Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
21 Cards in this Set
- Front
- Back
Corynebacterium Diphtheriae
|
- gram -
- aerobic - nonmotile - rod shaped - does not form spores - forms club shape |
|
Diphtheria Disease
|
- inhalation
- upper respiratory tract - infection/invasion is superficial: nasal/throat tissues - children in developing countries |
|
Diphtheria First Symptoms
|
- low grade fever and sore throat
- pseudomembrane forms and adheres to underlying tissue |
|
What happens with pseudomembrane forms?
|
- damage to epithelial /mucosa cells
- can block airway |
|
Diphtheria severe symptoms
|
- irregular heartbeat
- difficulty swallowing - coughing - heart failure > death |
|
Diphtheria vaccination
|
- prevents disease
- long term resistance - developed against the toxoid (works bc single toxin is involved with toxicity |
|
Diphtheria Toxin Gene
|
- located on bacteriophage
- not all strains carry toxin gene |
|
How does the toxin spread and affect?
|
- spreads through the blood system and lymphatic network
- heart, lungs, and other internal organs |
|
Diphtheria Toxin in High Fe conditions? dtxR?
|
- repressed toxin production
- dtxR binds to tox gene promoter |
|
Diphtheria Toxin in low Fe conditions? dtxR?
|
1. initiates synthesis of siderospores
2. diphtheria toxin synthesis 3. repressor is not functioning - dtxR free |
|
dtxR
|
- transcriptional repressor dimer
- chromosomally encoded Fur (Fe utilization regulator) like repressor protein |
|
Diphtheria toxin production
|
1. single protein
2. cleaved by bacterial protease A/B |
|
what holds AB together?
|
disulfide bond until reducing condition
|
|
A
|
- source of toxicity
|
|
B
|
1. repressor binding (recognizes binding site)
2. translocation domain: forms channel across to host membrane for translocation of A |
|
Toxin activity is most active against what? wht?
|
- heart and nerve cells bc number of ↑ [receptors]
- different cells = different susceptibility bc of abundance of toxin receptors |
|
What happens in the cytoplasm?
|
- frag A catalyzes ADP ribosylation of EF-2
EF-2 = protein synthesis peptide elongatoin |
|
ADP ribosylating group
|
1. attaches to diphthamide (derivative of histidine)
2. attaches to EF-2 inactivating it = cell death |
|
Diphtheria diagnosis and treatment
|
- isolating and confirming C. diphtheria from culture of nasal or throat swabs or membrane tissue
- respiratory diphtheria = hospitalization to monitor treatment and complications |
|
Equine diphtheria antitoxin (DAT)
|
- mainstay treatment
- administered after specimen testing |
|
what's the appropriate antibiotic/anitmicrobial prophylaxis?
|
- erthromycin and penicillin
1. eliminate causative organismsm stop exotoxin production, and reduce communicability 2. prophylaxis: close contant of pts |