microbial foodborne infections and intoxications part 1 W4

Question 1

definition of gastro-enteritis?

Answer 1

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

Question 2

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

Answer 2

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

Question 3

examples of viral causes of gastro-enteritis?

Answer 3

norovirus
rotavirus
adenovirus

Question 4

types of bacterial causes of gastro-enteritis?

Answer 4

infection = viable microorganisms
intoxication = only toxin

Question 5

examples of infection bacterial causes of gastro-enteritis?

Answer 5

campylobacter spp
salmonella spp
e. coli

Question 6

examples of intoxication bacterial causes of gastro-enteritis?

Answer 6

clostridium perfringens
bacillus cereus
staphylococcus aureus
clostridium botulinum
e. coli

Question 7

ways to distinguish mechanisms of microbial infections

Answer 7

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?

Question 8

mild gastro-enteritis clinical description?

Answer 8

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

Question 9

moderate gastro-enteritis clinical description?

Answer 9

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

Question 10

serious gastro-enteritis clinical description?

Answer 10

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

Question 11

small bowel infection features

Answer 11

role = fluid secretion/nutrient absorption

watery diarrhoea
abdominal cramping
bloating
gas

Question 12

large bowel infection features

Answer 12

role = absorb fluid and salt

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

Question 13

differential diagnosis: watery diarrhoea, no fever?

Answer 13

Cholera

Question 14

differential diagnosis: watery diarrhoea, fever?

Answer 14

norovirus
rotavirus
ETEC
bacillus cereus
staphylococcus aureus

Question 15

differential diagnosis: bloody diarrhoea, no fever

Answer 15

(rare, mainly parasitic causes)
entamoeba histolytica
campylobacter
salmonella

Question 16

differential diagnosis: bloody diarrhoea, fever?

Answer 16

shigella
campylobacter
non-typhi salmonella
C perfringens
EIEC/EHEC

Question 17

what is infective dose?

Answer 17

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

Question 18

general infective dose for viruses/parasites/bacteria?

Answer 18

viruses low, parasites medium, bacteria high

Question 19

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

Answer 19

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

Question 20

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

Answer 20

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)

Question 21

diagnosis and treatment of campylobacter species?

Answer 21

clinical + stool culture
antibiotics

Question 22

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

Answer 22

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

Question 23

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

Answer 23

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.

Question 24

non-typhi salmonella spp:
diagnosis?
treatment?

Answer 24

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

Question 25

clostridium perfringens: where does it act? infective/intoxication? features? diarrhoea/fever?

Answer 25

small bowel, intoxication aerotolerant, gram-positive rods, forming endospores watery diarrhoea, +/- fever

Question 26

clostridium perfringens: intoxication pathway?

Answer 26

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

Question 27

clostridium perfringens: incubation? duration? diagnosis? treatment?

Answer 27

incubation 8-22h duration 1-2 days diagnosis: stool culture + detection of toxin treatment: supportive

Question 28

clostridium botulinum: where does it act? infective/intoxication? features? diarrhoea/fever?

Answer 28

small bowel, intoxication anaerobic, spore-forming, toxin types A-G watery diarrhoea, +/- fever

Question 29

clostridium botulinum: 3 big clinical manifestations?

Answer 29

(botulism = toxin-mediated paralytic illness) neuro-botulism foodborne botulism wound botulism

Question 30

clostridium botulinum: associated with? diagnosis? treatment? other important features?

Answer 30

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

Question 31

staphylococcus aureus: where does it act? infective/intoxication? features? diarrhoea/fever?

Answer 31

acts on small intestine, intoxication gram-positive coccus, aerobe, nonmotile, non-spore forming watery diarrhoea +/- fever

Question 32

staphylococcus aureus: associated with? incubation? duration? clinical features? other important features?

Answer 32

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

Question 33

staphylococcus aureus: diagnosis? treatment?

Answer 33

diagnosis not necessary treatment is supportive

Question 34

bacillus cereus: where does it act? infective/intoxication? features? diarrhoea/fever?

Answer 34

acts on small bowel, intoxication aerobic (or facultatively anaerobic), spore forming gram-positive bacilli watery diarrhoea +/- fever

Question 35

bacillus cereus: associated with? clinical features? other important features?

Answer 35

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

Question 36

bacillus cereus: incubation? duration? diagnosis? treatment?

Answer 36

incubation: 1-5h duration:12-24h diagnosis: not necessary treatment: supportive