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