微生物肠杆菌科课件

Outline

GeneralpropertiesofentericbacilliEscherichia（埃希菌属）Shigella（志贺菌属）Salmonella（沙门菌属）MorphologyGram-negativeRodshaped(bacilli)Mostformpiliandperitrichousflagella(周鞭毛)DonotformsporesCulturecharacteristicsFacultativeanaerobes(兼性厌氧)oraerobes(需氧)Growreadilyonsimplemedia.Colonies:circular,convex,smoothBloodagarplate:somecanformhemolyticzones.Liquidmedia:turbid.AntigensOantigens:LPS,IgMHantigens:

flagellin,IgGCapsularantigens:typespecific,ViantigenandKantigen.Resistance:

relativelyweakVariationGram-negativerod-shapedbacilliMacConkeyagar

AculturemediumdesignedtogrowGram-negativebacteriaandstainthemforlactosefermentation.Itcontainsbilesalts(toinhibitmostGram-positivebacteria,exceptEnterococcusandsomespeciesofStaphylococcus),crystalvioletdye(whichalsoinhibitscertainGram-positivebacteria),neutralreddye(whichstainsmicrobesfermentinglactose),lactose(乳糖)andpeptone(蛋白胨).Macconkeyagarwithlactose(left)andnon-lactose(right)fermenters.

SmoothRoughHOSection1

Escherichia(埃希菌属)

E.coliE.coliBiologicalcharacterizationPathogenesisandsyptomatologyPathogenicsubstancesClinicalfindingsLaboratorydiagnosisTreatmentMorphologyGram-negativeRodshaped(bacilli)Mostformpiliandperitrichousflagella(周鞭毛)DonotformendosporesCulturecharacteristicsFacultativeanaerobes(兼性厌氧)Liquidmedia:turbid.Growreadilyonsimplemedia.Colonies:circular,convex,smooth.Gram-negativerod-shapedbacilliSSagar

(SalmonellaShigellaagar)Ingredients:Nutrientagar100ml

Lactose(乳糖)1.00gBilesalts0.85ginhibitorSodiumcitrate0.85ginhibitorSodiumthiosulfate0.85g10%ferriccitrate1ml

1%Neutralred0.25mlindicator1%brilliantgreen0.033mlinhibitorEscherichiacolionSSagar(pinkcolony)KliglerIronAgar(KIagar)Ingredients:

Peptones2.00gNaCl0.50g

Glucose

0.10g

Lactose1.00g

Ferroussulfate0.05gSodiumthiosulfate0.075gAgar0.50g0.2﹪phenolred1.25mlDistilledwater100mlSlantButtInacidcondition:yellowInbasecondition:redReadingresultsofKIagar(sulfuretedhydrogen)2-Shigella

3-Salmonella4-E.ColiSemisolidmediumE.coliSSagar:reddishcolonyKIagar:yellowslantsandbutts,

bubbleinthebottom,thelineofinoculationisblurrynoH2SSemisolid:turbidgrowth,withflagella色氨酸吲哚对二甲基氨基苯甲醛玫瑰吲哚+E.coli某些细菌在糖代谢过程中，分解葡萄糖产生丙酮酸，丙酮酸可进一步分解，产生甲酸、乙酸、乳酸等，使培养基的pH降至4.5以下，当加入甲基红试剂则呈红色，为甲基红试验阳性。若细菌分解葡萄糖产酸量少，或产生的酸进一步转化为其他物质（如醇、酮、醚、气体和水等），则培养基的酸度仍在pH6.2以上，故加入甲基红指示剂呈黄色，是为阴性。某些细菌在葡萄糖蛋白胨水培养基中能分解葡萄糖产生丙酮酸，丙酮酸缩合，脱羧成乙酰甲基甲醇，后者在强碱环境下，被空气中氧氧化为二乙酰，二乙酰与蛋白胨中的胍基生成红色化合物，称V-P（+）反应。大肠埃希菌V-P试验阴性，产气肠杆菌V-P试验阳性。以枸橼酸钠为唯一碳源、PH值7.0的培养基上，产气杆菌分解枸橼酸钠产生碳酸盐，使培养基由中性变为碱性，培养基中指示剂溴麝香草酚蓝（BTB）由浅绿色变为深蓝色，此为枸橼酸盐利用试验阳性。大肠杆菌因不能利用枸橼酸盐，此试验为阴性反应。

AdhesinsExotoxinsOthervirulencefactorsEndotoxinCapsulesTypeⅢsecretionsystemsPathogenicsubstancesAdhesins（黏附素）Function:facilitatethespecificadherence.Severaltypes:Colonizationfactorantigen,CFAⅠ/Ⅱ/Ⅲ（定植因子抗原Ⅰ,Ⅱ,Ⅲ）Aggregativeadherencefimbriae,AAFⅠ/Ⅲ（集聚黏附菌毛Ⅰ和Ⅲ）Bundleformingpili,Bfp（束形成菌毛）Intimin（紧密黏附素）Ppili（P菌毛）Exotoxins（外毒素）Shigatoxins(Stx-1,Stx-2)（致贺毒素Ⅰ和Ⅱ）Heatstableenterotoxins(STa,STb)（耐热肠毒素a和b）Heatlabileenterotoxins(LT-Ⅰ,LT-Ⅱ)（不耐热肠毒素Ⅰ和Ⅱ）Hemolysin（溶血素A）:uropathogenicE.coli(UPEC)ClinicalfindingsDiarrhea-causingE.coliETEC:enterotoxigenicE.coli肠产毒型大肠埃希菌“Traveler’sdiarrhea”&Children’sdiarrheaWaterydiarrheawithoutbloodSelf-limiting(3~4days)EIEC:enteroinvasiveE.coliEPEC:enteropathogenicE.coliEHEC:enterohemorrhagicE.coliEAEC:enteroaggregative

E.coliEnterotoxigenic(ETEC)Pathogenicsubstances★EnterotoxinsHeatlabileenterotoxin,LT-ⅠHeatstableenterotoxin,ST-aColonizationfactorantigens(CFAⅠ/Ⅱ/Ⅲ)Heatlabileenterotoxin（不耐热肠毒素）EncodedbyplasmidLT-Ⅰ:amajorvirulencefactor

HeatlabileLikecholeragen(霍乱肠毒素)1subunitA(toxic)+5subunitB(binding)SubunitB:bindtoGM1-ganglioside（神经节苷脂）SubunitA:Activatesadenyl

cyclase(腺苷环化酶)ATP→cAMP

Secretionwater/ions霍乱肠毒素的作用机制Heatstableenterotoxin（耐热肠毒素）EncodedbyplasmidSTa:amajorvirulencefactor

HeatstableFunctions:Activatesguanylyl

cyclase(鸟苷环化酶)cGMP

Secretionwater/ionsLT-Ⅰ&STa

TheresultisthestimulationofchloridesecretionoutofthecellandtheblockageofNaClabsorption.Theneteffectistheaccumulationofwaterandelectrolytesintothebowellumen.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≤3个大肠菌群/1L饮水≤5个大肠菌群/100ml瓶装汽水、果汁卫生学指标我国饮用水卫生标准：Section2Shigella

Biological

characterizationShigella(small,colorless,transparentcolony)E.coli(large,reddishcolony)Shigellasonneionbloodagar.Mediumsized,greycoloniesthatcausenoalterationoftheblood.2-Shigella

3-Salmonella4-E.ColiSemisolidmediumShigellaSSagar:flaxencolonyKIagar:redslantsandyellowbutts,nobubbleinthebottom,thelineofinoculationisclearnoH2SSemisolid:lineargrowth,withoutflagellaPathogenesis★PathogenicsubstancesInvasivenessEndotoxinExotoxinClinicalfindingsBacillarydysentery(菌痢)HumansareonlyknownreservoirsOral-fecaltransmissionAcuteChronic:>2MInternalizedshigellaeinduceapoptosisofmacrophageandreleaseofthebacteriaAttractedbythecytokinesreleasedbymacrophageActivatestheinvasiongenesonthevirulenceplasmidMcell3.Exotoxin2.Endotoxin1.Invasiveness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M细胞致病过程：黏附→Ⅲ型分泌系统→细胞膜内陷、细菌内吞→胞内生长繁殖→扩散脓血黏液便：坏死的黏膜、死亡的WBC、细胞碎片、纤维蛋白和血液1、侵袭力：2、毒素：内毒素作用于肠壁通透性增加（腹泻）粘膜炎症、溃疡（脓血黏液便）局部全身内毒素血症（发热、神志障碍、中毒性休克）外毒素

志贺毒素植物NS功能紊乱（腹痛、里急后重）干扰蛋白合成，导致上皮细胞损伤所致疾病——细菌性痢疾急性细菌性痢疾急性典型：发热、腹痛、里急后重、脓血粘液便急性中毒型：小儿常见，全身性中毒症状慢性细菌性痢疾：病程迁移二月以上传染源：病人和带菌者传播途径：粪—口传播

中毒性痢疾病人

Specimens:Freshstool,mucusflecks,andrectalswabs.LargenumbersoffecalleukocytesandsomeRBCsmayoftenbeseenmicroscopically.

Culture:Differentialandselectivemediaasusedforsalmonellae.Serology:Multipledrugresistance.LaboratorydiagnosisTreatment:Humansaretheonlyreservoirforshigellae.Transmissionofshigellae:water,food,fingers,feces,andflies.Mostcasesoccurinchildrenunder10yearsofage.Preventionandcontrolofdysentery:Sanitarycontrolofwater,foodandmilk;sewage

disposal;andflycontrol.Isolationofpatientsanddisinfectionofexcreta.Detectionofsubclinicalcasesandcarriers.Preventionandcontrol

SalmonellaMorphologyGram-negativeRodshaped(bacilli)Mostformpiliandperitrichousflagella(周鞭毛)DonotformendosporesCulturecharacteristicsFacultativeanaerobes(兼性厌氧)Growreadilyonsimplemedia.BacterialcharacterizationSalmonellaonSSagar（colourlesscolonywithablackcenter）SalmonellaonSSagar2-志贺菌

3-沙门菌

4-大肠埃希菌SemisolidmediumSalmonellaSSagar:flaxencolonywithblackcenterKIagar:yellowslantsandbutts,nobubbleinthebottom,thelineofinoculationisblurryproduceH2SSemisolid:turbidgrowth,withflagellaPathogenicsubstancesInvasiveness(侵袭力)——小肠黏膜（M细胞）Pili（特异性菌毛）SPI-ⅠandSPI-Ⅱ（Ⅲ型分泌系统）Acidtoleranceresponse,atr（耐酸应答基因）Oxidase（氧化酶）,SOD（超氧化物歧化酶）Viantigen（微荚膜）Endotoxin(内毒素)