Corynebacterium

Question 1

Corynebacterium cell morphology

Answer 1

— Gram positive but contains cell wall components characteristic of G- and acid-fast
— resembling Chinese letters
—

Question 2

Corynebacterium growth on blood agar

Answer 2

Raised, translucent and grey colonies

Question 3

Corynebacterium catalase

Answer 3

Catalase positive

Question 4

Corynebacterium colonization

Answer 4

Ubiquitous on plants, humans and animals

— colonize in skin, respiratory, gastrointestinal, urinary, and genital tracts

Question 5

Corynebacterium Diptheriae Epidemiology

Answer 5

Human is the only natural host, carried asymptomatically in oropharynx or skin immune individuals
- Virulent version transmitted by respiratory droplets

Question 6

Corynebacterium Diptheriae virulence factors

Answer 6

Diphtheria toxin- introduced by lysogenic bacteriophage AB toxin

Question 7

Corynebacterium Diptheriae toxin

Answer 7

Enters through receptor mediated endocytosis- acidification of endocytosis vesicle allows A to dissociated from B and enters cytoplasm

Question 8

Corynebacterium Diptheriae clinical symptoms

Answer 8

Toxigenic strains cause diphtheria in humans. This organism can only infect human and has a limited ability (respiratory vs cutaneous diphtheria)

Question 9

Cutaneous diphtheria

Answer 9

More common in tropical climates (and subtropical)
Acquired by skin contact/ breakage
Chronic, non-healing necrotic lesions with occasional local pseudomembrane formation

Question 10

Respiratory Diptheriae

Answer 10

Initially: sore throat, low-grade fever, strep-throat-like pseudomembrane (large and white) formation on tonsils and pharynx
Later stages include localized damage, bleeding, difficulty breathing, myocarditis and peripheral neural inflammation
Death mostly from systemic toxin-mediated heart failure

Question 11

C. Diptheria Identification

Answer 11

Confirmed diagnosis only be made by isolating bacteria from primary lesion, inoculating on blood agar and run with the Elek Test

Question 12

C Diptheriae Prevention

Answer 12

Part of the DPT vaccine— very dangerous risk to children before vaccine was wildly available

Question 13

C Diptheriae treatment

Answer 13

Antiserum for the toxin (though not effective once the toxin is bound. Only works against unbound toxin)
Penicillin is effective in eliminating the organism (Erythromycin is an alternative
— Also common to require surgery to remove the pseudomembrane and open the airway