Term
Drug Modification by B-lactamase production.
Drugs affected |
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Definition
Causes B-lactam hydrolysis. Open the garage door.
Penicillins, cephlosporins, carbapenems, aztreonam |
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Term
| Drug Modification of Fluoroquinolones |
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Definition
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Term
| Drug modification of Aminoglycosides |
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Definition
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Term
| Drug Modification by Clindamycin |
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Definition
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Term
Beta Lactamases can be mediated two ways..
They can be produced two ways... |
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Definition
Plasmid or Chromosomally.
Constitutive or Inducible |
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Term
The most common plasmid-mediated Beta-lactamases in Gram Negative bacteria are...
Drugs stable in the presence of these... |
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Definition
TEM-1, TEM-2, SHV-1
Extended-spectrum cephlosporins (2,3,4)
Beta-lactamase inhibitors
Carbapenems |
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Term
TEM and SHV-Beta Lactamases
Extended spectrum beta-lactamases (ESBL
How to treat ESBL |
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Definition
They are mutants of classical enzymes - change by 2 amino acids. And hydrolyze most extended-specturm cephlasporins and aztreonam.
Treat with Carbapenems and are inhibited by clavulanic acid. |
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Term
| Organisms that produce ESBL |
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Definition
Klebsiella, E.coli, other Enterobacteriacea and non-fermenting Gram-neg bacteria (SPACE bugs)
nosacomial gram neg, pseudomonas and acintobacter |
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Term
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Definition
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Term
Laboratory Detection of ESBL
suceptability
CP |
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Definition
Suceptible <8mcg/ml
Intermediate 16 mcg/ml
Resistant >32 mcg/ml
you may miss the ESBL producer in the intermediate phase. but there is no marker for ESBL producing organism. |
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Term
Recommended ESBL detection Process
CP |
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Definition
| If MCI >2ug/ml to ceftazidime, cefotaxime, ceftriaxone, then must do an ESBL confirmatory test. |
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Term
What is an ESBL confirmatory test?
CP |
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Definition
| >3 two-fold concentration decrease in an MIC for antimicrobial tested in combo with clavulanic acid or >5mm increase in ceftaz/clavulanic zone diameter. Then it must be reported as RESISTANT to cephlasporins and PCN. |
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Term
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Definition
| chromosomal and inducible. |
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Term
| AmpC B-lactamses are not inhibited by |
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Definition
| beta-lactmase inhibitors. Different form ESBL. |
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Term
| AmpC B-lactmases are resistant to ... |
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Definition
1st, 2, 3 cephlaosporins
Broad-spectrum PCN assocaiated with Beta lactamases |
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Term
AmpC B-lactamases are produced by
CP |
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Definition
SPACE bugs
Seratia
Pseudomonas
Acinetobacter
Citrobacter
Enterobacter. |
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Term
How does the AmpC B-lactmase work?
CP |
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Definition
B-lactamase under the control of ampC gene (it is turned on) and the repressor gene (turn off).
The mutation is the loss of repressor gene - stably depressed. |
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Term
| how to treat Amp-C beta-lactamase |
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Definition
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Term
What are the 2 categories of Carbapenemases?
How are they encoded. |
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Definition
Serine B-lactamases and Metallo-B-lactamases (MBL)
Chromosomally or plasmid. |
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Term
| Most common bug that carries transferable MBLs? |
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Definition
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Term
What are the 2 categories of Carbapenemases?
How are they encoded. |
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Definition
Serine B-lactamases and Metallo-B-lactamases (MBL)
Chromosomally or plasmid. |
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Term
How to treat Carbapenemase?
MIC >32 mcg/ml |
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Definition
Polymixin B (91%)
in vitro synergy - +rifampin or + imipenem
Mix with other agents to reduce the occurance of resistance.
Tigecycline (100%) |
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Term
Altered Protein Target Site
MRSA works by
CP |
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Definition
Loss of PBP2 to PBP2a
mecA gene |
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Term
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Definition
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Term
True or False:
CA-MRSA is less susceptible than HA-MRSA
CP |
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Definition
False.
CA-MRSA has higher virulance but has more suceptibility. |
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Term
Clindamycin Inducible Resitance is common in many _____ resistant strains
CP |
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Definition
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Term
Test Clindamycin inducible resitance by...
CP |
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Definition
D-Test
presence of erm genes and if D test posiive (erthromycin induces expression and decreases activity of clindamycin) do not use Clinda. |
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Term
| What is altered in Vancomycin Resistant strains |
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Definition
D-ala-D-ala
changed to:
D-ala-D-lac (VanA, B, D)
D-ala-D-ser (Van C, E, L)
Enterococcous species (espeically E. faecium)
Van A is on a plasmid. |
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Term
| VISA is resistance to Vanc by... |
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Definition
increased cell wall structure.
Not realted to VRSA - MRSA aquares VanA gene. |
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Term
| Tetracycline has a resistance to organisms my |
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Definition
efflux pum.
Tet A-E: pumps drug out of cells
tetM-Tet 0 - protects ribosomes. |
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Term
| Why does Tigecycline not get pumped out by the Tet |
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Definition
| Because it has a D-ring side chain that gives steric hindernce. |
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Term
| MexXY-OprM in Pseudomonas aeruginosa is a constiuative efflux pump. Which drug is susceptible to this pump? |
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Definition
| Tigecycline - will not cover pseudomonas. |
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Term
When is Pseudomonas and Acinetobacter resistant to Meropenem?
CP
Combination of mechanisms. |
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Definition
When you have BOTH
1)Up-regulation of efflux pump genes
2) loss of porin channel protein. |
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Term
| how do you treat ESBL producers? |
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Definition
| Carbapenem is the drug of choice. |
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