The club or bar appearance of the cells is due to pockets of inorganic phosphate which form metachromatic granules when stained
Normal flora of skin and nasopharynx
Enters upper respiratory tract and cutaneous
Spread by inhalation of airborne bacteria
Direct contacted with an infected person
Diphtheria toxin gene is encoded by a bacteriophage
DT inhibits of protein synthesis (elongation factor 2)
C. Diphtheria without this gene is not as harmful
Repressor (DtxR) gene, is activated by iron and prevents transcription of the tox gene
High iron levels = no toxin release
Low iron levels = toxins released
Respiratory diphtheria is caused by C. diphtheriae bacteria adhering to and colonizing the tonsils, nasal cavity, and throat
Cutaneous diphtheria can be caused by both the toxigenic and the nontoxigenic strains of C. diphtheriae
Creates deep, erosive ulcers
If left untreated could damage the heart and nerves and eventually lead to death.
Upper-respiratory tract illness characterized by sore throat, low-grade fever, and an adherent membrane of the tonsils, pharynx, and/or nose
Creates a pseudomembrane, a greenish-gray film that hardens in the pharynx from inflammation and can cause asphyxiation.
Sample of the bacteria is isolated from the patient’s throat/mouth and cultured
“ Bull Neck” appearance
To test for toxigenicity, the Elek test is performed
Cystine-Tellurite blood agar, incubated at 35 degrees C in A CO(2)-enriched atmosphere. Colonies of Corynebacterium diphtheriae on tellurite containing agar are gray-black, while most of the usual oral flora are inhibited.
Diphtheria infection is treated with diphtheria antitoxin
Formalin eliminated the toxicity of DT without destroying its immunogenicity. Formalin-treated DT, now called diphtheria toxoid
14-day course of antibiotics, preferably Erythromycin or Penicillin
Tdap (Adults) or DTaP (Under 7 yrs old) Vaccines
combined vaccine against diphtheria, tetanus (Lockjaw), and pertussis (whooping cough)
Children should get 5 doses of DTaP vaccine, one dose at each of the following ages:
A single dose of Tdap is recommended for people 11 through 64 years of age.
Td , protects only against tetanus and diphtheria
recommended every 10 years.
What is a common symptom of a toxigenic C. diphtheriae infection?
a) Chickens Neck
b) Bulls Neck
c) Giraffe’s neck
d) None of the Above
C. diphtheriae infection is treated with:
c) no treatment except replenish water
d) both a and b
Mandlik, A., Swierczynski, A., Das, A. and Ton-That, H. (2007), Corynebacterium diphtheriae employs specific minor pilins to target human pharyngeal epithelial cells. Molecular Microbiology, 64: 111–124. doi: 10.1111/j.1365-2958.2007.05630.x
Holmes, R.K. (2000) Biology and molecular epidemiology of diphtheria toxin and the tox gene. J Infect Dis 181 (Suppl. 1): S156–S167.
Coordinating Center for Infections Diseases/Division of Bacterial and Mycotic Diseases "Diphtheria" 6 October 2005
Todar, Kenneth, University of Wisconsin-Madison Department of Bacteriology, "Diphtheria" 2002
National Center for Immunization and Respiratory Diseases: Division of Bacterial Diseases, “Diphtheria” February 7, 2011 http://www.cdc.gov/ncidod/dbmd/diseaseinfo/diptheria_t.htm