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TRANSCRIPT
104/19/23
Corynebacteria
Filename: Coryne.ppt
204/19/23
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.