BioMi404 Final

BioMi404 Final - Foodborna Toxin Producing Pathogens 2/25...

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Foodborna, Toxin Producing Pathogens 2/25 In general, toxin alone can cause disease for foodborne intoxications. Types: - Exotoxin= excreted/released from cell when the cell lyses - Endotoxin= embedded in bacterial surface - Enterotoxin= toxin that causes diarrhea or vomiting - Type I= bind to host surface but don’t go in. - Type II= act in the eukaryotic cell membrane, such as by making pore - Type III= A-B toxin!! B is binding and binds receptor and induces translocation in, and A portion is enzymatic which acts intracellularly. Secretion systems: how toxin gets out of bacterial cell Type I= specialized proteins through membrane-spanning pore, used by type II toxins. Type II= Sec-generalized secretory pathway dependent, used by many AB toxins Type III= toxin injected directly through pore between two cells. Yersinia. Type IV= like the conjugal DNA transfer system A. Clostridium - strictly anaerobic and sporeforming, and is uniquitous in soil and microbial flora of humans and animals. - Various types: botulism, tetani, perfringens 1) Clostridium botulinum - toxin is pretty much totally resistant to heat… only a little kills us, dogs and chickens are resistant to it. - Spore will germinate when pH is above 4.6* and anaerobic environment… the toxin then released when cells lyse… then IF people don’t reheat food sufficiently, then toxin is not destroyed and person gets sick. - The toxin: absorbed by GI and enters blood… toxin is specific for neurons and blocks release of neutrotrasmitter at nerve endings… FLACCID paralysis - Nause/vom… then paralysis of face… then you die when diaphragm paralyzed - treatment: antitoxin - ** infants are vulnerable cuz they don’t have microflora to fight of bacteria. - 4 major groups of botulinum that produce different toxins… Group I produces toxin that is most lethal but most likely to be noticed cuz it makes food smell yucky. - THE TOXIN: is an AB toxin. B binds to molecules on neurons (especially at junction), which allows A chain to go in. 2) Perfringens -found in low numbers in animal and human intestine, toxin made when it sporulates… diarrhea and cramping B. Staphylococcus aureus - common in nose and skin. Produce exotoxin that can cause foodborne infection… rapid onset of nausea, acute vomiting, diarrhea. - Also has enterotoxin that makes nerve endings in stomach to make bad response.
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Streptococcus 2/27 -differentiated based on hemolytic pattern… different species A) Pyrogenes - most common cause of upper resp. infection. . high fever and swollen tonsils… can become scarlet fever is rash spreads - also causes impetigo (a localized skin disease) and various other bad things - LPS causes initial weak interaction - Various different M protein types, seems to bind skin keratinocytes, second step stronger interaction - Various others bind fibronectin - Avoiding immune system: capsule. M protein binds Factor H and fibrinogen and does not let c3b bind to oposinize… some proteins bind IgG and IgA… cleave c5a -
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BioMi404 Final - Foodborna Toxin Producing Pathogens 2/25...

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