Antibiotics

Question 1

Saving commensals and overall population susceptibility (Bacterial Refugia) is achieved by what treatment approach

Answer 1

Specific

Question 2

What is one of the best treatment approaches on finding an increase in fibrinogen, white cell count and presence on phagocytosed bacteria on microscopy?

Answer 2

Combination showing synergism/appropriate broad spectrum

Question 3

Explain antibiotic combination antagonism

Answer 3

Static + cidal

Question 4

For how long should antibiotic therapy be continued after the clinical symptoms disappear?

Answer 4

2 days

Question 5

Name one factor that may increase the necessity of antibiotic use during surgical procedures.

Answer 5

Tissue handling

Question 6

How does polar antibiotics (water soluble) antibiotics cross cell membranes?

Answer 6

Active/receptor assisted

Question 7

Define Area Under the curve (AUC)

Answer 7

Amount of absorbed drug in blood stream

Question 8

What is the half life of a drug?

Answer 8

Time to half concentration

Question 9

Explain the mechanism of time dependent antibiotics.

Answer 9

Time above MIC 40-70%. Average of 50%

Question 10

Name 1 factor which will influence the volume of distribution of an antibiotic.

Answer 10

Protein binding/charge/ size/ pH

Question 11

How can the amount of free antibiotic in the blood be increased

Answer 11

Increase dose

Question 12

Define bioavailability.

Answer 12

Amount of drug in blood measured by AUC

Question 13

Name 3 factors that will influence bioavailability.

Answer 13

Dose, Injection site and volume

Question 14

Define Volume of distribution.

Answer 14

(Total dose-bioavailability) – blood concentration= Vd example. Inject 100mg absorbed 60%. Total amount in body 60mg Blood concentration 20mg 60/20 = 3L/KG

Question 15

Which group of antibiotics generally have a large volume of distribution?

Answer 15

Lipid soluble

Question 16

What are the rules regarding ELDU in pet animals?

Answer 16

Does not apply. Need confirmation animal wont enter food chain.

Question 17

Which are the major food producing species?

Answer 17

Cattle/swine/poultry

Question 18

Where is the best location to give a sc injection in a small ruminant?

Answer 18

axilla

Question 19

What is a side effect giving propylene glycol intravenously?

Answer 19

Lower blood pressure

Question 20

Give an example of a time dependent antibiotic.

Answer 20

Tetracyclines

Question 21

Give an example of an concentration dependent antibiotic.

Answer 21

Fluroquinolones. Depend on concentration. Does not equate to multiple dosing because of post antibiotic effect

Question 22

AUC of penicillin would be affected if which organ fails?

Answer 22

Renal

Question 23

What is the spectrum of penicillin?

Answer 23

Gram positive anerobe

Question 24

Why is penicillin commonly used for the following wound infections, black leg and listeria?

Answer 24

Gram positive

Question 25

In which production animals is the use of penicillin prohibited?

Answer 25

Lactating dairy cows and veal calves

Question 26

You have a animal with a lymph adenopathy. There are phagocytosed bacteria in the lymphocytes. Culture show susceptibility to both procaine penicillin and Tulathromycin (macrolide). Which of the 2 antibiotics would you choose as a initial treatment and why?

Answer 26

Penicillin. Bactericidal preferred over intracellular

Question 27

You have 2 antibiotics. One has a Vd of 10l/kg and the other 36L/kg which of the 2 antibiotics would you choose for a case of septic meningitis. Assume that the sensitivity of both for the infection is the same.

Answer 27

Vd 10L, bactericidal

Question 28

Give 2 advantages of using synthetic penicillin over procaine penicillin.

Answer 28

Gram negative spectrum/can be used in lactating dairy cows and veal calves

Question 29

Why is the meat withdrawal time for procaine penicillin problematic.

Answer 29

Because of variation in dose rates

Question 30

For what type of antibiotic treatment is potassium penicillin often used.

Answer 30

Regional iv antibiosis

Question 31

What is the indication of long acting ceftiofur?

Answer 31

Metaphylaxis. Treatment of Footrot,metritis,BRD

Question 32

What part of the cephalosporin ELDU cannot be violated?

Answer 32

Dose, route, treatment schedule

Question 33

From an antimicrobial perspective give 2 reasons why cephalosporin might give a better clinical response than ampicillin.

Answer 33

Less susceptible to penicillinase and wider gram negative spectrum

Question 34

Under what circumstances would you have to use ampicillin rather than ceftiofur?

Answer 34

Lactating dairy cow and veal calf

Question 35

Name a non-antibacterial effect of tetracycline.

Answer 35

Inhibits MMP’s (anti-inflammatory)

Question 36

Oxytetracycline is not labeled to be used in lactating dairy cows but it is used topically for foot warts – Why?

Answer 36

Doesn't get into the milk if used topically

Question 37

What is the mechanism of action of oxytetracycline?

Answer 37

Reversible 30S ribosome binding. Relates to relapses as it is a time dependent antibiotic. bacteriostatic.

Question 38

Define the extended spectrum of Oxytetracycline.

Answer 38

mycoplasma, richettsia, erlichia, protozoa, babesia

Question 39

Name one of the mechanisms of bacterial resistance to oxytetracycline.

Answer 39

Formation of the efflux pump by the bacteria

Question 40

In a time dependent antibiotic what needs to be done to increase the dose interval.

Answer 40

Increase the dose to extend the time

Question 41

What effect of oxytet in the blood may make it go down?

Answer 41

Binding to ionized calcium

Question 42

What are the absolute restrictions on the ceftiofur label

Answer 42

Dose,route,dose interval

Question 43

You are asked to treat a septic joint caused by Ecoli in a veal calf. Which of the following antibiotics would you choose and give inclusion /exclusion criteria for each

Answer 43

Ampicillin: Gram –ve; small Vd; Polar; Bactericidal Enrofloxacin: Gram-ve; Larger Vd; Lipid soluble; gram -ve ; intracellular; bactericidal; intracellular

Question 44

What are 2 main indications of Danofloxacin

Answer 44

Treatment and control of BRD

Question 45

What is a major problem using Tilmicosin

Answer 45

Can be lethal in humans and pigs

Question 46

What is the main indication of Pirsue

Answer 46

Mastitis

Question 47

Name 5 groups of organisms for which Macrolides are used

Answer 47

Gram +ve; Gram –ve; Spirochaetes; anerobes; mycoplasma

Question 48

Name antibiotic groups specifically labeled for foot rot

Answer 48

Oxytetracyclines , macrolides, Florfenicol, Sulfadimethoxine, Excede

Question 49

Some macrolides have extended dose intervals through what mechanism

Answer 49

Entero-hepatic cycle

Question 50

Name 2 time dependent antibiotic groups with bactericidal capabilities

Answer 50

Florfenicol; Penicillins

Question 51

What is the main indication of oral sulfas for calves

Answer 51

coccidiosis

Question 52

What is the mechanism of action of Sulfonamides

Answer 52

Inhibit formation of folic acid necessary for the formation of bacterial RNA

Question 53

What makes sulfas bactericidal

Answer 53

Addition of diaminopyridimidines (trimethoprim)

Question 54

What does sulfas have in common with penicillins

Answer 54

Depend on rapid growth of the organism. | Not good for chronic infections

Question 55

Why do the sulfonamides have a latent period

Answer 55

Bacteria use stored folic acid

Question 56

What tissues are sulfonamides least active

Answer 56

Necrotic material and puss