《病原生物学（医学微生物学）》课程教学课件（英文）21_Non-spore-forming G+ bacilli_Corynebacterium_Listeria_Actinomycetes

Section III BacteriologyNon-Spore-Forming Gram-Positive BacilliCorynebacterium, Propionibacterium, ListeriaActinomycetesSHIHEZIUNIVERSITY

Section III Bacteriology Non-Spore-Forming Gram-Positive Bacilli: Corynebacterium, Propionibacterium, Listeria, Actinomycetes SHIHEZI UNIVERSITY

KEY TERMS Corynebacterium+Corynebacterium diphtheriaeMetachromatic granule ListeriaActinomycetesSHIHEZI UNIVERSITY

KEY TERMS  Corynebacterium  Corynebacterium diphtheriae  Metachromatic granule  Listeria  Actinomycetes SHIHEZI UNIVERSITY

Table13-1.Someofthemorecommongram-positivebailli of medicalimportanceAerobic Gram-Ppsitive Bacll With HighG+CAerobicGramPositiveBailli ithLoweContentandrregularShapeG+CContentand MoreReqular ShapeGeneraGeneraCommonCommonListeriaCorynebacteriumUncommonErysipelothrxArcanobacteriumGardnerllaRhodococcusAerotolerantanaerobes/strictanaerobesRothiaLactobailusMany other genera of skin and environmental foraClostrdium (spore-forming) (Chapter12)AerotolerantanaerobesAerobesActinomycesBails (spore-forming) (Chapter 12)PropionibacterumMajor pathogensMajor pathogen:CorynebacterumdiphtheriaeListeria monocytogenesCommon o clinicll important isolates of theEyiplothrxrhusiopthiegenus corynebacteriumCamycolatumC mintsimumCjiekeiumCpseudodiphtheriticumCstriatumCurealyticumC xerosisG+C= guanine plus ytosine base1The medially important coryneform bacteria.SHIHEZI UNIVERSITY

SHIHEZI UNIVERSITY

CORYNEBACTERIACorynebacterium diphtheriae Rodclubed-shaped Bacterium(causes diphtheria), (SEMx240) Copyright Dr Dennis Kunkel,University of Hawai Used with permission

CORYNEBACTERIA Corynebacterium diphtheriae. Rod,clubed-shaped Bacterium (causes diphtheria), (SEM x24,000) Copyright Dr Dennis Kunkel, University of Hawaii. Used with permission

diphtheriaeCorynebacteriumGrows best under strictaerobic conditions Nonmotile, noncapsulated.club-shaped, Gram-positivebaillusMetachromatic granules atthe endsSHIHEZI UNIVERSITY

Corynebacterium diphtheriae  Grows best under strict aerobic conditions  Nonmotile, noncapsulated, club-shaped, Gram-positive bacillus  Metachromatic granules at the ends SHIHEZI UNIVERSITY

Classification, and Antigenic Types Toxigenic strains are lysogenic for one of afamily of corynebacteriophages that carry thestructural gene for diphtheria toxin, tox Corynebacterium diphtheriae is classified into Biotypes (mitis, intermedius, and gravis according to colony morphologyLysotypes-based upon corynebacteriophage sensitivitySHIHEZI UNIVERSITY

Classification, and Antigenic Types  Toxigenic strains are lysogenic for one of a family of corynebacteriophages that carry the structural gene for diphtheria toxin, tox  Corynebacterium diphtheriae is classified into Biotypes (mitis, intermedius, and gravis)  according to colony morphology Lysotypes  based upon corynebacteriophage sensitivity SHIHEZI UNIVERSITY

Pathogenesis Colonize at the upper respiratory tract(nasopharynxToxigenic strains secrete a potent exotoxin which maycause diphtheriaDoes not produce a systemic infection Systemic toxemia may be involved A pseudomembrane forms locally+composed of fibrin, bacteria, and inflammatory cells+ which can cause chockingSHIHEZI UNIVERSITY

Pathogenesis  Colonize at the upper respiratory tract (nasopharynx)  Toxigenic strains secrete a potent exotoxin which may cause diphtheria  Does not produce a systemic infection  Systemic toxemia may be involved  A pseudomembrane forms locally  composed of fibrin, bacteria, and inflammatory cells  which can cause chocking SHIHEZI UNIVERSITY

Clinical ManifestationsPharyngitis, fever, swelling ofthe neck oarea surrounding the skin lesionDiphtheritic lesions are covered by apseudomembraneThe toxin is distributed to distant organsby the circulatory system and may causeparalysis and congestive heart failureSHIHEZI UNIVERSITY

Clinical Manifestations  Pharyngitis, fever, swelling of the neck or area surrounding the skin lesion  Diphtheritic lesions are covered by a pseudomembrane  The toxin is distributed to distant organs by the circulatory system and may cause paralysis and congestive heart failure SHIHEZI UNIVERSITY

This child has diphtheria resulting in a thickgray coating over back of throat. Thiscoating can eventually expand down throughairway and, if not treated, the child could diefrom suffocation

This child has diphtheria resulting in a thick gray coating over back of throat. This coating can eventually expand down through airway and, if not treated, the child could die from suffocation

Pathogenesis of Diphtheria3.DiseaseEntryPhayngeal diphthenia4. ExitPharyngitisHypoxia-pseudomermbraneobstructionFever2.Spread -bactenaLympradenitisrarely becomeCutaneous diphtheriadisseminated butSystemic complicationstaxin becomesToxicperipheralneuropathyblood bormneToxic myocarditis andcongestiveheart failureSHIHEZI UNIVERSITY

Pathogenesis of Diphtheria SHIHEZI UNIVERSITY