corynbacterium 2-12-2015.pptx
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Genus: Corynebacterium
Species: C.diphtheriae
Gram positive rod
clubbing at both ends
metachromatic granules or volutin are composed ofpolyphosphates and act as energy storage sites
nonsporting, noncapsulated and nonmotile
appear in pairs, palisades, or small group (Chinese letters).12/13/15Dr Ellabib MS1
Non spore forming gram positivebacilli
D i p h t h e r i a
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General characteristics
Found as free-living saprophytes
embers of the usual flora of humans and animals
Corynebacterium diphtheriae is the most significant pathogen
Biotypes Varities
based on colony shape, biochemical propertiesand virlence
!ravis, Mitis, "ntermedis and #lfanti !ther species may cause infections in the immunocompromised hosts
12/13/15Dr EllabibMS
2
Corynebacterium Species
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C. pseudotuberculosis
C. jekeium
C. ulcerans
12/13/15Dr Ellabib MS3
$ther Corynebacteria
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"o#igenic Corynebacterium diphtheriae
$orld%ide distribution
rare in places %here vaccination programs e#ist
&#oto#in as the virulence factor
'iphtheria to#in% "o#in is produced by certain strains
% ysogenied by bacteriophage %ith to#in gene (to#*)
% "o#in is antigenic12/13/15Dr Ellabib MS&
C. diphtheriae: Agent of Diphtheria
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"o#in consists of t%o fragments +: +ctive fragment
nhibits protein synthesis
Catalyes transfer of +' to lin/ %ith &F0 +'.&F
(inactive)
eads to cell1tissue death
2 fragment
2inds to specific cell membrane receptors
ediates entry of fragment +
12/13/15Dr Ellabib MS5
'o(igenic Corynebacteriumdiphtheriae
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12/13/15Dr Ellabib MS)
heparin*binding epidermal gro+th
factor speci-c membranereceptor.
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espiratory +c3uired by droplet spray
4nimmunied individuals are susceptible
5onrespiratory Systemic
S/in and cutaneous forms
12/13/15Dr Ellabib MS
Clinical Forms of Diphtheria
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ncubation period60 to 7 days
Symptoms: sore throat, fever, malaise
"o#in is produced locally, usually in the pharyn# or tonsils
"o#in causes tissue necrosis
Forms a tough grey to %hite pseudomembrane
12/13/15Dr Ellabib MS0
espiratory diseasediphtheria
#lls nec4
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Systemic infections "o#in is absorbed in the blood stream and carried systemically
+ffects the /idneys, heart, and nervous system
'eath occurs due to cardiac failure
Cutaneous formore prevalent in the tropics
nfections occur at the site of minor abrasions
aybe superinfected %ith Streptococcus pyogenes and1or Streptococcus aureus12/13/15Dr EllabibMS
Clinical Infections:
Non-Respiratory Disease
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Clinical observation
solation of the organism
"ested for virulence
+nimals or immunological precipitin reaction (&&8 "est)
2lood agar and "ellurite agar (blac/ colonies)
12/13/15Dr Ellabib MS16
Diagnosis
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1. Clinical
2. Laboratory Diagnosis
a. Cltral Characteristics. oeffler9s slant or ai9s slant4sed to demonstrate pleomorphism and
metachromatic granules; <2abes= &rnst bodies
. Serum "ellurite or modified "insdale- bro%n or grayish to blac/ halos
around the colonies
12/13/15Dr Ellabib MS11
Diagnosis
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. In vivo toxin test using guinea pigs
. Subcutaneous
. Intracutaneous
. In vitro tests
. Elek’s gel precipitation test
. Tissue culture test 12/13/15Dr EllabibMS
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DETECTION OF TOXIGENICITY
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Life-threatening infection
Prompt neutralization of toxin
Eradication of the organism
A single dose of horse antiserum Inactivates any circulating toxinDoes not affect toxin already bound to a cell-surface receptor
Penicillin or erythromycin
12/13/15Dr Ellabib MS13
"reatment
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Immunization with toxoid
sually administered in the D!P triple vaccine together with
tetanus toxoid and pertussis antigens
"hould be started in infancy #ooster dose at $% years interval
12/13/15Dr Ellabib MS1&
7revention
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Corynebacterium species 8ommon 9ora of the nose, throat, nasopharyn(,
s4in, rinary tract and con:nctiva
'hey do not prodce e(oto(in 8ommon blood cltre commensal May case infective endocarditis of prosthetic
valves, lng abscess, rinary tract infection;
12/13/15Dr Ellabib MS15
D"7<'<E$"DS
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12/13/15Dr Ellabib MS1)