Bacterial foodborne pathogens

Question 1

Which bacterial foodborne pathogens are gram negative?

Answer 1

Salmonella
Campylobacter
E.coli 
Shigella
Yersinia
Vibrio

Question 2

Which bacterial foodborne pathogens are gram positive?

Answer 2

Listeria
Staphylococcus
Clostridium
Bacillus

Question 3

What is foodborne intoxication?

Answer 3

Organism produces toxins that are ingested

Question 4

Does foodborne intoxication have a slower or faster onset?

Answer 4

Rapid onset

Question 5

What are the two types of food borne infection? What do these mean?

Answer 5

Invasive infection - bacteria ingested in food and penetrate intestinal mucosa (can cause local or systemic disease)
Toxicoinfection - bacteria ingested in food and produce toxins in the GI tract

Question 6

What bacteria causes Yersioniosis? Cool fact about Yersinia?

Answer 6

Yersinia enterocolitica

Another species caused the black death

Question 7

Yersinia is the 3d most common food disease. Is it’s bacteria gram positive or negative? What shape is it? Is it motile?

Answer 7

Gram negative
Rod shaped - NON spore forming
Motile at room temperature only - not body temp

Question 8

Where is Yersinia enterocolitica found?

Answer 8

Throat, tonsils and faeces of PIGS

avoid during evisceration

Question 9

How is yersioniosis transmitted?

Answer 9

Faecal oral route

Asymptomatic carriers

Question 10

What symptoms does Yersioniosis cause?

Answer 10

Fever
Gastroenteritis with haemorrhage diarrhoea
Pseudo-appendicitis

Question 11

Vibrio species are what type of bacteria? (O2 requirement, shape, salt requirement)

Answer 11

Facultative anaerobes
Straight or curved rods
Halophilic - need NaCl

Question 12

What is the primary source of Vibrio infection?

Answer 12

Contaminated water or shellfish

Poor sanitation

Question 13

What bacteria causes cholera? What is the incubation period and symptoms?

Answer 13

Vibrio cholerae
6 hrs
Severe pain, profuse watery diarrhoea, vomiting, dehydration, acidosis shock and death if not rehydrated

Question 14

How can Vibrio bacteria be controlled?

Answer 14

Consume clean water
Dispose of sewage correctly
Don’t eat seafood from waters containing cholera

Question 15

What are the two other species of Vibrio (except cholerae). Which is mild and which is severe?

Answer 15

Vibrio parahaemolyticus - mild

Vibrio vulnificus - severe

Question 16

What bacteria causes invasive listeriosis infection? What is the main source of this bacteria (organisms)?

Answer 16

Listeria monocytogenes
Animal intestines (asymptomatic carries) and humans

Question 17

Is listeria motile at room or body temperature? What is it very resistant to?

Answer 17

Room temperature = motile

Desiccation

Question 18

What foods can listeria monocytogenes be found in?

Answer 18

Raw milk
Soft cheese
Vegetables
Unpasteurised juice

Question 19

What is the incubation period of invasive listeriosis? How does it enter the CNS?

Answer 19

Up to 21 days

Invades GI mucosa, enters macrophages which go through the bloodstream to the CNS

Question 20

What are the symptoms of invasive listeriosis?

Answer 20

Septicaemia
Meningitis
Encephalitis
Abortion

Question 21

What are the symptoms of non-invasive listeriosis?

Answer 21

Diarrhoea
Mild fever
Headache
Myalgia (muscle pain)

Question 22

How long is the incubation period of non-invasive listeriosis?

Answer 22

Much shorter = 1-3 days

Question 23

Where is staph aureus found and what is the name of the disease it causes?

Answer 23

Skin, hands, nares, milk, environment

Staphyloenterotoxicosis

Question 24

Is staph aureus motile or non-motile? What air conditions does it prefer? What is it very resistant to?

Answer 24

Non-motile
Facultative anaerobe
Desiccation (enterotoxin also resistant to heat)

Question 25

Which bacteria are resistant to desiccation?

Answer 25

Listeriosis | Staph aureus

Question 26

How many toxins does staph aureus produce? Which are the most common?

Answer 26

8 | A and B

Question 27

What is the incubation period of staphyloenterotoxicosis? What are the symptoms

Answer 27

1-6 hrs NO FEVER D+, V+, abdo pain

Question 28

What bacteria causes botulism and infant botulism? What foods is it associated with?

Answer 28

Clostridium botulinum | Honey, poorly canned foods

Question 29

What environment does clostridium botulinum need to form spores? How does it cause cell death?

Answer 29

Anaerobic | Produces toxins which block nerves - paralysis and death

Question 30

What is the difference between botulism and infant botulism?

Answer 30

Botulism - intoxication, affects adults | Infant botulism - toxico-infection, children <1

Question 31

Why are children more susceptible to infant botulism? What ar eat symptoms?

Answer 31

Don't have established gut flora | Constipation, respiratory distress

Question 32

How long is the incubation period of Botulism?

Answer 32

1-3 days

Question 33

Are botulism spores heat resistant? How can botulism be prevented?

Answer 33

No | Toxins sensitive to heat - heat at 80 degrees for 30 mins

Question 34

What two syndromes does bacillus cereus form?

Answer 34

Emetic syndrome | Diarrhoeal syndrome

Question 35

What type of gram is bacillus cereus? What shape is it? Is it motile? Does it have spores/toxins?

Answer 35

Gram positive Rod Motile Spores and toxins - v resistant to heat

Question 36

What foods are associated with bacillus cereus?

Answer 36

Rice | Pulses

Question 37

What type of infection is Bacillus cereus emetic syndrome? Can the cells be killed by cooking? What are the symptoms?

Answer 37

Intoxication No - vegetative cells killed but spores and toxins are not Rapid vomiting (within minutes)

Question 38

What type of infection is Diarrhoeal syndrome by bacillus cereus? How is it caused? What are the symptoms?

Answer 38

Toxico-infection Spores/vegetative cells ingested and toxins produced in the GI Short, profuse painful D+ within hrs

Question 39

Clostridium perfringens produce what type of toxin? What is interesting about this?

Answer 39

Type A toxin | Survives in GI tract = asymptomatic carriers

Question 40

What affect does cooking have on spores? Why?

Answer 40

Activates them | Germinate in anaerobic conditions

Question 41

What is the most common source of Clostridium perfringens?

Answer 41

Cooked meat | TURKEY

Question 42

What are the symptoms of Clostridium perfringens infection? How long does it last?

Answer 42

Severe abdo pain D+++ 2 days - fatal if immunocompromised

Question 43

How can foodborne bacterias be prevented?

Answer 43

Cook thoroughly Rapid chill Reheat to 75/80 degrees for over 30 mins