ENTEROBACTERIACEAE Morphology Identification Gram negativenon sporeformingrods Whenmotile byperitrichousflagella Primarilynormalfloraofgastrointestinaltract E coli Klebsiella Proteus EnterobacterFreeliving alsotransientcolonizersofskin Facultativeanaerobes mixedacidfermentationAllfermentglucose allreducenitratestonitrites alloxidasenegative Lactosefermentation normalflorapositiveandpathogensnegative Primaryisolationmediaincludeeosin methylene blue EMB andMacConkeyagar Differentialselectivemediaforspecificorganismsincludingdyesandbilesalts Salmonella Shigella SS medium bismuthsulfitemedia Classification 29genera over100species EscherichiaShigellaEdwardsiellaSalmonellaCitrobacterKlebsiellaEnterobacterHafniaSerratia ProteusProvidenciaMorganellaYersiniaErwiniaPectinobacterium AntigenicStructure Mostaremotilebyperitrichousflagella Hantigens Capsule Kantigen ViforSalmonella Cellenvelope wall LPS endotoxin Oantigen variousoutermembraneproteins Pili variousantigentypes someencodedbyplasmids 鞭毛抗原 H 菌体抗原 O K或Vi抗原 septicemia pneumonia meningitisurinarytractinfections CitrobacterEnterobacterEscherichiaHafniaMorganellaProvidenciaSerratia Opportunisticdiseases Enterobacteriaceae Enterobacteriaceae gastrointestinaldiseases EscherichiacoliSalmonellaShigellaYersiniaentercolitica Histocompatibilityantigen HLA B27EnterobacteriaceaeSalmonellaShigellaYersinia NotEnterobacteriaceaeCampylobacterChlamydia Reiter ssyndrome communityacquiredotherwisehealthypeopleKlebsiellapneumoniaerespiratorydiseasesprominentcapsuleurinarytractinfectionfecalcontaminationE coliProteusurease degradesurea alkalineurine Enterobacteriaceae Enterobacteriaceae gramnegativefacultativeanaerobicrods oxidasenegative nocytochromeoxidase Emon healthyintestineShigella Salmonella Yersinialactosenegativeidentified Feces othersitesidentifiedbiochemically Enterobacteriaceae Serotypes referencelaboratoryantigensO lipopolysaccharide H flagellar K capsular Escherichiacoli Escherichiacoli Toxins twotypesofenterotoxin Shiga typetoxin EnteroaggregativeST liketoxin Hemolysins EndotoxinTypeIIIsecretionsystemAdhesions colonizationfactors bothpiliorfimbriae non fimbrialfactorsinvolvedinattachment Thereareatleast21differenttypesofadhesions Virulencefactorsthatprotectthebacteriafromhostdefenses Capsule Ironcapturingability enterochelin Outermembraneproteins E colifimbriae mannose Type1 galactoseglycolipidsglycoproteins P E coli urinarytractinfectionIstheleadingcauseofurinarytractinfectionswhichcanleadtoacutecystitis bladderinfection andpyelonephritis kidneyinfection E coli MeningitisandSepsis Neonatalmeningitis istheleadingcauseofneonatalmeningitisandsepticemiawithahighmortalityrate UsuallycausedbystrainswiththeK1capsularantigen EnteropathogenicE coli feverinfantdiarrheavomitingnauseanon bloodystoolsDestructionofsurfacemicrovillilooseattachmentmediatedbybundleformingpili Bfp Stimulationofintracellularcalciumlevel rearrangementofintracellularactin EnterotoxigenicE coli Awaterydiarrhea nausea abdominalcrampsandlow gradefeverfor1 5days TravellersdiarrheaanddiarrheainchildrenindevelopingcountriesTransmissionisviacontaminatedfoodorwater EnterotoxigenicE coli diarrhealikecholeramildernurserytravellersdiarrheacausedbyLT ST orLT ST EnterotoxigenicE coli HeatlabiletoxinlikecholeragenAdenylcyclaseactivatedcyclicAMPsecretionwater ionsHeatstabletoxinGuanylatecyclaseactivatedcyclicGMPuptakewater ions LTvsSTactivity E coli Enteroinvasive EIEC TheorganismattachestotheintestinalmucosaviapiliOutermembraneproteinsareinvolvedindirectpenetration invasionoftheintestinalcells anddestructionoftheintestinalmucosa Thereislateralmovementoftheorganismfromonecelltoadjacentcells Symptomsincludefever severeabdominalcramps malaise andwaterydiarrheafollowedbyscantystoolscontainingblood mucous andpus resemblesshigellosis EnteroinvasiveE coli EIEC Dysenteryresemblesshigellosiselderchildrenandadultdiarrhea E coli c Enteropathogenic EPEC Malaiseandlowgradefeverdiarrhea vomiting nausea non bloodystoolsBundleformingpiliareinvolvedinattachmenttotheintestinalmucosa Thisleadstochangesinsignaltransductioninthecells effacementofthemicrovilli andtointimateattachmentviaanon fimbrialadhesioncalledintimin Thisisaproblemmainlyinhospitalizedinfantsandindaycarecenters E coli d Enterohemorrhagic EHEC Hemorrhagicbloody copiousdiarrheafewleukocytesafebrilehemolytic uremicsyndromehemolyticanemiathrombocytopenia lowplatelets kidneyfailure EnterohemorrhagicE coli UsuallyO157 H7 Transmissionelectronmicrograph EnterohemorrhagicE coli Verotoxin shiga like Hemolysinsyoungerthan5yearsold causinghemorrhagiccolitis EnteroaggregativeE coli肠集聚型大肠杆菌 acauseofpersistent waterydiarrheawithvomitinganddehydrationininfants Thatisautoagglutinationina stackedbrick arrangement thebacteriaadherestotheintestinalmucosaandelaboratesenterotoxins enteroaggregativeheat stabletoxin EAST Theresultismucosaldamage secretionoflargeamountsofmucus andasecretorydiarrhea E coli Enteroaggregative EAggEC Mucousassociatedautoagglutininscauseaggregationofthebacteriaatthe