Corynebacterium Flashcards
Taxonomy of corynebacterium
Gram + pleomorphic rods, often club shaped “V” and “L” shaped characters, NOT acid fast
Are corynebacterium normal flora?
Diphtheria species are not, but the others are. The normal flora bacteria are the ones causing disease now because the vaccine is preventive of diphtheria.
Who is at risk for disease of all other species of corynebacterium?
Those that are immunocompromised
What is the name of the “other” corynebacterium that do not cause diphtheria?
Diphtheroids
What does arcanobacterium haemolyticum cause? and in what population?
Pharyngitis, esp in adolescents
Taxonomy/reactions of arcanobacterium haemolyticum?
Beta-hemolytic
What may arcanobacterium haemolyticum be confused with?
strep pyogenes
Why is it ok to not tell the difference between s. pyogenes and a. haemolyticum?
They are both sensitive to PCN and macrolide.
Virulence factors of corynebacterium diphtheria
- Cell wall antigens
- Diphtheria toxin
What is the vaccine target for diphtheria?
Diphtheria toxin
Where/What produces diphtheria toxin?
The to gene on the phage genome
How does diphtheria toxin cause disease?
It binds to surface of susceptible cells (especially in the heart) and results in inhibition of the protein synthesis and cell death.
Transmission of corynebacterium diphtheria
person to person via respiratory droplets, exchanging secretions, and direct skin to skin contact
Classical Diphtheria
Respiratory infection-local infection with systemic toxemia
What is the process of classical diphtheria disease?
2-6 days incubation with pharyngitis, slight fever, and malaise. The toxin causes necrosis of the mucosal tissue and it enters the bloodstream!
Physical findings of diphtheria toxin:
- Grayish white exudate of pseudomembrane in throat and tonsils.
- Marked edema of neck “bull neck”
- Respiratory obstruction
Systemic complications of classical diphtheria
Necrosis in heart muscle, kidneys, and nerves.
What is cutaneous diphtheria
Skin infections, more common in the tropics.
Diagnosis of classical diphtheria:
- Clinical presentation with pharyngitis, pseudomembrane,
- Swab from nose, throat, and skin-culture on blood agar
- Test for toxin production
Treatment of classical diphtheria
- Antitoxin Ab therapy
- Antibiotic therapy
Specific antibiotics used in classical diphtheria treatment
Erythromycin or PCN G
Antibiotics used in classical diphtheria treatment in immunocompromised pts
Vancomycin OR PCN G + aminoglycosides
DTP vaccine:
DTap contains diphtheria, tetanus and pertussis
What is the active portion of the vaccine?
Toxoid! It is inactivated diphtheria toxin. The toxoid is immunogenic but not toxin.
