医学授课ppt蓝黑模板之微生物学MedicalMicrob

MedicalMicrobiologyLecture3Dr.SalehMYOTHPhDMedicalMolecularBiotechnologyandInfectiousDiseases02/10/2010IMS-MSUSystemicBactreiologySTREPTOCOCCISystemicBactreiologyWordsmusttobeknown1.GroupAstreptococcus(S.pyogenes)2.Lancefieldgroups3.Hemolysis(alpha,beta,gamma)4.Bacitracinsusceptibilitytest5.M,T,Rproteins6.StreptolysinsOandS7.Fprotein/lipoteichoicacid8.Rheumaticfever/carditis/arthritis9.Glomerulonephritis10.Scarletfever11.Toxicshock-likesyndrome/bacteremia12.“Flesh-eatingbacteria”13.Pyrogenictoxin14.Erythrogenictoxin1.GroupBstreptococcus(S.agalactiae)2.Neonatalsepticemia/meningitis3.CAMPtest4.Hippuratehydrolysistest5.GroupDstreptococcus6.Urinarytractinfection/endocarditis7.Bile-esculintest8.Enterococci9.Non-enterococci10.Largecolony11.Minutecolony12.Viridansstreptococci13.Dentalcaries/endocarditisStreptococcuspyogenesDuringtheinfection,thisbacteriaproducepus-Oneofthemostimportantpathogens-Grampositivecocciinchains-LancefieldSerologicalGroupA-BetaHemolyticonbloodagarGramStainofS.pyogenesStreptcoccuspyogenesS.agalactiaS.peumoniaeHemolysisonBloodAgarPlatesBetahemolysis-organismsexcretespotenthemoysinswhichcompletelylyseRBCs(completehemolysis)thusaclearzoneappearsaroundcolony.S.pyogenesAlphahemolysis-organismexcreteshemolysinswhichpartiallybreakdownrbc(incompletehemolysis)thusagreenishzoneappearsaroundcolony.S.pneumoniaeS.pyogenesS.pneumoniaBetahemolysisAlphahemolysisStreptococci–facultativeanaerobe–Gram-positive–chainsorpairs–catalasenegative(staphylococciarecatalasepositive)Streptococcusinchains(Gramstain)Streptococci•Lancefieldgroups*oneormorespeciespergroup*carbohydrateantigensGroupablestreptococci1-A,BandDfrequent2-C,G,FlessfrequentNon-groupable1-S.pneumoniaepneumonia2-viridansstreptococcie.g.S.mutans*dentalcarieshemolysisreaction-sheepbloodagara-(beta-β)completeclearingAandBb-(alpha-α)partialhemolysisgreencolorc-(gamma-δ)nolysisWhitecoloniesHemolysis1-GroupsAanBβ-hemolysis2-GroupDαorδ-hemolysis3-S.pneumoniaeandS.viridansα-hemolysishemolysisreaction+onecharacteristicpresumptiveidentificationGroupAstreptococcus(S.pyogenes)GroupAstreptococcalinfectionsaffectallagespeakincidenceat5-15yearsofageS.pyogenes–suppurative1-non-invasive-pharyngitis-skininfection,impetigo2-invasivebacteremia-toxicshock-likesyndrome-flesheatingbacteria-pyrogenictoxinPyrogenictoxinStreptococcuspyogenesandStaphylococcusaureusexpresspyrogenictoxinsuperantigens(PTSAgs)thatareassociatedwithtoxicshocksyndrome(TSS)andstaphylococcalfoodpoisoning(SFP).MostPTSAgscauseTSSindeep-tissueinfections,whereasonlyTSStoxin1(TSST-1)isassociatedwithmenstrual,vaginalTSS.Incontrast,SFPhasbeenlinkedonlywithstaphylococcalenterotoxins(SEs).Pyrogenictoxin…BecauseofthedifferentialabilitiesofPTSAgstocausesystemicorlocalizedsymptomsinasite-dependentmanner,thesetoxinshaveabilitiestocrossmucosalbarriers.TheactivityofthreePTSAgswhendeliveredorally,vaginally,orintravenouslytorabbitsandorallytomonkeysinsomeexperimentalstudies.Pyrogenictoxin1-superantigen2-Tcellmitogen3-activatesimmunesystemScarletfever-rash-erythrogenictoxinnon-suppurativerheumaticfever-inflammatorydisease-lifethreatening-chronicsequalae•fever•heart•joints•rheumaticNOTrheumatoidarthritisRheumaticfeverisaninflammatorydiseasethatoccursfollowingaGroupAstreptococcalinfection,(suchasstrepthroatorscarletfever).Believedtobecausedbyantibodycross-reactivitythatcaninvolvetheheart,joints,skin,andbrain,theillnesstypicallydevelopstwotothreeweeksafterastreptococcalinfection.Acuterheumaticfevercommonlyappearsinchildrenbetweentheagesof5and15,withonly20%offirst-timeattacksoccurringinadults.Theillnessissonamedbecauseofitssimilarityinpresentationtorheumatism.Rheumaticfever-etiology•Mprotein–cross-reactsheartmyosin–autoimmunity•Cellwallantigens–poorlydigestedinvivo–persistindefinitelyRheumaticfever•Penicillin-terminatespharyngitis-decreasescarditisAcuteglomerulonephritisimmunecomplexdiseaseofkidneyMajorpathogenesisfactorslipoteichoicacid/FproteinfimbriaebindstoepithelialcellsMproteinanti-phagocyticS.pyogenesfibronectinlipoteichoicacid/F-proteinepithelialcellsMproteinMproteinfibrinogenrrrpeptidoglycanrrrIgGComplementIMMUNENON-IMMUNEMproteinmajortargetnaturalimmunitystrainvariationantigenicityre-infectionoccurswithdifferentstrainCapsulesAnti-phagocyticmucoidstrainsIsolationandidentificationβ-hemolyticcoloniesbacitracininhibitsgrowthβ-hemolyticcoloniesgroupAantigenBacitracinisamixtureofrelatedcyclicpolypeptidesproducedbyorganismsofthelicheniformisgroupofBacillussubtilisvarTracy,isolationofwhichwasfirstreportedin1945.Asatoxicanddifficult-to-useantibiotic,bacitracindoesnotworkwellorally.However,itisveryeffectivetopically,andisacommoningredientofeyeandskinantibioticpreparations.Itsactionisongram-positivecellwalls.Itcancausecontactdermititisduetoallergicsensitivitytoit.Β-hemolysishemolysinOsensitiveoxygenhemolysinSinsensitiveoxygenModernRapid“Strep”TestThroatswabextract(+/-streptococcalantigen)AntibodyLiposome+-StreptococcalantigenPost-infectiousdiagnosis(serology)antibodiestostreptolysinOimportantifdelayedc