endotoxins and some gram positive stuff p127 Flashcards Preview

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Flashcards in endotoxins and some gram positive stuff p127 Deck (6):
1

What do endotoxins do? classic endotoxin?

lipid A is the classic endotoxin from gram negative bacteria.
it activates macrophages, complement, and tissue factor.
macrophages release IL-1 (fever), TNF (fever and hypotension) and NO (hypotension). complement C3a causes hypotension and edema; C5a does neutrophil chemotaxis.
tissue factor can activate the coag cascade and cause DIC.
(edema, NO, DIC, outer membrane, TNF-alpha, O-antigen, eXtremely heat stable, IL-1, neutrophil chemotaxis)

2

F+ X F- conjugation vs. Hfr X F- conjugation

both involve exchange of bacterial DNA. F+ X F- is just exchange of plasmid DNA through sex pili; HfrX F- means the plasmid has been incorporated into the chromosme and may transfer both plasmid and flanking chromosomal genes

3

transduction

transfer of bacterial DNA via a bacteriophage. in generalized transduction, a lytic phage accidentally picks up bacterial chromosomal info in the viral capsid. In specialized transduction, a lysogenic phage infects the bacterium, viral DNA incorporates into bacterial chromosme. when DNA is excised flanking bacterial DNA may come along for the ride.

4

What bacterial toxins are encoded in a lysogenic phage?

ABCDE: ShigA-like toxin (EHEC), some botulism strains, cholera toxin, diptheria toxin, and erythrogenic toxin of strep pyrogenes

5

lactose fermenting bacteria

grow pink colonies on MacConkey agar. Klebsiella, E coli, serratia (citrobacter, enterobacter)

6

EMB agar

lactose fementers grow as purple/black colonies. E coli grows with a green sheen