Antimicrobial Agents: Antibiotics Exam 1

Question 1

Bacteriostatic

Answer 1

prevents bacteria from continuing to grow/multiply

Question 2

Bactericidal

Answer 2

kills bacteria

Question 3

Can bacteriostatic or bactericidal be used longer?

Answer 3

bacteriostatic

Question 4

Pharmacokinetics

Answer 4

movement of a drug from administration site to the place of its activity, distribution in the body, metabolism/bioavailability, and elimination/excretion from the body

Question 5

What organ metabolizes drugs?

Answer 5

liver

Question 6

What happens if bioavailability is low?

Answer 6

the drug cannot be metabolized as well by the liver

Question 7

Pharmacodynamics

Answer 7

the effect of the drug in the body

Question 8

Factors affecting kinetics:

Answer 8

-release from dosage form
-absorption from the site of administration into the bloodstream
-distribution to various parts of the body, including site of action
-rate of elimination from the body via metabolism or excretion of unchanged drug (how long will it circulate in the body)

Question 9

Blood brain barrier purpose:

Answer 9

prevents drugs from reaching the brain

Question 10

Time-dependent drugs

Answer 10

bactericidal activity continues as long as the plasma concentration is greater than the minimum bactericidal concentration

Question 11

How often do time-dependent drugs need to be administered?

Answer 11

-several times a day
-drugs should be maintained above the MIC

Question 12

Concentration-dependent drugs

Answer 12

the rate and extent of killing increases as the peak drug concentration increases
-want to stay just above the line

Question 13

What drugs exhibit a Post-Antibiotic Effect?

Answer 13

concentration-dependent drugs

Question 14

Post-antibiotic effect

Answer 14

persistent suppression of bacterial growth after dose
-long post-antibiotic effect = longer dosing intervals

Question 15

How many antibiotics can we use at a time (generally speaking?)

Answer 15

1

Question 16

Gram (+) bacteria examples

Answer 16

-staph
-strep

Question 17

Gram (-) bacteria examples

Answer 17

-E. Coli
-salmonella
-pseudomonas

Question 18

Which gram type is more difficult to kill?

Answer 18

gram (-)
-requires non-simple and more toxic antibiotics

Question 19

4 Classes of Antibiotics

Answer 19

1. cell wall synthesis inhibitors
2. protein synthesis inhibitors
3. folic acid synthesis inhibitors
4. DNA synthesis inhibitors

Question 20

Which class of antibiotic is the oldest?

Answer 20

cell wall synthesis inhibitors

Question 21

Cell Wall Synthesis Inhibitors

Answer 21

-beta-lactam antibiotics
-cephalosporins
-penicillins
-cannot harm our cells because we do not have cell walls

Question 22

Protein synthesis inhibitors

Answer 22

-tetracyclines
-macrolides
-act on ribosomes (different from the ribosomes in our cells)

Question 23

Folic Acid Synthesis inhibitors

Answer 23

-sulfonamides (SMZs, TMZs)
-trimethoprim
-work on the folic acid (we also need folic acid in our cells so these can be toxic to us)

Question 24

DNA synthesis inhibitors

Answer 24

quinolones

Question 25

How does bacteria spread?

Answer 25

-some move -most spread by multiplying and through blood circulation

Question 26

Principles of antibiotic therapy:

Answer 26

-harm the parasite, not the host -mechanism of action: processes unique to bacteria -processes common to bacteria and host = more affinity for bacteria

Question 27

Types of bacteria

Answer 27

-gram + -gram - -aerobic -anaerobic

Question 28

What type of bacteria is penicillin great for?

Answer 28

gram +

Question 29

What is the oldest antibiotic?

Answer 29

penicillin

Question 30

How can penicillin be unstable?

Answer 30

-in acidic pH - pus is acidic and penicillin cannot survive in the stomach so it cannot be taken orally -susceptible to destruction by beta-lactamase (in some bacteria)

Question 31

Beta-lactamase

Answer 31

-found in some bacteria -can lead to super infection = bacteria feeds on penicillin and multiplies -destroys penicillin

Question 32

Types of penicillin

Answer 32

-penicillin G -penicillin V -procaine penicillin -benzathine penicillin

Question 33

How is penicillin adminstered?

Answer 33

-in hospitals: IV -most common outside of hospitals: IM (hurts a lot)

Question 34

What are common diseases penicillin is used to treat?

Answer 34

-strangles -strep -meningococcus -anthrax -clostridium

Question 35

Side effects of penicillin

Answer 35

-non-toxic unless host is allergic -anaphylactic shock -diarrhea (super infection) -resistance -yeast infection

Question 36

Semi-synthetic penicillins

Answer 36

-ampicillin -amoxicillin -methicillin (MRSA)

Question 37

Cephalosporins

Answer 37

-similar to penicillins: chemically, mechanism of action, and toxicity -more stable to bacterial beta-lactamase

Question 38

How are cephalosporins divided?

Answer 38

into 1st, 2nd, 3rd, and 4th generations 1 = gram + 2 = gram + and - 3 = gram + and - 4 = gram -

Question 39

How can cephalosporins be given?

Answer 39

PO, IM, IV

Question 40

What two beta-lactamase inhibitors work well together?

Answer 40

amoxicillin and clavulonic acid

Question 41

Vancomycin

Answer 41

-beta-lactam -can only be given IV (in hospital setting) -can be toxic to kidneys and ears

Question 42

Bacitracin

Answer 42

-excellent in killing bacteria -VERY toxic -reduced toxicity by putting it in an ointment

Question 43

Triple antibiotic ointment is made up of what?

Answer 43

1. bacitracin 2. neomycin 3. polymyxin

Question 44

Tetracyclines treat what types of bacteria?

Answer 44

Broad spectrum -gram + -gram - -rickettsia -anaerobic -protozoa

Question 45

Tetracyclines

Answer 45

-protein synthesis inhibitor -accumulates inside the bacterial cell, binds to ribosomes, impedes formation of new protein -bacteria will slowly die (starve the bacteria)

Question 46

What does tetracycline bind to/join with?

Answer 46

chelate calcium and other divalent cations (Mg2+)

Question 47

How are tetracyclines administered?

Answer 47

PO IV - diluted and administered slowly (bc calcium is needed for muscle contraction)

Question 48

Who should avoid tetracyclines?

Answer 48

young and pregnant individuals -bc it chelates with Ca which is needed for bone growth

Question 49

What is the one time tetracycline would be used in foals?

Answer 49

in foals with contracted tendons -it removes the Ca that is contracting the tendons to get them to relax

Question 50

How should you take tetracyclines orally?

Answer 50

not with any Ca containing product (milk) because it nulls the drug

Question 51

Oxytetracycline

Answer 51

LA 200! -what is given to foals with contracted tendons

Question 52

What tetracycline does not chelate Ca as much as oxytetracycline?

Answer 52

Doxycycline -given orally -must wear gloves (iron gets absorbed) -can lead to anemia after long-term use

Question 53

What horses do not use Macrolides?

Answer 53

any horses over the age of 1

Question 54

What happens if adults take macrolides?

Answer 54

severe diarrhea

Question 55

Most common macrolide

Answer 55

erthromycin

Question 56

Two examples of macrolides

Answer 56

-clarithromycin -azythromycin (2-pac)

Question 57

What is used with macrolides to treat Rhodococcus equi pneumonia in foals?

Answer 57

rifampin (if rhoda is resistant-use doxycycline)

Question 58

Side effects of macrolides

Answer 58

-diarrhea -light sensitivity -fever

Question 59

Aminiglycosides

Answer 59

very good in killing bacteria but very toxic, destroys kidneys and has more severe side effects -used against enteric bacteria -only used in ointments (except gentamicin)

Question 60

Types of aminoglycosides (protein synthesis inhibitors)

Answer 60

-streptomycin -neomycin (eye ointment) -gentamicin -amikacin (join injections to prevent joint infections) -trobramycin (eye ointment)

Question 61

What is essential for nucleic acid synthesis?

Answer 61

folic acid (some microbes need extracellular PABA to form folic acid)

Question 62

What are sulfonamides structurally similar to?

Answer 62

PABA

Question 63

Sulfonamides

Answer 63

-folic acid synthesis inhibitor -reversibly block folic acid synthesis (PABAs pick up sulfas instead of creating folic acid) -bacteriostatic -not very useful by itself anymore

Question 64

Trimethoprim

Answer 64

-folic acid synthesis inhibitor -used generally in conjunction with SMZs -synergism SMZs and TMPs

Question 65

Sulfonamides + what makes them bacteriocidal?

Answer 65

trimethoprim

Question 66

Fluoroquinolones: Floxacins

Answer 66

-newest antibiotic -DNA synthesis inhibitor -broad spectrum -MRSA

Question 67

Side effects of Floxacins

Answer 67

tendon laxity (usually in young animals)

Question 68

Floxacins are useful against what bacteria?

Answer 68

all but especially E.Coli when it becomes resistant to SMZ-TMP

Question 69

What is usually the last resort drug type in horses?

Answer 69

Flaxacins