What are the characteristics of Salmonella? - gram - shape - motile (capable of motion)? - flagella

- gram neg - rod - yes, motile - peritrichous flagella (distributed evenly around cell)

Lect 5 : Foodborne pathogens Flashcards by Faith Yeo

What are the 3 foodborne illness associated with MOs in food?

Infection, intoxication, toxico-infection

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How does infection cause us to fall ill?

Food/water contaminated with virus/bacteria is ingested
MOs multiply within the gastrintestinal infection to high enough levels to cause sickness

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MOs must be viable when consumed to cause infections. True or False?

True

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What is the infectious dose for infectionsin general ? (amount of MO we need to consume before causing infection)

Low infectious dose of 10 to 10^6

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How long does it take before we get infectons (from time of ingestion)?

> 14 h

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What symptom are food infections associated with?

Fever

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How to food intoxications occur?

Ingestion of a preformed microbial toxin in a food

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does MO need to be viable for intoxication to occur?

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How long does it take to get intoxication after ingesting the affected food?

< 1-14h

way shorter than infection as bacteria do not need time to multiply, the toxin alr formed

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How long does symptoms occur in a toxicoinfection?

12h to 12 days

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Are most foodborne pathogens gram positive or negative? Why?

Gram negative, because they have an outer membrane consisting of many virulence factors, which causes sickness

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What are the characteristics of Salmonella?

gram
shape
motile (capable of motion)?
flagella

gram neg
rod
yes, motile
peritrichous flagella (distributed evenly around cell)

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The genus is Salmonella.
What is the family and 2 pathogenic species of salmonella we are concerned with?

Family : Enterobacteriaceae
Species : S. enterica !!!!! and S. bongori

ENTERica ! ENTERS and invades your gastrointestinal tract

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How many different types of serovars does Salmonella have?

> 2600

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What is the main type of foodborne illness associated with Salmonella?

Infection

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** What are the 2 main serovars of Salmonella that cause foodborne infections?

S. Enteritidis

S.Typhimurium

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Humans get Salmonellosis from Salmonella. What are some typical symptoms?

Fever/ chills
2. Headache
Abdominal pain
Diarrhea
Nausea / vomitting

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What is the infective dose of salmonella?

10-10^6 (considered low infectious dose)

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How can salmonella be treated usually, and for severe cases ?

Self-limiting (self treated)
- by drinking oral fluids

Severe cases :
- IV fluid drip for severe diarrhea
- antibiotics

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Why does WHO report more cases of salmonella infections in DEVELOPED countries rather than developing countries?

Though developing countries may have poorer hygiene, developed countries have more robust surveillance systems to report cases of salmonella outbreaks

developing countries -> cases may not be reported

Thus WHO reports higher incidence of Salmonella cases

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Where do Salmonella colonise? [4]

Gastrointestinal tracts of
- farm animals
- wild animals (including bird, reptiles)
- pets and zoo animals
- humans after infection

TLDR : gastrointestinal tracts of animals + infected humans

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What does it mean by Salmonella is very “smart”?

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Salmonella can sense subtle environmental cues brought about by genotype or physiological state of plant host and respond with distinct patterns of gene expression accordingly

What are the implicated foods for Salmonella?

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Almost all foods
**Meat, eggs
Fruits and vegetables, seafood, cereals, bakery, RTE foods

Is Salmonella aerobic/anaerobic/facultative anaerobic?

Is it a thermophile/mesophile/psychrophile/psychrotroph?

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facultative anaerobic (can survive harsh processing conditions, so prob not fully aerobic/fully anaerobic)

mesophile

How to prevent salmonella from growing? [5]

- maintain cold chain!!! (storing food at 4°C, slows growth as Salmonella is a mesophile) - good hygiene on farm and during slaughtering - avoid cross contamination - cleaning and disinfection of food preparation surfaces - thorough cooking and heating of foods

What kinds of foods can increase heat resistance of Salmonella?

High fat/protein food --> offer protection for salmonella to hide in

What are the characteristics of STEC (shiga like toxin producing E. Coli)? - gram - shape - motile (capable of motion)? - flagella

- gram neg - rod - yes, motile - petrichous flagella (distributed evenly around cell) ** Same as salmonella

Most strands of E.Coli are non pathogenic. True or False?

True. E.coli belong to normal intestinal microbiota of humans and animals

What are pathogenic E.Coli classified by?

Classified by their different virulence factors.

What are the names of the 2 important pathogenic E.Coli and what symptoms do they cause?

1. Enterohemorrhagic E.Coli (EHEC) - bloody diarhea and hemoytic uermic syndrome 2. Shiga like toxin-producing E.Coli - severe diarrhea, stomach cramps, vomitting

What is the infectious dose of EHEC in what kind of food product and how to treat EHEC?

0.3-15 CFU/g in frozen groud BEEF patties (cattle) - No treatment available and antibiotics only promote Shiga toxin production

What does EHEC haemolytic uraemia syndrome result in?

Lifelong disability and defects

Why is EHEC/STEC important/relevant?

Although it is not very prevalent (less incidence), it results in severe disease

What is the major reservoir of STEC? reservoir : habitat where MO multiply

in cattle

What are the characteristics of Virbrio? - gram - shape - motile (capable of motion)? - flagella

- gram-negative - straight/curved rods - motile - polar flagella (1 flagella on 1 side)

The three impt species of Vibrio are V.parahaemolyticals V. vulnificus V. cholerae What is the infectious dose of V.parahaemolyticals? What are its symptoms?

10^5-10^7 CFU SYMPTOMS : -WATERY DIARRHEA - fever - abdominal cramps - nausea / vomitting

In general, Vibrio is mild/serious with a high/low infectious dose

mild high -> need more to get infected

in which regions of the world is vibrio most prevalent in?

Coastal / tropical areas

How to prevent Vibrio from growing to very high levels and causing sickness? [3]

- keep at 4°C or frozen - cook sufficiently - prevent cross ccontamination of raw and cooked seafood

What are the characteristics of Campylobacter? - gram - shape - motile (capable of motion)? - flagella

- gram neg - spirally curved rods (spiralla) - RAPID motility, corkscrew-like motion - AMPHITRICHOUS : single polar flagellum at one or both ends of the cell

What are the 2 species of Campylobacter that are foodborne pathogens? (Not impt)

** C. jejuni C.coli

What is the infectious dose of C. jejuni (campylobacter)? What are its symptoms? [3]

<1000 CFU Fever, diarrhea, abdominal cramps

How to treat infection by Campylobacter?[2]

- fluids as long as diaarrhea lasts - antibiotics

In terms of foodborne outbreaks for Campylobacter, are most cases from general outbreaks or sporadic cases in household settings?

Household settings

What is the main reservoir of Campylobacter?

Animal reservoir - gastrointestinal tract of poultry, cattle, pigs, wild birds, rodent, flies - detected in 25-80% POULTRY (domestic fowl, such as chickens, turkeys, ducks, and geese.)

What foods are affected by Campylobacter?

25-80% of poultry common in raw milk

Does Campylobacter develop in the food chain?

How to prevent food infection by Campylobacter?

Cook raw meats well and avoid cross contamination

What are the characteristics of Listeria Monocytogenes? - gram - shape - motile (capable of motion)? - flagella

- ** gram positive - short rods - motile - peritrichous flagella (same as salmonella and STEC) just gram diff

What is the minimum infectious dose for Listeria monocytogenes?

Difficult to determine but around >100 viable cells

Which are the at risk population groups for Listeria Monocytogenes?

YOPI Young Old Pregnant Immunocompromised

What are the symptoms of listeriosis?

Dependant on state of host - fever and muscle pain (nausea and diarrhea is rare) - inflammation of brain - abortion/stillbirth/premature labour (preg)

What are the reservoirs of Listeria Monocytogenes? [3]

- ubiquitous (present everywhere) in the envrionment such as water, soil,.... - food processing environments - preserved products with a long shelf life in the refrigerator

How to prevent Listeria Monocytogenes?[2]

- raw foods of animal origins must be completely cooked - no cross-contamination of raw and uncooked foods NOTE : impossible to completely eradicate from foods (ubitiqous in environment)

Lect 5 : Foodborne pathogens Flashcards

(54 cards)