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Microbiology > Antimicrobials and Resistance > Flashcards

Antimicrobials and Resistance Flashcards

1
Q

Inhibition of cell wall synthesis

A

B lactam antimicrobials
Polypeptide antimicrobials
Glycopeptide antimicrobials

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2
Q

B lactam antimicrobials

A

contain B lactam ring
differentiated by the chemical side chains attached to the ring
prevent cross linking of peptidoglycan

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3
Q

B lactam antimicrobials mode of action

A

ability to inhibit PBPs that are essential for peptidoglycan synthesis

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4
Q

PBPs

A

transpeptidases that cross link peptidoglycan

located on the external side of the bacterial plasma membrane

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5
Q

Penicillins

A

Penicillin
Ampicillin
Oxacillin

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6
Q

Carbapenems

A

Meropenem

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7
Q

Monobactem

A

Aztreonem

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8
Q

Cephalosporins

A

1-5th gen

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9
Q

Polypeptide antimicrobials

A

Bacitracin

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10
Q

Bacitracin

A

inhibits synthesis of cell wall at an earlier stage than B lactam antimicrobials
interferes with synthesis of the linear carbohydrate strands for peptidoglycan

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11
Q

Glycopeptide antimicrobials

A

Vancomycin

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12
Q

Vancomycin

A

inhibition of cell wall synthesis by complexing with the D-alanyl-D-alanine portion of the peptide cross links

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13
Q

B lactam antimicrobials

A

penicillins
carbapenems
monobactem
cephalosporins

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14
Q

Inhibition of protein synthesis

A 
chloramphenicol
aminoglycosides
tetracyclines
macrolides
lincosamides
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15
Q

Chloramphenicol

A

binds to 50S portion and inhibits formation of peptide bond

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16
Q

Aminoglycosides

A

changes shape of 30S portion, preventing 50S ribosome from forming 70S complex causing code on mRNA to be read incorrectly

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17
Q

Tetracyclines

A

interfere with attachment to tRNA to mRNA - 30S ribosome complex

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18
Q

Macrolides

A

bind to 50S subunit blocking the translocation reaction of polypeptide chain elongation

19
Q

Lincosamides

A

bind to 50S subunit blocking the translocation reaction of polypeptide chain elongation

20
Q

Inhibition of nucleic acid replication and transcription

A

Rifamycin

Fluoroquinolones

21
Q

Rifamycin

A

forms a complex with bacterial RNA polymerase preventing the initiation process of DNA transcription

22
Q

Fluoroquinolones

A

block bacterial DNA synthesis by inhibiting bacterial topoisomerase II (DNA gyrase) and topoisomerase IV (ciprofloxacin, levofloxacin)

23
Q

Injury to plasma membrane

A

lipopeptides

24
Q

Lipopeptides

A

daptomycin

polymyxin B

25
Q

Daptomycin

A

binds to cell membrane and alters structure making it more permeable which leads to cell death

26
Q

Polymyxin B

A

interacts with phospholipids of bacterial cell membranes increasing cell permeability and causing cell lysis

27
Q

Inhibition of essential metabolite synthesis

A

sulfonamides

trimethoprim

28
Q

Sulfonamides

A

structurally similar to folic acid precursor (PABA), allowing them to competitively bind with the enzyme meant for PABA and thereby block folic acid production

29
Q

Folic acid

A

important coenzyme in bacteria needed for synthesis of proteins

30
Q

Trimethoprim

A

structurally similar to dihydrofolic acid allowing for competitive inhibition of enzyme meant for dihydrofolic acid thereby blocking folic acid production

31
Q

Bacterial enzymatic destruction of antimicrobial agent

A

B lactamase mediated resistance

32
Q

B lactamase mediated resistance

A

able to break down some penicillins, cephalosporins, and carbapenems

33
Q

Bacterial enzymatic alteration of antimicrobial agent

A

aminoglycoside resistance

34
Q

Aminoglycoside resistance

A

bacterial enzymes modify aminoglycosides resulting in decreased binding to 30S ribosome therefore making the antimicrobial inactive

35
Q

Efflux (ejection) of antimicrobial agent from bacteria

A

Tetracycline resistance

36
Q

Tetracycline resistance

A

efflux pump removes antimicrobial from cytoplasm so that it can’t interfere with tRNA attachment so proteins synthesis can continue

37
Q

Alteration of the antimicrobial agents target site

A

Oxacillin (methicillin) resistance

Vancomycin resistance

38
Q

Oxacillin (methicillin) resistance

A

penicillin binding protein mediated resistance

MRSA has PBP2a coded by mecA gene

39
Q

Vancomycin resistance

A

altered peptidoglycan cross link target so vancomycin can’t bind and prevent the transpeptidase cross linking of peptidoglycan
vanA and vanB most common genes coding for resistance

40
Q

Blocking entry to antimicrobial agents target site in bacteria

A

B lactam, Tetracycline, and Fluoroquinolone resistance

41
Q

B lactam, Tetracycline, and Fluoroquinolone resistance

A

porin channel mediated blocked entry prevents antimicrobial from reaching target site

42
Q

Target bypass

A

Trimethoprim/Sulfamethoxazole resistance

43
Q

Trimethoprim/Sulfamethoxazole resistance

A

Bacteria increases the production of the antimicrobial target with the objective of overwhelming the antibiotic by increasing the amount of targets available
2 enzymes DHFR or DHPS are overproduced through mutations in the DNA encoding these enzymes so folate production can continue

Microbiology (37 decks)

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