Corynebacterium diphtheriae b.carl


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Corynebacterium diphtheriae b.carl

  1. 1. Corynebacterium diphtheriae
  2. 2. General Characteristics <ul><li>Gram Positive </li></ul><ul><li>Club shaped rod </li></ul><ul><li>Forms clusters of “Chinese-characters” </li></ul><ul><li>Aerobic </li></ul><ul><li>Non-spore forming </li></ul><ul><li>Exterior fimbriae </li></ul><ul><li>Contains no plasmids </li></ul><ul><li>Toxigenic and Non-toxigenic forms </li></ul>
  3. 3. Compound Light Microscope <ul><li>The club or bar appearance of the cells is due to pockets of inorganic phosphate which form metachromatic granules when stained </li></ul>
  4. 4. Electron Microscope
  5. 5. Reservoir <ul><li>Human Body </li></ul><ul><li>Normal flora of skin and nasopharynx </li></ul><ul><li>Enters upper respiratory tract and cutaneous </li></ul>
  6. 6. Transmission <ul><li>Spread by inhalation of airborne bacteria </li></ul><ul><li>Direct contacted with an infected person </li></ul><ul><li>Open wounds </li></ul>
  7. 7. Virulence Factors <ul><li>Diphtheria toxin </li></ul><ul><ul><li>Diphtheria toxin gene is encoded by a bacteriophage </li></ul></ul><ul><ul><li>Phage Beta </li></ul></ul><ul><ul><li>DT inhibits of protein synthesis (elongation factor 2) </li></ul></ul><ul><ul><li>C. Diphtheria without this gene is not as harmful </li></ul></ul><ul><li>Repressor (DtxR) gene, is activated by iron and prevents transcription of the tox gene </li></ul><ul><ul><li>High iron levels = no toxin release </li></ul></ul><ul><ul><li>Low iron levels = toxins released </li></ul></ul>
  8. 8. Clinical Diseases <ul><li>Respiratory diphtheria is caused by C. diphtheriae bacteria adhering to and colonizing the tonsils, nasal cavity, and throat </li></ul><ul><li>Cutaneous diphtheria can be caused by both the toxigenic and the nontoxigenic strains of C. diphtheriae </li></ul><ul><ul><li>Creates deep, erosive ulcers </li></ul></ul><ul><li>If left untreated could damage the heart and nerves and eventually lead to death. </li></ul>
  9. 9. Identification/Diagnosis <ul><li>Upper-respiratory tract illness characterized by sore throat, low-grade fever, and an adherent membrane of the tonsils, pharynx, and/or nose </li></ul><ul><ul><li>Creates a pseudomembrane, a greenish-gray film that hardens in the pharynx from inflammation and can cause asphyxiation. </li></ul></ul><ul><li>Sample of the bacteria is isolated from the patient’s throat/mouth and cultured </li></ul><ul><li>“ Bull Neck” appearance </li></ul><ul><li>To test for toxigenicity, the Elek test is performed </li></ul>
  10. 10. Symptoms
  11. 11. <ul><li>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. </li></ul>
  12. 12. Treatment <ul><li>Diphtheria infection is treated with diphtheria antitoxin </li></ul><ul><li>Formalin eliminated the toxicity of DT without destroying its immunogenicity. Formalin-treated DT, now called diphtheria toxoid </li></ul><ul><li>14-day course of antibiotics, preferably Erythromycin or Penicillin </li></ul>
  13. 13. Prevention <ul><li>Tdap (Adults) or DTaP (Under 7 yrs old) Vaccines </li></ul><ul><ul><li>combined vaccine against diphtheria, tetanus (Lockjaw), and pertussis (whooping cough) </li></ul></ul><ul><li>Children should get 5 doses of DTaP vaccine, one dose at each of the following ages: </li></ul><ul><ul><li>2 months </li></ul></ul><ul><ul><li>4 months </li></ul></ul><ul><ul><li>6 months </li></ul></ul><ul><ul><li>15-18 months </li></ul></ul><ul><ul><li>4-6 years </li></ul></ul>
  14. 14. Prevention (cont.) <ul><li>Tdap </li></ul><ul><ul><li>A single dose of Tdap is recommended for people 11 through 64 years of age. </li></ul></ul><ul><li>Td </li></ul><ul><ul><li>Td , protects only against tetanus and diphtheria </li></ul></ul><ul><ul><li>recommended every 10 years. </li></ul></ul>
  15. 15. Questions <ul><li>What is a common symptom of a toxigenic C. diphtheriae infection? </li></ul><ul><li>a) Chickens Neck </li></ul><ul><li>b) Bulls Neck </li></ul><ul><li>c) Giraffe’s neck </li></ul><ul><li>d) None of the Above </li></ul><ul><li>C. diphtheriae infection is treated with: </li></ul><ul><li>a) antibiotics </li></ul><ul><li>b) antitoxins </li></ul><ul><li>c) no treatment except replenish water </li></ul><ul><li>d) both a and b </li></ul>
  16. 16. References <ul><li>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 </li></ul><ul><li>Holmes, R.K. (2000) Biology and molecular epidemiology of diphtheria toxin and the tox gene. J Infect Dis 181 (Suppl. 1): S156–S167. </li></ul><ul><li>Coordinating Center for Infections Diseases/Division of Bacterial and Mycotic Diseases &quot;Diphtheria&quot; 6 October 2005 </li></ul><ul><li>Todar, Kenneth, University of Wisconsin-Madison Department of Bacteriology, &quot;Diphtheria&quot; 2002 </li></ul><ul><li>National Center for Immunization and Respiratory Diseases: Division of Bacterial Diseases, “Diphtheria” February 7, 2011 </li></ul>