病原生物学英文版课件：Gram negative bacilli

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1、Gram negative bacilliBrucellaY. pestisP. aeruginosaH. infuenzaeL. pneumophilaB. pertussisGram-negative BacillusChapter 9 EnterobacteriaceaeEscherichia埃希菌属埃希菌属讲解讲解 Shigella志贺菌属志贺菌属讲解讲解Salmonella沙门菌属沙门菌属讲解讲解Chapter 10 Vibrio & AeromonasV. cholerae霍乱弧菌霍乱弧菌讲解讲解V. paraheomlyticus副溶血性弧菌副溶血性弧菌讲解讲解Aeromonas

2、气单胞菌自学Chapter 11Helicobacter &Campylobacter Helicobacter pylori 幽门螺杆菌幽门螺杆菌讲解讲解Campylobacter jejuni空肠弯曲菌自学Chapter 16 Nonfermentative bacilliPseudomonas假单胞菌属假单胞菌属讲解讲解Acinetobacter不动杆菌属自学Stenotrophomonas嗜麦芽窄食单胞菌属自学Legionella军团菌属军团菌属讲解讲解Chapter 17 Zoonotic BacteriaBrucella 布氏菌属布氏菌属讲解讲解Yersinia 耶尔森菌属耶尔森菌

3、属讲解讲解Francisella弗朗西斯菌属自学Pasteurella巴斯德菌属自学Chapter 18 Bordetella & HaemophilusBordetella鲍特菌属鲍特菌属讲解讲解Haemophilus嗜血杆菌属嗜血杆菌属讲解讲解EnterobacteriaceaeIntroduction The Enterobacteriaceae are a large and diverse family of Gram-negative rods, members of which are both free-living and part of the indigenous flo

4、ra of humans and animals. A few are adapted strictly to humans. The Enterobacteriaceae grow rapidly under aerobic or anaerobic conditions and are metabolically active. They are by far the most common cause of urinary tract infections (UTIs), abscess, and a limited number of species are also importan

5、t etiologic agents of diarrhea. Spread to the bloodstream causes Gram-negative endotoxic shock, a dreaded and often fatal complication.EnterobacteriaceaeGram negative non-spore forming rods ，most of peritrichous flagellaNatural habitat is intestinal tract , part of normal flora and only occasional p

6、athogensprimary pathogens:Salmonella, Shigella, Some Escherichia coli, e.g ETECFacultative anaerobesAll ferment glucose; all oxidase negative. Lactose fermentation: normal flora positive and pathogens negative.Differential selective media: Salmonella-Shigella (SS) agarPicture showing non- lactose fe

7、rmenting colonies (left)and lactose fermenting colonies (right) on MAC agar.MacConkey agar is often used to demonstrate lactose fermentation. normal flora is positive and the colonies are pink, while the pathogens are negative and the colonies are colourless.A: Gram stain of Escherichia coli. Origin

8、al magnification x1000. (Courtesy of H Reyes.) Antigenic StructureLPS (endotoxin) O antigen. O antigens are the most external part of the cell O antigens are the most external part of the cell wall lipopolysaccharide (LPS)and consist of wall lipopolysaccharide (LPS)and consist of repeating units of

9、polysaccharide. O antigens are repeating units of polysaccharide. O antigens are resistant to heat and alcohol and usually are resistant to heat and alcohol and usually are detected by bacterial agglutination. Antibodies to detected by bacterial agglutination. Antibodies to O antigens are predominan

10、tly IgM.O antigens are predominantly IgM. Antigenic StructureMost are motile by peritrichous flagella -H antigens, which extend well beyond the cell wall. which extend well beyond the cell wall. They are denatured or removed by heat or alcohol. They are denatured or removed by heat or alcohol. They

11、may undergo antigenic variation. They may undergo antigenic variation. Such H antigens agglutinate with anti-H antibodies, Such H antigens agglutinate with anti-H antibodies, mainly IgG. mainly IgG. Within a single serotype, flagellar antigens may be Within a single serotype, flagellar antigens may

12、be present in either or both of two forms, called phase 1 present in either or both of two forms, called phase 1 (conventionally designated by lower-case letters) and (conventionally designated by lower-case letters) and phase 2 (conventionally designated by Arabic numerals).phase 2 (conventionally

13、designated by Arabic numerals). Antigenic StructureCapsule K antigen ( Vi for Salmonella). are external to O antigens. Cell surface are external to O antigens. Cell surface polysaccharides may form a well-defined capsule or polysaccharides may form a well-defined capsule or an amorphous slime layer

14、and are termed the K an amorphous slime layer and are termed the K antigen. antigen. some but not all Enterobacteriaceae. K antigens some but not all Enterobacteriaceae. K antigens may interfere with agglutination by O antisera, and may interfere with agglutination by O antisera, and they may be ass

15、ociated with virulence. They have they may be associated with virulence. They have different names in different genera. We call it Vi different names in different genera. We call it Vi antigen in Salmonella.antigen in Salmonella. Pathogenicity determinantsEndotoxin. The main toxic effect is from lip

16、oid A as a component of LPS. Exotoxin. act on host cells by damaging membranes, inhibiting protein synthesis, or altering metabolic pathways. The end result of these actions may be cell death (cytotoxin) or a physiologic alteration. ( enterotoxins act on intestinal enterocytes, causing the secretion

17、 of water and electrolytes into the gut to produce diarrhea.)Pathogenicity determinantsAdhesion factors. Attachment fimbriae, attachment pili, colonizing factor antigens (CFAs).Invasive factors. Proteins localized in the outer membrane (invasins) that facilitate the invasion of target cells.Escheric

18、hia埃希菌属 Escherichia coli (E. coli) is the most common and clinically important.in the normal intestinal tract within a few days after birthconstitute a main portion of the normal aerobic microbial flora. generally do not cause diseaseMorphology, culture, and antigen structure.The Gram-negative, stra

19、ight rods, are peritrichously flagellated. Lactose is broken down rapidly. The complex antigen structure of these bacteria is based on O, K, and H antigens. Specific numbers have been assigned to the antigens, e.g., serovar O18:K1:H7.Chemical characteristicEscherichiaE.coli typically produces positi

20、ve tests for indole, lysine decarboxylase, and mannitol fermentation and produces gas from glucose.lactose, glucose +Extraintestinal infectionsinclude urinary tract infections, which occur when the tract is obstructed. The most important other coli infections are cholecystitis, appendicitis, periton

21、itis, postoperative wound infections, meningitis and sepsis.Escherichia coli urinary tract infection A drop of urine has been placed on a slide and Gram stained. The ready observation of the large Gram negative bacilli and WBCs indicate the number of bacteria in the urine is high. Intestinal infecti

22、onsE. coli that cause intestinal infections are now classified in five pathovars with differing pathogenicity and clinical picturesEPEC, ETEC, EIEC, EHEC, EAggEC. Enterotoxigenic E.coli ETECtravelers diarrhea infant diarrhea Virulence factorenterotoxinheat labile enterotoxin(LT) (inactivation at 60

23、for 30 minutes)heat stable enterotoxin(ST) (can tolerate temperatures up to 100 )the colonization factor (CFA)Diarrhea caused by Diarrhea caused by E. coliE. coliEnterotoxigenic E.coli ETECThe clinical picture of an ETEC infection is characterized by massive watery diarrhea. The disease can occur at

24、 any age. Once the illness has abated, a local immunity is conferred lasting several months.Enteroinvasive E.coli EIECmost commonly in children and in elder fever and cramps, with blood and leukocytes in stool specimens very similar to Shigellosis EIEC strains are often lac-negativePathogenic mechan

25、ism invade and destroy the colonic epitheliumendotoxinEnteropathogenic E.coli, EPECThese bacteria cause epidemic or sporadic infant diarrheas, now rare in industrialized countries but still a main contributor to infant mortality in developing countries. EPEC attach themselves to the epithelial cells

26、 of the small intestine by means of the EPEC adhesion factor (EAF), then inject toxic molecules into the enterocytes.Enterohemorrhagic E. coliEHEC100 cases, 1 deathIllness characterized by diarrhea and hemolytic-uremic syndromeEHEC possess specific, plasmid coded fimbriae for adhesion to enterocytes

27、. They can also produce prophage- determined cytotoxins (shigalike toxins or verocytotoxins).serotype O157:H7 outbreak 2006Associated withbagged freshspinachnationwiderecallEnteroaggregative E.coli EAECa cause of persistent, watery diarrhea in infants and small children.Pathogenic mechanismadheres t

28、o the intestinal mucosa and elaborates enterotoxins （entero-aggregative heat-stable toxin, EAST) DiagnosisExtraintestinal infections are diagnosed by identifying the pathogen in relevant materials. Specific gene probes are now being used to make identification of intestinal pathogen E. coli bacteria

29、 less difficult.TherapyAntibiotic therapy must take into consideration the resistance pattern of the pathogen. Aminopenicillins, ureidopenicillins, cephalosporins,4-quinolones, or cotrimoxazole are useful agents. Severe diarrhea necessitates oral replacement of fluid and electrolyte losses.Epidemiol

30、ogyTransmission of intestinal infections is usually indirect via food, drinking water, or surface water. Fifty percent of travelers diarrhea cases are caused by E. coli, in most cases ETEC.The most effective preventive measureswhen travelling in countries with warm climates, is to eat only thoroughl

31、y cooked foods and drink only disinfected water.ShigellaShigella is the causative pathogen in bacterial dysentery. The genus comprises the species S. dysenteriae, S. flexneri, S. boydii, and S. sonnei. Shigellae are nonmotile. The three primary species can be classified in serovars based on the fine

32、 structure of their O antigens. ShigellaShigellae are characterized by invasive properties. They can penetrate the colonic mucosa to cause local necrotic infections. Humans are the sole source of infection since shigellae are pathologically active in humans only. The pathogens are transmitted direct

33、ly, more frequently indirectly, via food and drinking water (oral-fecal route). Shigellabacillary dysenteryshigellosisintestinal pain abdominal cramps腹痛and tenesmus 里急后重bloody feces: blood in the stool abundant pus and ShockInfection almost always limited to the gastrointestinal tract: dont see bact

34、eremiaHighly communicable: infective dose is 102 organisms (much less than Salmonella or Vibrio)Shigella ClassificationThe genus Shigella includes four species: S. dysenteriae, S. flexneri, S. boydii, and S. sonnei. The first three are subdivided into 10, 6, and 15 serovars, respectively, based on t

35、heir antigen structures. Shigellae are nonmotile and therefore have no flagellar (H) antigens.MorphologyGram negative rods0.5-0.7 m 2-3mNo flagellum, caplsueCulture & Biochemical ReactionsLactose NOT fermented SS selective mediaBi-sugar iron agar: K/AUrease Motility -All ferment mannitol except S. d

36、ysenteriaeS. sonnei may show delayed lactose fermentationGlucose +Lactose - (except S. sonnie ) Virulence factor1、Invasiveness侵袭力：侵袭力：The shigellae are taken up by enterocytes and they undergo intracellular replication and cell-to-cell spread2、toxin毒毒 素素：Endotoxin内毒素内毒素abundant pus and blood in the

37、stool abdominal cramps腹痛and tenesmus 里急后重ShockExotoxin外毒素Shiga toxin志贺毒素 ST(VT : verocytotoxins)protein synthesisDiagnostic Laboratory TestSS agarSlide agglutinationdiagnosiscultureFresh stool, mucus flecks，rectal swabsBi-sugar iron agarrapid diagnosissmearstool for white cells (fecal leukocytes) an

38、d red blood cellsTreatmentReplace fluids and electrolytesAntibiotics:a. Ciprofloxacin or trimethoprim-sulfamethoxazoleb. Shorten duration of symptomsc. Reduce spread to other peopleMany cases are self-limitedControl efforts:a. Sanitary conditions (water, food, milk, sewage disposal)Isolation of pati

39、ents and disinfection of excretaThe source of infection is always humans, in most cases infected persons whose stools contain pathogens for up to six weeks after the disease has abated.Detection of subclinical cases and carriers, especially food handlersThe SalmonellaSalmonellae are often pathogenic

40、 for humans and animalsTransmitted from animals and animal products to humans acquired by the oral routeCause human enteritis, systemic infection, and enteric feverIt is not known why typhoid salmonellae only cause systemic disease in humans, whereas enteric salmonella infections occur in animals as

41、 well and are usually restricted to the intestinal tract.Salmonella ClassificationSalmonellaClassification has been changing in the last few years.There is now 1 species: S. enteritica, and 7 subspecies: 1, 2 ,3a ,3b ,4 ,5, and 6.Subgroup 1 causes most human infectionsClinically Salmonella isolates

42、are often still reported out as serogroups or serotypes based on the Kauffman-White scheme of classification.Based on O and H (flagella) antigensBiological propertiesMotile, piliDo not ferment lactoseAntigens and classification ODifferent strains possess different O antigens and flagellar H antigens

43、Loss of O antigen causes a change from smooth to rough coloniesH -The H antigens occur in two phases; 1 and 2 and only 1 phase is expressed at a given time.Vi: screening of carriers (titer 1:10 )-a capsular antigen called the Vi antigen (stands for virulence)Morphology & BiologyRods vary in lengthPe

44、ritrichousGrow readily on simple mediaLactose/sucorose fermentation Hydrogen sulfide +Be resistant to chemicals such as brilliant green, sodium deoxycholate BiochemistryGlucose + Lactose -KIA K/A + gas and H2S: S. typhi produces only a small amount of H2S and no gas , and S. paratyphi A produces no

45、H2SUrea Motility +Citrate +/-Indole -PathogenesisInfective dose is relatively high : 105 108 organismsTransmission by oral route from contaminated food and drink (fecal contamination)Salmonella typhi, Salmonella paratyphi A and B only colonize humans:Animals are the major reservoir for other Salmone

46、lla:Poultry: fecal contamination during processingEggs: Less frequently: dairy products, meat, contaminated water, pets Typhoid FeverProduced by only a few of the salmonellae, of which Salmonella Typhi is the most importantThe ingested salmonellae reach the small intestine, from which they enter the

47、 lymphatics and then the bloodstreamThey are carried by the blood to many organs, including the intestineThe organisms multiply in intestinal lymphoid tissue and are excreted in stoolsIncubation period: 1014 daysSymptomsFever, malaise, headache, constipation, and myalgia occur Further symptoms:stupo

48、r, leukopenia, bradycardia, splenic swelling, abdominal roseola, beginning in the third week diarrhea, sometimes with intestinal bleeding due to ulceration Chief complications of enteric fever Intestinal hemorrhage and perforationMortality rateLess than 1% with antibioticsEnteric fever: Rose spotsPa

49、ratyphoid feverTyphoid feverPeters, W. & Gilles, H.M.A Colour Atlas of Tropical Medicine & Parasitology.3rd edition, 1989, p. 129GastroenteritisMost common Salmonella infection.Abrupt onset of low grade fever, nausea, vomiting, profuse diarrhea( fecal leukocytes)Usually resolves spontaneously in 2-3

50、 daysBlood cultures usually negative. Stool cultures positive.SepticemiaPathogens:S. choleraesuisS. typhimuriumS. enteritidis Diseases:5-10% of salmonellosissevere symptoms, meningitis, osteomyelitisintestinal manifestaions: often absentculture: blood(+), stool (-)Diagnostic Laboratory TestsSpecimen

51、s标本enteric fever肠热症肠热症 food poisoning食物中毒食物中毒 septicemia败血症败血症1st week blood food，stool，vomit blood1-3rd week Bone marrow 2nd week Urine尿尿, stool粪粪 Salmonella-shigella agar SS平板Biochemical reaction生化反应Serological test血清学鉴定bi-sugar iron agar双糖发酵等slide agglutination tests玻片凝集试验Widal testA test of bloo

52、d serum that uses an agglutination reaction to diagnose typhoid feverAfter Fernand Widal (18621929), French physicianWidal TestMethodsAt least two serum specimens, obtained at intervals of 710 days, are needed to prove a rise in antibody titerSerial (twofold) dilutions of unknown serum are tested ag

53、ainst antigens from representative salmonellaeResultsSerum agglutinins rise sharply during the second and third weeks High or rising titer of H ( 1:160)and O (1:80) suggests that active infection is presentHigh titer of H ( 1:160) but normal level for O suggests past immunization or past infectionHi

54、gh titer of antibody to the Vi antigen occurs in some carriersResults of serologic tests must be interpreted cautiouslyThe possible presence of cross-reactive antibodies limits the use of serology in the diagnosis of salmonella infectionsCaution during interpreting the resultsConsider the manifestat

55、ion, course, history, and local epidemiological conditionsNormal valueO titer 1:80 , H titer 1:160 Dynamic observation: antibody titer give a rise gradually titer of convalescence serum 4 times of that of early specimenCaution during interpreting the resultsO, H antibodyO and H: high possibilityO an

56、d H: low possibilityO and H: early stage of infection or cross-reaction of O antigen with other salmonellaeO and H: vaccination or nonspecific memory reactionFalse negative:preantibiotic or immunosuppressedSalmonella: prevention & treatmentThoroughly cook meat (especially poultry) and eggsCarriers s

57、hould not be food handlersTwo typhoid vaccines available (against Salmonella typhi)attenuated vaccine & killed vaccineEnteric Fever, Septicemia: AntibioticsGastroenteritis is self-limited: Replace fluids and electrolytesVibrioSpecies of VibrioVibriosVibrio choleraeCause CholeraV. parahaemolyticuscau

58、seGastroenteritisAllied vibriosSaprophyticClassical typeV. choleraeEl-Tor-typeV. El-TorSpecies of VibrioV. cholerae is the causative agent of choleraV. cholerae divided serologically into 6 groups based on somatic O-antigensV. cholerae O1 and O139 are the most important agents that cause choleraVibr

59、io parahaemolyticus is the cause of acute gastroenteritis following ingestion of contaminated sea-food such as raw fishV. cholerae & V. parahaemolyticus, are pathogens of human, produce diarrhea, but in ways those are entirely different. V. parahaemolyticus is an invasive organism affecting the colo

60、nV. cholerae is noninvasive, affecting the small intestine through secretion of an enterotoxin. Allied Vibrios are a large group of organisms; some of them are saprophytic while others cause disease in animalsVibrioGram negative rods, curved, comma shaped bacilliMotile by single polar flagellaNon sp

61、ore forming Non capsulatedMost vibrios have relatively simple growth factor requirements and grow well in alkaline pH Facultative anaerobesOxidase and catalase positiveLives in fresh and salt water: infection from eating contaminated seafood or contact with contaminated waterCholeraCholera is toxin

62、mediated, a severe diarrheal disease caused by V. cholerae O1 & 139 serotype and others. It is endemic in southern Asia (India, Pakistan, and Bangladesh).Incubation period of the disease is 1-4 days.Sudden onset of intense vomiting and rice water diarrhea with rapid dehydration.The disease progresse

63、s from the first liquid stool to shock in 4-12 hours, with death following in 18 hours to several days. Antigens and classification.V. cholerae bacteria are subdivided into serovars based on their O antigens (lipopolysaccharide antigens). The serovar pathogen is usually serovar O:1. Strains that do

64、not react to an O:1 antiserum are grouped together as nonO:1 vibrios. O:139 strains were recently described in India as also causing the classic clinical picture of cholera. O:1 vibrios are further subclassified in the biovars cholerae and eltor based on physiological characteristics. The var eltor

65、has a very low level of virulence.Identification of V. cholerae Specimen and microscopical examination: Rice watery stool or rectal swap collected in acute stage of diseaseDark-field microscopy of stool specimen from patients with cholera reveal large numbers of Vibrio (short, curved rods) with a ch

66、aracteristic motility that gives the appearance of shooting stars Culture:Inoculation of rice water stool in enrichment media (alkaline peptone water, pH8.5), in which the organisms multiply rapidly and tend to form pellicle at the surface of the medium after 6-8 h at 37 C.Subculture is made into Th

67、iosulphate Citrate Bile Sucrose (TCBS) agar. TCBS medium is selective because Also, contains bile salts High conc. of thiosulfate and citrate & strong alkalinity of this medium (pH9) TCBS medium is differential because It contains sucrose It contains bromothymol blue Some species ferment sucrose & o

68、thers not ferment Sucrose fermenting Vibrio spp (V. cholerae) appears as yellow colonies Sucrose non fermenting Vibrio spp (V. parahemolyticus) appears as blue to green coloniesAlkaline pH: blueNeutral pH: greenAcidic pH: yellow Sucrose fermentation on TCBS is the gold standard in its identification

69、 kills most intestinal commensalsIdentification of V. choleraeGrowth on TCBSvPrinciple Identification of Vibrio Differentiation between SF & NSF by Growth on TCBSMethod:TCBS agar is inoculated with tested organism recovered from alkaline peptone water using streak plate techniqueIncubate the plate i

70、n incubator at 37 C/24 hrs Results:SF organism appears as yellow colonies (V. cholerae)NSF organism appears as blue to green colonies (V. parahaemolyticus)Flame & CoolFlame & CoolFlame & Cool12345V. cholerae can be selectively cultured out of bacterial mixtures at pH 9Vibrio cholerae: EpidemiologyWo

71、rldwide epidemics caused by different biotypesClassic biotype caused 6 pandemics through early 1960sCurrent seventh pandemic with El Tor biotype since late 1960s( Asia, Middle East)El Tor biotype has spread rapidly because of higher ratio of cases to carriersO139 strain appeared in 1992spread by con

72、taminated water and foodVibrio cholerae: ClinicalMost cases are asymptomaticIncubation period: 1-4 daysSudden onset of nausea, vomiting, profuse watery diarrhea, abdominal crampsRice water stool (20-30 L/day)Contains mucus, epithelial cells, large numbers of vibriosRapid loss of electrolytes: profou

73、nd dehydration, circulatory collapseMortality rate without treatment: 25-50%Rice water stoolSevere dehydrationVibrio cholerae:Immunity & immunizationGastric acid provides some protectionAntitoxin antibodies are not protectiveNatural immunity is short-livedLimited and short-lived protection with vacc

74、inePrevention & TreatmentControl rests on improvement of sanitation, particularly of food and water. Patients should be isolated, their excreta disinfected, and contacts followed up.Vaccination Inactivated oral vaccines against O 1 strain and live attenuated oral vaccines against O 1 and O 139 strai

75、ns Patients with cholera must be promptly treated with fluid and electrolyte replacementThe key of treatmentControl source of infectionCut down Route of transmissionImprove immunityOral rehydration therapyV. parahemolyticusHalophilic:3.5%NaClSusceptible to heat and acid不耐热，不耐酸hemolysinacute gastroen

76、teritis急性胃肠炎（食物中毒）急性胃肠炎（食物中毒）following ingestion of contaminated seafood such as raw fish or shellfish varies from mild to quite severe cases 5-to72-hour incubation period (mean, 24 hrs) The illness is transient in most cases and symptomatic therapy is sufficient.Pathogenesis Helicobacter and campyl

77、obacter螺杆菌属和弯曲菌属Helicobacter pylori幽门螺杆菌Campylobacter jejuni空肠弯曲菌 The genera Campylobacter, Helicobacter, belong to the group of aerobic, microaerophilic, motile, Gram-negative rod bacteria with a helical/ vibrioid form. Human pathogens are found in both genera.Barry Marshall, M.D.H. pyloriBarry Mar

78、shall won the Nobel Prize in medicine for discovering that H. pylori. Nobel laureates Barry Marshall and Robin Warren showed it could cause gastric ulcers and stomach cancer.Morphology & Biology- rods with comma，S，or “gull-wing” shapesflagella at pole and is actively motilemicroaerophilic environmen

79、t510O2 、512CO2 enrichment culture mediaBrain-heart infusionBrucella ager strong producer of urease Helicobacter pylori is specific for humans & other primates. Other mammals have their own Helicobacter species. Route of transmission is primarily person-to-person rather than water contamination. feca

80、l-oral, oral-oral routes. Infections cluster in families.Helicobacter pylori transmission H. pylori infection: 60-70% prevalence overall in the world. Higher prevalence in developing than developed countries. % prevalence of H. pylori infectionDiagnostic laboratory testsGastric biopsy specimenshisto

81、logical examinationculture stains can show the curved or spiraled organisms detect serum specific antibodiesbreath test urease breath test A noninvasive breath test involving ingestion of 13C-labeled urea and measurement of 13CO2 in the expelled air.三联疗法三联疗法应用胶体次枸橼酸铋加2种抗生素70%95% 的病人治疗14天可根治幽门螺杆菌感染。T

82、reatment Triple therapy with bismuth subcitrate plus 2 antibiotics(Clarithromycin metronidazole) for 14 days eradicates H.pylori infection in 70%95% of patients。Chapter 16 Nonfermentative bacilliPseudomonas假单胞菌属假单胞菌属Acinetobacter不动杆菌属Stenotrophomonas嗜麦芽窄食单胞菌属Legionella军团菌属aerobeO2O2O2 P.aeruginosaGr

83、am-negative rods. Motile with polar flagella.Obligate aerobe.Oxidase-positive.Do not ferment carbohydrates.Resistant to multiple drugs.P. aeruginosaForms round colonies with a fluorescent greenish color, sweet odor, and b-hemolysis.Pyocyanin- nonfluorescent bluish pigment;pyoverdin- fluorescent gree

84、nish pigment; Some strains have a polysaccharide capsule.Identification of P. aeruginosa is usually based on colonial morphology, b b-hemolysis, oxidase positivity, the presence of characteristic pigments and sweet odor, and growth at 42 oC. Pathogenesisis pathogenic only when introduced into areas

85、devoid of normal defenses a nosocomial pathogenThe bacterium attaches to and colonizes the mucous membranes or skin, invades locally, and produces systemic diseaseinfection of wounds and burns，meningitis, urinary tract infection, necrotizing pneumonia and infection of eye。In infants or debilitated p

86、ersons: invade the bloodstream and result in fatal sepsis。Corneal Ulcer角膜溃疡角膜溃疡Legionella (Legionnaires Disease)Legionella is the only genus in the family Legionellaceae. The species Legionella pneumophila is responsible for most legionelloses in humans.aerobic ，fastidious营养要求较苛刻营养要求较苛刻(BCYE medium(

87、BCYE medium活性炭活性炭- -酵母浸出液琼脂培养基酵母浸出液琼脂培养基),),grow slowly ( (buffered charcoal-yeast extract agar )often stain poorly by Grams method, Silver stains can be usedubiquitous in warm moist environmentssurvives temperature up to 63Legionella pneumophilaPathogenesis inhalation of the bacteria from aerosols/

88、 droplets generated from heavily contaminated cooling towers, air-conditioning systems and shower heads Symptomatic infection：a severe form of pneumoniaThe incubation period is two to 10 days. The clinical picture is characterized by a multifocal, sometimes necrotizing pneumonia. TherapyMacrolide an

89、tibiotics are now the agent of choice, having demonstrated clinical efficacy. Alternatively, 4-quinolones can be used.Epidemiology and prevention.Legionellosis can occur in epidemic form or in sporadic infections. Soil and damp biotopes are the natural habitat of Legionella. Sources of infection inc

90、lude hot and cold water supply systems, cooling towers, air moisturizing units in air conditioners. Human-to-human transmission has not been confirmed. Legionella bacteria tolerate water temperatures as high as 63 and are not killed until the water is briefly heated to 70 .Chapter 17 Zoonotic Bacter

91、iaBrucella 布氏菌属布氏菌属Yersinia 耶尔森菌属耶尔森菌属Francisella弗朗西斯菌属Pasteurella巴斯德菌属Bacillus芽孢杆菌属directly from the animal reservoirtransmitted by vectorsZoonosis are human diseases caused by organisms that are acquired from animals.Brucella (Brucellosis) Human人人 undulant fever波浪热波浪热 Animals 畜畜 abortion流产流产B.Meli

92、tensis 羊布氏菌羊布氏菌B.Abortus 牛布氏菌牛布氏菌 B.Suis 猪布氏菌猪布氏菌 These bacteria can also be transmitted from diseased animals to humans, causing a uniform clinical picture, so-called undulant fever. small, non-motile, non-capasulate, gram-negative coccobacilli G-They only reproduce aerobically. In the initial isol

93、ation the atmosphere must contain 510% CO2. Enriched mediums such as blood agar are required to grow them in cultures.Morphology and culturePrevention and TreatmentControl and slaughtering of infected animalsImmunization of animals and humanAntibacterialDoxycycline is administered in the acute phase

94、, often in combination with gentamicin. The antibiotic regimen must be continued for three to four weeks.Yersinia耶尔森菌属 Y. pestis Plague Y. enterocolitica Y. pseudotuberculosis cause generalized zoonoses in wild animals and livestock. Diseased animals contaminate their surroundings. Humansthen take u

95、p the pathogens orally in water or food. The organismspenetrate the mucosa of the lower intestinal tract, causing enteritis.The Enteric Yersinia PathogensNonenteric Yersinia pestis and PlagueNonentericTiny, Gram-negative rod, unusual bipolar staining and capsulesVirulence factors capsular and envelo

96、pe proteins protect against phagocytosis and foster intracellular growthcoagulase, endotoxin, murine toxinYersiniaYersinia pestisHumans develop plague through contact with wild animals or domestic or semidomestic animals or infected humans.It spreads among them by direct contact or via the rat flea.

97、 Earlier plague epidemics in humans resulted from these same transmission pathways.The rare human infections seen today result from contact with rodents that are infected with or have died of plague.Pathology of PlagueID 3-50 bacilliBubonic bacillus multiplies in flea bite, enters lymph, causes necr

98、osis and swelling called a bubo in groin or axillaSepticemic progression to massive bacterial growth; virulence factors cause intravascular coagulation subcutaneous hemorrhage and purpura black plaguePneumonic infection localized to lungs, highly contagious; fatal without treatmentDiagnosis depends

99、on history, symptoms, and lab findings from aspiration of buboes.Treatment: streptomycin, tetracycline or chloramphenicolKilled or attenuated vaccine availablePrevention by quarantine and control of rodent population in human habitatsChapter 18 Bordetella & HaemophilusBordetella鲍特菌属鲍特菌属Haemophilus嗜血

100、杆菌属嗜血杆菌属Bordetella (Whooping Cough, Pertussis)The genus Bordetella, among others, includes the species B. pertussis, B. parapertussis, and B. bronchiseptica. Of the three, the pathogen responsible for whooping cough, B. pertussis, is of greatest concern for humans. The other two species are occasion

101、ally observed as human pathogens in lower respiratory tract infections.Pertussis = “violent cough”minute gram-negative coccobacilli.capsulea strict aerobe, requires enriched media Bordet-Gengou media. Some species (B. pertussis) are highly susceptible to toxic substances (need charcoal, starch, bloo

102、d or albumin to absorb toxic substance in medium)can be grown aerobically on special culture mediums at 37 for three to four days. Bordetella pertussisMorphology and culturePathogenesisBordetella pertussis is a human pathogen: no animal reservoirPerson-to-person spread by airborne dropletsOrganism a

103、dheres to and then kills ciliated epithelial cells of upper respiratory tractOrganism doesnt invade the bloodstreamDisease is mainly from the local effect of toxins on the upper respiratory tractClinicalThree stages:Catarrhal stage (about 1 week)Paroxysmal stage (1-6 weeks)Convalescence (weeks to mo

104、nths)ClinicalCatarrhal phase (卡他期): resemble common cold, sneezing, serous rhinorrhea, malaise, low-grade fever, 1-2wk, infectious (disease not recognized with high number of bacteria produced)Paroxysmal phase (突發期): repetitive coughs and inspiratory whoop, vomiting and exhaustion, 40-50 paroxysms d

105、aily, bronchopneumonia, 2-4wk.Recovery phase (恢復期): lasts for above 3 wks.Classic presentation may not be seen in patients with partial immunity.ClinicalPertussis occurs worldwide. Humans are the only hosts. Sources of infection are infected persons during the catarrhal phase, who cough out the path

106、ogens in droplets. There are no healthy carriers.The lethality level for pertussis during the first year of life is approximately 12%. The infection confers a stable immunity. Adults who were vaccinated as children have little or no residual immunity and often present atypical pertussis.PreventionTh

107、e most important preventive measure is the active vaccinationPertussis vaccine used for the past 50+ years is a killed, whole cell vaccineDTP is an inactivated preparation of B. pertussis combined with diphtheria and tetanus toxoidsPrimary series of 3 shots at 2, 4 and 6 months + 2 booster shots lat

108、erHaemophilusHaemophilus species these are fastidious “blood loving” organisms that require one or both of two factors present in blood:X=hemin which is necessary for the synthesis of iron containing respiratory enzymes such as cytochrome, cytochrome oxidase, catalase, and peroxidase.V=NAD which is

109、a coenzyme required for oxidation-reduction reactions (nicotinamide adenine dinucleotide, NAD)X is heat stable while V is heat labileHaemophilus = blood-lovingsmall，gram-negative bacillus, Non-motile & non-spore-forming. on rich medium it has a defined capsulerequires fresh blood (X and V factors) f

110、or growth chocolate agarsatellite phenomenonAntigenic structurecapsular polysaccharides antigen (six types a-f )The capsular polysaccharides of type b is the major virulence factor Haemophilus influenzaeSmall, pleomorphic gram-negative bacteria; coccobacilli. Erythrocytes supply two factors, X (= he

111、min) and V (NAD), which are required for growth. A standard blood agar plate does not contain sufficient free V factor. Some bacteria, in particular Staphylococcus aureus, produce excess NAD and even secrete this coenzyme into the medium Rich medium, usually containing heated blood (chocolate agar”)

112、.Satellite-ing of H. influenzae around Staph. aureus streak on agar.Clinical significance H. influenzaeH. influenzae is a mucosal parasite of the upper respiratory tract present in 3050% of healthy persons. The strains usually found are non-encapsulated and therefore hardly virulent.H. influenzae ty

113、pe b (Hib) is a major pathogen, particularly in children where the initial focus of infection is the nasopharynx followed by invasion of local tissue and sometimes the bloodstream.Meningitis occurs in individuals between 2 months and three years of age. Before 2 months the infant is protected by res

114、idual antibodies from mom and after 3 years active immunity has occurred. Epiglottitis occurs in 2-4 year olds with mostly boys being affected. Starts as a sore throat and progresses to cough and fever and then to respiratory distress with blockage of the air passage .Pneumonia - frequently associat

115、ed with otitis media, meningitis, and septicemiaEpidemiology and prevention.H. influenzae is found only in humans. Theincidence of severe invasive infections(meningitis, sepsis, epiglottitis) in childrenhas been reduced drastically, since a vaccination program was started. Immunization is achieved with the conjugate vaccine Hib in which thecapsule polysaccharide epitope “b” conferring immunity is conjugated to protein.