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Corynebacteria. Causative agents of diphtheria. Pathogenesis, laboratory diagnostics, prophylaxis and therapy of diphtheria. Vinnitsa National Pirogov Memorial Medical University / Department of microbiology. Taxonomy and classification of corynebacteria. Genus Corynebacterium
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Corynebacteria. Causative agents of diphtheria. Pathogenesis, laboratory diagnostics, prophylaxis and therapy of diphtheria. Vinnitsa National Pirogov Memorial Medical University / Department of microbiology
Taxonomy and classification of corynebacteria • Genus Corynebacterium • Species: C. diphtheria • Conditionary-pathogenic species: C. ulcerans. C. haemolyticum, Cpseudodiphthericum. C. xerosis and others
Morphological features of C.diphtheria Nasser's staining to reveal volutin granules
Cultural properties C. diphtheria is an aerobe and facultative anaerobe, has an optimum temperature for growth of 37°C, Media : • Loeffler's coagulated serum • blood agar • selective tellurite media
Classification of C.diphtheria • gravis, • intermedius • mitis. Gravis mitis
Virulent factors • Exotoxin (cytotoxin) • Enzymes: fibrinolysin, neuramidase, hyaluronidase..
Epidemiology • The source of infection is either a ill person or a carrier. • Infection is spread by droplets, dust, secretions, or direct contact. It is air-borne infection
Clinical appearance Nasal bleeding Membrane onto the tonsils
Laboratory diagnostics • Microscopy (by Neisser or Loeffler) • Culture method and determination of toxigenecity (confirming diagnosis!) • Immunofluorescence microscopy (rapid diagnostics) • Experimental infection for toxigenecity detection
Prophylaxis • Diphtheria can be controlled by immunization. • Three methods of immunisation are available: active, passive and combined Active: diphtheria toxoid (DT) , DPT vaccine, DTT
Therapy of diphtheria • Antitoxic therapy should be started immediately (!). • The dose of antitoxic horse serum depends on the severity disease and is from 20 000 to 100 000 IU • Antibiotics (penicillin, erythromycin)