Pharmacology Antibiotics Flashcards

1
Q

Opportunistic Pathogens

A

Organisms that do not normally produce disease

  • Malnutrition, immunodeficiency, antibiotic treatment
    • Staphylococcus aureus, E. coli, candida
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2
Q

Circle shaped bacteria

A

(Coccus)

Ex: streptococcus, staphylcoccus

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3
Q

Rod shaped bacteria

A

(bacillus)

Ex: escherichia, balicus

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4
Q

Spiral shaped bacteria

A

(spirillum)

Ex: leptospira, spirillum

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5
Q

Gram-Negative

A

do not retain the gram stain

  • thin cell wall surrounded by an outer lipopolysaccharide membrane
  • Examples:
    • E. coli, gonorrhoeae, pseudomonas, pneumoniae, proteus mirabilis
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6
Q

Gram-Positive

A

retain gram stain

  • thicker cell wall
  • Example:
    • bacillus anthracis, Staph, Strep, C. diff
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7
Q

Two names for a cell wall

A

peptidoglycan or murein

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8
Q

Chemotherapeutic agents

A

antibacterial, antifungal, antiparasitic, antiviral, antineoplastic

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9
Q
A
  • Inhibition of cell wall synthesis
    • penicillins, cephalosporins, bacitracin, and vancomycin
  • Inhibition of protein synthesis
    • chloramphenicol, erythromycin, tetracyclines, and streptomycin
  • Inhibition of Nucleic acid Replication
    • Quinolones, Rifampin
  • Injury to plasma membrane
    • polymyxin B
  • Inhibition of synthesis of essential metabolites
    • sulfanilamide, trimethoprim
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10
Q

Which chemotherapy agents are most and least toxic?

A

least: antibacterials
most: antineoplastics

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11
Q

Bacteriostatic

A

agents that inhibit the growth of bacteria

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12
Q

bactericidal

A

agents that kill bacteria

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13
Q

Pseudomembranous Colitis

A

associated with Clostridium difficile overgrowth

(C. diff)

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14
Q

Vaginal yeast infection

A

Candida albicans overgrowth

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15
Q

Cell Wall Synthesis Inhibitors

A
  • B-lactam
    • penicillins
    • cephalosporins
  • Polypeptides
    • vancomycin
    • bacitracin
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16
Q

B-Lactam Antibiotics

A

covalently and irreversibly inhibit Penicilin Binding Proteins (PBPs)

PBPs are enzymes that catalyze the crosslinking of the peptidoglycan cell wall

  • Transpeptidases
  • Carboxypeptidases
  • Endopeptidases
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17
Q

Resistance to B-Lactam Antibiotics

A
  1. Inactivation by B-lactamase
  2. modification of penicillin binding proteins
  3. impaired penetration of drug
  4. effux of drug
    • gram-negative bacteria may synthesize an efflux pump that transports B-lactams
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18
Q

B-Lactamase Inhibitors

A

Clavulanic acid, sulbactam, tazobactam

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19
Q

Penicillin G

A
  • narrow spectrum
    • high activity against gram-positive bacteria
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20
Q

Ampicillin

A
  • extended spectrum
    • high activity against gram positive
    • greater activity against gram-negative
  • Associated with pseduomembranous colitis
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21
Q

Unasyn

A

Ampicillin + Sulbactam

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22
Q

Nafcillin

A
  • high activity against gram-positive
  • resistant to B-lactamases
  • may cause Neutropenia
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23
Q

Hypersensitivity reactions to Penicillins

A
  • immediate ( <20 min)
    • anaphylactic shock
  • accelerated
    • uticaria
  • late (72hrs - weeks)
    • rashes
24
Q

Cephalosporin Spectrum

A

Gram-Positive activity decreases by generation

( 1 > 2 > 3 )

Reversed for gram-negative activity

25
Q

Cephalosporins

A
  • organized into “generations”
  • more resistant to B-lactamases
  • spectrum of activity
26
Q

1st generation Cephalosporins

A

Cefazolin

drug of choice for surgical prophylaxis

27
Q

2nd generation Cephalosporin

A

Cefotetan

greater activity against anaerobic bacteria

28
Q

Vancomycin

A
  • glycopeptide
  • inhibits transglycosylase enzyme
  • active against gram-positive
    • staph
    • C. diff
29
Q

Red-Man Syndrome

A

adverse effect of Vancomycin

  • histamine release promotes chills, fevers, and rash
  • avoid by slowing rate of infusion
30
Q

Bacitracin

A
  • Cyclic polypeptides isolated from Bacillus
    • mixture of bacitracin A, B, and C
  • Mechanism of Action
    • disrupts peptidoglycan synthesis
  • Mechanism of Resistance
    • BcrABC transporter
  • Active against gram-positive
    • usually give topically
31
Q

Inhibitors of DNA Replicaiton and Transcription

A

Quinolones and Riflampin

32
Q

Quinolone Examples

A

Ciprofloxacin (Cipro) and Levofloxacin (Levaquin)

33
Q

Quinolone Mechanism of Action

A

Inhibits topoisomerases II (DNA gyrase) and IV

34
Q

DNA gyrase

A

relaxes supercoiled DNA required for normal transcription

(inhibitied by Quinolones)

35
Q

Topoisomerase IV

A

separates replicated chromosomal DNA into daugter cells

(inhibited by Quinolones)

36
Q

Protein Synthesis Inhibitors

A
  • Aminoglycosides
    • Gentamicin
  • Tetracyclines
    • Doxycycline
  • Lincosamides
    • Clindamycin

Inhibits translation by targeting either 30S or 50S ribosomal subunits

37
Q

Aminoglycosides

A

Irreversibly inhibits the 30S ribosomal subunit

Example: Gentamicin

  • Bactericidal
  • Postantibiotic effect
    • persists beyond the time during which measurable drug is present
38
Q

Gentamicin

A

Most active against aerobic gram-negative

Aminoglycosides

39
Q

Tetracyclines

A

binds reversibly to the 30S ribosomal unit

blocks binding of aminoacyl-tRNA to “A” site

Doxycycline (Adoxa)

  • bacteriostatic
  • caused bad teeth
40
Q

Lincosamides

A

binds to 50S ribosomal subunit

  • Example: Clindamycin (Cleocin)
  • Bacteriostatic or bactericidal depending on concentration
41
Q

Clindamycin

A

Wide range of aerobic gram-positive and anaerobic gram-negative

(also gram-positive organisms)

42
Q

Anti-Metabolites

A

Folate, Sulfonamides, Trimethoprim

43
Q

Folate

A

substrate for bacterial synthesis of purines and nucleic acid

(synthesized from PABA)

44
Q

Sulfonamides

A

inhbit formation of dihydrofolic acid by competing with PABA

Example: Sulfamethoxazole

45
Q

Trimethoprim

A

Selective inhibitor of bacterial dihydrofolate reductase (DHFR)

46
Q

Bactrim

A

Sulfamethoxazole and Trimethoprim

(SMX-TMP)

Often used to treat pneumonia

synergism: combination therapy is synergistic through inhibition of sequential steps in the same pathway

47
Q

Which one is known as the “last resort” drug?

A

Vancomycin

active agonist for MRSA

48
Q

Which one promotes the red man syndrome?

A

Vancomycin

49
Q

Cephalosporins are considered as narrow, intermediate, and broad spectrum of antibacterial activity as the generation goes from ______

A

low to high

50
Q

Drugs that block tubular secretions such as probenecid may increase the levels of some cephalosporins. Why?

A

because those drugs are dependent on this mechanism to be excreted in the urine

51
Q

What are the mechanisms of acquired bacterial resistance

A
  • enzyme that degrades antibiotic
  • mutation in target
  • synthesis or activation of transport proteins
52
Q

Name examples of cephalosporins of the 3rd and 4th generation

A

3rd: Cefoxtaxime, Ceftriaxone

4th:

53
Q

Vancomycin is usually administered by ____ route as opposed to Bacitracin, which is used ____

A

IV

topically

54
Q

Ampicilin, Penicilin G, and Nafcilin are all highly active against ____

A

gram-positive

55
Q

What are the mechanisms to combat acquired bacterial resistance

A
  • inhibitor of drug-degrading enzyme
  • multi-drug therapy
  • use antibiotics carefully