Bugs and Drugs

Question 1

Mechanisms of resistance

Answer 1

Mutations (chromosome)
-up regulate chromosomal (AmpC) B lactamases
-up regulate multi drug effluc
-reduce permeability of membranes
-alterations in DNA gyrase
Acquisition of DNA elements (plasmid)
-beta lactamases
-aminoglycoside-modifying enzymes

Question 2

Gram Pos cocci

Answer 2

Peptospreptococcus

Question 3

Gram pos rods

Answer 3

Bacillus anthracis
Propionibacterium
Clostridium botulinum
Clostridium difficile
Clostridium tetani

Question 4

Gram neg rods

Answer 4

Bacteroides fragilis
Bacteroides spp
Eikenella corrodens

Question 5

Atypical Bacteria

Answer 5

Legionella pneumophila
Mycoplasma pneumoniae
Chlamydia pneumoniae

Question 6

Penicillins MOA

Answer 6

Bind to transpeptidase enzymes in the bacterial cell and disrupt cell wall formation
-bactericidal

Question 7

Cephalosporins MOA

Answer 7

Bind to transpeptidase enzymes in the bacterial cell wall and disrupt cell wall formation
-bactericidal

Question 8

Carbapenem

Answer 8

-Most broad spectrum single agents available
-Spectrum of activity
–active against most gram positive aerobes
–drugs of choice for ESBL producing organisms
–No MRSA coverage
–active against most gram negative aerobes including Pseudomonas aeruginosa
**ertapenem does not have Pseudomonas or enterococcal activity
–active against gram negative anaerobes including B. fragilis

Question 9

Aminoglycosides MOA

Answer 9

(Gentamicin, Tobramycin, Amikacin)
Bind to the 30s ribosomal subunit and inhibit bacterial protein synthesis
-bactericidal
*gentamicin is used in combo with cell wall active agents for gram positive IE

Question 10

Macrolides MOA

Answer 10

(Erythromycin, clarithromycin, azithromycin)
Reversibly bind to the 50s ribosomal subunit and inhibit bacteria protein synthesis
-bacteriostatic

Question 11

Lincosamides MOA

Answer 11

(Clindamycin)
Reversibly bind to the 50s ribosomal subunit and inhibit bacteria protein synthesis
-bacteriostatic

Question 12

Fluoroquinolones MOA

Answer 12

(Ciprofloxacin, levofloxacin, moxifloxacin)
Inhibit DNA gyrase which results in breakage of bacterial DNA
-bactericidal

Question 13

Glycopeptides MOA

Answer 13

(Vancomycin)
Bind to the D-alanyl- D- alanine terminal residue in the growing peptidoglycan chain.
-Inhibits cell wall formation
-bactericidal
*nephrotoxicity
**drug of choice for MRSA infections

Question 14

Daptomycin MOA

Answer 14

Irreverisbly binds to the bacterial cell membrane.
- Calcium-dependent membrane insertion of molecule
Rapidly depolarizes the cell membrane
-efflux of potassium
-destrys ion-concentration gradient

Question 15

Trimethoprim/ Sulfamethoxazole MOA

Answer 15

Inhibits sequential steps in the formation of tetrahydrofolate in bacteria which inhibits purine synthesis
-bacteriostatic

Question 16

Nitroimidazoles MOA

Answer 16

(metronidazole)
Reduced to a toxic intermediate that produces damage by interaction with bacterial DNA
-bactericidal