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Corynebacterium mahadi ppt


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Corynebacterium mahadi ppt

  1. 1. Sharq Elneil CollegeSchool of Medical Laboratory SciencesDepartment of MicrobiologyMedical Bacteriology courseU.Mahadi Hassan MahmoudBsc, Msc, MIBMS Microbiology
  2. 2.  The bacterium that causes diphtheriawas first described by Klebs in 1883,and was cultivated by Loeffler in1884, who applied Kochs postulatesand properly identified Coryneb-bacterium diphtheriae as the agent ofthe disease. In 1884, Loeffler concluded that C.diphtheriae produced a solubletoxin, and thereby provided the firstdescription of a bacterial exotoxin
  3. 3. G +ve BacilliAerobic and Facultativeanaerobes Strict anaerobicNon spore forming Spore formingClostridium speciesActinomycetesspeciesNon Branching BranchingActinomycetes speciesNocardia speciesStreptomycetes speciesSpore formingNon spore formingBacillus speciesCatalase -veCatalase +veErysipellotherix speciesLactobacillus speciesCorynebacterium speciesMycobacterium speciesListeria monocytogenes
  4. 4.  C. diphtheriae. Cause diphtheria Diphthroides. Opportunisticpathogens that cause infection toimmunocompromized individual. C. ulcerance. Cause Dimphtherialike illness C. pseudotuberculosis. CauseDiphtheria like disease.Species of medical importace:
  5. 5. They are Pleomorpic G+vebacilli found bind to each otherlike Chinese litter or Arrangedin V forms or PalisadesNon motile, Non spore formingNon capsulated, aerobic orfacultative anaerobes.
  6. 6.  i. Loefflers Serum Slope. ii. Tellurite BA.- Temp. 37oC,- Aerobic and Facultative AnO2.
  7. 7. They form Polyphosphate(volutin or metachromatic)granules when cultured onhighly enriched media.They are highly resistant todrying.They are fastidious organismthat need Blood, serum or eggfor growth.
  8. 8.  solely amonghumans spread by droplets secretions direct contact Poor nutrition Crowded orunsanitary livingconditions Low vaccine coverageamong infants andchildren Immunity gaps inadults
  9. 9.  Diphtheria is an infection of pharynex thatcharacterized by formation of gray whitepseudomembrane which consist of inflammatorycells, dead tissue and bacilli which may block therespiratory tract leading to Asphexia. This disease occurred due to Exotoxins whichproduced from the bacilli after infection withprophage β which contain tox gene. This toxins spread through the blood causedestruction of cardiac, kidney and nervous tissue byinhibition of Elongation factor 2 leading to inhibitionof protein synthesis. The toxin have 2 fragments A & B. Fragment Benhance entrance of fragment A to the cell, andFragment A inhibit protein synthesis.
  10. 10.  Largely controlled now by vaccination However, factors such as poverty and othersocial factors have led to diphtheria being anendemic/epidemic in many regions of theworldEpidemiology
  11. 11.  Specimens: Throat swab. Direct examination: Gram stain showing G+ve bacilliarrange in Chinese letter. Inoculation of the specimens onLofflere’s serum media or Dorset eggmedia for 6 hours and stain fixed smearby Albert stain or Neisser stain. Thevolutin granules staind dark green toblack in Albert and dark blue to blackin Neisser stain.
  12. 12.  Culture: Blood agar. Selective media is Tellurite Blood agar (contain 0.03%-0.04% K. tellurite) and Modified Tinsdale’s medium(contain cystein). Incubation: At 37 C in aerobic condition. Colonial morphology: B.A Produce small gray or gray white convex colonies. Tellurite blood agar produce black colonies due toformation of K. tellurate, C. garvis, mitis and ulceranceprodue β haemolysis. Modified tinsdale’s media produce brown hallow dueto H2S production.
  13. 13. Biochemical characters: Catalase +ve. Oxidase and Urease –ve. Ferment glucose and maltose withacid production. C. gravis ferment starch andTerialose. C. ulcerance are urease +ve andliquefy gelatin.
  14. 14.  Invitrotoxigenicity test (ELEK’S gelprecipitation reaction): Toxigenic strain will secrete toxins that reactwith antitoxin in the filter paper producingprecipitin line. We need: Elek’s plate media with low iron concentration. Tested organism Control strain (Known toxoginic strain). Sterile filter paper impregnated in antitoxin. Procedure. Results (interpretation of results).
  15. 15. Invivotoxigenicity test: Inoculation of toxigenic strain to guineapig will lead to death of animal after 48hours.Schick test Intradermal test used to detectimmunization to diphtheria. 0.2 ml of Highly diluted diphtheriatoxin is injected intradermally in thearm, and heat inactivated toxin isinjected on the other hand. Interpretation:
  16. 16.
  17. 17. ______________________________________________________________________Result Test Arm Control Arm Interpretation Diphthri(Toxin) Inactivated Toxin Immunization36h 120h 36h 120h______________________________________________________________________Negative -- -- -- -- Immune, NotNot Hypersensitive Required----------------------------------------------------------------------------------------Positive + + -- -- Not Immune, Not RequiredHypersensitive---------------------------------------------------------------------------------------------------------------------Negative + -- + -- Immune NotHypersensitive Required---------------------------------------------------------------------------------------------------------------------Positive & + + + -- Not Immune Contra-Pseudo Hypersensitive indicated______________________________________________________________________
  18. 18. PenicillinErythromycin Gentamicin
  19. 19.  Sanitary: Reduce carrier rate byuse of vaccine. Immunological: A vaccine (DPT)prepared from an alkalineformaldehyde inactivated toxin(i.e. toxoid) is required. Passiveimmunization with antitoxin canbe used for patients.
  20. 20. For therapy ofDTtumortumors!!