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Y2S1_FST2110 - Microbiology and fermentation > Lect 5 : Foodborne pathogens > Flashcards

Lect 5 : Foodborne pathogens Flashcards

1
Q

What are the 3 foodborne illness associated with MOs in food?

A

Infection, intoxication, toxico-infection

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2
Q

How does infection cause us to fall ill?

A
  1. Food/water contaminated with virus/bacteria is ingested
  2. MOs multiply within the gastrintestinal infection to high enough levels to cause sickness
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3
Q

MOs must be viable when consumed to cause infections. True or False?

A

True

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4
Q

What is the infectious dose for infectionsin general ? (amount of MO we need to consume before causing infection)

A

Low infectious dose of 10 to 10^6

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5
Q

How long does it take before we get infectons (from time of ingestion)?

A

> 14 h

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6
Q

What symptom are food infections associated with?

A

Fever

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7
Q

How to food intoxications occur?

A

Ingestion of a preformed microbial toxin in a food

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8
Q

does MO need to be viable for intoxication to occur?

A

No

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9
Q

How long does it take to get intoxication after ingesting the affected food?

A

< 1-14h

way shorter than infection as bacteria do not need time to multiply, the toxin alr formed

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10
Q

How long does symptoms occur in a toxicoinfection?

A

12h to 12 days

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11
Q

Are most foodborne pathogens gram positive or negative? Why?

A

Gram negative, because they have an outer membrane consisting of many virulence factors, which causes sickness

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12
Q

What are the characteristics of Salmonella?

  • gram
  • shape
  • motile (capable of motion)?
  • flagella
A
  • gram neg
  • rod
  • yes, motile
  • peritrichous flagella (distributed evenly around cell)
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13
Q

The genus is Salmonella.
What is the family and 2 pathogenic species of salmonella we are concerned with?

A

Family : Enterobacteriaceae
Species : S. enterica !!!!! and S. bongori

ENTERica ! ENTERS and invades your gastrointestinal tract

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14
Q

How many different types of serovars does Salmonella have?

A

> 2600

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15
Q

What is the main type of foodborne illness associated with Salmonella?

A

Infection

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16
Q

** What are the 2 main serovars of Salmonella that cause foodborne infections?

A

S. Enteritidis

S.Typhimurium

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17
Q

Humans get Salmonellosis from Salmonella. What are some typical symptoms?

A
  1. Fever/ chills
    2. Headache
  2. Abdominal pain
  3. Diarrhea
  4. Nausea / vomitting
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18
Q

What is the infective dose of salmonella?

A

10-10^6 (considered low infectious dose)

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19
Q

How can salmonella be treated usually, and for severe cases ?

A

Self-limiting (self treated)
- by drinking oral fluids

Severe cases :
- IV fluid drip for severe diarrhea
- antibiotics

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20
Q

Why does WHO report more cases of salmonella infections in DEVELOPED countries rather than developing countries?

A

Though developing countries may have poorer hygiene, developed countries have more robust surveillance systems to report cases of salmonella outbreaks

  • developing countries -> cases may not be reported

Thus WHO reports higher incidence of Salmonella cases

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21
Q

Where do Salmonella colonise? [4]

A

Gastrointestinal tracts of
- farm animals
- wild animals (including bird, reptiles)
- pets and zoo animals
- humans after infection

TLDR : gastrointestinal tracts of animals + infected humans

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22
Q

What does it mean by Salmonella is very “smart”?

A

Salmonella can sense subtle environmental cues brought about by genotype or physiological state of plant host and respond with distinct patterns of gene expression accordingly

23
Q

What are the implicated foods for Salmonella?

A

Almost all foods
**Meat, eggs
Fruits and vegetables, seafood, cereals, bakery, RTE foods

24
Q

Is Salmonella aerobic/anaerobic/facultative anaerobic?

Is it a thermophile/mesophile/psychrophile/psychrotroph?

A

facultative anaerobic (can survive harsh processing conditions, so prob not fully aerobic/fully anaerobic)

mesophile

25
Q

How to prevent salmonella from growing? [5]

A
  • maintain cold chain!!! (storing food at 4°C, slows growth as Salmonella is a mesophile)
  • good hygiene on farm and during slaughtering
  • avoid cross contamination
  • cleaning and disinfection of food preparation surfaces
  • thorough cooking and heating of foods
26
Q

What kinds of foods can increase heat resistance of Salmonella?

A

High fat/protein food –> offer protection for salmonella to hide in

27
Q

What are the characteristics of STEC (shiga like toxin producing E. Coli)?

  • gram
  • shape
  • motile (capable of motion)?
  • flagella
A
  • gram neg
  • rod
  • yes, motile
  • petrichous flagella (distributed evenly around cell)

** Same as salmonella

28
Q

Most strands of E.Coli are non pathogenic. True or False?

A

True. E.coli belong to normal intestinal microbiota of humans and animals

29
Q

What are pathogenic E.Coli classified by?

A

Classified by their different virulence factors.

30
Q

What are the names of the 2 important pathogenic E.Coli and what symptoms do they cause?

A
  1. Enterohemorrhagic E.Coli (EHEC)
    - bloody diarhea and hemoytic uermic syndrome
  2. Shiga like toxin-producing E.Coli
    - severe diarrhea, stomach cramps, vomitting
31
Q

What is the infectious dose of EHEC in what kind of food product and how to treat EHEC?

A

0.3-15 CFU/g in frozen groud BEEF patties (cattle)

  • No treatment available and antibiotics only promote Shiga toxin production
32
Q

What does EHEC haemolytic uraemia syndrome result in?

A

Lifelong disability and defects

33
Q

Why is EHEC/STEC important/relevant?

A

Although it is not very prevalent (less incidence), it results in severe disease

34
Q

What is the major reservoir of STEC?

reservoir : habitat where MO multiply

A

in cattle

35
Q

What are the characteristics of Virbrio?

  • gram
  • shape
  • motile (capable of motion)?
  • flagella
A
  • gram-negative
  • straight/curved rods
  • motile
  • polar flagella (1 flagella on 1 side)
36
Q

The three impt species of Vibrio are
V.parahaemolyticals
V. vulnificus
V. cholerae

What is the infectious dose of V.parahaemolyticals?

What are its symptoms?

A

10^5-10^7 CFU

SYMPTOMS :
-WATERY DIARRHEA
- fever
- abdominal cramps
- nausea / vomitting

37
Q

In general, Vibrio is mild/serious with a high/low infectious dose

A

mild

high -> need more to get infected

38
Q

in which regions of the world is vibrio most prevalent in?

A

Coastal / tropical areas

39
Q

How to prevent Vibrio from growing to very high levels and causing sickness? [3]

A
  • keep at 4°C or frozen
  • cook sufficiently
  • prevent cross ccontamination of raw and cooked seafood
40
Q

What are the characteristics of Campylobacter?

  • gram
  • shape
  • motile (capable of motion)?
  • flagella
A
  • gram neg
  • spirally curved rods (spiralla)
  • RAPID motility, corkscrew-like motion
  • AMPHITRICHOUS : single polar flagellum at one or both ends of the cell
41
Q

What are the 2 species of Campylobacter that are foodborne pathogens? (Not impt)

A

** C. jejuni
C.coli

42
Q

What is the infectious dose of C. jejuni (campylobacter)?

What are its symptoms? [3]

A

<1000 CFU

Fever, diarrhea, abdominal cramps

43
Q

How to treat infection by Campylobacter?[2]

A
  • fluids as long as diaarrhea lasts
  • antibiotics
44
Q

In terms of foodborne outbreaks for Campylobacter, are most cases from general outbreaks or sporadic cases in household settings?

A

Household settings

45
Q

What is the main reservoir of Campylobacter?

A

Animal reservoir

  • gastrointestinal tract of poultry, cattle, pigs, wild birds, rodent, flies
  • detected in 25-80% POULTRY (domestic fowl, such as chickens, turkeys, ducks, and geese.)
46
Q

What foods are affected by Campylobacter?

A

25-80% of poultry

common in raw milk

47
Q

Does Campylobacter develop in the food chain?

A

No

48
Q

How to prevent food infection by Campylobacter?

A

Cook raw meats well and avoid cross contamination

49
Q

What are the characteristics of Listeria Monocytogenes?

  • gram
  • shape
  • motile (capable of motion)?
  • flagella
A
  • ** gram positive
  • short rods
  • motile
  • peritrichous flagella

(same as salmonella and STEC) just gram diff

50
Q

What is the minimum infectious dose for Listeria monocytogenes?

A

Difficult to determine but around >100 viable cells

51
Q

Which are the at risk population groups for Listeria Monocytogenes?

A

YOPI
Young
Old
Pregnant
Immunocompromised

52
Q

What are the symptoms of listeriosis?

A

Dependant on state of host

  • fever and muscle pain (nausea and diarrhea is rare)
  • inflammation of brain
  • abortion/stillbirth/premature labour (preg)
53
Q

What are the reservoirs of Listeria Monocytogenes? [3]

A
  • ubiquitous (present everywhere) in the envrionment such as water, soil,….
  • food processing environments
  • preserved products with a long shelf life in the refrigerator
54
Q

How to prevent Listeria Monocytogenes?[2]

A
  • raw foods of animal origins must be completely cooked
  • no cross-contamination of raw and uncooked foods

NOTE : impossible to completely eradicate from foods (ubitiqous in environment)

Y2S1_FST2110 - Microbiology and fermentation (12 decks)

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