Food-borne bacterial infections Flashcards

1
Q

What are the defences against infection in the GI tract of the mouth?

A

Flow of liquids
Saliva
Lysozyme
Normal bacterial flora

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2
Q

What are the defences against infection in the GI tract of the oesophagus?

A

Flow of liquids

Peristalsis

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3
Q

What are the defences against infection in the GI tract of the stomach?

A

Acid pH

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4
Q

What are the defences against infection in the GI tract of the small intestine?

A
Flow of gut contents
Peristalsis
Mucus: bile
Secretory IgA
Lymphoid tissue (Peyer’s patches)
Shedding and replacement of epithelium
Normal flora
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5
Q

What are the defences against infection in the GI tract of the large intestine?

A

Normal flora
Peristalsis
Shedding and replication of Mucus

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6
Q

What are food-borne diseases?

A

Results from contamination of food by pathogens that can or cannot multiply in the food

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7
Q

What is food poisoning?

A

Results from microorganisms having grown on the food to produce

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8
Q

What are the two types of food poisoning?

A

Infection-type food poisoning

Toxin-type food poisoning

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9
Q

What is toxin-type food poisoning?

A

Toxin (s) in the food (toxin causes clinical symptoms)

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10
Q

What is infection-type food poisoning?

A

A sufficiently large population to produce an infective dose

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11
Q

What are some examples of infection-type food poisoning?

A

Salmonella, Clostridium perfringens, E. coli- GI symptoms

Listeria monocytogenes- systemic symptoms

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12
Q

What are some examples toxin-type food poisoning?

A

Staphylococcus aureus- enterotoxin
Clostridium botulinum- neurotoxin
Bacillus cereus- emetic and diarrhoeal toxins

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13
Q

What are the two main food-related pathogens in the UK?

A

Campylobacter- food-borne

Salmonella- food poisoning

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14
Q

What are the main food vesicles for passing disease?

A

Meat and poultry

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15
Q

What are the greatest singe cause of human morbidity and mortality in the world?

A

Diarrhoeal diseases

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16
Q

How many people are affected with a gastrointestinal infection in the UK each year?

A

1 in 5

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17
Q

What is the cost of gastrointestinal infection?

A

£0.75 billion

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18
Q

How many people with a gastrointestinal infection attend a GP?

A

1 in 6 cases

19
Q

What are the possible reasons for the increase in food-related illness?

A

Increase in large-scale catering
Fast food, convenience foods, packed meals-inadequate storage and reheating
Increase in factory farming (more potential pathogens in animals)
Changing patterns of shopping and food storage in the hormone
“Healthy eating”- non-processed, non-preserved food (not cooking fresh food, preserved foods have anti-bacterial products)
Staff, untrained in hygiene, working in catering establishments
Increase in travel

20
Q

What is the structure of salmonella

A

Motile, non-sporing Gram-negative rods

Facultative anaerobes

21
Q

How many types of serotypes are there in Salmonella?

A

> 2000

22
Q

What are serotypes?

A

Serotypes are groups within a single species of microorganisms, such as bacteria or viruses, which share distinctive surface structures.

23
Q

What is S. Typhi?

A

Human, systemic infection (typhoid fever)- no animal source- bloodstream and reticuloendothelial system infection

24
Q

Where does food poisoning salmonella come from?

A

Animal source

e.g. S. Enteritidies, S. Typhimurium- fever, diarrhoea, vomiting, abdominal pain

25
Q

What is typhoid and enteric fever?

A

Invasive disease restricted to humans

26
Q

What is typhoid and enteric fever associated with?

A

Associated with lack of public health services

Associated with contaminated food/water

27
Q

What is typhoid and enteric fever caused by?

A

Salmonella Typhi

Salmonella Paratyphi A, B, C

28
Q

What is the source of salmonella?

A

Live in food animals GI tract

29
Q

How can cross-contamination spread?

A

From raw meat and poultry to cooked food

Inadequate cooking and storage temperature

30
Q

What is the steps of pathogenesis for salmonella?

A

Toxins not clearly demonstrated
Localised invasion of intestinal mucosa- facultative intracellular parasites
Type III secretion systems essential for virulence
Bacteria pass through M cells, taken up by macrophages, multiply and lyse macrophages
Inflammatory response gives rise to disease symptoms
Patients may continue to excrete the organism for weeks/months after recovery

31
Q

What are the steps of salmonella invading epithelial cells?

A
Cell opens up
Produces a ruffle 
Induce membrane ruffle
Goes inside the cell
Goes into a vacuole
Into the lamina propria of the gut
Immune response produces macrophages
Results in blood in diarrhoea
32
Q

What induces membrane ruffles?

A

Proteins

33
Q

What type of pathogen is salmonella?

A

Intracellular

Can survive and grow inside cells

34
Q

What does salmonella prevent allowing it to live in the cell?

A

Prevents the phagolysosome fusion

35
Q

What is Campylobacter?

A

C. jejuni (normal flora in chicken)- slender, motile, Gram-negative curved or spiral rods

36
Q

What are sources of getting campylobacter?

A

Common gut inhabitants of animals, poultry, domestic pets
Meat infected with gut contents at slaughter
Survive well on chickens processed rapidly and staying moist
Cross contamination

37
Q

How does campylobacter survive in the GI tract?

A

Capsule

38
Q

At what age is person to person transmission of campylobacter more likely?

A

Children

39
Q

What is c. jejuni and c. coli most frequently identified to cause?

A

Acute infective bacterial diarrhoea

40
Q

What is zoonosis?

A

Pathogens acquired from animals via food (or direct contact)

41
Q

What is the pathogenesis of c. jejuni and c. coli?

A

Facultative intracellular parasites

42
Q

What do c. jejuni and c. coli invade?

A

The mucous membranesof the gut and produce
Cytotoxin (s)- responsible for tissue
Destruction and inflammatory diarrhoea

43
Q

What does c.jejuni and c.coli cause?

A

Causes blood in diarrhoea
Sets up response in lamina propria
Causes white cell production
Caused by tissue invasion

44
Q

What are the 3 general preventative measures?

A

Prevention of contamination of food
Prevention of growth of pathogen
Rejection of suspected foods