Term
| Name 5 species of Enterobacteriaceae, and specify whether or not they ferment lactose. |
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Definition
- Escherichia coli (fermenter)
- Enterobacter cloacae (fermenter)
- Klebsiella pneumoniae (fermenter)
- Serratia marcescens (NON-fermenter)
- Proteus mirabilis (NON-fermenter)
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Term
| How do Enterobacteriaceae Gram stain, and what shape are they? |
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Definition
| They are Gram-negative bacilli. |
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Term
| What 2 diseases do Enterobacteriaceae commonly cause? |
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Definition
| Enterobacteriaceae are the most common cause of urinary tract infections and diarrhea. If they subsequently spread to the blood stream after these infections, they can also cause Septic Shock. |
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Term
| How do Klebsiella Pneumoniae gram stain and what shape are they? What is special about their capsule? |
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Definition
| Klebsiella Pneumoniae are Gram- rods. They have a large polysaccharide capsule conferring mucoid properties. |
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Term
| How do Enterobacter Cloacae gram stain and what shape are they? |
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Definition
| Enterobacter Cloacae are Gram- rods |
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Term
| What color is the pigment that Serratia Marcescens produces? |
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Definition
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Term
| Contrast Conjutation with High Frequency Recombination (Hfr) mating. |
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Definition
| In conjugation, the F+ donor will transfer the genetic material of a plasmid carrying F factor gene. In Hfr, the donor's F factor gene has integrated into the bacterial chromosome so when mating occurs the F+ donor transfers its entire genome. |
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Term
| Name the 4 different states of the F (Fertility) Factor. |
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Definition
- F+ = Extra chromosomal
- Hfr = integrated into chromosome
- F' = Extra chromosomal containing small chromosomal segments
- F- = No F factor
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Term
| How do Escherichia Coli gram stain and what shape are they? |
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Definition
| E. coli are Gram- motile rods with flagella |
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Term
| How do E. coli react to distinguishing media for lactose fermenters, catalase, and oxidase? |
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Definition
| E. coli is a lactose fermenter, catalase positive, and oxidase negative |
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Term
| What serotypes are used to classify Enterobacteriaceae species? |
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Definition
- H antigen: flagellae
- K antigen: capsule
- O antigen: endotoxin (LPS)
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Term
| How does MacConkeys Agar distinguish Enteric Bacteria? |
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Definition
| MacConkeys agar is pH sensitive and can produce a color change in response to lactose fermentation. Lactose + fermenters turn pink, whereas non-Lactose fermenters leave the agar colorless. |
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Term
| How does Mannitol Salt Agar (MSA) distinguish Enteric Bacteria? |
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Definition
| First of all, only Gram+ bacteria will grow on MSA. Furthermore, coagulase positive colonies will turn the agar yellow, whereas coagulase negative colonies will produce no color change. |
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Term
| How does Eosin Methylene Blue agar distinguish Enteric Bacteria? How does E.coli look in this agar? |
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Definition
| Eosin Methylene Blue only allows growth of Gram- bacteria. Moreover, lactose fermenter colonies will become purple black, while non-lactose fermenters will have no color change. E. coli colonies look metallic green on this agar. |
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Term
| Name the 3 "pathotypes" of E. coli that have emerged through horizontal gene transfer. |
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Definition
- Sepsis/meningitis
- UTI
- Enteric Disease
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Term
| What aspects of host cells is bacteria K antigen (capsule) structurally and antigenically related to? |
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Definition
| K antigen is related to host polysialic moieties. K antigen is poorly immunogenic, and inhibits complement activation via the alternate pathway. |
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Term
| How does bacterial LPS interact with host cells? |
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Definition
| LPS can bind Toll-like receptors (TLR4) and cause the dimerization of TLRs. Dimerization/conformational change of TLR4 causes a signal transduction cascade that results in NFκB activation and the production of cytokines. |
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Term
| Name 3 hallmarks of Sepsis that result from cytokine release. |
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Definition
- Intravascular coagulation (can be inhibited by APC)
- Activation and Binding of macrophages
- Increased NO leading to vasodilation and tachycardia
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Term
| Name 3 situations in which one can present with bacteriuria. |
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Definition
- Asymptomatic bacteriuria
- Cystitis (bladder infection)
- Pyelonephritis
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Term
| Name 5 traits of a patient that would classify their UTI as "complicated." |
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Definition
- Functional or anatomic abnormalities
- Catheters
- Chronic renal failure
- Diabetes
- Immunocompromised
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Term
| How often is E. coli the cause of uncomplicated UTI, how often is it the cause of complicated UTI? |
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Definition
| E. coli causes 80% of uncomplicated UTI, but only 20% of complicated UTI |
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Term
| Name 3 virulence factors of uropathogenic E. coli that are carried on pathogenicity islands. |
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Definition
- P Fimbriae (adherence factor binds mannose moieties on glycoproteins of epithelial cells)
- hemolysin
- siderophore (iron acquisition proteins)
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Term
| How do E. coli regulate adherence to epithelium. |
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Definition
| The P fimbriae gene is part of an operon that can be turned on or off depending on the circumstances. There is an invertible element in the operon, and it's inversion state determines whether the gene is off or on. |
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Term
| True or false: P-fimbriae are immunogenic. |
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Definition
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Term
| Explain how Siderophore proteins obtain Iron from the environment. |
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Definition
| Siderophore proteins are secreted from the bacteria and "fish" for iron. They have a VERY high affinity for iron. Once they bind to iron, they travel back to Siderophore receptors which take them into the cell. Siderophore expression is a virulence factor. |
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Term
| Is proteus mirabilis more common in complicated or uncomplicated UTI |
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Definition
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Term
| What is the main virulence factor associated with Proteus. |
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Definition
| Proteus mirabilis secretes urease which hydrolyzes urea thus increasing the pH of the urine. As the pH rises normally soluble ions precipitate and form Struvite Crystals. These crystals can eventually form stones which protect Proteus. |
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