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Corynebacteria Filename: Coryne.ppt
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Outline Microbes Diseases Corynebacterium,Listeria, Erysipelothrix
Diphtheria,Listeriosis, Erysipeloid
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Corynebacterium: Habitat
Skin upper respiratory tract GI tract Urogenital tract of humans
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Cornyebacterium: Pathogens
C. diphtheriae Diphtheria C.pseudotuberculosis humans sheep, cattle, suppurative lymphadenitis C. ulcerans humans pharyngitis cattle -mastitis C. haemolyticum pharyngitis cutaneous infection C. pyogenes cattle, sheep, swine suppurative infection C.pseudodiphtheriticum endocarditis
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C. xerosis opportunistic infections Group J K immunocompromised host
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Related Organisms Listeria monocytogenes Erysipelothrix rhusiopathiae
Listeriosis Erysipelothrix rhusiopathiae Erysipeloid
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Diphtheria
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Diphtheria Laboratory diagnosis
Speedy diagnosis Differentiate from commensals “diphteroids” nose & throat C. xerosis C. hofmanni Throat swabs (confirmatory) Blood Tellurite Virulence test
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Corynebacterium Aerobic gram + rods -pleomorphic: club-shaped
-pallisades -snapping cell division -metachromatic granules methylene blue stain volutin: polyphosphate
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Cellular Morphology Gram positive rods “Snapping division”
Palisade cells “Chinese letters” Erysipelothrix
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Specialized media Tellurite: black colonies
Not diagnosticallly significant tellurite inhibits many organisms but not C. diphtheriae Loeffler best colonial morphology Dextrose horse serum (1887) now Dextrose beef serum
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Blood tellurite Selective & differential medium
Corynebacteria are resistant to tellurite Reduced to tellurium Forms deposit in colonies Colonies appear dark Biotypes gravis, intermedius, mitis
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Corynebacterium Biotypes
C diphtheriae gravis C diphtheriae intermedius C diphtheriae mitis Helpful for epidemiological tracing Culture identified by biochemical tests.
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DIAGNOSIS MUST BE CLINICAL!!!!
Diphtheria Nasopharyngeal diphtheria Pharyngeal Larygngeal Cutaneous diphtheria Systemic complications DIAGNOSIS MUST BE CLINICAL!!!!
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Pharyngeal diptheria Inflammation Leucocytes TOXIN !!
similar to strept throat Leucocytes infiltrated killed embedded in fibrin clot TOXIN !!
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All SIGNS & SYMPTOMS CAUSED BY TOXIN
Diphtheria Symptoms Pharyngitis Hypoxia Choking “Garitillo” Fever (103 F) Lymphadenitis All SIGNS & SYMPTOMS CAUSED BY TOXIN
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Diphtheria Pseudomembrane
No True membrane Very few live cells Deposit of dead cells and protein
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Pseudomembrane CONTAINS COVERS tonsils, bacteria uvula, lymphocytes
plasma cells fibrin dead cells COVERS tonsils, uvula, palate nasopharynx larynx.
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Diphtheria Systemic complications
Nerves toxic peripheral neuropathy paralysis of short nerves mouth, eye, facial extremities Cardiac Congestive heart failure high amount of toxin hours Low amount of toxin 2-6 weeks
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Virulence Factors Diphtheria toxin !!! Dermonecrotic toxin Hemolysin
blocks protein synthesis Dermonecrotic toxin sphingomyelinase increases vascular permeability Hemolysin Cord factor -Toxic trehalose corynemycolic acid, corynemyolenic acid 6,6’-di-O-mycoloyl- a,a’-D-trehalose
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DiphtheriaToxin Blocks protein synthesis Protein 63Kd
controlled by Tox gene lysogenic phage Beta-corynephage expressed if [iron] low 2 components A-B
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Regulation of Diphtheria Toxin High [Fe 2+]
NO Toxin Produced P o tox Corynebacteriophage beta Fe 2+ + apo DtxR [Fe 2+ *DtxR] p dtxR C diphtheriae dtxR= repressor protein
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Regulation of Diphtheria Toxin Low [Fe 2+]
Toxin Produced!!! tox Corynebacteriophage beta o P Fe 2+ + apo DtxR [Fe 2+ *DtxR]
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Toxin Part A Part B Active site N terminal Enzyme Binding site
Binds to membrane receptor Transmembrane
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Diphtheria toxin: Part A
Active site Enzyme Blocks protein synthesis ADP-ribosyl transferase elongation factor 2 (EF2) Specific for mammalian cells Prokaryotes have different EF2
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Diphtheria Toxin: Part B
Binding Site Binds to cell receptor Bound receptor internalized Endosome Hydrolysed by protease Disulfide broken Part A released
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Activation of Diphtheria Toxin
B A B A B A B
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Toxingenicity Tests In Vitro Elek test In Vivo Animal inoculation
rabbit skin test-necrosis guinea pig challenge test- lethal low [Fe 2+] induces toxin
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Elek test
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Animal inoculation Inject 2 mice with 5ml C.diphtheria cells
one mouse protected with 1000 units C.diphtheriae antitoxin Autopsy - adrenals hemorrhagic
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Control Immunization diphtheria toxoid Schick test Passive immunity
check for antibodies Passive immunity Antibodies Antibiotics Penicillin & erythromcyin
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Schick Test for Diptheria
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Epidemics Immune individuals Non immune individuals may be carriers
antibiotics Non immune individuals Exposed passive immunity antibodies Not exposed immunize with toxoid
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Diphtheria: Russian Federation
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Diphtheria in the Soviet Union and NIS
Emerging infectious diseases: 4(4) 1998 Vitek & Wharton
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Diphtheria Incidence
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Diphtheria in the Russian Federation
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The End
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Performance Objectives
Key terms, concepts short answers
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Key Terms pseudomembrane
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Key Terms Schick test Elek Test Diphtheria toxin larnygeal diphtheria
pharyneal diphtheria
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Key Organisms Corynebacterium Listeria Erysipelothrix
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Key Concepts
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Epidemiology of Diphtheria
Disease/bacterial factors Transmission Who is at risk Geography/ season Incidence Modes of control
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Short Answers Construct a table of the virulence factors associated with diphtheria and the biological activity of each Use a series of no more than four diagrams to describe the mechanism of action of diphtheria toxin Describe the clinical manifestations of diphtheria Construct a table listing the common Corynebacteria and the associated diseases.
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