Antibiotics Flashcards

1
Q

Which antibiotics are bactericidal?

A
Very Finely Proficient At Murder
Vancomycin
Fluoroquinolones
Penicillins
Aminoglycosides
Metronidazole
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2
Q

Which antibiotics are Bacteriostatic

A
ECSTaTiC about bacteriostatics
Erythromycin
Clindamycin
Sulfamethoxazole
Trimethoprim
Tetracycline
Chloramphenicol
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3
Q

lowest concentration of antibiotic capable of inhibiting growth of an organism in a defined growth medium

A

Minimum Inhibitory Concentration

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4
Q

As plasma level is increased above the MIC, an increasing proportion of bacteria are killed at a more rapid rate

A

CONCENTRATION DEPENDENT KILLING ACTION

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5
Q

Killing action continues even after plasma levels decline below measurable levels

A

POST-ANTIBIOTIC EFFECT

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7
Q

Efficacy is directly-related to the time above the MIC

Efficacy independent on concentration once the MIC has been reached

A

TIME DEPENDENT KILLING ACTION

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10
Q

Eradicates an infection in the absence of host defense mechanisms

A

Bactericidal

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11
Q

Inhibits microbial growth but requires host defense mechanisms to eradicate the infections

A

Bacteriostatic

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12
Q

Drugs with Post antibiotic effect

A

Aminoglycosides
Fluoroquinolone
Azithromycin
Streptogramin

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13
Q

Cell wall synthesis inhibitors

A
Penicillins
Cephalosporins
Monobactams
Carbapenems
Vancomycin
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14
Q

Protein Synthesis Inhibitors

A
Aminoglycosides
Tetracyclines
Chloramphenicol
Erythromycin/macrolides
Lincosamides (clindamycin)
Linezolid
Streptogramins
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15
Q

Nucleic Acid Synthesis Inhibitor

A
Sulfonamides
Trimethoprim
Sulfamethoxazole
Fluoroquinolones
Co trimoxazole
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17
Q

MOA BETA-LACTAMS

pcns, cephalosporins, monobactams, carbapenems

A

Binds to penicillin-binding proteins located in bacterial cell walls

Inhibits transpeptidation

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18
Q

MOA BACITRACIN

A

Interferes with late stage in cell wall synthesis in Gram (+)

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19
Q

MOA CYCLOSERINE

A

Blocks incorporation of D-Ala-D-Ala into the pentapeptide side chain of peptidoglycan

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20
Q

MOA DAPTOMYCIN

A

binds to cell membrane causing depolarization and rapid cell death

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21
Q

MOA FOSFOMYCIN

A

inhibits UDP-N-acetylglucosamine-3-enolpyruvyltransferase (very early stage of bacterial cell wall synthesis)

Prevents formation of N-acetylmuramic acid (peptidoglycan precursor molecule)

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22
Q

MOA CHLORAMPHENICOL

A

Inhibits transpeptidation at 50S

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23
Q

MOA AMINOGLYCOSIDES

Gentamicin, Neomycin, Amikacin, Tobramycin, Steptomycin, Paromomycin, Spectinomycin

A

Bind 30S subunit
— cidal
Cannot kill anaerobes

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24
Q

MOA SULFONAMIDES

A

Competitive inhibitor of dihydropteroate synthase

—static

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25
Q

MOA Beta Lactamase Inhibitor

A

Inhibits inactivation of penicillins by bacterial B-lactamases

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26
Q

MOA TETRACYCLINE

A

Binds 30S Subunit

— static

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27
Q

MOA ERYTHROMYCIN

Class Macrolide

A

Binds 50S ribosomal subunit

— static

28
Q

MOA FUSIDIC ACID

A

Inhibits translocation during protein synthesis

29
Q

MOA CLINDAMYCIN, LINCOMYCIN

Class LINCOSAMIDE

A

Binds 50S

— static

30
Q

MOA METRONIDAZOLE, TINIDAZOLE, SECNIDAZOLE
CLASS NITROIMIDAZOLE
Antiprotozoal

A

Reactive reduction by ferredoxin forming free radicals that disrupt Electron transport chain
— cidal

31
Q

MOA QUINIPRISTIN-DALFOPRISTIN

Class STREPTOGRAMIN

A

Binds 50S

— cidal

32
Q

MOA TRIMETHOPRIM

A

Selective inhibitor of bacterial dihydrofolate reductase

— static

33
Q

MOA QUINOLONES

A

Inhibit topoisomerase II (DNA Gyrase) in Gram neg
— prevents relaxation of supercoiled DNA
Inhibit topoisomerase IV in Gram pos
— interferes with separation of replicated chromosomal DNA during cell division

— CIDAL

34
Q

MOA NITROFURANTOIN

CLASS NITROFURAN

A

Forms multiple reactive intermediates when acted upon by bacterial nitrofuran reductase —> disrupt protein, RNA, DNA synthesis
— cidal

36
Q

MOA MUPIROCIN

Class topical anti-infective pseudomonic acid

A

Inhibits staphylococcal isoleucyl tRNA synthetase

— cidal

37
Q

MOA POLYMYXIN

CLASS CATIONIC DETERGENTS

A

Attach to and disrupt bacterial cell membrane, bind and inactivate endotoxin
— cidal

38
Q

MOA FIDAXOMICIN

CLASS MACROCYSTIC, NARROW SPECTRUM

A

Inhibits bacterial protein synthesis by binding to sigma subunit of RNA polymerase
— static

39
Q

Drugs of Last Resort

A
Imipenem
Amikacin
Meropenem
Linezolid
Streptogramins
Vancomycin

(I AM your Last Shot at Victory)

40
Q

Excellent penetration of BBB

A
Sulfonamides
Chloramphenicol
Trimethoprim
Metronidazole
Rifampicin
Isoniazid
Fluconazole
Fluctosine
41
Q

Able to cross BBB with inflammation

A
Penicillins
Cephalosporins 
— 2G - only Cefuroxime
— 3G - all except cefoperazone
— 4G
Imipenem + Cilastin
Meropenem 
Aztreonam
Ciprofloxacin
Vancomycin
42
Q

Able to cross BBB but very Minimal

A

Aminoglycosides
Tetracyclines
Lincosamides
Macrolides

43
Q

Cannot cross BBB

A
Polymyxins
Cephalosporins 
— 1G
— 2G - all except Cefuroxime
Amphotericin B
44
Q

MOA CO-TRIMOXAZOLE

A

Sequential blockade of dihydropteroate synthase and dihydrofolate reductase
— CIDAL

47
Q

MOA LINEZOLID, TEDIZOLID

CLASS OXAZOLIDINONE

A

Binds to 23S ribosomal RNA of 50S subunit

— static

64
Q

MOA VANCOMYCIN

A

Binds D-ALA-D-ALA of peptidoglycan

Inhibits transglycosylation

65
Q

Penicillin Resistance

Staphylococcus aureus

A

Enzymatic hydrolysis of beta-lactam ring by formation of beta-lactamases (penicillinases)

66
Q

Penicillin Resistance

MRSA, Pneumococci, enterococci

A

Structural changes in target PBPs

67
Q

Penicillin Resistance

Pseudomonas aeruginosa

A

Changes in porin structures in outer cell wall impeding access of PCNs to PBPs

68
Q

Mechanism of Resistance

Tetracyclines

A

Efflux pumps
Ribosomal protection proteins

Except to Tigecycline (but not pseudomonas and proteus)

69
Q

Mechanism of Resistance

Macrolides

A

Efflux pumps
Methylase adding methyl group to ribosomal binding site
Cross-resistance complete
Partial with 50s drugs

70
Q

Mechanism of Resistance
Macrolides
By Enterobacteriaceae

A

Drug metabolizing esters

71
Q

Mechanism of Resistance

Lincosamide

A

Methylation

72
Q

Mechanism of Resistance

Oxazolidinones — Linezolid

A

Decrease affinity to binding site

73
Q

Mechanism of Resistance

Chloramphenicol

A

Plasmid-mediated acetyltransferase

74
Q

Mechanism of Resistance

Aminoglycosides

A

Plasmid-mediated inactivating enzymes (group transferases)

75
Q

Mechanism of Resistance

Streptomycin (aminoglycoside)

A

Changes in ribosomal binding site

*enterococci are S to streptomycin

76
Q

Mechanism of Resistance (3)

Antifolate drugs

A
  • Decreased intracellular accumulation of the drugs
  • Increased production of PABA by bacteria
  • Decrease in the sensitivity of dihydropteroate synthase to Sulfonamides
77
Q

Mechanism of Resistance
FLUOROQUINOLONES
Gram(-)

A
  • Decreased intracellular accumulation of the drug via production of efflux pumps
  • changes in porin structures
78
Q

Mechanism of Resistance

Gonococci to Fluoroquinolones

A

Changes in sensitivity of the target enzymes via point mutations in antibiotic binding regions

gyrA gene in gonococci