醫(yī)學(xué)授課藍(lán)黑模板之微生物學(xué)MedicalMicrob

MedicalMicrobiology

Lecture3Dr.SalehMYOTHPhDMedicalMolecularBiotechnologyandInfectiousDiseases02/10/2010IMS-MSUSystemicBactreiologySTREPTOCOCCISystemicBactreiologyWordsmusttobeknownGroupAstreptococcus(S.pyogenes)LancefieldgroupsHemolysis(alpha,beta,gamma)BacitracinsusceptibilitytestM,T,RproteinsStreptolysinsOandSFprotein/lipoteichoicacidRheumaticfever/carditis/arthritisGlomerulonephritisScarletfeverToxicshock-likesyndrome/bacteremia“Flesh-eatingbacteria”PyrogenictoxinErythrogenictoxinGroupBstreptococcus(S.agalactiae)Neonatalsepticemia/meningitisCAMPtestHippuratehydrolysistestGroupDstreptococcusUrinarytractinfection/endocarditisBile-esculintestEnterococciNon-enterococciLargecolonyMinutecolonyViridansstreptococciDentalcaries/endocarditis

Streptococcuspyogenes

Duringtheinfection,thisbacteriaproducepus-Oneofthemostimportantpathogens-Grampositivecocciinchains-LancefieldSerologicalGroupA-BetaHemolyticonbloodagarGramStainofS.pyogenesStreptcoccuspyogenesS.agalactiaS.peumoniaeHemolysisonBloodAgarPlatesBetahemolysis-organismsexcretespotenthemoysinswhichcompletelylyseRBCs(completehemolysis)thusaclearzoneappearsaroundcolony.S.pyogenesAlphahemolysis-organismexcreteshemolysinswhichpartiallybreakdownrbc(incompletehemolysis)thusagreenishzoneappearsaroundcolony.S.pneumoniaeS.pyogenesS.pneumoniaBetahemolysisAlphahemolysisStreptococci

facultativeanaerobeGram-positivechainsorpairscatalasenegative

(staphylococciarecatalasepositive)Streptococcusinchains(Gramstain)

Streptococci

Lancefieldgroupsoneormorespeciespergroup carbohydrateantigensGroupable

streptococci1-A,BandDfrequent2-C,G,FlessfrequentNon-groupable1-S.pneumoniaepneumonia2-viridansstreptococcie.g.S.mutansdentalcarieshemolysisreaction-sheepbloodagara-(beta-β)completeclearingAandBb-(alpha-α)partialhemolysisgreencolorc-(gamma-δ)nolysisWhitecoloniesHemolysis1-GroupsAanBβ-hemolysis2-GroupDαorδδ-hemolysis3-S.pneumoniaeandS.viridansα-hemolysishemolysisreaction+onecharacteristicpresumptiveidentificationGroupAstreptococcus(S.pyogenes)GroupAstreptococcalinfectionsaffectallagespeakincidenceat5-15yearsofageS.pyogenes–suppurative1-non-invasive-pharyngitis-skininfection,impetigo2-invasivebacteremia-toxicshock-likesyndrome-"flesheating"bacteria-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-chronicsequalaefeverheartjointsrheumaticNOTrheumatoidarthritisRheumaticfeverisaninflammatorydiseasethatoccursfollowingaGroupAstreptococcalinfection,(suchasstrepthroatorscarletfever).Believedtobecausedbyantibodycross-reactivitythatcaninvolvetheheart,joints,skin,andbrain,theillnesstypicallydevelopstwotothreeweeksafterastreptococcalinfection.Acuterheumaticfevercommonlyappearsinchildrenbetweentheagesof5and15,withonly20%offirst-timeattacksoccurringinadults.Theillnessissonamedbecauseofitssimilarityinpresentationtorheumatism.Rheumaticfever-etiologyMproteincross-reactsheartmyosinautoimmunityCellwallantigenspoorlydigestedinvivopersistindefinitelyRheumaticfeverPenicillinterminatespharyngitisdecreasescarditisAcuteglomerulonephritisimmunecomplexdiseaseofkidneyMajorpathogenesisfactorslipoteichoicacid/FproteinfimbriaebindstoepithelialcellsMproteinanti-phagocyticS.pyogenesfibronectinlipoteichoicacid/F-proteinepithelialcellsMproteinMproteinfibrinogenrrrpeptidoglycanrrrIgGComplementIMMUNENON-IMMUNEMproteinmajortargetnaturalimmunitystrainvariationantigenicityre-infectionoccurswithdifferentstrainCapsulesAnti-phagocyticmucoidstrainsIsolationandidentificationβ-hemolyticcoloniesbacitracininhibitsgrowthβ-hemolyticcoloniesgroupAantigenBacitracinisamixtureofrelatedcyclicpolypeptidesproducedbyorganismsofthelicheniformisgroupofBacillussubtilisvarTracy,isolationofwhichwasfirstreportedin1945.Asatoxicanddifficult-to-useantibiotic,bacitracindoesnotworkwellorally.However,itisveryeffectivetopically,andisacommoningredientofeyeandskinantibioticpreparations.Itsactionisongram-positivecellwalls.Itcancausecontactdermititisduetoallergicsensitivitytoit.Β-hemolysishemolysinOsensitiveoxygenhemolysinSinsensitiveoxygenModernRapid“Strep”TestThroatswabextract(+/-streptococcalantigen)AntibodyLiposome+-StreptococcalantigenPost-infectiousdiagnosis(serology)antibodiestostreptolysinOimportantifdelayedclinicalsequelaeoccurTraditionalserotypingofproteins:-M-T-RTypingModern:-SequencingofMproteingeneGroupBstreptococcusneonatalmeningitissepticemiatransmissionvaginalfloraGroupBstreptococcus

-identificationhemolysishippuratehydrolysisCAMPreactionincreaseshemolysisofS.aureusGroupDstreptococcusGrowthonbileesculinagarblackprecipitate6.5%salinegrowenterococcinogrowthnon-enterococciEnterococcidistantlyrelatedtootherstreptococcigenusEnter