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1、i.Enteric肠道的肠道的Gram-NegativeRods&ii.Vibrio cholerae霍乱弧菌霍乱弧菌i.EntericGram-NegativeRods(Enterobacteriaceae肠杆菌肠杆菌)The Enterobacteriaceae are a large heterogenousgroup of gram-negative rods whose natural habitat istheintestinaltractofhumansandanimals.Thefamilyincludesabout29genera,over100species:Escheri
2、chiaShigellaSalmonellaCitrobacterKlebsiella Enterobacter 肠杆菌属肠杆菌属Yersinia 克雷伯氏菌属克雷伯氏菌属柠檬酸细菌属柠檬酸细菌属耶尔森氏菌属耶尔森氏菌属Someoftheentericbacilli(e.g.,Escherichia coli)arepart of the normal flora and major causing agent ofopportunisticinfection.SalmonellaeandShigellaearepathogenicforhumans.Generalcharacteristic
3、sA.AllbacillibelongingtoEnterobacteriaceaeareshortGram-negativerods,eithermobileornon-mobile,nospore,somehavecapsulesandpili.Size:0.4X3mGeneralcharacteristicsB.All bacilli belonging to Enterobacteriaceae arefacultative anaerobes or aerobes. They grow incommon media. Most of the enteric bacilli formc
4、ircular,gray,smoothcolonieswithdistinctedges.lactosefermentation乳糖发酵乳糖发酵Mechanism:Non-pathogenicentericbacilliareabletofermentlactosewhilepathogenicentericbacillisuchasShigellaandSalmonellaarenot.Basiccomponents:lactoseandapHindicatorlactosefermentation ResultsResultscolored colonies (red)colored co
5、lonies (red) non-pathogenic non-pathogenicyesnowhite colonieswhite colonies pathogenic pathogenicUsetodifferentiatenon-pathogenicE.Coli frompathogenicShigellaandSalmonella-SSagarplatelactoselactose Doublesugarironagarslants: containsglucose,lactose,ironacetate醋酸亚铁醋酸亚铁 andpHindicator. Results:hydroge
6、nsulfide(Hhydrogensulfide(H2 2S)S) +-lactosefermentationGeneralcharacteristicsD.EnterobacteriaceaehavecomplexantigenicstructuresH(flagellar)AgsomaticOAg(lipopolysaccharide)K/Vi(capsular)AgGeneralcharacteristicsE.E.CommonpathogenicmaterialsforEnterobacteriaceaeCommonpathogenicmaterialsforEnterobacter
7、iaceaeinclude:include:bacterialstructures(flagella,capsules)bacterialstructures(flagella,capsules)toxins(enterotoxin,endotoxin)toxins(enterotoxin,endotoxin)Escherichia coli大肠埃希菌大肠埃希菌MorphologyandidentificationGramnegativebacillusMotilewithflagellaRedcoloniesonSSagarmediummoststrainsfermentlactosepro
8、ductionofacidandgaswithin2448hAntigens:O-Ag,H-Ag,K-AgIMViC:+TransmissionTransmissionisbyfecal-oralroute.isbyfecal-oralroute. VirulencefactorsVirulencefactors include:include:1.Flagella:induceadhesion2.Cytotoxicenterotoxins:causediarrhea(sometimeswithblood) andtissuedamage.3.Invasionfactors:permitinv
9、asionofbacteriaintomucosa.PathogenesisPathogenesisInfectionsoutsideofintestines (causedbybacterialtranslocation寄居部位改变寄居部位改变) Opportunisticinfectionincludingsepticemia败血症败血症,pneumonia肺炎肺炎,meningitis脑膜炎脑膜炎andurinarytractinfections泌尿系泌尿系统感染统感染E.coli associatedurinarytractinfectionE.coli causes urinary
10、tractinfections such as acutecystitis急性膀胱炎andnephritis肾炎.PathogenesisInfectionsinsideofintestines:Gastroenteritis肠胃炎肠胃炎,diarrhea腹泻腹泻causedbyPathogenicE.coli.EnterotoxigenicE. coli (ETEC)肠产毒型肠产毒型Itcausesdiarrheasimilartocholerabutmuchmilderindegree.Theycancausetravellersdiarrhea“anddiarrheaininfant.T
11、wotypesofplasmid-encodedtoxinsareproduced.a)Heatlabiletoxins(LT):不不耐耐热热肠肠毒毒素素similartocholeratoxin(seecholerasectionbelow)b)Heatstabletoxins(ST):耐热肠毒素耐热肠毒素Clinicalsignsofcauseddiseasearewaterydiarrhea,feverandnausea头晕头晕.EnteroinvasiveE. coli (EIEC)肠侵袭型肠侵袭型It is commonly found associated with elder c
12、hildren and adultdiarrhea，withnoproductionofenterotoxins，infectandgrowintheenterocytes.Morphologically,itisaShigella-likeE.coliwithoutflagella.AverysmallnumberofEIECcancauseseriousillness(highvirulence).Acute inflammatory response 炎炎症症反反应应 and tissue destructionproducediarrheawithlittlefluid,muchblo
13、odandmucus脓血便。脓血便。EnteropathogenicE. coli (EPEC)肠致病型肠致病型Itiscommonlyfoundassociatedwithinfantdiarrhea，noproductionofenterotoxins,noinvasiveness.There is a characteristic morphological lesion withdestructionofmicrovilli微微绒绒毛毛withoutinvasionoftheorganism,suggestingimportanceofbacterialadhesion.Clinica
14、l signs: fever, watery diarrhea with and non-bloodystools,vomiting呕吐呕吐andnausea.EHECproducesexotoxin.Theillnessischaracterizedbyseriousabdominalpain腹腹痛痛anddiarrheawhichisinitiallywaterybutthenbecomesbloody.Inchildren,thediseasemaybeprogressedtoasystemicstagecalled as hemolytic uremic syndrome 溶溶血血性性
15、尿尿毒毒综综合合征征 (kidneyinjury)with10%deathrate.EnterohemorrhagicE. coli (EHEC)肠出血型肠出血型Itcausesapersistent,mucus-waterydiarrheawithvomitinganddehydrationininfants.Itproducesenteroaggregativeheat-stabletoxin.It produces mucous associated autoagglutinin自自体体凝凝集集素素 whichcausesaggregationofthebacteriaatthecell
16、surfaceaswellasformationofbiofilm生物膜生物膜.EnteroaggregativeE.coli (EAggEC)肠聚集型肠聚集型Sanitary卫生的卫生的significance Total bacterialnumber: The number of bacteria containedpermlorpermgofthesample,andthestandardfordrinkingwaterislessthan100bacteria.Coliformbacteriaindex大大肠肠杆杆菌菌指指数数:Thenumberofcoliformbacteria
17、contained per 1000 ml of the sample, and thestandardfordrinkingwaterislessthan3.Shigella 志贺菌志贺菌ClassificationAccordingtothedifferenceofOantigen,Shigellastrainsaredividedinto4groups:S. dysenteriae S. dysenteriae 痢疾志贺菌痢疾志贺菌痢疾志贺菌痢疾志贺菌 S. flexneri S. flexneri 福氏志贺菌福氏志贺菌福氏志贺菌福氏志贺菌 S. boydii S. boydii 鲍氏志
18、贺菌鲍氏志贺菌鲍氏志贺菌鲍氏志贺菌 S. sonnei S. sonnei 宋内志贺菌宋内志贺菌宋内志贺菌宋内志贺菌Morphologyandidentification Gram-negativebacilli，nosporeandcapsulenon-motile(withoutflagella)non-fermentationoflactoseMotility Test（-）（+）Onregularagarplate:Onregularagarplate:Mediumsize,smooth,semitransparentcoloniesMediumsize,smooth,semitran
19、sparentcoloniesantigenic structures: O and K antigensO and K antigensPathogenicfactors pilipiliendotoxinendotoxin： fever，toxicshock,inflammationresponse,ulcer,bloodystool,abdominalpainexotoxin:exotoxin: Shigella dysenteriae canproduceanexotoxincalledas shiga-toxin志贺毒素志贺毒素.Shiga-toxinisenterotoxic,cy
20、totoxicandneurotoxic.Sothedysenterycausedbythismicrobeismoreseriousthanthatbytheotherthreegroups.Clinicalfindings Shigella isthemostcommonofbacteriatocausebacterialdysentery细菌性痢疾细菌性痢疾inhumanwithcharacteristicbloodandmucusstools.Shigella onlyinvadesintestinalmucosaandneverentersbloodstream不入血不入血. The
21、endotoxincanbeabsorbedintobloodstreamtocauseendotoxemia内毒素症内毒素症. Toxicdysentery: Inchildren,Shigella infectioncancausesystemictoxicsymptoms全身毒性症状.Childrensufferingfromtoxicdysenterydisplayahighdeathrate. Systemic toxic symptomsAbdominalcramps,diarrhea,fever,andbloodystoolsPrevention of fecal-oral tr
22、ansmission is the mosteffectivecontrolstrategy.Dysenteryistreatedwithantibiotics.ButmultipledrugresistancemediatedbyplasmidsarecommoninmanyShigellastrains.Vaccinesarenotcurrentlyavailable.ControlSalmonella 沙门菌属沙门菌属 Gramnegativebacilli,withpili,nospore,nocapsule(butwithslimecapsule)motilewithflagella
23、Non-fermentationoflactoseantigenicstructures:O,HandViantigensO,HandViantigens(Morethan2000serotypesbasedonantigenicdifference) )MorphologyandidentificationPathogenicfactorsViantigen:Viantigen:consisted of capsular polysaccharide. It resists phagocytosis and plays an important role during invasion of
24、 Salmonella.Endotoxin:Endotoxin:fever, toxic syndrome, shock, enteric inflammationEnterotoxin:Enterotoxin:watery diarrheaDiseasesHumanandmanydifferentanimalscanbecarriedorinfectedwithSalmonella Salmonella .SalmonellaSalmonellacansurviveingallbladderbecauseofitsbileresistanceandestablishchroniccarria
25、ge.DiseasesEntericfever(typhoidfever)肠热症肠热症Food-poisoning肠胃炎（食物中毒）肠胃炎（食物中毒）Septicemia败血症败血症Entericfever/typhoidfeverEnteric fever / typhoid fever is the mostseriousformofsalmonellainfectionwhichonlyoccursinhuman.Carryingstateofthemicrobesinhumaniscommonsothatonecarriercancausealotofspread.Inuntreate
26、dpatients,thedeathrateisfrom7%to14%.Antibiotic therapy is essential, vaccines are notwidelyeffectiveandnotgenerallyused.living storehouses and factories of disease and human culture tubes. TyphoidMaryAhealthycarrieroftyphoidwhobythistimehadalreadyinfectednumerouspeoplethroughhercooking.Shehadbeenqua
27、rantinedagainstherwillforovertwoyearsonanisland.1.Themicrobeinitiallyinvadesintestinalmucosalepitheliumandpropagateinthelocal.2.Themicrobepenetratesintothebloodstreamtocausethefirstbacteremia菌菌血血症症withsymptomsoffever,generaldiscomfortandpain.3.The microbe enters many organs such as liver, spleen 脾脾,
28、kidney 肾肾 脏脏 , gall bladder 胆胆 囊囊 and marrow for furtherpropagation.4.The microbe penetrates into the bloodstream again to causethe second bacteremia with serious symptoms of high fever,swellofspleenandliver,rose-coloredspotsinskin,andtissueinjury.(Majorpathogenicfactors:Viantigenandendotoxin)Diseas
29、edevelopmentrose-coloredspotsinskinEntericfeverGastroenteritisandsepticemiaGastroenteritis(foodpoisoning):ItisthemostcommonSalmonellainfectionsandusuallytransmittedfromcontaminatedfood.However, only a few of food poisoning-causingsalmonellaserotypescanproduceenterotoxin.Septicemia:ManySalmonellasero
30、typescancausesepticemia.Thisdiseaseiscommonlyfoundinchildrenoradultwithlowimmunity.LaboratoryDiagnosis1.Specimencollection ofentericfever: In the first week, blood is collected as samples because of the first bacteremia. From the second week on, stool and urine are collected as samples because of ef
31、fluence of the bacteria from stool and urine. 2.WidaltestDefinition:aagglutinationtestusingtheknownOandHantigensofS.typhitodetectspecificserumantibodies.ii. Vibrio cholerae(Cholera霍乱霍乱) GeneralindroductionofcholeraCholeracausedbyVibrio cholerae ischaracterizedby profuse watery diarrhea and serious v
32、omitingwhich resulting in extreme loss of fluid andelectrolytes电电解解质质,shockandkidneyprostration肾肾衰衰竭竭.Ifpatientsareuntreated,thedeathrateisashighas60%.Cholera remains a major global epidemic disease.Therehavebeen8greatoutbreaksintheworld.*In1991,agreatoutbreak(7th)startedinPeru.Morethanamillionpatie
33、ntswerefoundinCentralandSouthAmerica.*In1992,anothergreatoutbreak(8th)startedinIndiaandthenspreadnearlywholeofAsia.Notthetypical serogroupO1buttheserogroupO139,anewfoundcholerapathogencausedthisoutbreak.Cholera:outbreakinIndiaA.BiologicalcharacteristicsV. choleraearehighlymotile,Gram-negative,curved
34、弧形弧形orcomma-shaped逗点状逗点状rodswithasinglepolarflagellum单鞭毛单鞭毛,nospore.MorphologyoftypicalorganismsCultureCharacteristically,V.choleraecangrowinmediawithvery high pH (pH8.5-9.0) and are rapidly killed byacid.Catalasepositive,IndoletestpositiveO and H antigensO and H antigensAntigenicstructuresB.Pathoge
35、nicityvirulentfactorsclinicalfindingsMajorvirulentfactorsofV.choleraeFlagellum:offersanabilitytopenetrateentericmucuslayertoreachthesurfaceofhostcells.Pilus:offersanabilitytoadherehostcells.Choleratoxin(enterotoxin):themostimportantvirulentfactorwhichinducingtheelectrolyteandwaterhypersecretion过度分泌过
36、度分泌ofhostcells.ThistoxinischromosomallyencodedanditsmoleculecontainssubunitsAandB.PathogenicmechanismofcholeratoxinSubunitBbindstoitsreceptoronthesurfaceofepithelialcellsandprovidesachannelforallowingsubunitAtoenterhostcell.Dehydration is the major reason for death. Soreplacementoffluidpluselectroly
37、teismostimportantduringthetreatment.Antibiotictherapyisadditionallyused.Vaccination疫疫苗苗预预防防isonlypartiallyeffectiveandnotgenerallyrecommended.Itismostcommonlyusedbyinternationaltravelers.C.ControlSummaryThe most important contents in this lecture:General introduction: 1)the significance of lactose f
38、ermentation; 2)the categories of major antigens of enterobacteriaceae.E.coli: 1) lactose fermentation; 2) different antigens Shigella: the major virulent factors Salmonella: 1)bile resistant; 2)the developing process of typhoid fever and the associated virulent factors; Vibrio: 1) V.cholerae grows in high pH media; 2) virulent factor: cholera toxin
