Gi-micro – Microbiology Answers – Flashcards
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Unlock answers| What are the major enteric bacteria with a type III secretion system? |
E.coli Yersina Salmonella Shigella Vibrio cholera |
What are the lactose fermenters grown on Maconkey or EMB agar? Which is indole (+)? |
E.coli-Indole (+) Klebsiella Enterobacter |
| What are the virulence factors of E.coli |
Enterotoxins: LT:ADPR->Gs like cholera(secretes ions) ST:cGMP(decreases ion absorption) Cytotoxins(shiga-like) Type III Secretion Endotoxin Capsule Bundle Forming Pillus |
What group of e.coli stains has prominent blood in the stool? Which has prominent WBC's in the stool? |
Blood: EHEC WBCs: EIEC |
| Which type of E.coli strains cause hemolytic uremic syndrome and why? |
EHEC Bc the Cytotoxin(shiga-like) has a predilection for the GB3 which predominate in the kidneys and GI |
| What are the main virulence factors of each of the types of E.coli stains? |
ETEC(1A:5B): LT-ADPR transferase activating adenylate cyclase ST-peptide activating Guanyl Cyclase EPEC: Bundle forming pillus Type III secretion-Injects TIR(autoreceptor), peptides for actin;rearrangement(pedicles) EHEC: Cytotoxin(Shiga-like) Type III secretion |
| What is the pathogenesis of the lesions seen in EPEC |
Attachment and Effacement lesions with loose villus structure and bacteria on pedicles Injection of Tir by Type III secretion allows strong attachment Other injected factors rearrange the cytosolic structure of the microvilli |
| What are the lab Characteristics of E.coli |
Gram (-) Rod Lactose Fermenter Indole (+) |
| What are the;lab characteristics of Vibrio cholera |
Gram (-) Comma-shaped Rod Oxidase (+) Motile |
| Which vibrio strain is responsible for epidemics and which type causes most pandemics? |
Epidemics: V. cholera O1(El Tor and Classic) Pandemics: El tor |
| What are the major virulence factors of V.cholera |
Cholera toxin: ADPR-; AC-; cAMP Adhesins Mucinase |
| What is the major clinical feature of V. cholera infection and how does it cause death? |
Rice water stool profound dehydration |
| Does immunity to V.cholera prevent reinfection? |
| Only strain specific |
| What areas are hotspots for cholera |
Brazil, Peru Northern Africa Southeast Asia Lousiana Texas |
How is Vibro parahemolyticus typically transmitted? Does the infection produce blood? |
Raw or Undercooked Seafood Frequently on cruiseships Blood: Occasionally blood in the stool |
Who most commonly gets a vibrio vulnificus infection? Who gets a more severe infection? |
Common: Shellfish handlers in the Gulf of Mexico Severe(Rapidly fatal Septicemia): Immunocompromised eating raw shellfish People with chronic liver disease |
What are the lab characteristics of Clostridium difficile? What people have the highest carrier rates? |
Lab: Large Gram(+) Spore-forming Rod Obligate Anaerobe Carriers: Common in health-care workers ; |
When does C.difficile typically cause infection? What is a severe manifestation? |
Antibiotic therapy allows resistant C.diff growth Pseudomembranous colitis: layer of fibrin, mucus, leukocytes and necrotic cells Toxic Megacolon |
| What are the toxins of C.diff and what are their effects? |
Toxin A(enterotoxin): Fluid secretion and Hemorrhagic Necrosis Toxin B(Cytotoxin): Blocks Protein Synthesis |
| How is C.diff diagnosed and treated |
DX Toxin Detection Endoscopy TX Antibiotic discontinuation Metronidazole or Vancomycin |
| What do the O, H, and K antigens refer to? |
O: Polysachirides H: Flagellar K: Capsular |
How does MacConkey agar and EMB agar inhibit gram (+) growth? How do lactose fermenters appear on each? |
Mac: Bile salts Lac-Purple/Red EMB: Aniline Dyes Lac: Black/Green(Strong fermenters) Pink-Purple(Mild fermenters) |
What virulence factor is important to the K1 strain of E.coli? What disease does this strain cause? |
Capsule Meningitis |
| What bacterial enteritis can you detect toxin in the stool? |
| Clostridium Difficil |
Which Toxins increase cAMP Which Toxins increase cGMP What toxins are Cytotoxins? What toxins are Emetic? |
cAMP LT E.coli toxin B. cereus LT toxin Cholera toxin ; cGMP E.coli ST toxin Y. Enterolytica ST toxin ; Cytotoxin EHEC Verotoxin Shiga Toxin C.diff B toxin ; Emetic Staph Enterotoxin B.cereus ST Toxin |
| What is the media used to culture V. cholera |
| TCBS Agar |
