microbial foodborne infections and intoxications part 1 W4 Flashcards

1
Q

definition of gastro-enteritis?

A

inflammation of the digestive tract (causing nausea, vomiting, abdominal pain, diarrhoea, eventually fever)

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2
Q

causes of gastro-enteritis? what are their different effects?

A

viral (most common) - stomach flu
parasite
bacterial - microbial food poisoning

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3
Q

examples of viral causes of gastro-enteritis?

A

norovirus
rotavirus
adenovirus

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4
Q

types of bacterial causes of gastro-enteritis?

A

infection = viable microorganisms
intoxication = only toxin

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5
Q

examples of infection bacterial causes of gastro-enteritis?

A

campylobacter spp
salmonella spp
e. coli

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6
Q

examples of intoxication bacterial causes of gastro-enteritis?

A

clostridium perfringens
bacillus cereus
staphylococcus aureus
clostridium botulinum
e. coli

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7
Q

ways to distinguish mechanisms of microbial infections

A

is food a vector or does the microorganism need it to grow?

does the microorganism have to replicate in the host to cause symptoms? (eg not the case in intoxication, some infection)

is ingestion of pre-formed toxin sufficient to cause symptoms?

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8
Q

mild gastro-enteritis clinical description?

A

self-limiting (usually)
2-3 days
3 or less stools/day
low/no fever
general condition = satisfactory

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9
Q

moderate gastro-enteritis clinical description?

A

> 3days
3-5 stools/day
T<38°C
general condition = moderate

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10
Q

serious gastro-enteritis clinical description?

A

invasive diarrhoea
> 3 days
≥ 5 stools/day
T>38°C
bloody diarrhoea
(dysentery, colitis)
general condition = bad

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11
Q

small bowel infection features

A

role = fluid secretion/nutrient absorption

watery diarrhoea
abdominal cramping
bloating
gas

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12
Q

large bowel infection features

A

role = absorb fluid and salt

watery or bloody/mucoid diarrhoea
low abdominal pain
fever++

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13
Q

differential diagnosis: watery diarrhoea, no fever?

A

Cholera

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14
Q

differential diagnosis: watery diarrhoea, fever?

A

norovirus
rotavirus
ETEC
bacillus cereus
staphylococcus aureus

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15
Q

differential diagnosis: bloody diarrhoea, no fever

A

(rare, mainly parasitic causes)
entamoeba histolytica
campylobacter
salmonella

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16
Q

differential diagnosis: bloody diarrhoea, fever?

A

shigella
campylobacter
non-typhi salmonella
C perfringens
EIEC/EHEC

17
Q

what is infective dose?

A

the number of pathogens needed to cause disease in the new host
varies with the pathogen, relatively high for all bacteria

18
Q

general infective dose for viruses/parasites/bacteria?

A

viruses low, parasites medium, bacteria high

19
Q

campylobacter species:
where does it act?
infective/intoxication?
features?
diarrhoea/fever?

A

infective, acts on small and large bowel
microaerophilic, gram negative curved rods, non-spore forming, grow well at 42C
bloody diarrhoea, fever

20
Q

campylobacter species:
types?
associated with?
epidemiology?
incubation/duration?
other important features?

A

C. jejuni and C. coli
associated with frozen poultry, wild birds, other animals, milk and water
sporadic in developed world, epidemic in non dev
incubation: 24-74 hours
duration: 1 week
commonest cause of diarrhoea in the developed world
Guillain-Barre Syndrome (from toxins)

21
Q

diagnosis and treatment of campylobacter species?

A

clinical + stool culture
antibiotics

22
Q

non-typhi salmonella spp:
where does it act?
infective/intoxication?
features?
diarrhoea/fever?

A

small and large bowel, infective
gram-negative, non-spore forming, facultatively anaerobic bacilli
can be watery/bloody diarrhoea, +/- fever

23
Q

non-typhi salmonella spp:
associated with?
epidemiology?
incubation and duration?
other important features?

A

associated with poultry/eggs (unlike typhi which has only human reservoir)
sporadic and outbreaks
incubation: 6-48h
duration: 1-7 days
often serious. wide range of clinical manifestations. 2nd cause of foodborne disease worldwide.

24
Q

non-typhi salmonella spp:
diagnosis?
treatment?

A

clinical + stool culture
antibiotics, MDR!!! (multi-drug resistant)

25
clostridium perfringens: where does it act? infective/intoxication? features? diarrhoea/fever?
small bowel, intoxication aerotolerant, gram-positive rods, forming endospores watery diarrhoea, +/- fever
26
clostridium perfringens: intoxication pathway?
associated with bulk cooking of meat warm food - contamination by spores which germinate a culture of vegetative bacteria is ingested bacteria sporulate in small intestine and produce an enterotoxin destruction of villus tips with resultant pain and diarrhoea (+ myonecrosis) often large outbreaks
27
clostridium perfringens: incubation? duration? diagnosis? treatment?
incubation 8-22h duration 1-2 days diagnosis: stool culture + detection of toxin treatment: supportive
28
clostridium botulinum: where does it act? infective/intoxication? features? diarrhoea/fever?
small bowel, intoxication anaerobic, spore-forming, toxin types A-G watery diarrhoea, +/- fever
29
clostridium botulinum: 3 big clinical manifestations?
(botulism = toxin-mediated paralytic illness) neuro-botulism foodborne botulism wound botulism
30
clostridium botulinum: associated with? diagnosis? treatment? other important features?
associated with soils, lake sediments, vegetables, GI tract of mammals, birds, fish. home canned or fermented foods. diagnosis: stool culture + detection of toxin treatment: supportive
31
staphylococcus aureus: where does it act? infective/intoxication? features? diarrhoea/fever?
acts on small intestine, intoxication gram-positive coccus, aerobe, nonmotile, non-spore forming watery diarrhoea +/- fever
32
staphylococcus aureus: associated with? incubation? duration? clinical features? other important features?
contaminates salted foods and dairy produce incubation 2-6h, duration 1-24h very acute vomiting response often followed with diarrhoea commonest skin organism, toxins = heat stable
33
staphylococcus aureus: diagnosis? treatment?
diagnosis not necessary treatment is supportive
34
bacillus cereus: where does it act? infective/intoxication? features? diarrhoea/fever?
acts on small bowel, intoxication aerobic (or facultatively anaerobic), spore forming gram-positive bacilli watery diarrhoea +/- fever
35
bacillus cereus: associated with? clinical features? other important features?
spore germinate in warm cooked rice acute vomit response followed by diarrhoea resist extreme temperature - form biofilms spores ingested - vegetative cells - toxins separate toxins for vomiting and diarrhoea responses
36
bacillus cereus: incubation? duration? diagnosis? treatment?
incubation: 1-5h duration:12-24h diagnosis: not necessary treatment: supportive