Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Escherichia coliVibrio choleraeCampylobacter spp.EntericsVibrio choleraeAn ancient pathogen“In Alexandria, the streets were still with fear: this ‘virus’, …sneaked into healthymen in the morning, doubled them into knots of spasm-racked agony byafternoon, and put them to rest beyond the reach of all pain by night”.-Microbe Hunters, Paul de Kruif (1926)“fok lun” - China, >2000 yrs agoShushruta Samhita - 400-500bc , Sanskrit1600’s - ‘flux du ventre” Goa, France, Brazil, Ghent, Tubingen, LondonJohn Snow - First instance of defining a source ofInfection using Epidemiology (1849)Broad St. Water PumpDeaths, 10 day period in 1849London, EnglandBacterium had NOT been identified !!Flagellum“…no healthy man can ever be attacked by cholera unless he swallows the ‘comma microbe’…it is only in the intestine of man, or in highly polluted water like that of India that is can grow”. - Robert Koch (1882)Bacterium identified in 1882by Robert KochVibrio cholerae - Severe diarrheal symptoms> ‘rice water stool’ (mucus)> 5-20 liters water loss/dayCholera cotDehydrationVibrio choleraeEndemic in Asia: >8 million cases annually, 124,000 deaths(Bangladesh, southern India, Vietnam, etc.)Seven pandemics since 1817 (Europe and Asia)Entry into the Western Hemisphere Peru, Alabama, Chile 1991-1994Haiti 2010Vibrio cholerae Gram-negative, motile (flagellated) bacillus“comma-shaped” bacteriumPilus (attachment)Facultative anaerobeFree-living and gutGlucose and sucrose utilization (ferments)Oxidase – positive reaction in assayCapsule (polysaccharides) - serotypingpilusflagellumcapsuleIndia ink stainCapsular polysaccharides are used toserologically differentiate Vibrio cholerae strains>138 O serotypesMost prevalent virulent strains: O1 and O139Prior to 1993: O1396th, 7th pandemics, Haiti caused by O1 serotypesTCBS Agar(selective!)-Bile salts (no gram+ )-pH 8.6 (high)-Thiosulfate (sulfur)-Citrate-Sucrose -Bromothymol blueVibrio cholerae -yellow (low pH) (sucrose fermentor)•Twenty (20) species of Vibrio have been identified•Twelve (12) of these species are responsible for human disease• V. cholerae - potentially lethal intestinal infection• V. vulnificus - fishermen; highly lethal systemic infectionHow do these factors cause disease?Infection: ORAL routeFlagella:Motility is requiredSwim thru the mucus lining to the gut epithelial cellsToxin-coregulated pilus:Attachment of bacterium to gut cellsHA protease (‘detachase’)V. cholerae is shed from the gut in diarrheal fluids-Dispersal to other personsContaminated water, food- 60% mortalityNon –invasive !!Attachment of V. cholerae to gut epithelial cells requires interaction between the bacterium’s pilus and the microvilli (“brush border”) on the gut cell’s surfacepilusCholera toxinHeat-labile protein (enterotoxin) secreted by V. cholerae into the lumen of the gutBinds to ganglioside GM1 receptor located on surface of gut epithelial cellsTransported inside the host cellElevates the level of intracellular cAMP; stimulates release of electrolytes (K+, Na+) from the cell. Cellular water follows the ion gradientSEVERE diarrheal symptomsDeath by electrolytic shock‘Helical-shaped’ bacteriumTwo polar flagellaeNext,…. Another enteric bacteriumthat elicits diarrheal symptomsCampylobacter spp. A “vibrio-like” bacteriumPromiscuous host range: Major cause of diarrheal disease in animals Cattle, sheep, rodents, poultry, dogs, cats, birdsRecently, these bacteria have been implicated in human diseaseReservoirs for Campylobacter spp.Domestic and wild animalsUndercooked meatsUnpasteurized milkcheese from raw milkCampylobacter spp. Gram-negative, encapsulated, helical bacillus(“curved or spiral rod”)Motile (flagellated) (Two!)Non-fermenter of sugarsMicroaerophilic (requires C02 for growth)Too small to be easily observable by brightfield microscopyCampylobacter spp. are exceptionally smallDifficult to observe using optical microscopy. (1600x)Scanning electron microscopy reveals the unique shape of C. jejuni cells.Domestic & wild animals are reservoirs for CampylobacterCampylobacter spp. C. jejuni Acute gastroenteritisC. fetus Systemic infection/bacteremiameningitis, andseptic fetal abortionsC. coli Proctitis/gastroenteritis septic fetal abortionsVirulence Features for Campylobacter spp.Factors have not been well-defined for: (1) attachment (2) motility (3) invasion Infection by C. jejuni: Mucosal surface of intestine is ulcerated, edematous, bloody, inflammedMonocytes are attracted to the areaRoles for cytopathic toxins, But, enterotoxins & endotoxic activity have not been well-definedGuillain-Barre Syndrome Autoimmune disease thought to be elicited by antigenic cross-reactivity between the capsule polysaccharides and sugar-containing lipids on the surface of neuronal cellsGastroenteritisUrinary tract infections Neonatal meningitis PeritonitisMastitisSepticemiaPneumoniaHemolytic-uremic syndrome???Escherichia coliGastroenteritisUrinary tract infections Neonatal meningitis PeritonitisMastitisSepticemiaPneumoniaHemolytic-uremic syndromeLess than 0.1% of the culturable microflora in the gut isnon-pathogenic Escherichia coliSymbiotic relationship between ourselves and our gut floraE. coli is a normal constituent of our gut floraCustom ProbioticsInfections caused by E. coliBarnes-Jewish Hosp, St. LouisEnteric infections 73 different locations were linked to “food poisoning” Hemolytic uremic syndrome (Shiga toxin) Isolated to Escherichia coli O157:H7 strain Sickened over 700 people in four states 171 hospitalizations, 4 deathsSEVERE disease by E. coliJack in the BoxOutbreak of a rare syndrome, 1993Escherichia coli Gram-negative bacillusNormal member of gut floraFacultative anaerobeFerments sugars (glucose, lactose)Flagellated or non-flagellatedOften express pili and/or fimbriaeDiverse genus: ~20% of the genome iscommon to all strainsLPS, flagellar, and capsular polysaccharidesare used toserologically differentiate strains of E. coliCapsule K