Coynebacterium!! MICROM 442 Deck 12 Flashcards
1
Q
kornyne = club, shape?
A
pleomorphic rods with clubbed ends
2
Q
GM?
A
+
3
Q
non-motile and non?
A
sporulating
4
Q
only resevoir
A
human
5
Q
spread by>
A
- spread by respiratory droplets, cutaneous lesions
and fomites; - pharyngeal/nasal carriage in some convalescent
cases
6
Q
Principal virulence factor is diphtheria toxin [DT]
A
- classic A-B subunit toxin: B unit accomplishes cell
binding [R] and translocation [T]; A subunit is catalytic [C]
7
Q
toxin taken up by?
A
- toxin uptake by endocytosis; acidification of endosome
releases active A into cytosol
8
Q
ADP-ribosylation of elongation factor 2 irreversibly
A
halts protein synthesis; cell dies
9
Q
DT encoded on lysogenic
A
bacteriophage
10
Q
DtxR [chromosomal gene, not phage encoded]
A
- represses expression in high-iron conditions
- host iron mostly heme-bound and intracellular
11
Q
- DT co-regulated with:
A
- endogenous genes encoding
bacterial iron transport system - hmuO [heme oxygenase] for utilizing heme and
hemoglobin as an iron source
12
Q
local toxin effects
A
- pharyngitis; epithelial cell necrosis & inflammation
- debris, fibrin, formation of pseudomembrane
- gray/yellow/white membrane with surrounding
inflammation - mechanical obstruction of airway
13
Q
this organism causes a psuedo what to form?
A
psuedo membrane
14
Q
systemic toxin effects
A
- myocarditis; significant cardiomyopathy [~25% cases]:
enlargement, arrhythmia, pump dysfunction,
shortness of breath - paralysis of soft palate and select muscle groups,
most seriously the diaphragm
15
Q
Superficial skin infections, tropical, hot, and arid
regions; usually without systemic complications
A
Sx’s contrasted with systemic illnesses as a result of
differential toxin distribution and action
