Corynebacterium diphtheriae
Biological Features
? Aerobic,Gram+,Noncapsulated,rods
? Gray-black colonies on tellurite亚碲酸盐 medium
? Metachromatic granules
Chinese-letter morphology in Gram stain
Transmission and Risk factors
? solely among humans
? spread by droplets
? secretions
? direct contact
? Poor nutrition
? Crowded or unsanitary
living conditions
? Low vaccine coverage
among infants and
children
? Immunity gaps in
adults
Pathogenesis of diphtheria
? Early stages,Sore throat,Low fever,Swollen
neck glands,
? Late stages,Airway obstruction and breathing
difficulty,Shock
Diphtheria Toxin (DT)
? Cleaved to yield A/B fragment,joined by S-S bond
- A (catalytic domain)
- B (transmembrane and receptor binding domains)
? Receptor,heparin-binding epidermal growth factor - rich on cardiac cells and nerve cells
? Toxin diffuses throughout body via blood
- Cardiac,neurologic complications
- Heart/respiratory damage,paralysis
Immunity
? Immunization of animals with altered toxin,
producing antitoxin,was first done in 1890,
1st used in humans in 1891
? Toxin-antitoxin introduced by Theobald
Smith in 1909,used little
? Toxoid introduced in 1923,now widely used
Schick test
? Be used to ascertain population risk
This test involves the injection of a minute amount of
the diphtheria toxin under the skin,The absence of a reaction
indicates immunity,
DIAGNOSIS
? Clinical,Muscle weakness,edema and a
pseudomembranous material in the upper
respiratory tract characterizes diphtheria,
? Laboratory,Tellurite media is the agar of
choice for isolation of Corynebacteria,which
produce jet black colonies
Control
? Sanitary,Reduce carrier rate by use of
vaccine,
? Immunological,A vaccine (DPT)
prepared from an alkaline formaldehyde
inactivated toxin (i.e,toxoid) is required,
Passive immunization with antitoxin can be
used for patients,
? Chemotherapeutic,Penicillin,
erythromycin or gentamicin are drugs of
choice,
Prospect
For therapy of
DT
tumor
tumors !!
Biological Features
? Aerobic,Gram+,Noncapsulated,rods
? Gray-black colonies on tellurite亚碲酸盐 medium
? Metachromatic granules
Chinese-letter morphology in Gram stain
Transmission and Risk factors
? solely among humans
? spread by droplets
? secretions
? direct contact
? Poor nutrition
? Crowded or unsanitary
living conditions
? Low vaccine coverage
among infants and
children
? Immunity gaps in
adults
Pathogenesis of diphtheria
? Early stages,Sore throat,Low fever,Swollen
neck glands,
? Late stages,Airway obstruction and breathing
difficulty,Shock
Diphtheria Toxin (DT)
? Cleaved to yield A/B fragment,joined by S-S bond
- A (catalytic domain)
- B (transmembrane and receptor binding domains)
? Receptor,heparin-binding epidermal growth factor - rich on cardiac cells and nerve cells
? Toxin diffuses throughout body via blood
- Cardiac,neurologic complications
- Heart/respiratory damage,paralysis
Immunity
? Immunization of animals with altered toxin,
producing antitoxin,was first done in 1890,
1st used in humans in 1891
? Toxin-antitoxin introduced by Theobald
Smith in 1909,used little
? Toxoid introduced in 1923,now widely used
Schick test
? Be used to ascertain population risk
This test involves the injection of a minute amount of
the diphtheria toxin under the skin,The absence of a reaction
indicates immunity,
DIAGNOSIS
? Clinical,Muscle weakness,edema and a
pseudomembranous material in the upper
respiratory tract characterizes diphtheria,
? Laboratory,Tellurite media is the agar of
choice for isolation of Corynebacteria,which
produce jet black colonies
Control
? Sanitary,Reduce carrier rate by use of
vaccine,
? Immunological,A vaccine (DPT)
prepared from an alkaline formaldehyde
inactivated toxin (i.e,toxoid) is required,
Passive immunization with antitoxin can be
used for patients,
? Chemotherapeutic,Penicillin,
erythromycin or gentamicin are drugs of
choice,
Prospect
For therapy of
DT
tumor
tumors !!
