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Disease and Defense > Antibacterial agents > Flashcards

Antibacterial agents Flashcards

1
Q

List 5 ways bacterial resistance to antibiotics

A 
efflux pump
decrease entry
altered target site
enzymatic degradation
Bypass pathways
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2
Q

Selective toxicity

A

affects microbes > hosts

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3
Q

Examples of selectivity toxicity

A

Folate metabolisms, protein/nucleic acid synthesis (ribosomes, gyrase), Cell walls, fungal cell membrane (cell wall diff structures)

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4
Q

Antibiotic spectrum (3)

A

Narrow
Extended
Broad

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5
Q

Narrow antibiotic

A

Gram + or -

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6
Q

Extended antibiotic

A

Gram + and -

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7
Q

Broad antibiotic

A

Gram + and - and atypical

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8
Q

Three categories of resistance

A

natural/intrinsic
escape
acquired

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9
Q

Natural/intrinisic resistance

A

lack drug targets

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10
Q

Escape resistance

A

Precursor still there. Drug stopped synthesis but source is not removed - important to surgically drain/remove precursors

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11
Q

Acquired resistance

A

Mutational (requires multiple steps/generations)
Plasmid mediated: Conjugation (physical contact), transduction (virus carrying resistance), Transformation (DNA from environment)

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12
Q

Drugs easily enter CSF

A

chloramphenicol
Sulfonamides - trimethoprim
Cephalosporins (3/4)
Rifampin - Metronidazole

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13
Q

Enter CNS with inflammation

A

Penicillins
vancomycin
ciprofloxacin
tetracycline

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14
Q

Enter CSF poorly

A

aminoglycosides
cephalosporins (1/2)
Erythromycin
Lindamycin

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15
Q

Cholesterol is in mammalian membrane as _______ is in fungal cell membran

A

ergosterol

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16
Q

Inhibition of synthesis of stage 1 cell wall

A

Alanine racemase: cycloserine; enolpyruvate transferase: fosfomycin

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17
Q

Inhibition of synthesis of stage 2 cell wall

A

D-ala-D-ala pentapeptide: Vancomycin; bactoprenol lipid carrier: bacitracin

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18
Q

Inhibition of synthesis of stage 3 cell wall

A

Transpeptidase: penicillins, cephalosporins, monobactams, carbapenems

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19
Q

inhibition of synthesis/damage to cell membrane

A

daptomycin, polymixin B

20
Q

Modification of synthesis or metabolism of nucleic acids

A

DNA gyrase: Fluoroquinolones
RNA pol: rifampin
DNA: metronidazole, nitrofurantonin

21
Q

Inhibition/modification of protein synthesis

A

30S: aminoglycosides (irrev), tetracyclines
50S: clindamycin, macrolides, chloramphenicol, treptogramins
Isoleucyl-tRNA synthetase: mupriocin

22
Q

Modification of intermediary metabolisms (ie. folate)

A

Dihydropteroate synthase: Sulfonamides

Dihydrofolate reductase: Trimethoprim

23
Q

bactericidal mechanisms

A

inhibition of cell wall synthesis
disruption of cell membrane function
interference with DNA function/synthesis

24
Q

Bacteriostatic mechanism

A

inhibition of protein synthesis (except aminoglycosides)

inhibitions of intermediary metabolic pathways

25
Q

When to use bactericidal over bacteriostatics reasons (4)

A
  1. severe infection
  2. quickly/irreversible
  3. impaired host defense
  4. Not accessible to host immune system responses
26
Q

example of altered targets

A

MRSA, s. pneumoniae, enterococci to b-lactam antibiotics (penicillin binding proteins)
Enteroccci (VRE), staphylococci (VRSA) –> vancomycin (peptidoglycan side chain)
S. aureus, pseudomonas to fluoroquinolones (DNA gyrase)
Strep/staph/etnerococci to macrolides, clindamycin (50S methylation)

27
Q

Examples of Enzymatic destruction

A

S. aureus, P. aeruginosa, bacteroides, enterococci to b-lactam antibiotic (b lactamase)
Aminoglycosidesstaph/strepneisseria - chloramphenicol (acetyltransferase)

28
Q

Examples of alternative resistant metabolic pathways

A

Streptococci to sulfonamides: over production of PABA or thymidine nucleotides

29
Q

Examples of decreased entry (natural resistance)

A

b lactam antibiotics (pseudomonas aeruginosa)
Fluoroquinolones (P species)
Aminoglycosides (E. coli, pseudomonas)

30
Q

Examples of increased efflux

A

Tetracyclines - strep, staph, entero
Fluoroquinolones (P species)
Macrolides

31
Q

antimicrobial action outpatients vs hospitalized patients

A

hospital:culture sensitive within 24 hrs
outpatient
prescribed empirically based on symptoms, anatomic site, local patterns of infections, patient demographics

32
Q

Selective distribution/accumulation (benefits)

A

Clindamycin - bone (osteomyelitis)
Macrolides - pulmonary cells (URI/pneumonia)
Tetracyclines - gingival crevicular fluids/sebum (periodontitis/acne)
Nitrofurantoin - urine (UTI)

33
Q

selective distribution (toxicity)

A

Aminoglycosides - inner ear/renal brush border (ototoxicity, nephrotoxicity)
Tetracyclines bind Ca in developing bone/teeth (abnormal bone grwoth/tooth discoloration)

34
Q

Renal excretion and formula between MD and CL

A

Antibiotics eliminated by renal excretions - monitored by serum creatinine and creatinine clearance (SCr and CrCl)
MD/t = CPss x CL

35
Q

Hepatic metabolisms considerations

A

Drug drug interactions
interpatient rate difference (genetic polymorphism)
Hepatotix action - generally avoid

36
Q

List narrow spectrum antibiotic drugs

A 
Aminoglycosides
Penicillinase-resistant penicillin
clindamycin
Vancomycin
Metronidazole
Penicillin G, V
37
Q

List of extended spectrum antibiotics drugs

A

aminopenicillins (amox, amp)
Cephalosporins
fluoroquinolones (cip, levo)
Carbapenems

38
Q

List of broad spectrum antibiotics drugs

A 
Macrolides
Chloramphenicol
Fluorquinolones (Moxi, Gemi)
Sulfonamides
Tetracyclines
Trimethoprim
39
Q

Adverse reaction/toxicity types

A

DIrect to the drug
Indirect - allergies, salt effects/fillers, drug drug interactions/affect CYP
Distrubance of host microflora - superinfection - overgrowth of normal suppresed pathogenic organisms (ie. Clostridium difficile - pseudomembranous colitis)

40
Q

stage 1 of bacterial cell wall synthesis

A

1: synthesis/assembly of cell wall subunits - in cytosol

41
Q

stage 2 of bacterial cell wall synthesis

A
  1. Linear polymerization of subunits - at cell membrane
42
Q

Stage 3 of bacterial cell wall synthesis

A
  1. Cross-linking of peptidoglycan polymers - at cell wall
43
Q

Antibiotics that block stage 1

A

fosfomycin, cycloserine

44
Q

Antibiotics that block stage 2

A

Bacitracin, vancomycin

45
Q

Antibiotics that block stage 3

A

Penicillins, cephalosporins

Disease and Defense (10 decks)

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