4. Foodborne diseases and pathogens

Question 1

What is the difference between food poisoning - and food infections

Answer 1

Food poisoning result from the action of microbial toxin

Food infections results from the growth of microorganism in the body

Question 2

What is the definition of foodborne illness

Answer 2

any illness resulting from the consumption of contaminated food, pathogenic bacteria, viruses or parasites, as well as chemical or natural toxins such as poisonous mushrooms

Question 3

What is the incubation period?

Answer 3

The delay between consumption of a contaminated food and appearance of the first symtoms of illness

Typically ranges from hours to days depending on the agent, and on how much was consumed. If symptoms occur within 1-6 hours after eating the food, it suggests that it caused by bacterial toxin or a chemical rather than live bacteria(If it is short incubation time  often bacteria toxin). Some illnesses take months or even years to develop (E.g. Listeriosis 3-70 days). During the incubation period, microbes pass through the stomach into the intestine, attach to the intestinal epithelia cells, and begin to multiply there. Some types of microbes stay in the intestine, and produce a toxin that is absorbed into the blood stream, and some can directly invade the deeper body tissues. The symptoms produced depend on the type of microbe.

Question 4

What is the Microbial rosetta-stone database?

Answer 4

Microbial rosetta-stone database of infectious microorganisms

Provides ‘up-to-date taxonomic classification of organisms that cause human diseases, improve the consistency of nomenclature in disease reporting, and provides useful links between different public genomic and public health databases’.
Information on human disease-related microorganisms listed by many organizations (e.g. CDC, NIAID(allergy) , USDA(agriculture), WHO)
Here genomic sequence data, taxonomic classification, and epidemiological information collected in a way that facilitates searches and data updates.

Question 5

Describe Aeromonas.

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 5

Fresh and brackish water.

G+, faculative anaerobic rod, motile

Grow at low temperature

A. solminicide - important disease in fish farming
A. hydrophila - human pathogen

Gastroenteritis(nercirus in immunocompromissed patients) and wound infections.

Produces several virulance factors (cytotoxins, heudysim)

Symptoms:
Watery diarrhea, blood and mucus in stool, septicamia and meningitis in immunosuppressed individuals.

Route of entry: meat, milk, seafood, soil, water(but not from ingestion but from open wounds)

Incubation: 24h
Duration: few days- several weeks.

Pathway: Toxin (aerolysim) forms pore in plama membrane.

Question 6

Describe A. hydrophila

Answer 6

A human pathogen, in the genus aeromonas.

Common in gut microbiota.

Important part of spoilage flora of meat.

Intolerant to high T, low pH and high salinity.

Question 7

What is aerolysin?

Answer 7

Toxin that forms pore in plama membrane. From Aeromonas.

Question 8

Describe B. Cereus

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 8

Species: Bacillus antracis, bacillus cerus, bacillus subtilis.

Cause: large molecular weight protein or highly heat stable toxin.

Incubation: 30 min- 15h

Symptoms: nausea, vomiting, cramps.

Contaminants: meat, milk, vegetables, fish, rice, potatoes, pasta. Found in soil, food in contact with soil. Spores in food with starch. Spores hydrophobic (pipelines where they can germinate)

G+, rod shaped, endospore forming, faculative aerobic.

Present in gut biota

Mesophilic 20-40 C

Spores can survive pasteurization and drying.

opportunistic pathogen

Diarrheal syndrome(3 enterotoxins): Disrupts epithelial membrane

Emetic syndrome: cyclic peptide, cereulide - toxic to mitochondria.

Question 9

Describe hemolysin BL (HBL).

Answer 9

One of the three toxins from B. cereus.

HBL main virulence factor of B. cerus, made up of three proteins B, L1, and L2. Disrupts epithelial membrane.

Question 10

What is Cerelide?

Answer 10

The emetic syndrome from B. cereus.

The cyclic peptide, cereulide - toxic to mitochondria.

Question 11

Describe Salmonella

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 11

G-, rod, related to E.coli ad Shigella. Enteribecteriaceae
family. Facultative anaerobes, motile (flagella), Effective commensals (relationships between two organism where one organism benefits from the other without affecting it)

Isolated from gastrointestinal tract of mammal, birds, insects…

Typhi
Typhoi fever, fatal disease (developing contries),, vomiting, diarrea, fever death. Can only infect humans. Found in contaminated water.

Typhimurium
Most common cause of food poidioning. gastroenteritis, diarrheal, abdominal cramps, vomiting and nausea, and generally lasts up to 7 days. Not as bad as typhi. In immunocompromised people are fatal.

Source: raw meat and poultry, sea food, raw eggs, fruits and vegetables, fecal.

The bacteria adhere to intestinal epithelia via different fimbriae. After adherence to the intestinal epithelia, salmonella interact with a receptor an the surface of the host cell, leading to massive cytoskeletal rearrangements and bacterial entry into the host cell. Produces both endotoxin and enterotoxin.

Question 12

Describe Salmonella enterica serovar typhi/typhimurium

Answer 12

Typhi
Typhoi fever, fatal disease (developing contries),, vomiting, diarrea, fever death. Can only infect humans. Found in contaminated water.

Typhimurium
Most common cause of food poidioning. gastroenteritis, diarrheal, abdominal cramps, vomiting and nausea, and generally lasts up to 7 days. Not as bad as typhi. In immunocompromised people are fatal.

Question 13

What is Typoid fever?

Answer 13

Fever as a result of Salmonella enterica serovar typhi

Question 14

Describe Shigella dysentereiae

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 14

Faculative anaerobe

G- rods

related to e.coli and salmonella

Cause shigellosis (bacillary dysentery)

Humans the only natural host

shiga toxin inhibit protein syntesis

Cause of illness: food or water contaminated with human feces (salads, dairy products, raw vegetables)

Very few cells needed (12-50 hours)

Symptomes: abidominal pain, cramps, fever, diarrhea, blood and pus.

Question 15

Describe clostridum botulinum

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 15

G+, rod

produces several toxins

anaerobe

produces endospores

Can cause botulism from improperly preserved or home-canned, low acid food that was not processed using correct preservation times and/or pressure.
Fish, salmon, herring.

Where: Soil, Sea/lake, sediments, vegetables.

proliferates if anaerobic conditions. Produces a potent neurotoxin. Toxin is sensitive to heat. Toxin attacks the nervous system. The neurotoxic effects can be deadly.

Causes trouble swallowing, muscle weakness, and slurred speech. When exposed to the lungs it inhibits respiration, causing asphyxia

Question 16

What is botulism?

Answer 16

Botulism är en förgiftning, inte en infektion.

Sjukdomen orsakas av ett bakteriegift (ett toxin) som är ett av de starkaste man känner till. Ett “snapsglas” rent botulinumtoxin skulle räcka till att döda hela Sveriges befolkning. Toxinet blockerar nervimpulserna till tvärstrimmig muskulatur och ger förlamningar i bland annat andningsmuskulaturen.

Question 17

What is a neurotoxin?

Answer 17

Neurotoxins can be found in a number of organisms, including some strains of cyanobacteria,[1] that can be found in algal blooms or washed up on shore in a green scum.[2]
Neurotoxins are toxins that are poisonous or destructive to nerve tissue

Question 18

Describe vibro vulnificous

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 18

G-, motile, curved, vibroid-shaped

Present in marine enviroments

Infection via raw undercooked oysters or wounds

Manily effect pepole with suppressed immunosystem or with reduced liver function

Infection with V. vulnificus leads to rapidly expanding cellultis pro septicaemia. Total mortality in treated patients (ingestion and wound) is araound 33%.

Disease (associated with increased serum iron) might be due to the capability of virulent strains to capture iron bound to transferrin.

Question 19

Describe vibrio cholerae

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 19

G-, common-shaped, faculative anaerobic

Flagellim at one cell pole.

Some strains cause cholera.

Secrete cholera toxin

Main reservoirs: people, aquatic sources, zooplakton, shellfish and aquatic plants.

Question 20

What is cholera toxin?

Answer 20

a protein that causes profuse (a lot!), watery diarrhea.

Question 21

Describe stophylococcus aureus

Answer 21

Present in 40-50% of populations, nails, skin nose. (common in skin infections)

incubation time 1-6 h (not always pathogenic)

If the T allows creates toxins.

Toxin very stable to heat. Three categories of toxin. Membrane-damaging. Interfere with receptor function. Secreted enzymes degrading host molecules/affect host defences.

Toxin intake leads to nausea, vomits and diarrhoea + fever.

The emergence of antibiotic-resistant forms of pathogenic S. aureus (MRSA) is a worldwide problem.

Question 22

Describe closteidium perfogenus

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 22

G+, anaerobic rod, very commonin nature.

Found in soil and gut in animals and humans.

3rd most common cause of food borne diseases

Found in meat and poultry.

Spores survive cooking

Produces toxins

incubation 6-24 h

Causes diarrhea, necrosis.

Question 23

Describe E- coli

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 23

G-, rod shaped, has adhesive fimbriae.

it is part of normal human biota

grow at 37C under aerobic conditions.

Best characterized bacterial species.

Some strains can cause severe diarrheal diseses.

EHEC - enterohemorrhagic e.coli: causes bloody diarrheae and colitis.

Incubation time 2-4 days.

Found in ground beef, raw milk.

10-100 E.coli can cause infection

EHEC attaches to intestinal epithelial cells and produces shiga toxins that are internalized, activated and can pass into the bloodstream to become systemic. The shiga toxins act by inhibiting protein synthesis of the target cells.

In the worst cases can cause thrombotic microangiopathies.

Question 24

Describe yersinia

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 24

G-, rod faculative anaerobe

Incubation 1-3 days

found in raw milk, chocolate milk, eater, pork, raw meats

Question 25

Describe listeria

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 25

G+, faculative anaerobe

risk: pregnant women, people with AIDS

T: 4-44 C

Motile by flagella

Can form biofilm -> problem for the industry.

Can live inside of our cells.

Ex. smoked salmon.

Causes listeriosis
Fever, nausea, diarrhea

Can spread in the nervous system (headache, stiff neck, confusion, loss in balance.

In pregnant women: still birth, premature delivery, infections in the new born.

Question 26

Describe campylobacter jejuni.

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 26

Associated with poultry, colonize in digestive tract of birds.

Incubation: 1-7 days

Casues headaches, nausea, vomiting.

Found in raw milk, poultry, cake icing, water

Non-spore, G- rod curved- S shaped, motile

Sensitive to O2 concentrations, salinity, freezing and pH <5

very raw disease: Guillan-barre syndrome.

C. jejuni circumvents the mucus layer in humans and interact with the intestinal epithelial cells causing interleukin (IL)-8 production: massive pro-inflammatory respons.

in chicken intestines, C. jejuni resides primarily in the mucosal layer.

Question 27

Describe Brucella G-

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 27

Small, G-, non-spore forming, coccobacilli

6 speciec -> strong preferences for particular animals e.g. goats, sheep, dogs.

All except B. ovis(sheep) and B. neotomae(desert wood rats) are known to be infectious to humans, able to invade and replicate in.

Transmitted from animals to humans.

Symptomes: intermittent fever, sweating, weaknees, msucle pain.

Severe = endocarditis or myocarditis, such as shortness of breath, arrhythmia, edema, or chest pain, meningoencephalitis, such as severe headache, stiff neck, confusion, or seizures; or spondylitis, such as back pain

May last for years

Transmitted, oral, inhalation, wounds, breast feeding.

incubation time within 3 weeks

Question 28

Describe Enterobacter sakazakii

Were can it be found
Symptoms 
Virulence factors
Incubation/duration 
Pathway

Answer 28

G-, motile, rod-shaped, non-sporulating

can produce a protective biofilm

Pathogenic, primarily among infants and immunocompromised adults.

It is able to survive in low-moisture foods (ex powder)

Symptoms: Often severe. May include poor feeding response, irritability, jaundice, grunting respirations, instability of body temperature, seizures, brain abscess. Hydrocephalus and development delay

. Rare cause of invasive disease, including bacteraemia, meningitis, and necrotizing enterocolitis,

Very high faiality rate 10-80%

Question 29

What is endotoxin and enterotoxin?

Answer 29

endotoxin (toxic compounds leaking out when bacteria die) and enterotoxin (toxin secreated by microorganism targeting the intestines).

Question 30

What is faculative anaerobe?

Answer 30

A facultative anaerobe is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent.[1]