Diphtheria

1. Diptheria
Presenter: Gia Phong Vu PhD

2. Diphtheria
• Greek diphthera (leather hide)
• Caused by Aerobic Gram +ve rods
• Cornyebacterium diphtheriae
• Exotoxin production only if infected by virus phage infected
carrying toxin gene

3. Culture
• Tellurite Blood Agar – tellurite inhibits other
bacteria
• Produce Grey/ Black Colonies

4. Diphtheria Epidemiology
Reservoir Human carriers
Usually asymptomatic
Transmission Respiratory
Skin and fomites rarely
Temporal pattern Winter and spring
Communicability Up to several weeks
without antibiotics

5. Diphtheria Clinical Features
Incubation period 2-5 days
(range, 1-10 days)
May involve any mucous membrane
• anterior nasal
• pharyngeal and tonsillar
• laryngeal
• cutaneous
• ocular
• genital
Classified based on site of infection

6. Pharyngeal and
Tonsillar
Diphtheria
• Insidious onset of exudative
pharyngitis
• Exudate spreads within 2-3
days and may form adherent
pseudo membrane
• Membrane may cause
respiratory obstruction
• Fever usually not high but
patient appears toxic

7. Pseudo membrane

8. ‘Bull Neck’

9. Skin Lesions

10. Diphtheria Complications
• Mostly attributable to toxin
• Severity generally related to extent of local disease
• Most common complications are myocarditis and toxic neuritis with palsy
• Death occurs in 5%-10% for respiratory disease

11. Diphtheria
Antitoxin (DAT)
• Produced in horses
• First used in the U.S. in 1891
• Used only for treatment of diphtheria
• Neutralizes only unbound toxin

12. 0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
1940 1950 1960 1970 1980 1990 2000
CasesDiphtheria – in USA, 1940-2005*
Year
*2005 provisional total

13. DTaP, DT, and Td
DTaP, DT
Td, Tdap (adult)
Diphtheria
7-8 Lf units
2-2.5 Lf units
Tetanus
5-12.5 Lf units
5 Lf units