus) particles
  2. 2-6 weeks
  3. Host that HAV infects
    - Epithelial cells of small intestine
    - Hepatocytes (liver cell)
  4. Fever, nausea, dark urine, jaundice (yellow skin/ eye whites)
62
Q

For HAV, if it infects children below 6 years old, is it symptomatic/asymptomatic?

What is the implication of children getting infected by HAV

A
  1. Asymptomatic
  2. Implication : children will gain life-long immunity
63
Q

What virus family is Hepatitis E from?

A

Hepeviridae

64
Q

There are 4 genotypes of Hepatitis E, genotype(gt) 1, gt 2, gt3 and gt4. Which genotype(s) is more prevalent in Asia?
[not so impt]

A

3 and 4

65
Q

What is the genome of hepatitis A like?

  • DNA/RNA? Strand?
  • how long?
A

Single stranded RNA

7.2kb

66
Q

which group of people are susceptible to Hepatitis E virus and what is the mortality rate in this group of people/

A

pregnant women, mortality rate of 20%

67
Q

Hepatitis E show similar clinical features to hepatitis A virus. True or False?

A

True

68
Q

How can genotype 3 and 4 of hepatitis E be transmitted to humans?

A

from animals such as pork, boar and deer meat

  • foodborne infections due to undercooked meat or orhans from infected animals
69
Q

We cannot cultivate viruses on mediums, unike bacteria. Why is this so?

A

Virus require an alive host to grow, thus making it impossible to cultivate it in laboratory settings

Y2S1_FST2110 - Microbiology and fermentation (12 decks)

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