Ross S3 Multifaceted Model – Flashcards
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| Common virulence factors for E.Coli |
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| Endotoxin (LPS), Exotoxins for some, Adhesion molecules, capsule, Antibiotic resistance. |
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| The Polysaccharide core portion of LPS that is heat stable |
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| O antigen |
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| Flagella on motile strains is called |
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| H antigen |
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| The capsule is also called |
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| The K antigen |
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| What does E.Coli ferment? What are the products of this fermentation? |
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| Ferments glucose to ACID and GAS |
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| MacConkey grows ONLY... |
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| Gram negative Rods. It contains Lactose, which also makes it a differential medium. |
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| The exogenous source via fecally contaminated food or water leads to what type of disease? |
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| Intestinal disease |
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| If E.Coli is from an endogenous source it causes these types of diseases... |
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| Extraintestinal diseases, UTIs and neonatal meningitis. |
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| What do differences in individual plasmids and integrated prophages lead to? |
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| Differences in degree of virulence |
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| ETEC (Enterotoxigenic E.Coli) is the most common cause of... |
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| Traveler's diarrhea. |
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| Define ETEC, EHEC, STEC, EPEC, EIEC, EAEC, DAEC. |
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Enterotoxigenic E. Coli (Traveler's) Enterohemorrhagic E. Coli (Shiga-toxin) Enteropathogenic E. Coli Enteroinvasive E. Coli Enteroaggregative E. Coli Diffuse aggregative E. Coli |
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| What are the different types of pili on different species of E. Coli called? |
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CFA = colonization factor. They provide for different types of virulence |
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| How does ST act? |
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| Heat Stable toxin increases cGMP |
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| How does LT act? |
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| Heat-labile toxin increases cAMP |
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| STa and LT are toxins associated with which strain of E.coli? |
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| ETEC |
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| Describe the pathogenesis of the watery diarrhea associated with ETEC. |
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| LT and STa cause prolonged hypersecretion of Cl- and water and inhibit reabsorption of Na+ leading to fluid in gut leading to watery diarrhea only |
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| Treatment of Traveler's Diarrhea |
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| It is self limiting. Replace fluids with ORS (oral rehydration solution) which has Salt, Baking soda, Sugar, and Water. This is also known as Pedialite |
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| EHEC/STEC has what toxins? |
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| Shiga-like or Vero toxin (SLT or VT) |
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| Your patient has watery, very bloody stool. What is the microbe responsible for this? |
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| EHEC/STEC |
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| What part of the intestine does EHEC/STEC involved in? |
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| Colon |
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| What are two unique virulence factors that EHEC/STEC posses? |
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| Intimin and Entero-hemolysin, which causes BLOODY poo. |
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| O157:H7 |
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This is the most common E.coli breakout. It is in the EHEC family. |
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Organisms efface (rub off) the microvilli and induce polymerization of actin filaments leads to form cuplike pedestal leads to intimin secretion allows intimate attachment to the surface of the host cells (A/E lesions) leads to secrete SLT (production controlled by a lysogenic phage) leads to inhibits protein synthesis by nicking the 60S ribosome. ; What organism does this describe? |
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EHEC O157:H7 |
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| This bug carries the Locus of enterocyte effacement pathogenecity island that allows it to encode for the ability to induce attaching and effacing lesions on the host mucosa. |
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| O157:H7 |
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| Maconkey + Sorbitol is a differential for... |
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| non-EHEC. O157:H7 is a non-sorbitol fermented so it will have clear colonies. |
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| Outbreaks of EHEC are usually associated with |
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| Fast food hamburger joints (Jack in the Box) |
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| Hemolytic-uremic syndrome occurs in what populations and are associated with which strain? |
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| HUS occurs in children and the elderly. It is associated with EHEC and leads to acute renal failure in children. This is seen as thrombotic microangiopathy and thrombocytopenia. |
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| Do NOT give antibiotics or antimotility agents for which strain? |
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| EHEC. Remember you may need to give these patients plasmapheresis or blood transfusions. |
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| Second most common cause of diarrhea in infants. Infected in utero or during birth. |
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| EPEC |
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| Had Bundle-forming pili (BFP) for adherence to form A/E lesions. |
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| EPEC |
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| Watery, bloody diarrhea with fever = |
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| EPEC |
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| This strain can move laterally within the epithelium. |
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| EIEC |
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| Starts at watery diarrhea which could progress to bloody diarrhea with mucus (dysentery) and WBCs in feces. |
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| EIEC |
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| This strain is found in the colon AND small intestine |
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| EIEC |
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| This strain forms a biofilm on the surface of the microvilli. Leads to diarrhea in babies and HIV patients. |
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| EAEC |
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| This strain leads to shortening and rounding of the microvilli leading to hemorrhagic necrosis. |
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| EAEC |
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| This strain causes an elongation of microvilli. |
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| DAEC. |
