Microbio 552 – Flashcards
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Unlock answersWhat are Gram Negative, Oxidase negative bacilli
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The enterobacteriaecaea |
What are common characteristics |
G- single rods Ferment glucose Oxidase negative Reduce nitrates to nitrites Facultative aerobes Soil and GI tract of mammals
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Coliforms of Enterobacteria |
Potential Pathogens -Escherichia, Morganella, Proteus, Enterobacter....? |
Obligate Pathogens of Enterobacteria |
Shigella Salmonella Yersinia |
Proteus Vulgaris -Enterobacteriae |
Motile No lactose fermentation Endogenous Nosocomial UTIs Wound/burn/surgical infections |
Proteus Vulgaris Virulence Factors |
Motility -move up urethra or uterers Urease -degrade uric acid (increase ph) Fimbriae -adhesion to eptihelium -(transitional?) IgA proteases Hemolysins |
Klebsiella Pneuomoniae
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Common on skin, pharynx, or Gi tract Community: -pneumonia in alcoholics -High fatality Nosocomial -UTIs and wounds -Chronically ill/immunosuppressed Endogenous, fomite, direct |
K. Pneumoniae Virulence Factors |
Capsule (K antigens) -polysaccharide -many serotypes -anti-phagocytic -complement resistant -fast capsule regeneration=increased virulence -thicker capsule=increased virulence Pili -Attachment to epithelium -Anti-phagocytic |
Enterobacter (E. Cloacae and E. aerogenes)
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Bacteremia lower respiratory tract infections skin infections UTI's; Deep tissue -Endocarditis, osteomyelitis Nosocomial; -prolonged hospitlatization (ICUs) -prior treatment with antibiotics; -immunosuppression |
Cloacae Virulence Factors; |
E. Cloacae Virulence Factors -Adhesin -Siderophore -Complement resistance; -Alpha-hemolysin -Tissue Invasins |
Edwardsiella Tarda -Enterobacteriae |
Rare Found in freshwater and on fish; sometimes in GI tract; Gasteroenteritis, wound infections, sepsis Contact with infected fish, contaminated water or endogenous Very Dangerous (50 fatality for sepsis) Emerging infection Edwardsellosis in fish -Chinook salmon, channel catfish, eel, tilapia, flounder ; |
Virulence factors for Edwardsiella Tarda ; |
Hemolysin Epithelial invasins; Phagocytic killing; Complement resistance; Dermatotoxins - cause erthema and edema |
Escherichia Coli- Enterobacteriae; Serotypes |
Over 700 serotypes -O antigen of LPS H=flagellar antigen; K= capsular antigen; ; |
Escherichia Coli; Different serotypes can cause |
UTIs; Neonatal meingitis Gastroenteritis -5 different types ; |
E. Coli UTI's
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Uropathogenic E.coli (UPEC) Virulence Factors -P fimbriae *Attach to uroepithelium Type I fimbriae adherence to uroepithelium Siderophores Hemolysins K antigen -capsular antigen -Decreases phaocytosis and complement lysis |
E. Coli Gastroenteritis |
5 classes *Different serotypes pathogenesis
**i dont think i have to know them....**
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Enterotoxigenic E. Coli |
Infant's and traveler's diarrhea Profuse, watery diarrhea; may have fever, comiting, headache Lasts 3-4 days Self Resolving |
Virulence Factors for Enterotoxigenic E.coli (ETEC) |
(ETEC) Fibriae -attach to cells in small intestine Heat-labile enterotoxin (LT) *Similar to cholera toxin -binds to G protein in intestinal epithelium -upregulates cAMP -Release of water and ions into lumen of intestine Heat-stable Enterotoxin (ST) -Very small, several types -increase cytosolic cAMP -Release of water and electrolytes
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Enteroinvasive E. Coli (EIEC)
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Like Shigella infections Dysentery: -Diarrhea containing blood and mucus -Fever -Cramps -Vomiting
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Virulence Factors for EIEC
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Adhesin -outer membrane protein Invasion of epithelial cells -induces inflammation and destruction of epithleium No exotoxins |
Enteropathogenic E. Coli (EPEC)
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Leading cause of infant diarrhea in 3rd World Usually children -Profuse watery diarrhea with mucus -Fever -Vomiting and abdominal pain Lasts 1-3 days Dangerous in infants |
Virulence Factors for EPEC |
EPEC adherence factor (EAF) -Adherence to intestinal epithelum Intimin -adhesion NO EXOTOXINS** Can invade host cells -Signs and Symptoms caused by inflammation |
Enteroaggregative E. Coli (EAEC)
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Persistent diarrhea in young children -Non-bloody diarrhea Not well studied or understood
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Virulence Factors for EAEC
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Adherence to epithleium Enteroaggregative ST toxin (EAST) -Heat-labile -Functions like ETEC ST toxin Hemolysin
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Enterohemorrhagic E.Coli (EHEC) |
Hemorrhagic colitis -seve abdominal pain -bloody diarrhea -vomiting -little to no fever 5 to 10 days Usually self-limiting Can progress to hemolytic uremic syndrom (HUS) Treatment -supportive care -if HUS: transfusions, dialysis |
Virulence Factors of EHEC |
Verotoxin/Shiga toxin (Stx) -same toxin as in Shigella -on plasmid -inactivates ribosomes in vascular epithelium -hemorrhaging -if kidneys are effected=HUS Adehsion to intesting epithelium by fimbriae |
Shigella
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4 species -s. boydii -S. dysenteriae -s. flexneri -s. sonnei All pathogens Different world wide distributions |
Transmission and Disease of Shigella |
Fecal-oral route -Shed bacteria during illness and 1-2 weeks after -few bacteria needed to cause infection (10-200) Dysentery: -bloody diarrhea, fever, stomach cramps, vomiting -Lasts 2-3 days; recovery in 5-7 -S. dysenteriae outbreaks in 3rd world **5-15% mortality |
Pathogensis of Shigella
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Ingested Survives gastric juices; travels to large intestine Attach, enter and spread thru epithelium Destruction/inflammation of epithelium -Mucosal layer is ulcerated -Leakage *blood *mucas *inflammatory elements -Absorption of water is inhibited
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Virulence Factors of Shigella
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Cell invasion Inter- and intra- cell movement Toxin (not in all cases) Invasions Movement **maybe ability to survive gastric juices and adhesion to epithelium as well.... |
Invasion of Shigella |
At 37 C VirF is expressed VirF induces expression of VirB VirB induces expression of mxi, spa, ipa Mxi, Spa, Ipa assmeble into Mxi-Spa complex Mxi-Spa activated when Shigella contacts epithelium Secretes IpaB, IpaC, Ipaa Ipa proteins induce endocytosis Ipa proteins induce escape endosome |
Movement of Shigella |
Can move inside cell or between cells Intracellular -bacteria travel along actin filaments Intercellular -Use IcsA |
Shigella toxin |
Shiga toxin= verotoxin S. dysenteriae and E.coli O157:H7 Attacks vascular endothelium -B subunit binds Gb3 on vascular endothelium -complex enters cell -A subunit modifies rRNA Endothelium cannot renew hemorrhage |
Shigella toxin symptoms |
Starts with bloody diarrhea Fever, V/D, bruising, paleness, decreased urine Attacks small vessels of kidney, lungs, digestive tract -hemolytic uremic syndrome (HUS) Treatment -dialysis, antibiotics, transfusions Death rate 5-15% |
Treatment for Shigella
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Ampicillin Tremethroprim/sulfamethoxazole (bactrim) Ciprofloxacin Some antibiotic strains exist Antidiarrheal meds can make illness worse |
Salmonella General |
2463 serotypes Horrible nomenclature -2 SPECIES: Senterica and S. bongori --divided into subspecies ---- divided into serotypes |
Salmonella
Habitat/transmission/main human pathogens |
Habitat -Gi tract of humans and animals -Can be found in water sewerage, soil Transmission -fecal oral -contaminated food/water Main human pathogens -S. Typhimurium (dysentery) -S. typhi (typhoid fever) |
Typhoid Fever |
Not typhus Effects 21.5 million people around the world No Tx --20% death rate S. Typhi lives only in humans |