Diphtheria, Tetanus and H. influenzae b

Diphtheria, Tetanus and H. influenzae b

 

Clostridium tetani is a slender, gram-positive, sporulating, anaerobic bacillus.

  • C. tetani spores are ubiquitous in the environment and usually enter body through puncture wounds, lacerations, abrasions or burns
  • If bacilli find a suitable deep wound with reduced oxidation (anaerobic conditions), they germinate, releasing toxin
    • Toxin is disseminated via blood and lymphatics
    • Clinical manifestations of tetanus are due to toxin
  • Manifestations
    • Tetanus is characterized by intermittent tonic spasms of voluntary muscles
    • Neonatal tetanus occurs secondary to unsterile treatment of umbilical cord associated with inadequately immunized mothers
    • When tetanus results in death, cause is usually interference with respiration
    • The death rate among reported cases of tetanus is about 30%
    • Tetanus in the U.S. mostly affects older adults not adequately immunized

Corynebacterium diphtheriae is an aerobic gram-positive rod.

  • Causes diphtheria - a contagious, airborne infection
  • Manifestations
    • Diphtheria is characterized by
      • Formation of fibrinous pseudo-membranes, usually on respiratory mucosa
        • Pseudomembrane formation is sine qua non for disease
        • Primary infection most often tonsillopharyngeal, but may be laryngeal, nasal or tracheobronchial
      • Myocardial and neural tissue damage secondary to exotoxin produced by diphtheria bacteria
    • In addition to respiratory form, diphtheria includes cutaneous form
      • Occurs in pre-existing dermatoses
      • Produces lesions resembling other cutaneous bacterial infections

H. influenza is a gram-negative coccobacillus.

  • 6 major typable serotypes (a-f)
  • Nontypeable strains also
  • Causes meningitis, epiglottitis, otitis media, sinusitis, cellulitis and pneumonia
  • Majority of disease (except pneumonia) affects children

Prevention

  • Prevention for all of these diseases is vaccination
  • Pre- and one-month post vaccination titers may be used for testing of suspected antibody deficiency states