Foodborne Illnesses

Question 1

What are the steps to reporting food borne illnesses

Answer 1

1) becomes an outbreak if two or more people experience a similar illness from eating/drinking the same food
2) physicians report to state health authority while treating the patients
3) states/local public heath departments investigate outbreak and then report findings to CDC’s
4) CDC’s system downloads and verifies the data from the health department then analyzes trends
5) FDOSS makes the date available for the public

Question 2

Clostridium botulinum

Answer 2

Characteristics:

• Gram (+) bacilli
• obligate anaerobic
• possess oval endospore in the mother cell

Types of toxins

• A -> G
• used to determine strain types
• possess the botulinum neurotoxin*
• binds to hemagluttin/RNA and proteins
• easily survives the gut environment
• easily diffuses to the bloodstream especially when pH is >7.2
• **doesnt cross BBB
• attaches to cholinergic nerve and binds receptors and cleaves SNARE proteins and blocks acetylcholine release = paralysis

Question 3

Signs of botulism toxicity

Answer 3

6-10 day incubation

Symptoms/signs:

• blurred vision
• drooping eyelids
• slurred speech
• muscle weakness
• difficulty swallowing

Question 4

What are common safety precautions in place for botulism?

Answer 4

No honey to children under 1

Avoid dented/cracked/buldging canned food

Follow home canning proceeds closely

Question 5

Bacillus cereus

Answer 5

most heavily tied to bad rice, vegetables

Characteristics:

• gram (+) bacilli
• endospore forming
• motile
• no capsule

Symptoms/signs:
- rapid onset of watery diarrhea and violent vomiting (due to cereus toxin)

Virulence factors:

• **emetic toxin: cerulide products stimulate vagus nerve and produces rapid projectile vomiting. Found in fried rice and cooked rice the most
• **enterotoxin: upregulated cAMP in small intestinal tissues which causes watery diarrhea and ab pain. Found in Mets/milk/ric

Question 6

Listeria monocytogenes

Answer 6

Most common in ice cream/daily products
- overcomes food safety barriers

Characteristics:

• gram (+) rods
• NON-spore forming
• catalase (+)
• intracellular facultative anaerobe
• forms in freezing temps
• good at growing in high salt areas
• grows on blood agar well and shows in a motility assay
• • cant use serology since it is a intracellular bug (no antibodies form)

most common serovar to cause infection = 4

Virulence factors:
- Listeriolysin O (LOO): forms pores in the phagolysosome membrane

Question 7

What is ActA?

Answer 7

Actin assembly inducing protein found in listeria

- forces host cell to make actin and uses it to produce cellular filopods

Question 8

How does listeria make sure to never be exposed to antibodies

Answer 8

Uses filopods to get engulfed by other cells via paracytophagy to avoid antibodies/complement and other extracellular protection mechanisms

Question 9

What clinical manifestations of listeriosis is possible?

Answer 9

1) food sickness
- actually has a high rate of death (30%)
- is asymptomatic at first and then develops into ab pain, fever, diarrhea and overall gastroenteritis

2) granulomatosis infantiseptica
- infection of the infant in utero
- develops neonatal sepsis, pustular lesions and granulomas
- can kill before or after delivery

3) meningitis

Question 10

Vibrio species

Vulnificus and cholerae

Answer 10

• highly associated with fresh water and raw oysters*
• also can get it with open wound exposure

Most are self limiting, except vulnificus sub species

characteristics:

• gram (-) comma shaped pathogen
• grows great on VVA agar and TCBS agar

Has a lot of virulence factors but LPS and MARTX factors develop sepsis

Vulnificus = Very high fatality and if it doesnt kill, often requires amputation.