Outline

GeneralpropertiesofentericbacilliEscherichia（埃希菌屬）Shigella（志賀菌屬）Salmonella（沙門菌屬）MorphologyGram-negativeRodshaped(bacilli)Mostformpiliandperitrichousflagella(周鞭毛)DonotformsporesCulturecharacteristicsFacultativeanaerobes(兼性厭氧)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(埃希菌屬)

E.coliE.coliBiologicalcharacterizationPathogenesisandsyptomatologyPathogenicsubstancesClinicalfindingsLaboratorydiagnosisTreatmentMorphologyGram-negativeRodshaped(bacilli)Mostformpiliandperitrichousflagella(周鞭毛)DonotformendosporesCulturecharacteristicsFacultativeanaerobes(兼性厭氧)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色氨酸吲哚對二甲基氨基苯甲醛玫瑰吲哚+E.coli某些細菌在糖代謝過程中，分解葡萄糖產(chǎn)生丙酮酸，丙酮酸可進一步分解，產(chǎn)生甲酸、乙酸、乳酸等，使培養(yǎng)基的pH降至4.5以下，當加入甲基紅試劑則呈紅色，為甲基紅試驗陽性。若細菌分解葡萄糖產(chǎn)酸量少，或產(chǎn)生的酸進一步轉(zhuǎn)化為其他物質(zhì)（如醇、酮、醚、氣體和水等），則培養(yǎng)基的酸度仍在pH6.2以上，故加入甲基紅指示劑呈黃色，是為陰性。某些細菌在葡萄糖蛋白胨水培養(yǎng)基中能分解葡萄糖產(chǎn)生丙酮酸，丙酮酸縮合，脫羧成乙酰甲基甲醇，后者在強堿環(huán)境下，被空氣中氧氧化為二乙酰，二乙酰與蛋白胨中的胍基生成紅色化合物，稱V-P（+）反應。大腸埃希菌V-P試驗陰性，產(chǎn)氣腸桿菌V-P試驗陽性。以枸櫞酸鈉為唯一碳源、PH值7.0的培養(yǎng)基上，產(chǎn)氣桿菌分解枸櫞酸鈉產(chǎn)生碳酸鹽，使培養(yǎng)基由中性變?yōu)閴A性，培養(yǎng)基中指示劑溴麝香草酚藍（BTB）由淺綠色變?yōu)樯钏{色，此為枸櫞酸鹽利用試驗陽性。大腸桿菌因不能利用枸櫞酸鹽，此試驗為陰性反應。

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（緊密黏附素）Ppili（P菌毛）Exotoxins（外毒素）Shigatoxins(Stx-1,Stx-2)（致賀毒素Ⅰ和Ⅱ）Heatstableenterotoxins(STa,STb)（耐熱腸毒素a和b）Heatlabileenterotoxins(LT-Ⅰ,LT-Ⅱ)（不耐熱腸毒素Ⅰ和Ⅱ）Hemolysin（溶血素A）:uropathogenicE.coli(UPEC)ClinicalfindingsDiarrhea-causingE.coliETEC:enterotoxigenicE.coli腸產(chǎn)毒型大腸埃希菌“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（不耐熱腸毒素）EncodedbyplasmidLT-Ⅰ:amajorvirulencefactor

HeatlabileLikecholeragen(霍亂腸毒素)1subunitA(toxic)+5subunitB(binding)SubunitB:bindtoGM1-ganglioside（神經(jīng)節(jié)苷脂）SubunitA:Activatesadenyl

cyclase(腺苷環(huán)化酶)ATP→cAMP

Secretionwater/ions霍亂腸毒素的作用機制Heatstableenterotoxin（耐熱腸毒素）EncodedbyplasmidSTa:amajorvirulencefactor

HeatstableFunctions:Activatesguanylyl

cyclase(鳥苷環(huán)化酶)cGMP

Secretionwater/ionsLT-Ⅰ&STa

TheresultisthestimulationofchloridesecretionoutofthecellandtheblockageofNaClabsorption.Theneteffectistheaccumulationofwaterandelectrolytesintothebowellumen.環(huán)境和食品衛(wèi)生學上，“大腸菌群數(shù)”常被用作糞便污染的檢測指標≤3個大腸菌群/1L飲水≤5個大腸菌群/100ml瓶裝汽水、果汁衛(wèi)生學指標我國飲用水衛(wèi)生標準：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靶細胞：回腸末端和結腸部位的黏膜上皮細胞首先侵犯派伊爾淋巴結的M細胞致病過程：黏附→Ⅲ型分泌系統(tǒng)→細胞膜內(nèi)陷、細菌內(nèi)吞→胞內(nèi)生長繁殖→擴散膿血黏液便：壞死的黏膜、死亡的WBC、細胞碎片、纖維蛋白和血液1、侵襲力：2、毒素：內(nèi)毒素作用于腸壁通透性增加（腹瀉）粘膜炎癥、潰瘍（膿血黏液便）局部全身內(nèi)毒素血癥（發(fā)熱、神志障礙、中毒性休克）外毒素

志賀毒素植物NS功能紊亂（腹痛、里急后重）干擾蛋白合成，導致上皮細胞損傷所致疾病——細菌性痢疾急性細菌性痢疾急性典型：發(fā)熱、腹痛、里急后重、膿血粘液便急性中毒型：小兒常見，全身性中毒癥狀慢性細菌性痢疾：病程遷移二月以上傳染源：病人和帶菌者傳播途徑：糞—口傳播

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(兼性厭氧)Growreadilyonsimplemedia.BacterialcharacterizationSalmonellaonSSagar（colourlesscolonywithablackcenter）SalmonellaonSSagar2-志賀菌

3-沙門菌

4-大腸埃希菌SemisolidmediumSalmonellaSSagar:flaxencolonywithblackcenterKIagar:yellowslantsandbutts,nobubbleinthebottom,thelineofinoculationisblurryproduceH2SSemisolid:turbidgrowth,withflagellaPathogenicsubstancesInvasiveness(侵襲力)——小腸黏膜（M細胞）Pili（特異性菌毛）SPI-ⅠandSPI-Ⅱ（Ⅲ型分泌系統(tǒng)）Acidtoleranceresponse,atr（耐酸應答基因）Oxidase（氧化酶）,SOD（超氧化物歧化酶）Viantigen（微莢膜）Endotoxin(內(nèi)毒素)