MICR123 - 6 - salmonella campylobacter yersinia Flashcards
What are the characteristics of salmonella?
- Gram negative,
- rod-shaped,
- faculatative anaerobe,
- peritrichous flagella motility,
- can survive freezing temperatures,
- can also adapt to higher temperatures (in slow heating/cooling).
As water activity decreases, heat resistance of Salmonella ___.
As water activity decreases, heat resistance of Salmonella increases.
In what pH conditions could Salmonella survive in?
Salmonella could survive in a wide range of pH conditions.
Optimum pH range is between 6.5 - 7.5.
Can grow well between pH 4.5 - 9.5.
Why would Salmonella be a risk for ready-to-eat foods?
Salmonella has methods to adapt and survive reductions in pH as low as 3.0.
Their presence and survival could affect safety of any Ready-to-Eat product.
How salt tolerant is Salmonella?
Salmonella is salt tolerant.
Salt tolerance increase with increasing temperatures up to 86F.
Salt in acidified foods can inhibit activity of organic acids thus making them less effective against Salmonella.
Why would Salmonella be a risk for modified atmospheric packages?
Salmonella can survive modified atmosphere packages.
Safety of MAP foods which are refrigerated and contain salt may be good environments for Salmonella growth.
What types of defenses does the human body have against Salmonella?
The human body has defenses against salmonella infection:
- antibacterial lactoperoxidase in saliva,
- gastric acidity,
- mucoid secretions of intenstinal cells,
- intestinal peristalsis,
- sloughing of intestinal epithelial cells to prevent colonization,
- phagocytic cells in the intestinal tract.
What are the steps of Salmonella infections?
Steps of infections:
- attachment to epithelial cells,
- production of proteinaceous appendages,
- signal between cells and host cells to allow invasion/penetration of the intestinal cells.
What does campylobacter look like?
a rod with two polar flagella on opposite ends.
What are the sources of campylobacter jejuni?
Sources of campylobacter jejuni are:
- intestinal tracts of animals and birds,
- polluted water,
- outbreaks associated with meat,
- water and raw milk.
What are the characteristics of Campylobacter?
- Curved, S-shaped/spiral rod,
- gram negative,
- non-sporeforming.
- Motile by a single polar flagellum on one or both ends.
- Microaerophilic.
- Sensitive to drying.
- Does not grow below 86F.
- Sensitive to low pH.
- Heat sensitive and irradiation.
- Survives well at refrigerated temperatures.
What are the symptoms of Campylobacter infection?
- Associated with diarrheal illness.
- Fever,
- abdominal cramping,
- diarrhea (with or without blood).
- Death is rare.
How long does Campylobacter infection/illness last?
The length of Campylobacter illness can last for a few days to more than a week.
What is the infective dose of Campylobacter?
An infective dose of Campylobacter may be up to 1000 cells.
However, infective dose depends on strain of Campylobacter.
What type of countries are more susceptible to Campylobacter infections?
Developing countries have a higher incidence of Campylobacter disease.
Hygienic conditions are a main reason for outbreaks.
What are the steps of Campylobacter infections?
- C. jejuni adheres to host cell.
- Produces 14 new proteins which causes a change in host membrane.
- Additional proteins are synthesized and enter the host cell cytoplasm.
- Infected cells release additional molecules that promote influx of white blood cells to the site of the infection.
- Induced host cell death (apoptosis/necrosis).
What are the characteristics of Yersinia enterocolitica?
- Gram negative,
- rod-shaped,
- falcultative anaerobe.
- Can survive freezing temperatures.
- Weak against pasteurization temperatures and ionizing radiation.
