5 - Staphylococcal Intoxication Flashcards
Foodborne intoxication occurs from ________________________
ingestion of a food containing a preformed toxin
What are the 5 general characteristics of a foodborne intoxication?
1) Toxin is produced by a pathogen while growing in the food
2) The toxin can be heat stable or heat liable
3) Ingestion of a food containing active toxin, not viable cells is necessary for poisoning
4) Symptoms generally occur quickly, as early as 30 minutes after ingestion
5) Febrile symptoms are not present
What are the 2 things that represent Staphylococcal intoxication:
- grape-like cocci
- vomiting
Staphylococcal typical scenario example:
temperature-abused breakfast on a flight
T or F: recently the prevalence of staph aureus has drastically declined
T, due to better use of refrigeration to store food and improved sanitary practices that can control contamination by Sa.
Staphylococcus aureus is gram_____
postive cocci
Give some characteristics about staph aureus:
- gram positive cocci
- exists as either single cells or grape like clusters
- nonmotile, noncapsular
- non-spore forming, sensitive to heat treatment
- facultative anaerobes but grow rapidly under aerobic conditions
Staph aureus cells are killed at ______ for 12 mins, or _____ for 15 seconds
66
72
Staphylococcus aureus are mesophiles and can grow between ______ but grow rapidly between _______
7-48C
20-37C
What is special about staph aureus?
They can grow at relatively low Aw (0.86), low pH (4.8) and under high salt and sugar conditions
*They can grow under several adverse conditions, but are poor competitors against other organisms, therefore they do very well when adverse environments give them a competitive advantage
T or F: S.aureus is a very common cause of human and animal infections
T
_____________ is commonly used to define the sequence type (ST) or allelic profile based on the sequences of 7 housekeeping genes found in all strains of S. aureus.
Multilocus sequencing typing (MLST)
How many housekeeping genes are found in all strains of S.aureus?
7
If a group of STs share at least _ of _ alleles, the group of STs can be defined as a __________
5, 7 clonal complex (CC).
Five CCs are predominant in human colonization and infection: __________
CC1 CC5 CC8 CC30 CC45
The Sa accessory genome is made of several _______________ which can be transferred horizontally (20% of the Sa genome)
mobile genetic elements
However, S. aureus has a very advanced _________________ that occurs in each of it’s lineages and prevents horizontal gene transfer from occurring between different clonal complexes.
restriction modification system
Most Sa genomes carry between ________ prophage genomes, phage genomes have enterotoxins
1-4
Many enterotoxins are on mobile genetic elements, ____________ are required for foodborne intoxication
enterotoxins
Sa causes foodborne illness through the ingestion of the ______ not the organism
toxin
Enterotoxin:
a toxin that acts on the gastrointestinal tract
Endotoxin:
a toxin that is structurally associated with the bacterial cell (LPS)
Exotoxin:
a toxin that is usually secreted into the extracellular fluid but can be intracellular or injected directly into eukaryotic cells
Exfoliative toxins:
dermolytic exotoxins produced exclusively by Sa that cause the symptoms of impetigo or scalded skin syndrome
