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Pharm 2 Undergrad > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

What are the 6 main groups of Antibiotics?

A
  1. Penecillins
  2. Cephalosporins
  3. Aminoglycosides
  4. Flouroquinolones
  5. Tetracyclines
  6. Macrolides
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2
Q

Which are the two most comply prescribed set of antibiotics?

A

Beta lactams and quinolones

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3
Q

Describe the mechanism of action of Beta- Lactams/ glycoprotein antibiotics?

A

–Act by inhibiting synthesis of bacterial cell walls

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4
Q

What is the main type of Beta- Lactam?

A

Penicillins

  • Used to treat Gram Positive microorganisms
  • Distribution to the eye, brain, CSF and prostatic fluid is low
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5
Q

-Clavulanate, Sulbactam and Tazobactam:

A

Beta Lactamase Inhibitors

  • Used in conjunctions with other antibioitcs to make commercial drugs
  • Clavulanate is under investigation as a NAALADase inhibitor (beta- lactamase inhibitor) with aphrodisiac & anti-depressant properties
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6
Q

What is the mechanism of action of Cephalosporins?

A

-Used to treat urinary tract infections (usually not in high concentrations in the CSF)
–use is dependent on it’s 1-4 generations.
1st generation- moderate spectrum agents (affinity for gram positives)
2nd generation- have a greater gram negative affinity
3rd generation- Broad spectrum of activity- high affinity for gram negative microorganisms
4th generation- extended spectrum drugs with affinity for gram positive microorganisms, similar to the first generation. Greater resistance to beta lacatamases than third generation cephalosporins

-Effective in treating Meningitis

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7
Q

Imipenem/ Citastatin

A

Carbapenems

  • Class of Beta- Lactam antibiotics that are HIGHLY resistant to beta- lactamases
  • broad spectrum of antibacterial activity
  • *Imipenem/ Citastatin
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8
Q

Aztreonam:

A
  • Only commercially available Monobactam
  • Beta lactam antibiotics where the beta lactam in singular (not fused to another ring)
  • Sensitive to Gram- Negative bacteria
  • NOT useful against Gram Positive bacteria
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9
Q

True or False:

Beta- Lactams are bactericidal.

A

True (under most conditions)

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10
Q

Bacitracin:

A

Glycoprotein antibiotic

Topical agent to treat Gram Positive and certain Gram negative microorganisms

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11
Q

Vancomycin:

A

Glycoprotein antibiotic

-Primarily active against Gram Positive bacteria

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12
Q

What is the different between beta lactams and glycoproteins?

A
  • Glycoprotiens don’t have a beta- lactam nucleus
  • They are still a bactericidal cell wall inhibitor
  • Beta lactams are receptive to resistance (last resort drug)
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13
Q

Tetracyclines:

A

–Bind to the 30S ribosome and prevent the binding of aminoacyl-tRNA to it’s acceptor site

  • Enter Gram Positives by an energy dependent process
  • Enter gram negatives by diffusion
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14
Q

Erythromycin and Ketolides (Telithromycin):

A

-Macrolides

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15
Q

Therapeutic Uses of Tetracyclines:

A
  • Rocky Mountain Spotted Fever; Typhus; mycoplasma pneumoniae, chalmydia pneumoniae, Lyme disease and Brucellosis.
  • Used to treat plague and pelvic anti-inflammatory disease
  • Can also be used as a low dose acne medication
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16
Q

Erythromycin:

A
  • Macrolide/ Bacteriostatic
  • Used to treat mycoplasma pneumoniae
  • Used for streptococcal group A (GAS) & upper respiratory tract infections to patients allergic to penicillins
  • Legionella infection
  • Can also be used to treat Lyme disease and Chlamydia infection
  • Can also be used to treat syndromes such as bacterial bronchitis, ear infections with sulphonamide, and topically for acne
  • Can also be used for large bowel surgery and oral surgery
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17
Q

Name 3 main Aminoglycosides:

A
  • Bactericidal
  • Streptomycin, Gentamycin and Neomycin
  • Streptomycin was the first effective drug for treating TB
  • Mostly inactive against fungi and anaerobic bacteria
  • Administered IV or IM
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18
Q

Chloramphenicol:

A

-Bacteriostatic antimicrobial agent
-VERY inexpensive (used in 3rd world countries)
AE’s: Can cause Aplastic Anemia (BAD)

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19
Q

What is the most common form of resistance among Aminoglycosides?

A

The most common form of resistance in ahminoglycosides is modifications of the enzymes through enzyme- catalyzed phosphorylation- acetylation and adenylation

-Resistance can also occur through altering the ribosomes, as well as inadequate transport of the drug within the cell.

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20
Q

Resistance Mechanisms to Tetracyclines:

A
  1. Drug efflux due to new protein
  2. Alteration of the outer membrane due to mutations in chromosomal genes
  3. The ribosomal binding site is protected due to the presence of the plasma- generated protein that binds ribosomes.
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21
Q

True or False:

-Inhibition of folic acid synthesis is a direction for selective antibiotic development.

A

True

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22
Q

Sulfmethoxazole:

A
  • Sulfonamide

- Inhibits dihydropteroate synthesis (competitive inhibition)

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23
Q

Trimethoprim:

A

-Dihydrofolate

Reversible inhibition of dihydrofolate reductase

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24
Q

Main Therapeutic Uses of Sulphonamides:

A
  • Prophylaxis
  • Urinary tract infections
  • -The most common adverse effects are gastrointestinal disturbances and allergic risk reactions
25
Q

Resistance of Sulphonamides:

A
  • Inhibition of sulphonamides can be REVERSED by purines, thymidines, methionine and serine
  • Resistance to sulphonamides is widespread, and its incidence continues to increase among all bacterial pathogens.
26
Q

Which class of drugs act to inhibit or damage bacterial DNA?

A

-Flouroquinolones and Nitrofurans

27
Q

Ciprofloxacin, Norfloxacin, Levofloxacin, Gatifloxacin and Moxcifloxacin

A

Flouroquinolones

  • Act by inhibiting Topoisomerases
  • Act by binding to and trapping the DNA synthesis and cell growth- has a lethal effect

Mutations in DNA Topoisomerases are the main reason for most bacterial resistances of quinolones, as well as active efflux of the drug.

28
Q

Nitrofurantione

A

Nitrofurans

  • Not used anymore due to carcinogenicity and mutagenicity (banned in Canada)
  • Used to treat Urinary Tract Infections
  • At high concentrations, nitrofuration is bactericidal
29
Q

Colistin (Polymixin E) and Polymyxin B:

A
  • Polymyxin
  • Administered by IM injection
  • Used to treat pseudomonas, aeruginosa & Acinetobacter baumannii
  • Can also be used topically for the treatment of eye and ear infections
30
Q

Polymyxins:

A
  • Branched chain cyclic decapeptides
  • Not absorbed well by the GI tract
  • Used only in patients with Cystic Fibrosis because of Toxicity
  • Lipophilic and Lipophobic groups interact with phospholipids & disrupt bacterial cell wall membranes
31
Q

Actinobacteria:

A

Mycobacteria is a type of Actinobacteria which can lead to severe disease such as TB and Leprosy, as well as soft tissue infections after trauma or surgery

32
Q

Drugs to Treat Tuberculosis:

A

First line drugs:
Isoniazid, Rifampin, Rifabutin, Rifapentine, Pyrazinamide and Ethambutol

Second line drugs:
Flouroquinolones, Streptomycin, Kanamycin, Amikacin, Capreomycin, Ethionamide, p-Aminosalicyclic acid (PAS), and Cycloserine

33
Q

Rifampin:

A

A mycobacterial DNA- dependent RNA polymerase inhibitor

-These drugs bind to the beta subunit of DNA dependent RNA polymerase and inhibit RNA synthesis

34
Q

Isoniazid:

A
35
Q

Drugs which inhibit protein synthesis:

A

-Aminoglycosides, streptomycin, kanamycin and amikacin

36
Q

p-Aminosalicyclic Acid:

A

Affect THF synthesis by competitive inhibition with p-aminobenzoic acid

37
Q

Pyrazinamide (PZA):

A

Disruptions of plasma membrane by targeting of fatty acid synthesis
-Has the ability to kill M. tuberculosis

38
Q

Thalidomide:

A
  • Immunomodulatory drug

- Never to be taken in pregnant women

39
Q

Anti- Leprosy Drugs:

A

-Rifampin, Dapsone and Clofazimine

40
Q

Rifampin for Leprosy:

A

-Acts by inhibition of m. Leprae DNA dependent RNA polymerase

41
Q

Dapsone for Leprosy:

A

-Acts as an inhibitor of dihydropteroate synthetase in folate synthesis to produce a bacteriostatic effect.

42
Q

True or False: Active TB can be treated with one drug.

A

False.

NEVER treat active TB with only one drug- requires multi drug therapy

43
Q

Why can’t antibiotics be used to treat Fungi’s?

A

-Fungi’s have different ribosomes, possess a discrete nuclear membranes and their cell walls have different components.

44
Q

Capsofungin:

A

-Kills fungi

Blocks the synthesis of major fungal cell wall components (1-beta-D-glucan)

45
Q

Triazoles (Fluconazole, Itraconazole and Voriconazole):

A
  • Kills fungi

- Inhibits fungal cytochrome P450 enzyme 14-alpha-demthylase resulting in inhibition of ergosterol synthesis

46
Q

Ketoconazole (Imidazoles):

A
  • Kills fungi

- Inhibits ergosterol synthesis

47
Q

Amphotericin (polyene):

A
  • Kills fungi

- Associates with ergosterol to inhibit fungal cell wall synthesis

48
Q

Terbinafine (allymines):

A

-Inhibits ergosterol biosynthesis via inhibition of squalene epoxidase

49
Q

Griseofulvin:

A
  • Inhibits fungal mitosis through interaction with polymerized microtubules
  • Inhibits mitosis
50
Q

Flucytosine:

A
  • Disruption of essential proteins of fungi or inhibition of fungal DNA synthesis
  • Replaces uracil with 5-flurouracil in fungal RNA
51
Q

Azoles:

A

-Inhibits the synthesis of ergosterol by blocking the action of 14-alpha-demethylase

52
Q

Nystatin:

A
  • Polyene anti-fungal
  • Minimal side effects
  • Bad tase & can produce nausea
  • Not allergic on the skin
53
Q

Amphotericin B:

A
  • IV administration of Amphotericin B may cause many adverse effects.
  • headache, chills, high fever, general discomfort, nausea, and hypertension may develop
  • Anemia with hematocrits between 22-35%
  • Leads to reduced eythromoiesis
  • Some degree of renal toxicity
  • Hepatotoxiticy has also been reported
54
Q

Mechanism of action of Polyenes (Amphotericin B and Nystatin):

A
  • Polyenes bind to sterols in the cell membrane, forming channels allowing K+ and Mg2+ to leak out.
  • The polyenes become integrated into the membrane & bind ergosterol
  • ->Polyenes only work in fungi’s which have ergosterol in their cell membranes
55
Q

Ideal Therapeutic Index Ratio:

A
  • Therapeutic Index= Lethal Dose (LD)/ Effective Dose (ED)

- Safer drugs have a higher therapeutic index, while drugs that easily cause toxicity have a low TI.

56
Q

MIC

A

Minimal Inhibitory Concentration:

-The lowest concentration of anti-microbial agent that prevents visible growth of 18-24 hours of incubation

57
Q

MBC

A

Minimal Bactericidal Concentration:

-The minimal concentration of antimicrobial agent that kills 99.9% of cells

58
Q

Ideal selective toxicity values for MIC/ MBC and TI:

A

Low MBC and a high TI

  • High lethal dose compared to effective dose
  • Low bactericidal concentration
59
Q

Penicillin Drugs:

A

Amoxicillin, Penicillin, ect.

-Target Gram Positive bacteria

Pharm 2 Undergrad (29 decks)

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