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Microbiology > Antibiotics > Flashcards

Antibiotics Flashcards

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Biology 101 flashcards
1
Q

empiric therapy

A

application of knowledge of the organisms most likely to cause infection in a given clinical setting and its most likely susceptibility to an antibiotic

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2
Q

factors to be considered when determining optimal choice of antimicrobial agent

A

history of adverse reactions, age, pregnancy, renal and hepatic function, site of the infection

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3
Q

pharmacokinetics

A

encompasses all the ways that the body manipulates the drug, including absorption, distribution, metabolism, and excretion

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4
Q

pharmacodynamics

A

describes the biochemical and physiologic effects of the drug and its mechanism of action on the bacteria

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5
Q

bacteriostatic

A

antimicrobial agents that inhibit the growth and/or reproduction of the infecting agent but fail to actually kill the agent

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6
Q

bacteriocidal

A

antimicrobial agent that is capable of causing irreversible damage or death to the organism

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7
Q

Antibiotics mechanisms of actions (List 5)

A
  1. Interference with cell wall synthesis, 2. Interference with protein synthesis, 3. Interference with cytoplasmic membrane function, 4. Interference with nucleic acid synthesis, 5. Interference with metabolic pathway
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8
Q

penicillin

A

bacteriocidal, mechanism of action: antibiotic binds at the active site of the transpeptidase enzyme that cross-links the peptidoglycan strands (inhibits cell wall synthesis)

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9
Q

cephalosporins

A

bacteriocidal, mechanism of action: antibiotic binds at the active site of the transpeptidase enzyme that cross-links the peptidoglycan strands (inhibits cell wall synthesis)

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10
Q

glycopeptides

A

bacteriocidal, act by binding to the D-alanyl-D-alanine residues thus preventing the cross linking of peptitoglycan sheets (inhibits cell wall synthesis)

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11
Q

macrolids

A

bacteriostatic, binds to the 23S rRNA molecule (in the 50S subunit) of the bacterial ribosome blocking the exit of the growing peptide chain. (inhibits protein synthesis)

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12
Q

tetracyclines

A

bacteriostatic, blocks attachment of transfer RNA amino acid to the ribosome 30S subunit. (inhibits protein synthesis)

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13
Q

fluoroquinolones

A

bacteriocidal, inhibits DNA gyrases or topoisomerases required for supercoiling of DNA (inhibits nucleic acid synthesis)

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14
Q

aminoglycosides

A

bacteriocidal, binds to 30S ribosome and changes its shape so it causes a misreading of the mRNA information (inhibits protein synthesis)

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15
Q

sulfonamides/trimethoprim

A

bacteriostatic, competes with p-aminobenzoic acid (PABA) preventing synthesis of folic acid

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16
Q

beta-lactam antibiotics

A

bacteriocidal, mechanism of action: antibiotic binds at the active site of the transpeptidase enzyme that cross-links the peptidoglycan strands (inhibits cell wall synthesis)

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17
Q

4 main classes of beta lactam antibiotics

A

Penicillin, Cephalosporins, Monobactams, Carbapenems

18
Q

Antibiotics that inhibit protein synthesis

A

Aminoglycosides (bacteriocidal), Linezolid (bacteriostatic), Macrolids (bacteriostatic), Clindamycin (bacteriostatic), Chloramphenicol, Tetracyclines (bacteriostatic)

19
Q

Intrinsic Resistance

A

innate ability of bacterial species to resist activity of antimicrobial agent through structure or functional characteristics

chromosomally mediated and is predictable

20
Q

Mutational Resistance

A

due to chromosomal mutation. can be spontaneous or random

secondary resistance occurring after therapy with the antimicrobial in question has begun

21
Q

Acquired Resistance

A

microorganism obtains ability to resist activity of antimicrobial agent to which it was previously susceptible

transferable drug resistance is plasmid mediated through conjugation, transduction, transformation

22
Q

horizontal gene transfer

A

process of swapping genetic material between neighboring bacteria

23
Q

transformation

A

uptake of short fragments of naked DNA

24
Q

transduction

A

transfer of DNA from one bacterium into another via bacteriophages

25
Q

conjugation

A

transfer of DNA via sexual pilus and requires cell to cell contact

26
Q

major mechanisms by which bacteria may be resistant to antibiotics (8 of them)

A

enzymatic inactivation, decreased permeability, efflux, alteration of target site, protection of target site, overproduction of target, bypass of inhibited process, binding of antibiotic

27
Q

classifications of beta lactamases

A

classified according to amino acid structure from A to D.

28
Q

action of beta lactamase

A

resists beta lactam antibiotics by splitting amide bond of the beta lactam ring (which is part of the molecular structure of beta lactam antibiotics).

29
Q

action of beta lactamase inhibitors

A

inhibitor prevents hydrolysis of antidote, restores activity.

30
Q

mechanism of resistance responsible for VRE (Vancomycin-Resistant Enterococci)

A

sequesters vancomycin so antibiotic can’t do anything

31
Q

mechanism of resistance responsible for MRSA

A

MecA gene that produces PBP2a gene product

PBP2a has structural changes that result in energetically unfavorable interactions between

32
Q

role of transposons in antimicrobial resistance

A

can translocate as a unit from one area of the bacterial chromosome to another or between the chromosome and plasmid or bacteriophage DNA

33
Q

role of integrons in antimicrobial resistance

A

mobile DNA elements with the ability to capture genes by site specific recombination

34
Q

Enzymatic Inactivation

A

Example: beta lactamases are enzymes that inactivate beta lactam antibiotics by splitting the amide bond of the beta lactam ring

35
Q

Decreased Permeability of Bacterial Membranes

A

Example: Mutations resulting in the loss of specific porins (allows passage of hydrophilic antibiotics through outer membrane)

36
Q

Antibiotic Efflux

A

mechanism responsible for the moving of toxic substances and antibiotics out of the cell

37
Q

Altered Target Sites

A

Prevents binding by alteration of ribosomal target sites, alteration of cell wall precursor target sites, or alteration of target enzymes

38
Q

Protection of Target Sites

A

protects enzymes or ribosomes from binding to antibiotics

39
Q

Overproduction of Target

A

overproduction of enzyme overwhelms inhibition by antibiotic

40
Q

Bypass of Antibiotic Inhibition

A

stop synthesizing certain growth factors and instead rely on acquiring them externally thereby rendering antibiotic inhibition of those enzymes that synthesize those growth factors useless

41
Q

Binding of Antibiotic

A

excess binding sites absorb antibiotics preventing it from reaching its target

Microbiology (13 decks)

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