Antibiotics

Question 1

T/F: Tetracycline works by killing bacteria.

Answer 1

F

Bacteriostatic; they work by inhibition of protein synthesis through reversible binding to bacterial 30S ribosomal subunits

Question 2

T/F: Penicillins work by inhibition of cell wall synthesis.

Answer 2

T

Question 3

T/F: Antimicrobials that affect the cell wall (ie penicillin, cephalosporin) or the cell membrane (polymixin B, colostin) are bactericidal.

Answer 3

T

They affect the integrity of the barrier of the cell to the environment. Without the integrity of the cell wall, the cell cannot survive.

Question 4

T/F: Ketoconazole works by inhibition of metabolic processes.

Answer 4

F

It inhibits nucleic acid synthesis

Question 5

T/F: A superinfection is more common following treatment with a narrow-spectrum antibiotic.

Answer 5

False

Superinfections are unrelated to the first infection which the antibiotic was originally taken for. The original antibiotic makes superinfection possible because it disrupts the normal bacterial microbiome of the body. Broad spectrum antibiotics disrupt the normal microbiome more than narrow spectrum antibiotics.

Question 6

For an antibiotic to be successful, it must accomplish these 3 things.

Answer 6

1. The pathogen must be susceptible to the drug.
2. The drug must reach the site of infection at a high enough concentration to inhibit/kill the pathogen.
3. The animal must be able to tolerate the concentration of drug needed to inhibit/kill the pathogen.

Question 7

What are the 3 ways bacteria become resistant?

Answer 7

1. Inherited a genetic mutation
2. Acquired from transfer of DNA from resistant bacteria
3. Picked up DNA from environment

Question 8

5 Steps to reduce selection pressure

Answer 8

1. use appropriate doses
2. administer drug for long enough period of time
3. educate clients to treat for entire dosage regimen
4. don’t use antibiotics to treat non-bacterial infections such as a virus
5. be aware of your patient’s immune status

Question 9

What are the 5 areas that an antibiotic can target?

Answer 9

cell wall
cell membrane 
protein synthesis
nucleic acids
folic acid pathways

Question 10

Targeting the bacterial cell wall usually results in __________.

Answer 10

-cidal

Question 11

What are drug classes that target the bacterial cell wall?

Answer 11

penicillins

cephalosporins

Question 12

Targeting the cell membrane usually results in bacterial cell _________.

Answer 12

-cidal

Question 13

What drugs target the cell membrane?

Answer 13

polymycins

Question 14

What route of admin are polymycins?

Answer 14

topical

Question 15

Antibiotics that target bacterial protein synthesis are __________

Answer 15

cidal or static

Question 16

Name the antibitoic(s) that target protein synthesis and are cidal

Answer 16

aminoglycosides

Question 17

Name the antibiotics that target protein synthesis and are static

Answer 17

tetracyclines

Question 18

Drugs that target nucleic acid synthesis are usually ___________

Answer 18

-cidal

Question 19

What antibiotic targets bacterial nucleic acids?

Answer 19

quinolones

Question 20

What antibiotic targets the folic acid pathway? When is it cidal vs static?

Answer 20

Sulfonamides
unpotentiated are static
potentialted are cidal

Question 21

What are the groups of penicillins?

Answer 21

Pen-G (natural)
Amoxicillin & ampicillin (upgraded from natural penicillins)
pencillinase-resistant penicillins (very narrow spectrum of activity)
Exteded spectrum (held in reserve)

Question 22

How can you identify a drug as a cephalosporin?

Answer 22

starts with “cef” or “ceph”

Question 23

How do you identify tetracycline antibiotics?

Answer 23

end in -cycline

Question 24

What are the 2 groups of tetracyclines?

Answer 24

Old: Tetra- & oxytetracycline
New: Mino- & doxycycline

Question 25

What is the difference between new vs old tetracyclines?

Answer 25

older bind to ions and cant diffuse through membranes; newer are less likely to bind ions and can diffuse through membranes

Question 26

What drugs should tetracyclines not be given with and why?

Answer 26

• Sucralfate, iron, kaopectate, peptobismol (b/c tetracyclines will bind to it)
• penicillins & cephalosporins (-cyclines are bacteriostatic)

Question 27

What species should doxy not be given via IV route?

Answer 27

Horses

causes sudden collapse, death

Question 28

How can you identify an antibiotic as an aminoglycoside?

Answer 28

ends in “mycin” or “micin”

Question 29

Why is it important to form a gradient with aminoglycosides?

Answer 29

If no gradient is formed, there drug will accumulate in the tissues and you will get a toxicity.

Question 30

What are macrolides typically used for?

Answer 30

respiratory infections

Question 31

List some examples of macrolides

Answer 31

azithromycin
erythromycin
tilmicosin
tylosin

Question 32

Similarities between chloramphenicol and floriphenicol

Answer 32

• excesllent at tissue penetration

- target protein synthesis

Question 33

Differences between chloramphenicol and floriphenicol

Answer 33

• Chloram. is banned from food animals b/c it causes aplastic anemia, whereas flori does not cause that and is FDA approved in cattle
• Chloram is either -static or -cidal based on amount, whereas flori. is only -static

Question 34

How can you identify an antibiotic as a fluroquinolone?

Answer 34

-ends in “floxacin”

Question 35

Why are fluoroquinolones good for treating UTIs?

Answer 35

they accumulate in higher concentrations in the urine

Question 36

What drugs should not be given at the same time as a fluroquinolone? Why?

Answer 36

• antacids (drug precipitates out)
• sucralfate (drug will stick to it)

If you must give together, give the fluroquinolone 4hrs after the other drug

Question 37

What is the special sulfonamide? How does it work?

Answer 37

Sulfasalazine

• gets broken down by bacteria in colon into azulfidie and mesalamine
• mesalamine is used for antiinflammatory properties in colon

Question 38

How do you identify a sulfonamide antibiotic?

Answer 38

starts with “sulfa”

Question 39

What do potentiated sulfonamides end in?

Answer 39

“prim”

Question 40

List Lincosamide drugs

Answer 40

lincomycin
clincamycin
pirlimycin

Question 41

What are lincosamdies good at?

What species are they toxic to?

Answer 41

Tx anaerobic bacteria

Toxic to rabbits, GPs, horses, ruminants

Question 42

What is metronidazole used for?

Answer 42

kill giardia

Question 43

Can metronidazole be used in calves?

Answer 43

NO