Walters - Antimicrobial Principles

Question 1

T/F bacteristatic antibiotics do not directly kill bacteria, instead they inhibit metabolic pathways thus weakening the organisms and then relying on the patients immune stystem to clear the infection

Answer 1

true; organism functionals normally until it runs out of product;

Question 2

____antibiotics outright kill bacteria, mostly by causing lysis

Answer 2

Bactericidal;

Question 3

What are factors to consider when choosing an antibiotic

Answer 3

1. Resistance
2. Age
3. hepatic function
4. genetics
5. disease state
6. pregnancy
7. site of infection
8. route of administration

Question 4

bacteriostatic or bactericoidal depend on:

Answer 4

dose and organism being treated

Question 5

How can resistance occur

Answer 5

1. pumping the antibiotic back out of cell before it causes damage
2. finding alternate routes to synthesize compound whose usual mode of synthesis is inhibited
3. increasing the expression of an enzyme otherwise inhibited by the antibiotic.

Question 6

Renal function deterioates with age which can cause drug _____ and inc side affects. Penicilin can cause ____ such as seizures and coma. Aminoglycosides increases ____ and ototixicity, especially in pregnant women

Answer 6

accumulation; neurotoxicity; nephrotoxicity

Question 7

Neonates have low ____. Sulfonamides also prefers to be bound to albumin and bounce bilirubin off which causes it to inc in circulation and brain and cause _____

Answer 7

albumin; kernicterus

Question 8

____cross the placenta and are excreted in breast milk and deposit in teeth and bone where they discolor teeth and cause slow bone growth

Answer 8

Tetracycline

Question 9

_____cause cartilage damage and arthropathy, especially in pregnant women or small kids

Answer 9

Fluroquinolones

Question 10

_____ , a macrolide, gets excreted unchanged in bile.

Answer 10

Azithromycine

Question 11

____is one route of drug metabolism and is more rapid in Asians. ______ phosphate dehydrogengase is a scavenger enzyme that protects cells from free radicals. A decrease in this causes risk of damage.

Answer 11

Acetylation; glucose 6

Question 12

increase of _____, nitrofurantoin, and _____ can cause a lot of free radicals if low levels of G6PD

Answer 12

sulfonamides; chloramphenicol

Question 13

____are structurally similar to oral hypoglycemic drugs used to stimulate insulin release in diabetics. Sulfonylureas, and sulfonamides block the ____channel causing positive charges to accumulate inside the cell which causes Ca++ to release insulin. This is how sulfonamides can potentiate the hypoglycemic effect of oral sulfonylureas.

Answer 13

Sulfonamides; K+

Question 14

IV antibiotics are often administered in ____. The extra sugar can contribulte to hyperglycemia in diabetics

Answer 14

D5W

Question 15

In most cases you try to reach the _____ or higher. However, absecess can alter ____ causing changes in drug activity. ____ are inactive due to unfavorable pH, so the site must be drained before giving aminoglycosides.

Answer 15

MIC; pH; Aminoglycosides (treat gram - infections)

Question 16

____ and ____ must be given parenterally for systemic effects, but they can be given orally for a local action in the gut

Answer 16

Aminoglycoside; vancomycin

Question 17

_____, cephalosporins, and _____ can give false + test for urine sugar if using a test that measures reducing substances such as _____. You can avoid this by using tests that measure glucose directly such as ____ or labstix

Answer 17

Penicillins; tetracycline; Dextrostix

Question 18

Why do we use drugs acting by different mechanisms

Answer 18

Organism wont find a way to get around of by both drugs.

Question 19

what does synergism mean

Answer 19

the two drugs together will produce a greater effect greater than the sum of either drug alone; its more than additive

Question 20

_____inhibit the very first step in the synthesis of folic acid: _____. Trimethroprim inhibits the synthesis of folic acid in a later step. Together sulfanomides and trimethroprim are synergistic.

Answer 20

Sulfonamide; dihydropteropate synthase

Question 21

Penicillins enhance the uptake of ______ and streptomycin; a combination useful in treating _____ endocarditis

Answer 21

gentamicin; enterococcal

Question 22

what are examples of aminoglycosides

Answer 22

gentamicin and streptomycin

Question 23

What type of antibiotic are sulfonamides

Answer 23

static

Question 24

what is the mechanism of action of sulfonamides

Answer 24

inhibit dihydropteroate synthase (first step in the synthesis of folic acid)

Question 25

Most sulfonamides are used with a ______ reductase inhibitor

Answer 25

dihydrofolate

Question 26

PABA + _____ gives you _____ acid and then you add glutamate. Dihydrofolate gets reduced by dihydrofolate reductase to ______. As a result, you wont be able to make _____, so no DNA

Answer 26

pterdine; dihydropteroic; tetrahydrofolate; thymidine

Question 27

Why dont sulfonamides inhibit human DNA synthesis?

Answer 27

Because we cannot synthesize folic acid…it comes form our diet.

Question 28

Sulfonamides are used with a ____ ____ ____ for a synergistic affect. Why?

Answer 28

dihydrofolate reductase inhibitor; DHFR reduces dihydrofolate back to tetrahydrofolate to be reused in the synthesis of thymidine. So we want to block this.

Question 29

What are the different types of DHFRI’s?

Answer 29

1. Trimethroprim: inhibits bacterial DHFR, and causes blood dyscrasias
2. Pyrimethamine: inhibits protozoal DHFR, and is antimalarial
3. Methotrexate: inhibits all forms. For cancer and psoriasis
4. Pralatrexate: for T cell lymphoma.

Question 30

Sulfonamides can cross the placenta and have antibacterial effects and unwanted side effects in fetus. They are in category _____.

Answer 30

B

Question 31

what are the oral asborbable sulfonamides?

Answer 31

1. Sulfisoxazole: only available with erythromycin as prophylaxis vs recurrent otitis media
2. Sulfamethoxazole: with trimethoprim
3. Dapsone

Question 32

What is the advantage of TMP-SMZ

Answer 32

To get synergistic affect

Question 33

What is TMP-SMZ used for

Answer 33

urinary, respiratory and GI infections

Question 34

What are topical agents of sulfonamides

Answer 34

1. Sulfacetamide (Bleph 10):
   - ulcerative belpharitis
   - conjunctivitis
2. Silver sulfadiazine: burns; prevents sepsis. releasing silver which is toxic to microorganisms (therapeutic effect)
3. Mafenide: burns; inhibits carbonic anhydrase –> metabolic acidosis

Question 35

What are side effects of all sulfonamides

Answer 35

1. Crystalluria: drink water! can damage renal tubules
2. Kernicterus: a form of jaundice from displacement of bilirubin from plasma proteins.
3. Blood dyscrasias: acute hemolytic anemia, agranulocytosis, aplastic anemia
   * Avoid topical if history of blood dyscrasias
4. Hypersensitivity
5. Hyperkalemia: High K+

Question 36

what are the different types of hypersensitivity reactions

Answer 36

1. Erythema multiforme: sudden onset of asymptomatic macules, papules, and vesicles on extremities and face.
2. Stevens-Johnson syndrome: fever, headache, couph and conjuntivitis followed by macules on face, neck and other areas eventually forming bullous eruptions on skin and mucous membranes
3. Rx fever: immune mediated hypersensitivity phenomenon

Question 37

What are drug interactions

Answer 37

1. potentiates hypoglycemic effect of oral sulfonylureas

2. displaces warfarin from albumin