1、rRNA Superfamily VI of Class Proteobacteria,Gram-negative Helical (spiral or curved) morphology; Tend to be pleomorphic Characteristics that facilitate penetration and colonization of mucosal environments (e.g., motile by polar flagella; corkscrew shape) Microaerophilic atmospheric requirements Beco
2、me coccoid when exposed to oxygen or upon prolonged culture Neither ferment nor oxidize carbohydrates,General Characteristics Common to Superfamily,First isolated as Vibrio fetus in 1909 from spontaneous abortions in livestock Campylobacter enteritis was not recognized until the mid-1970s when selec
3、tive isolation media were developed for culturing campylobacters from human feces Most common form of acute infectious diarrhea in developed countries; Higher incidence than Salmonella Estimated 200-700 deaths,History of Campylobacter,Small, thin (0.2 - 0.5 um X 0.5 - 5.0 um), helical (spiral or cur
4、ved) cells with typical gram-negative cell wall; “Gull-winged” appearance Tendency to form coccoid & elongated forms on prolonged culture or when exposed to O2 Distinctive rapid darting motility Long sheathed polar flagellum at one (polar) or both (bipolar) ends of the cell Motility slows quickly in
5、 wet mount preparation Microaerophilic & capnophilic 5%O2,10%CO2,85%N2 Thermophilic (42-43C) (except C. fetus) Body temperature of natural avian reservoir May become nonculturable in nature,Morphology & Physiology of Campylobacter,Campylobacter Species Associated with Human Disease,Low incidence pot
6、ential sequela Reactive, self-limited, autoimmune disease Campylobacter jejuni most frequent antecedent pathogen Immune response to specific O-antigens cross-reacts with ganglioside surface components of peripheral nerves (molecular or antigenic mimicry) Acute inflammatory demyelinating neuropathy (
7、85% of cases) from cross reaction with Schwann-cells or myelin Acute axonal forms of GBS (15% of cases) from molecular mimicry of axonal membrane,Guillain-Barre Syndrome (GBS),Zoonotic infections in many animals particularly avian (bird) reservoirs Spontaneous abortions in cattle, sheep, and swine,
8、but generally asymptomatic carriage in animal reservoir Humans acquire via ingestion of contaminated food (particularly poultry), unpasteurized milk, or improperly treated water Infectious dose is reduced by foods that neutralize gastric acidity, e.g., milk. Fecal-oral transmission also occurs,Epide
9、miology of Campylobacteriosis,Contaminated poultry accounts for more than half of the camylobacteriosis cases in developed countries but different epidemiological picture in developing countries In U.S. and developed countries: Peak incidence in children below one year of age and young adults (15-24
10、 years old) In developing countries where campylobacters are hyperendemic: Symptomatic disease occurs in young children and persistent, asymptomatic carriage in adults,Epidemiology of Campylobacteriosis(cont.),Sporadic infections in humans far outnumber those affected in point-source outbreaks Spora
11、dic cases peak in the summer in temperate climates with a secondary peak in the late fall seen in the U.S. Globally, C. jejuni subsp. jejuni accounts for more than 80% of all Campylobacter enteriti C. coli accounts for only 2-5% of the total cases in the U.S.; C. coli accounts for a higher percentag
12、e of cases in developing countries,Epidemiology of Campylobacteriosis(cont.),Infectious dose and host immunity determine whether gastroenteric disease develops Some people infected with as few as 500 organisms while others need 106 CFU Pathogenesis not fully characterized No good animal model Damage
13、 (ulcerated, edematous and bloody) to the mucosal surfaces of the jejunum, ileum, colon Inflammatory process consistent with invasion of the organisms into the intestinal tissue; M-cell (Peyers patches) uptake and presentation of antigen to underlying lymphatic system Non-motile & adhesin-lacking st
14、rains are avirulent,Pathogenesis & Immunity,Cellular components: Endotoxin Flagellum: Motility Adhesins: Mediate attachment to mucosa Invasins GBS is associated with C. jejuni serogroup O19 S-layer protein “microcapsule” in C. fetus: Extracellular components: Enterotoxins Cytopathic toxins,Putative
15、Virulence Factors,Specimen Collection and Processing: Feces refrigerated & examined within few hours Rectal swabs in semisolid transport medium Blood drawn for C. fetus Care to avoid oxygen exposure Selective isolation by filtration of stool specimen Enrichment broth & selective media Filtration: pa
16、ss through 0.45 m filters Microscopy: Gull-wing appearance in gram stain Darting motility in fresh stool (rarely done in clinical lab) Fecal leukocytes are commonly present Identification: Growth at 25o, 37o, or 42-43oC Hippurate hydrolysis (C. jejuni is positive) Susceptibility to nalidixic acid &
17、cephalothin,Laboratory Identification,Laboratory Identification (cont.),Gastroenteritis: Self-limiting; Replace fluids and electrolytes Antibiotic treatment can shorten the excretion period; Erythromycin is drug of choice for severe or complicated enteritis Fluroquinolones are highly active (e.g., c
18、iprofloxacin was becoming drug of choice) but fluoroquinolone resistance has developed rapidly since the mid-1980s apparently related to unrestricted use and the use of enrofloxacin in poultry Azithromycin was effective in recent human clinical trials Control should be directed at domestic animal re
19、servoirs and interrupting transmission to humans Guillain-Barre Syndrome (GBS) Favorable prognosis with optimal supportive care Intensive-care unit for 33% of cases,Treatment, Prevention & Control,History & Taxonomy of Helicobacter,Family not yet named (17 species by rRNA sequencing) First observed
20、in 1983 as Campylobacter-like organisms (formerly Campylobacter pyloridis) in the stomachs of patients with type B gastritis Nomenclature of Helicobacter was first established in 1989, but only three species are currently considered to be human pathogens Important Human Pathogens: Helicobacter pylor
21、i (human; no animal reservoir) H. cinaedi (male homosexuals; rodents) H. fenneliae (male homosexuals; rodents),Helicobacter pylori is major human pathogen associated with gastric antral epithelium in patients with active chronic gastritis Stomach of many animal species also colonized Urease (gastric
22、 strains only), mucinase, and catalase positive highly motile microorganisms Other Helicobacters: H. cinnaedi and H. fenneliae Colonize human intestinal tract Isolated from homosexual men with proctitis, proctocolitis, enteritis, and bacteremia and are often transmitted through sexual practices,Gene
23、ral Characteristics of Helicobacter,Gram-negative; Helical (spiral or curved) (0.5-1.0 um X 2.5-5.0 um); Blunted/rounded ends in gastric biopsy specimens; Cells become rod-like and coccoid on prolonged culture Produce urease, mucinase, and catalase H. pylori tuft (lophotrichous) of 4-6 sheathed flag
24、ella (30um X 2.5nm) attached at one pole Single polar flagellum on H. fennellae & H. cinaedi Smooth cell wall with unusual fatty acids,Morphology & Physiology of Helicobacter,Helicobacter on Paramagnetic Beads,Helicobacter Species Associated with Human Disease,Family Clusters Orally transmitted pers
25、on-to-person (?)Worldwide: 20% below the age of 40 years are infected 50% above the age of 60 years are infected H. pylori is uncommon in young children,Epidemiology of Helicobacter Infections,Developed Countries: United States: 30% of total population infected Of those, 1% per year develop duodenal
26、 ulcer 1/3 eventually have peptic ulcer disease(PUD) 70% gastric ulcer cases colonized with H. pylori Low socioeconomic status predicts H. pylori infection Developing Countries: Hyperendemic About 10% acquisition rate per year for children between 2 and 8 years of age Most adults infected but no dis
27、ease Protective immunity from multiple childhood infections,Epidemiology of Helicobacter Infections (cont.),Colonize mucosal lining of stomach & duodenum in man & animals Adherent to gastric surface epithelium or pit epithelial cells deep within the mucosal crypts adjacent to gastric mucosal cells M
28、ucosa protects the stomach wall from its own gastric milleu of digestive enzymes and hydrochloric acid Mucosa also protects Helicobacter from immune response Most gastric adenocarcinomas and lymphomas are concurrent with or preceded by an infection with H. pylori,Pathogenesis of Helicobacter Infecti
29、ons,Virulence Factors of Helicobacter,Multiple polar, sheathed flagella Corkscrew motility enables penetration into viscous environment (mucus) Adhesins: Hemagglutinins; Sialic acid binding adhesin; Lewis blood group adhesin Mucinase: Degrades gastric mucus; Localized tissue damage Urease converts u
30、rea (abundant in saliva and gastric juices) into bicarbonate (to CO2) and ammonia Neutralize the local acid environment Localized tissue damage Acid-inhibitory protein,Virulence Factors of Helicobacter,Urease C=O(NH2)2 + H+ + 2H2O HCO3- + 2 (NH4+)Urea Bicarbonate Ammonium ions And then HCO3- CO2 + O
31、H-,Urea Hydrolysis,Tissue damage: Vacuolating cytotoxin: Epithelial cell damage Invasin(s)(?): Poorly defined (e.g., hemolysins; phospholipases; alcohol dehydrogenase) Protection from phagocytosis & intracellular killing: Superoxide dismutase Catalase,Virulence Factors of Helicobacter (cont.),Labora
32、tory Identification,Recovered from or detected in endoscopic antral gastric biopsy material; Multiple biopsies are taken Many different transport media Culture media containing whole or lysed blood Microaerophilic Grow well at 37oC, but not at 25 nor 42oC Like Campylobacter, does not use carbohydrat
33、es, neither fermentatively nor oxidatively,Triple Chemotherapy (synergism): Proton pump inhibitor (e.g., omeprazole = Prilosec(R) One or more antibiotics (e.g., clarithromycin; amoxicillin; metronidazole) Bismuth compound Inadequate treatment results in recurrence of symptoms,Treatment, Prevention &
34、 Control,REVIEW Campylobacter & Helicobacter Superfamily,Gram-negative Helical (spiral or curved) morphology; Tend to be pleomorphic Characteristics that facilitate penetration and colonization of mucosal environments (e.g., motile by polar flagella; corkscrew shape) Microaerophilic atmospheric requ
35、irements Become coccoid when exposed to oxygen or upon prolonged culture Neither ferment nor oxidize carbohydrates,General Characteristics Common to Superfamily,REVIEW,Campylobacter Review,First isolated as Vibrio fetus in 1909 from spontaneous abortions in livestock Campylobacter enteritis was not
36、recognized until the mid-1970s when selective isolation media were developed for culturing campylobacters from human feces Most common form of acute infectious diarrhea in developed countries; Higher incidence than Salmonella Estimated 200-700 deaths,History of Campylobacter,REVIEW,REVIEW,REVIEW,Sma
37、ll, thin (0.2 - 0.5 um X 0.5 - 5.0 um), helical (spiral or curved) cells with typical gram-negative cell wall; “Gull-winged” appearance Tendency to form coccoid & elongated forms on prolonged culture or when exposed to O2 Distinctive rapid darting motility Long sheathed polar flagellum at one (polar
38、) or both (bipolar) ends of the cell Motility slows quickly in wet mount preparation Microaerophilic & capnophilic 5%O2,10%CO2,85%N2 Thermophilic (42-43C) (except C. fetus) Body temperature of natural avian reservoir May become nonculturable in nature,Morphology & Physiology of Campylobacter,REVIEW,
39、Campylobacter Species Associated with Human Disease,REVIEW,Low incidence potential sequela Reactive, self-limited, autoimmune disease Campylobacter jejuni most frequent antecedent pathogen Immune response to specific O-antigens cross-reacts with ganglioside surface components of peripheral nerves (m
40、olecular or antigenic mimicry) Acute inflammatory demyelinating neuropathy (85% of cases) from cross reaction with Schwann-cells or myelin Acute axonal forms of GBS (15% of cases) from molecular mimicry of axonal membrane,Guillain-Barre Syndrome (GBS),REVIEW,Zoonotic infections in many animals parti
41、cularly avian (bird) reservoirs Spontaneous abortions in cattle, sheep, and swine, but generally asymptomatic carriage in animal reservoir Humans acquire via ingestion of contaminated food (particularly poultry), unpasteurized milk, or improperly treated water Infectious dose is reduced by foods tha
42、t neutralize gastric acidity, e.g., milk. Fecal-oral transmission also occurs,Epidemiology of Campylobacteriosis,REVIEW,Contaminated poultry accounts for more than half of the camylobacteriosis cases in developed countries but different epidemiological picture in developing countries In U.S. and dev
43、eloped countries: Peak incidence in children below one year of age and young adults (15-24 years old) In developing countries where campylobacters are hyperendemic: Symptomatic disease occurs in young children and persistent, asymptomatic carriage in adults,Epidemiology of Campylobacteriosis(cont.),
44、REVIEW,Sporadic infections in humans far outnumber those affected in point-source outbreaks Sporadic cases peak in the summer in temperate climates with a secondary peak in the late fall seen in the U.S. Globally, C. jejuni subsp. jejuni accounts for more than 80% of all Campylobacter enteriti C. co
45、li accounts for only 2-5% of the total cases in the U.S.; C. coli accounts for a higher percentage of cases in developing countries,Epidemiology of Campylobacteriosis(cont.),REVIEW,Helicobacter Review,History & Taxonomy of Helicobacter,Family not yet named (17 species by rRNA sequencing) First obser
46、ved in 1983 as Campylobacter-like organisms (formerly Campylobacter pyloridis) in the stomachs of patients with type B gastritis Nomenclature of Helicobacter was first established in 1989, but only three species are currently considered to be human pathogens Important Human Pathogens: Helicobacter p
47、ylori (human; no animal reservoir) H. cinaedi (male homosexuals; rodents) H. fenneliae (male homosexuals; rodents),REVIEW,Helicobacter pylori is major human pathogen associated with gastric antral epithelium in patients with active chronic gastritis Stomach of many animal species also colonized Urea
48、se (gastric strains only), mucinase, and catalase positive highly motile microorganisms Other Helicobacters: H. cinnaedi and H. fenneliae Colonize human intestinal tract Isolated from homosexual men with proctitis, proctocolitis, enteritis, and bacteremia and are often transmitted through sexual pra
49、ctices,General Characteristics of Helicobacter,REVIEW,REVIEW,REVIEW,Gram-negative; Helical (spiral or curved) (0.5-1.0 um X 2.5-5.0 um); Blunted/rounded ends in gastric biopsy specimens; Cells become rod-like and coccoid on prolonged culture Produce urease, mucinase, and catalase H. pylori tuft (lophotrichous) of 4-6 sheathed flagella (30um X 2.5nm) attached at one pole Single polar flagellum on H. fennellae & H. cinaedi Smooth cell wall with unusual fatty acids,Morphology & Physiology of Helicobacter,REVIEW,Helicobacter Species Associated with Human Disease,
