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Corynebacteria Filename: Coryne.ppt 1 5/24/201 Outline Microbes – Corynebacterium,Listeria, Erysipelothrix Diseases – Diphtheria,Listeriosis, Erysipeloid 2 5/24/201 Corynebacterium: Habitat Skin upper respiratory tract GI tract Urogenital tract of humans 3 5/24/201 Cornyebacterium: Pathogens C. diphtheriae Diphtheria C.pseudotuberculosis humans sheep, cattle, suppurative lymphadenitis C. ulcerans humans pharyngitis cattle -mastitis 4 C. haemolyticum pharyngitis cutaneous infection C. pyogenes cattle, sheep, swine suppurative infection C.pseudodiphtheriticum endocarditis 5/24/201 C. xerosis opportunistic infections Group J K immunocompromised host 5 5/24/201 Related Organisms Listeria monocytogenes – Listeriosis Erysipelothrix rhusiopathiae – Erysipeloid 6 5/24/201 Diphtheria 7 5/24/201 Diphtheria Laboratory diagnosis Speedy diagnosis Differentiate from commensals – “diphteroids” – nose & throat – C. xerosis C. hofmanni Throat swabs (confirmatory) – Blood Tellurite Virulence 8 test 5/24/201 Corynebacterium Aerobic gram + rods -pleomorphic: club-shaped -pallisades -snapping cell division -metachromatic granules – methylene blue stain – volutin: polyphosphate 9 5/24/201 Cellular Morphology Gram positive rods “Snapping division” Palisade cells “Chinese letters” 10 Erysipelothrix 5/24/201 Specialized media Tellurite: black colonies Not diagnosticallly significant tellurite inhibits many organisms but not C. diphtheriae 11 Loeffler best colonial morphology Dextrose horse serum (1887) now Dextrose beef serum 5/24/201 Blood tellurite Selective & differential medium Corynebacteria are resistant to tellurite – Reduced to tellurium Forms deposit in colonies – Colonies appear dark Biotypes – gravis, intermedius, mitis 12 5/24/201 Corynebacterium Biotypes C diphtheriae gravis C diphtheriae intermedius C diphtheriae mitis Helpful for epidemiological tracing Culture identified by biochemical tests. 13 5/24/201 Diphtheria Nasopharyngeal diphtheria – Pharyngeal – Larygngeal Cutaneous diphtheria Systemic complications 14 DIAGNOSIS MUST BE CLINICAL!!!! 5/24/201 Pharyngeal diptheria Inflammation – similar to strept throat Leucocytes – infiltrated – killed – embedded in fibrin clot TOXIN 15 !! 5/24/201 Diphtheria Symptoms Pharyngitis Hypoxia – Choking – “Garitillo” Fever (103 F) Lymphadenitis All SIGNS & SYMPTOMS CAUSED BY TOXIN 16 5/24/201 Diphtheria Pseudomembrane No True membrane Very few live cells Deposit of dead cells and protein 17 5/24/201 Pseudomembrane CONTAINS – – – – – 18 bacteria lymphocytes plasma cells fibrin dead cells COVERS – tonsils, – uvula, – palate – nasopharynx – larynx. 5/24/201 Diphtheria Systemic complications Nerves – toxic peripheral neuropathy – paralysis of short nerves – mouth, eye, facial extremities Cardiac – Congestive heart failure – high amount of toxin 48-72 hours – Low amount of toxin 2-6 weeks 19 5/24/201 Virulence Factors Diphtheria toxin !!! – 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 20 5/24/201 DiphtheriaToxin Blocks protein synthesis Protein 63Kd controlled by Tox gene lysogenic phage Betacorynephage expressed if [iron] low 2 components A-B 21 5/24/201 Regulation of Diphtheria Toxin High [Fe 2+] NO Toxin Produced P o tox Corynebacteriophage beta [Fe 2+ *DtxR] Fe 2+ + apo DtxR p dtxR C diphtheriae dtxR= repressor protein 22 5/24/201 Regulation of Diphtheria Toxin Low [Fe 2+] Toxin Produced!!! P o tox Corynebacteriophage beta [Fe 2+ *DtxR] 23 Fe 2+ + apo DtxR 5/24/201 Part A – Active site – N terminal – Enzyme Part Toxin B – Binding site – Binds to membrane receptor – Transmembrane 24 5/24/201 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 25 5/24/201 Diphtheria Toxin: Part B Binding Site Binds to cell receptor Bound receptor internalized Endosome – Hydrolysed by protease – Disulfide broken – Part A released 26 5/24/201 Activation of Diphtheria Toxin A A B B B 27 A B A 5/24/201 28 5/24/201 Toxingenicity Tests In Vitro Elek test In Vivo Animal inoculation rabbit skin test-necrosis guinea pig challenge test- lethal 29 low [Fe 2+] induces toxin 5/24/201 Elek test 30 5/24/201 Animal inoculation Inject 2 mice with 5ml C.diphtheria cells one mouse protected with 1000 units C.diphtheriae antitoxin Autopsy - adrenals hemorrhagic 31 5/24/201 Control Immunization Schick diphtheria toxoid test – check for antibodies Passive immunity – Antibodies Antibiotics – Penicillin & erythromcyin 32 5/24/201 Schick Test for Diptheria 33 5/24/201 Epidemics Immune individuals – may be carriers – antibiotics Non immune individuals – Exposed passive immunity antibodies – Not exposed immunize with toxoid 34 5/24/201 Diphtheria: Russian Federation 35 5/24/201 Diphtheria in the Soviet Union and NIS Emerging infectious diseases: 4(4) 1998 Vitek & Wharton 36 5/24/201 Diphtheria Incidence 37 5/24/201 Diphtheria in the Russian Federation 38 5/24/201 The End 39 5/24/201 Performance Objectives Key terms, concepts short answers 40 5/24/201 Key Terms pseudomembrane 41 5/24/201 Key Terms Schick test Elek Test Diphtheria toxin larnygeal diphtheria pharyneal diphtheria 42 5/24/201 Key Organisms Corynebacterium Listeria Erysipelothrix 43 5/24/201 Key Concepts 44 5/24/201 Epidemiology of Diphtheria Disease/bacterial factors Transmission Who is at risk Geography/ season Incidence Modes of control 45 5/24/201 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. 46 5/24/201