OutlineMorphologyGram-negativeRodshaped(bacilli)Mostformpiliandperitrichousflagella(周鞭毛)DonotformsporesCulturecharacteristicsFacultativeanaerobes(兼性厌氧)oraerobes(需氧)Growreadilyonsimplemedia.Colonies:circular,convex,smoothBloodagarplate:somecanformhemolyticzones.Liquidmedia:turbid.BiochemicalreactionsCatalase（触酶）test:+Reducenitrate(硝酸盐)tonitrite(亚硝酸盐)Oxidase(氧化酶)test:-Lactosefermentationtest(乳糖发酵试验)乳糖发酵试验可用于初步鉴别肠道致病菌和非致病菌肠道致病菌多数不发酵乳糖（沙门菌、志贺菌）肠道非致病菌多数发酵乳糖（埃希菌）AntigensOantigens:LPS,IgMHantigens:flagellin,IgGCapsularantigens:typespecific,ViantigenandKantigen.Resistance:relativelyweakVariationGram-negativerod-shapedbacilliMacConkeyagarMacconkeyagarwithlactose(left)andnon-lactose(right)fermenters.SmoothHOSection1Escherichia(埃希菌属)E.coliE.coliMorphologyGram-negativeRodshaped(bacilli)Mostformpiliandperitrichousflagella(周鞭毛)DonotformendosporesCulturecharacteristicsFacultativeanaerobes(兼性厌氧)Liquidmedia:turbid.Growreadilyonsimplemedia.Colonies:circular,convex,smooth.BiochemicalreactionsLactosefermentationtest(乳糖发酵试验):⊕(SSagar,KIagar)H2Stest:-Motilitytest:+IMViCtests:++--Antigens:Oantigens:>170typesHantigens:>50typesKantigens:>100typesGram-negativerod-shapedbacilliSSagar(SalmonellaShigellaagar)EscherichiacolionSSagar(pinkcolony)KliglerIronAgar(KIagar)ReadingresultsofKIagar2-Shigella3-Salmonella4-E.ColiMotilitytestE.coliIndoletestsMethylredtestsVoges-ProskauertestCitrateutilizationtestAdhesinsExotoxinsOthervirulencefactorsEndotoxinCapsulesTypeⅢsecretionsystemsAdhesins（黏附素）Exotoxins（外毒素）ClinicalfindingsDiarrhea-causingE.coliEnterotoxigenic(ETEC)Heatlabileenterotoxin（不耐热肠毒素）霍乱肠毒素的作用机制Heatstableenterotoxin（耐热肠毒素）LT-Ⅰ&STa环境和食品卫生学上，“大肠菌群数”常被用作粪便污染的检测指标Section2ShigellaBiologicalcharacterizationShigellasonneionbloodagar.Mediumsized,greycoloniesthatcausenoalterationoftheblood.2-Shigella3-Salmonella4-E.ColiMotilitytestShigellaPathogenesis★Internalizedshigellaeinduceapoptosisofmacrophageandreleaseofthebacteria靶细胞：回肠末端和结肠部位的黏膜上皮细胞首先侵犯派伊尔淋巴结的