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Between what temperature is the danger zone for food storage?
- 40-140 F
- (refrigerator temp is 40f (4C), and food holding temp is 140F (60C)
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Which microbe is often found in rice?
Bacillus cereus
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What is the gram stain and shape of Bacillus cereus?
Gr + rods
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Is Bacillus cereus catalase positive or negative? Spore forming or non-forming
- Positive
- Spore forming (Central spores)
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What is Bacillus’ oxygen need?
Facultative anaerobes
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What are the enterotoxins produced by Bacillus, if there are any?
- AB Toxin
- Superantigen
- Heat-resistant cereulide toxin
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Which microbe forms heat-resistant cereulide toxin?
Bacillus cereus
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Bacillus can cause which GI symptoms?
- Severe vomiting and nausea (in less than 6 hours) due to Cereulide toxin that can last 8-10 hours
- Diarrhea (caused by AB and superantigen, Greater than 6 hours incubation)
- Epigastric pain(caused by AB and superantigen, Greater than 6 hours incubation)
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True/false: in diarrheal form of Bacillus infection, there is no vomiting involved
True
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AB toxin and Superantigen of Bacillus will result _______ of food poisoning, while Cerulide toxin will result in ____ food poisoning
- Diarrheal form
- Enteric form
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What is the mechanism in which AB toxin cause diarrheal food poisoning?
Stimulates adenylate cyclase and increased cAMP concentration which leads to water and ion release
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What is the mechanism in which Cereulide toxin can cause vomiting and nausea?
this toxin is prefromed on food and stops oxidativec phosphorylation, and stimulate vagus
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Which microbe contaminates salty foods?
Staphylococcus aureus
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S aureus is catalase _____, coagulase ____ and mannitol ______. Spore formers?
- Positive
- Positive
- Fermenting
- Non-spore formers
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True/false: S aureus produces 9 different enterotoxins and they are all heat stable and all superantigens
True. Those bitches
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Which is the most common S aureus enterotoxin?
SEA – Staph enterotoxin A!
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True/false: once S aureus contaminated food is heated, toxins is killed along with the bacteria
False; S aureus is killed with reheating, but the toxin survives
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True/false: S aureus is resistant to heat, freezing, drying, low pH and proteolytic enzymes such as pepsin and trypsin
True. Jeezus
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Clostridium gram stain and shape?
Gr + rod
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Clostridium are catalase positive or negative?
Negative
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What is the oxygen need clostridium?
OBLIGATE anaerobe
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Which microbe has bottle-shaped endospore? Which is oblong?
- Bottle-shaped: Clostridium
- Oblong- Bacillus
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Which foodborne bacteria is an obligate anaerobe, and catalase negative?
Clostridium
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Which microbe is associated with home-canned/preserved food?
C botulinum
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Botulinum endospore can survive in which environment?
- Anaerobic, nutrient-rich
- pH ABOVE 4.5
- temperature ABOVE 4C
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Feeding infant honey is bad because it is associated with this microbe:
C botulinum
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Virulence factor for C botulinum:
AB toxin : binds to motor nerve endings, and inactivate Ach release
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What is the mechanism of botulinum neurotoxin?
Binds and cleave SNARE protein which leads to Ach not able to be released leading to flaccid paralysis
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Floppy baby is associated with which microbe?
C botulinum
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Which microbe can cause respiratory paralysis causing death in adult?
C botulinum
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How to diagnose C botulinum?
Find toxin in left over food, stool (for infants) or serum (infants and adult)
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In RARE adult intestinal toxemia caused by C botulinum, what is being ingested from food?
Ingestion of SPORES, not toxins. (unlike the more common adult food borne which is ingestion of the toxin)
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Infant ingest _____ of C botulinum and then they turn floppy.
Spores. (not toxin, toxin is later produced after infection)
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Rare adult intestinal toxemia, is rare because:
Usually our normal gut flora will out compete the spores, but in people without normal flora, they get affected by the spores of C botulinum
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Which foodborne bacterial requires administration of antitoxin to treat?
C botulinum
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True/false: Immunity against C botulinum does not develop after exposure
True
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Egg yolk agar is used in association with diagnosing which microbe?
Clostridium (both botulinum and perfringens)
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Halo colonies on egg yolk agar tells you it is this organism:
C perfringens
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Food that are prepared in large quantities and kept warm for a long time before serving usually associated with this organism:
C perfringens
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Which foodborne bacterial infection actually does not result in fevers or vomiting?
C perfringens
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What can be seen on blood agar for C perfringens?
Double halo of hemolysis
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What is stormy milk fementation and which microbe is this associated with?
C perfringens can ferment a variety of sugar; milk becomes acidic and proteins are attacked
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True/false: C botulinum are Lecinthase (alpha toxin) positive
False; it is C perfringen. Lecthinase activity is what yields the halo colonies
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What is the temperature that left over food needs to be reheated at?
165F or (74C)
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True/false: foods that have dangerous bacteria in them will always smell, taste and look different
False! They may not!
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Why isn’t necrotizing enteritis common with bacterium that commonly causes necrotizing fasciitis such as Clostridum?
Because those toxins are degraded by intestinal proteases, only the enterotoxins survive the intestinal proteases
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