1 9/10/2015 corynebacteria filename: coryne.ppt 2 9/10/2015 outline u microbes...

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Corynebacteria

Filename: Coryne.ppt

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Outline

Microbes– Corynebacterium,Listeria,

Erysipelothrix Diseases

– 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– Listeriosis

Erysipelothrix rhusiopathiae– Erysipeloid

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Diphtheria

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DiphtheriaLaboratory 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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Diphtheria

Nasopharyngeal diphtheria– Pharyngeal – Larygngeal

Cutaneous diphtheria Systemic complications

DIAGNOSIS MUST BE CLINICAL!!!!

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Pharyngeal diptheria Inflammation

– similar to strept throat

Leucocytes– infiltrated– killed– embedded in fibrin

clot TOXIN !!

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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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COVERS– tonsils, – uvula, – palate – nasopharynx – larynx.

Pseudomembrane

CONTAINS– bacteria– lymphocytes – plasma cells– fibrin– dead cells

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DiphtheriaSystemic 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

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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

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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+]

dtxR

Fe 2+ + apo DtxR [Fe 2+ *DtxR]

p

C diphtheriae

dtxR= repressor protein

NO Toxin Produced

toxCorynebacteriophage beta

oP

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Regulation of Diphtheria Toxin Low [Fe 2+]

Fe 2+ + apo DtxR [Fe 2+ *DtxR]

Toxin Produced!!!

toxCorynebacteriophage beta

oP

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Toxin Part A

– Active site– N terminal– Enzyme

Part B– 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

A

A

B

B

A

B

A

B

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Toxingenicity Tests

In Vitro Elek test

In Vivo Animal inoculationrabbit 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

– check for antibodies Passive immunity

– Antibodies Antibiotics

– Penicillin & erythromcyin

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Schick Test for Diptheria

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Epidemics 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.