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health and the community > lectures 1-4 > Flashcards

lectures 1-4 Flashcards

1
Q

what are the three types of food born disease and what do they entail?

A
  • infection - bacterial, fungi, eukaryotic parasites, viruses
  • intoxication - bacterial and fungal toxins, shellfish toxins, metals and chemicals
  • allergy
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2
Q

what are the stages of the causative chain of food-borne infections?

A

agent -> source -> contamination -> suitability -> growth conditions -> consumption

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3
Q

what are the most common sources of food-borne contamination?

A
  • food handler
  • natural food contamination
  • direct contamination
  • water based contamination
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4
Q

what are the benefits of microbe presence in food?

A
  • food enhancement
  • food additives - food safety and stability, probiotics
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5
Q

what are the drawbacks of microbe presence in food?

A
  • food spoilage - shortened shelf life & failure to meet legal requirements
  • food safety - morbidity & mortality
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6
Q

how can lactobacillaceae be a beneficial bacteria?

A
  • it ferments sugars to lactic acid, which is used in probiotics, yoghurt, and cheese
  • it outcompetes pathogens
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7
Q

what pH range does lactobacillaceae grow at?

A

pH 4-5

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8
Q

what is intrinsic food preservation?

A
  • putting things in food to reduce pathogens and help in preservation
  • water activity and food acidity are used for growth inhibition
  • other methods are used, including antimicrobial chemicals and biological methods (competitive microflora, bacteriocins, and enzymes
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9
Q

what are methods of extrinsic food preservation?

A
  • heat treatment - destruction of cells and spores
  • low temperature storage - growth inhibition
  • modified atmosphere packaging - growth inhibition/destruction of cells
  • radiation - destruction of bacterial cells
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10
Q

what is hurdle technology?

A
  • multiple preservation factors are combined to improve food safety which allows each individual measure to be milder
  • can be more effective than individual processing methods
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11
Q

what are the key features of salmonella bacteria shape and growth?

A
  • the bacteria is Gram negative, motile, and rod shaped
  • grows at pH 4-5
  • ferments sugars to lactic acid
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12
Q

what are salmonella’s virulence factors?

A
  • salmonella invasion proteins
  • secreted proteins
  • lipopolysaccharides
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13
Q

what disease does salmonella cause?

A

enteric salmonellosis

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14
Q

how does human infection by salmonella occur?

A
  • consumption of contaminated animals, animal products, or water
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15
Q

what does infection by salmonella result in?

A
  • gastroenteritis
  • typhoid fever
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16
Q

how many lab confirmed cases are there of salmonella each year in the UK?

A

8,500

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17
Q

what are the symptoms, incubation period, morbidity period, and infection type of gastroenteritis?

A
  • symptoms - occasional vomiting, severe diarrhoea, mild fever, muscle aches
  • incubation period - 8-48hrs
  • morbidity period - 3-6 days
  • infection type - superficial infection of the gut
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18
Q

what are the symptoms, incubation period, morbidity period, and infection type of typhoid fever?

A

symptoms - occasional vomiting, occasional diarrhoea, severe fever, sore throat/cough
incubation period - 10-14 days
morbidity period - 2+ weeks
infection type - invasive infection of the lymph nodes, the liver, the spleen, and the gall bladder

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19
Q

what are the key features of campylobacter sp. shape and growth?

A
  • structure - Gram negative, mobile, spiral shaped
  • growth - microaerophilic, non-fermenting
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20
Q

what are the virulence factors of campylobacter sp.?

A
  • enzymatic colonisation
  • adherence and invasion factors
  • flagellum
  • toxin (cytolethal distending toxin)
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21
Q

what disease is caused by the bacteria campylobacter sp.?

A

campylobacteriosis

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22
Q

where is campylobacter sp. normally found in hosts?

A

normally inhabits the GI tract of animals

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23
Q

how many people globally do not have access to safe drinking water?

A

785m

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24
Q

how is sewage treated?

A

1 - the raw sewage is passed through screens to separate out the grit
2 - the water moves through a series of clarifiers
3 - the clean water is floated through an aeration tank and is then disinfected

25
Q

how is water treated to be used as bottled water?

A

1 - ozonisation occurs to help destroy all the bacteria and viruses
2 - it goes through filters to remove coarse particles, pesticides, and salts and minerals
3 - reverse osmosis occurs to remove remaining salts and minerals
4 - mineral control adds back in some minerals

26
Q

name 2 waterborne diseases caused by bacteria

A
  • cholera
  • gastroenteritis (E.coli)
27
Q

name 2 viral waterborne diseases

A
  • norovirus
  • rotavirus
28
Q

name 3 protozoan waterborne diseases

A
  • cryptosporidiosis
  • schistosomiasis
  • malaria
29
Q

what are some structural features of norovirus?

A
  • non-enveloped
  • icosahedral
  • single stranded RNA
30
Q

what are the host and virulence factors of norovirus?

A
  • highly contagious
  • small dose needed for infection
  • sheds billions of viral particles
31
Q

what are the 3 open reading frames in norovirus?

A

ORF 1 - encodes for replicase proteins
ORF 2 - encodes the capsid proteins
ORF 3 - encodes the minor structural proteins

32
Q

what type of pathogen is cryptosporidium?

A
  • protozoan (eukaryotic parasite)
33
Q

what are the 2 human pathogens associated with cryptosporidium?

A

C. parvum
C. hominis

34
Q

what are the risk factors of cryptosporidium?

A
  • defecating in swimming pools
  • petting zoos
35
Q

what are the host factors and virulence of cryptosporidium?

A
  • symptomatic episodes of uncontrolled diarrhoea
  • immune suppression
36
Q

what is the life cycle of cryptosporidium?

A

1 - an oocyte is ingested
2 - the pathogen excyses out of the oocyte
3 - it adheres to the gut and invades and multiplies
4 - future oocytes are released in faeces

37
Q

what does HACCP stand for and what are its 7 principles?

A
  • Hazard analysis and critical control points
    7 principles:
    1 - list all potential hazards
    2 - determine the critical control points
    3 - establish critical limits for each CCP
    4 - establish a monitoring system
    5 - establish corrective measures
    6 - establish verification procedures
    7 - establish documentation and record keeping
38
Q

what elements are considered in HACCP?

A
  • biological
  • physical
  • chemical
  • allergen
39
Q

what is hurdle technology?

A
  • a number of preservation factors are combined to improve food safety
  • it allows individual measures to be milder, increasing the naturalness of food
40
Q

what is the Maillard reaction and how does it prevent microbial contamination?

A
  • it is the non enzymatic browning of food
  • it removes nutrient sources for bacteria
41
Q

describe the structure and growth conditions of Listeria sp.

A
  • structure: Gram positive, motile, rod-shaped
  • growth: facultative anaerobe
42
Q

what are the virulence factors of Listeria sp. ?

A
  • biofilm formation
  • haemolysis factors
  • adhesion and invasion factors
  • flagella
43
Q

what disease does Listeria sp. cause?

A

Listeriosis

44
Q

what are the symptoms of listeriosis?

A
  • can be invasive or non invasive
    invasive: severe headache, stiff neck, confusion, seizures, tremors
    non-invasive: fever, nausea, diarrhoea, chills
45
Q

what is the structure and growth conditions of Escherichia coli ?

A

structure: Gram negative, rod shaped
growth: facultative anaerobe

46
Q

what are the virulence factors of Escherichia coli?

A
  • LPS
  • flagella
  • shiga-like toxin
47
Q

what disease does E.coli cause?

A

gastroenteritis

48
Q

what was the first suggestion about the existence of the gut microbiome?

A

in the early 1900s, Metchnikoff was the first scientist to suggest that it was possible to modify the gut microbiome by replacing bad bacteria with good bacteria

49
Q

what are commensal bacteria?

A

bacteria that derive an advantage from the body but do no damage

50
Q

what relationship is displayed between the GI tract and the intestinal microbiota?

A

symbiotic

51
Q

what is disruption of the intestinal microbiota homeostasis called?

A

dysbiosis

52
Q

what are the important phyla and genera in the microbiome (give Gram stain result and examples)

A
  • firmicutes - Gram pos - e.g. Clostridia & Lactobacillales
  • bacteroidetes - Gram neg - e.g. Bacteroides spp.
  • actinobacteria - Gram pos - e.g. Bifidobacteria spp.
  • proteobacteria - Gram neg - e.g. Escherichia, Shigella
  • fusobacteria - Gram neg - e.g. fusobacterium spp.
53
Q

what did the Human microbiome project do?

A
  • reported the structure and function of 300 healthy adults at 18 body sites
  • isolated and sequenced over 1300 strains of bacteria
54
Q

what factors can influence the microbiome?

A
  • mode of delivery (vaginal/c-section)
  • mode of initial feeding (breastfed/formula)
  • ageing process
  • diet
  • geography
  • medication
  • stress
55
Q

how does first contact influence the microbiome?

A
  • in utero - meconium is shown to contain microorganisms but most gut microbes are acquired post-partum
  • delivery mode - in vaginal births the infant is inoculated with vaginal microbiota, and skin microbiota in c-sections
56
Q

when does the majority of colonisation of the microbiome occur and what influences this stage?

A
  • environmental exposure early in life is crucial
  • colonisation occurs in stages with initially only aerobic organisms
  • breast milk contains over 600 species of bacteria (such as Bifidobacterium)
  • breast fed infants have lower concentrations of some pathogens such as Clostridia spp.
  • the microbiome stabilises in adulthood
57
Q

how can ageing lead to dysbiosis and what are the effects of this?

A
  • change in diet can lead to dysbiosis
    effects:
  • intestinal permeability
  • immune dysregulation
  • potential for GIT disorders
  • increased risk of C.diff infections
58
Q

how can exercise induced stress lead to dysbiosis?

A
  • the gut signals that the human host is in exercise
  • the autonomic nervous system is activated, and there is bidirectional communication between the ANS and the GI tract (the gut-brain axis) mainly by the vagus nerve
  • this leads to an increase in cytokines
59
Q

how does alcohol cause dysbiosis? how can this be prevented?

A
  • some people will develop alcohol induced pathology
  • there is a potential decrease in the abundance of bacteroidetes and firmicutes, and an increase in proteobacteria and actinobacteria
  • probiotic supplements can prevent this

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