Antibiotics: General Principles

Question 1

Gram positive bacteria (3):

Answer 1

• Staphylococcus
• Streptococcus
• Enterococcus

Question 2

Gram negative “piddly” bacteria (7):

Answer 2

• Haemophilus
• Morexella
• Morganella
• Shigella
• Salmonella
• Providencia
• Neisseria

Question 3

Gram negative “fence” bacteria (3):

Answer 3

PEK

• Proteus
• Eschericia coli
• Klebsiella

Question 4

Gram negative “SPACE” bacteria (5):

Answer 4

• Serratia
• Pseudomonas
• Acinetobacter
• Citrobacter
• Enterobacter

Question 5

Atypical bacteria (3):

Answer 5

CML

• Chlamydia
• Mycoplasma
• Legionella

Question 6

Anaerobic bacteria (3):

Answer 6

• Peptostreptococcus
• Bacteroides
• Clostridium

Question 7

Bactericidal:

Answer 7

Lethal to susceptible microorganisms.

Question 8

Bacteriostatic:

Answer 8

Inhibitory to growth of susceptible microorganisms.

Question 9

Resistant microorganism:

Answer 9

Concentration of drug required to inhibit or kill a microorganism cannot be achieved safely.

Question 10

Postantibiotic effect:

Answer 10

PAE

• Persistent effect of an antimicrobial on bacterial growth following brief exposure of organisms to a drug.
• Aminoglycosides and fluoroquinolones.

Question 11

Concentration dependent killing:

Answer 11

Killing dependent on peak concentration. Optimal kill occurs when concentration exceeds 10x MIC.
- Quinolones and aminoglycosides.

Question 12

Time dependent killing:

Answer 12

Killing is dependent on amount of time the concentration stays above the MIC (40-50% of the time).
- Beta-lactam antibiotics.

Question 13

MOA of Penicillins/cephalosporins/carbapenems/aztreonam:

Answer 13

Prevents cross-linking of peptidoglycan strands by inhibiting transpeptidases.

Question 14

MOA of Vancomycin:

Answer 14

Inhibits peptidoglycan synthetase and polymerization of linear peptide.

Question 15

MOA of aminoglycosides:

Answer 15

Inhibits 30 S ribosome; causes misreading of mRNA.

Question 16

MOA of chloramphenicol:

Answer 16

Inhibits peptidyl transferase and peptide band formation.

Question 17

MOA of erythromycin, clindamycin and lincomycin:

Answer 17

Inhibits 50 S ribosome.

Question 18

MOA of tetracyclines:

Answer 18

Inhibits binding of aminoacyl tRNA to ribosome; 30 S ribosome.

Question 19

Polymixin B and colistin:

Answer 19

Interference with cell membrane function.

- Cationic detergent.

Question 20

Rifampin:

Answer 20

Inhibits DNA-dependent RNA polymerase.

Question 21

Fluoroquinolones:

Answer 21

Interferes with supercoiling of DNA by action on DNA gyrase.

Question 22

Isoniazid and ethambutol:

Answer 22

Inhibits lipid synthesis.

Question 23

Sulfonomides and trimethoprim:

Answer 23

Prevents synthesis of folic acid.

Question 24

Mechanisms of resistance to penicillins and cephalosporins (3):

Answer 24

• Beta-lactamases.
• PBP changes.
• Porin channel changes.

Question 25

Mechanism of resistance to aminoglycosides:

Answer 25

Enzyme inactivating.

Question 26

Mechanism of resistance to macrolides:

Answer 26

• Methyltransferases that alter drug binding sites on 50 S ribosomal subunit.

Question 27

Mechanism of resistance to tetracyclines:

Answer 27

Transport systems that pump drugs out of the cell.

Question 28

Mechanisms of resistance to sulfonamides (2):

Answer 28

• Increased PABA formation.

- Target enzyme sensitivity.

Question 29

Mechanisms of resistance to fluoroquinolones (2):

Answer 29

• Target enzyme changes.

- Drug efflux.

Question 30

SPACE bug coverage:

Answer 30

Box and One:

• One of:
  
  • PNC, cephalosporin, carbapenem, (aztreonam).
• One of:
  
  • Fluoroquinolones, aminoglycosides
• Ace In The Hole: aztreonam

Question 31

SPACE bug PCN’s (2):

Answer 31

• Piperacillin

- Ticarcillin

Question 32

SPACE bug cephalosporins (2):

Answer 32

• Ceftazadime

- Cefepime

Question 33

SPACE bug carbapenems (2):

Answer 33

• Imipenem

- Meropenem

Question 34

SPACE bug aminoglycosides (2):

Answer 34

• Gentamicin

- Tobramycin

Question 35

SPACE bug fluoroquinolones (2):

Answer 35

• Ciprofloxacin

- Levofloxacin