Microbial Toxins Flashcards
Infectious diseases cause about ________ of deaths worldwide.
1/3
________ is the most toxic microbial toxin known.
Botulinum
Polysaccharides make lipid A _________.
soluble
Endotoxin can cause ___________.
(1) inflammation, by activating the complement cascade; (2) fibrinolysis, by activating Hagemen factor; (3) hypotension, by activating bradykinin (also through Hagemen); and (4) DIC, by activating TNF-alpha -> factor VII -> factor X
Hemolysins are often __________.
pore-forming toxins
Gram-positive bacteria tend to make ___________ more than Gram-negative bacteria.
pore-forming cytolysins
Superantigens can cause _____________.
toxic-shock syndrome and necrotizing fasciitis
Staphylococcus aureus and streptococcus pyogenes together produce __________.
more than 19 different superantigens
Diphtheria infection leads to ___________.
bull neck, conjunctivitis, myocarditis, and colonization of the pharyngeal membrane
How does diphtheria toxin kill cells?
It modifies EF-2 (elongation factor-2) and thereby inhibits protein synthesis.
Diphtheria is only taken up by ___________.
susceptible cells–those with the membrane receptor for diphtheria toxin (epidermal growth factor receptor, EGFR)
Diphtheria binds with its ___ subunit and kills with its ______ subunit.
B; A
________ treat diphtheria.
Anti-toxin and erythromycin
Diphtheria toxin and Pseudomonas aeruginosa exotoxin A both _________.
inhibit protein synthesis by transferring the ADP-ribose portion of NAD to EF-2
Although they do the same thing inside cells, diphtheria toxin and P. aeruginosa toxins _________.
are not cross-reactive; they have different antigenic regions and affect different cells based on membrane-receptor affinity
____________ all also inhibit protein synthesis, similar to diphtheria and P. aeruginosa toxin, but they do so by ________.
Shiga toxin, enterohemorrhagic E. coli toxin, and ricin; modifying the 60S subunit of eukaryotic ribosome
Type III secretion is ____________.
injection directly into host cells through needles; common in Gram-negative bacteria
Type VI secretion is _______________.
needle insertion into other bacteria
Botulinum toxin works on __________, while tetanus toxin works on _________.
motor neurons; spinal interneurons
Botulinum toxin is released by __________.
cell lysis
Some exotoxins that degrade the extracellular matrix are _________.
hyaluronidase, collagenase, elastase, and streptokinase
Although they both inhibit cell protein synthesis, diphtheria toxin and pseudomonas aeruginosa exotoxin act on ________.
different cells; PAE targets liver cells, and DT attacks heart, liver, and kidney cells
The exotoxins that affect intracellular signaling pathways are __________.
Vibrio cholerae, E. coli, anthrax, C. diff, and B. pertussis
Tetanus toxin inhibits ___________.
VAMP (and the subsequent release of vesicles)
Staphylococcal enterotoxins and streptococcal exotoxins are both _________.
superantigens
Diphtheria does not leave the __________.
respiratory tract or skin–only its toxin does
