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1、Rickettsia,Chlamydia,Mycoplasma,Legionella,andGardnerellaEverythingelsetotheend……….RickettsiaClassification–FamilyRickettsiaceaewith3medicallyimportantgeneraRickettsiaCoxiellaRochlimaeaMorphologyandculturalcharacteristicsAllareobligateintracellularparasites(exceptRochlimaea)thatca
2、ngrowinbothphagocyticandnonphagocyticcells.RochlimaeacanbecultivatedonartificialmediacontainingbloodRickettsiaOthersaregrowninembryonatedeggsortissuecultureCultivationiscostlyandhazardousbecauseaerosoltransmissioncaneasilyoccurSmall,pleomorphiccoccobacilliGramstainpoorly,butappear
3、tobeG-StainreadilywithGiemsaAll,exceptCoxiella,aretransmittedbyarthropodvectors.RickettsiaDiagnosis/serologicaltestsDirectdetectionofRickettsiaintissues(Giemsastainordirectfluorescentantibodytest)Weil-Felixreaction–incertainrickettsialinfections(typhusgroup)antibodiesareformedthat
4、willagglutinateOXstrainsofProteusvulgaris.Thisisusedasapresumptiveevidenceoftyphusgroupinfection,however,thetestisnotverysensitiveorspecificandmanyfalsepositivesoccur.RickettsiaAgglutinationorcomplementfixationtestsusingspecificRickettsialantigensarebetterserologicaldiagnostictest
5、s.VirulencefactorsRickettsialsp.InducedphagocytosisRecruitmentofactinforintracellularspreadCoxiellaburnettiIsresistanttolysosomalenzymesRickettsiacell-to-cellspreadRickettsiarickettsiiRickettsiaClinicalsignificance–thediseasescausedbyRickettsiaareallcharacterizedbyfever,headache,m
6、yalgias,andusuallyarash.Typhusfevers–incubationis5-18days.Symptomsincludeasevereheadache,chills,fever,andafterafourthday,amaculopapularrashcausedbysubcutaneoushemorrhagingasRickettsiainvadethebloodvessels.Therashbeginsontheuppertrunkandspreadtoinvolvethewholebodyexcepttheface,palm
7、softhehands,andthesolesofthefeet.Thediseaselastsabout2weeksandthepatientmayhaveaprolongedconvalescence.Twotypesoftyphusmayoccur:RickettsiaEpidemictyphus–causedbyR.prowazekiiandtransmittedbyhumanliceasitbitesanddefecatesinthewound.Thisoccursincrowdedareascausingepidemics.Mortalityr
8、atesarehighinuntreatedcases.Follo