Microbes in Foods Flashcards
What is the definition of a foodborne disease?
any disease of an infectious or toxic nature caused by the consumption of food or water
What are the causes of foodborne disease?
bacteria
virus
parasites
the food itself eg cherry pits, rhubarb leaves
chemicals incorporated during processing eg halogenated organic compounds
microbial products eg toxins
What is the process of infection by a foodborne bacteria?
ingestion -> colonise intestines of host and produce virulence factors -> disease -> shedding -> transmission via faecal-oral route
What is the process of infection by a foodborne microbial product?
bacteria colonise food product but don’t always multiply in food -> produce virulence factors -> disease
What is serotyping?
typing of microbes based on surface antigens
bacteria w same antigens will clump together
What is phage typing?
based on pattern of susceptibility to lysis by a set of phages w different specificity
eg salmonella has over 300 phage types
What is molecular typing?
based on differences in gene sequences
eg multilocus sequence typing (MST)
- based on differences in sequences of housekeeping genes
- can determine relationships between strains
What is the mode of the pathogenesis of Campylobacter?
has flagella for motility and gives the ability to dig through the mucous layers in intestines
capsule for attachment
survives the acidic environment of the stomach
pro-inflammatory cytokines
How does the shape of Campylobacter contribute to its virulence?
has a spiral shape, like a corkscrew, allows burrowing through surfaces
this is because of the peptidoglycan arrangement
also allows motility
What is a capsular polysaccharide?
outer envelope of repeating backbone of two or more sugars
allows attachment and invasion
protection from complement system
reduces cytokine production by dendritic cells
