AED - Anti-bacterial Agents II - Week 6

Question 1

What 8 factors are taken into account when prescribing an antibiotic?

Answer 1

Age
Weight
General health status
Mental status
Allergy history
Liver and kidney function
Present medications
Pregnancy status

Question 2

List the 5 classes of commonly used antibiotics.

Answer 2

Penicillins
Cephalosporins
Macrolides
Fluoroquinolones
Tetracyclines

Question 3

Are penicillins commonly used in eyecare?

Answer 3

No, rarely used

Question 4

Are penicillins bacteriostatic or bactericidal?

Answer 4

Bactericidal

Question 5

Which bacterial species produce penicillinase?

Answer 5

Most staphylococcal species

Question 6

Can penicillins be penicillinase resistant?

Answer 6

Yes

Question 7

What is the dosage for dicloxacillin and why? Must it be taken with meals?

Answer 7

It has a short half life, so therefore 250mg q.i.d

Can be taken without regard to meals

Question 8

What is a classic synthetic penecillin? Give its alternate name as well and describe why it is named so (name the component as well).

Answer 8

Amoxycillin
It is combined with a beta lactam inhibitor, potassium clavulanate
This increases its spectrum
It is also known as augmentin

Question 9

What is the dosage of amoxycillin based on? Give the dosage (4).

Answer 9

Based on severity of the condition
Mild - 500mg
Most - 750mg
Severe - 1000mg
Taken b.i.d for 1 week

Question 10

What are most penicillin side effects limited to?

Answer 10

Skin rashes

Question 11

Up to what percentage are penicillin hypersensitivity reactions reported?

Answer 11

20%

Question 12

Is severe anaphylaxis common with penicillins?

Answer 12

Uncommon

Question 13

Does penicillin alter the normal flora of t respiratory tract?

Answer 13

Yes

Question 14

What are three options if the patient is allergic to penicillins?

Answer 14

Cephalosporins
Macrolides
Fluoroquinolones

Question 15

What is the first choice ophthalmic antibiotic?

Answer 15

Cephalosporins

Question 16

How are cephalosporins related to penicillins?

Answer 16

Has a beta lactam ring, but with different amino acids

Question 17

Give an example of a cephalosporin and the usual dose.

Answer 17

Cephalexin

500mg q.i.d for 1 week

Question 18

What is a consequence of taking cephalosporins and in patients with which disease is it contraindicated?

Answer 18

It can kill intestinal bacteria necessary for synthesising vitamin K, which can impair clotting
Contraindicated in haemophiliacs

Question 19

What is the primary adverse reaction to cephalosporins?

Answer 19

Hypersensitivity

Question 20

What percentage of individuals allergic to penicillin are also allergic to cephalosporins, if any?

Answer 20

5-10%

Question 21

If there is a minor adverse reaction to penicillin, is selection of cephalosporins still common? What about if there is a history of anaphylaxis to penicillins (2)?

Answer 21

Minor - selection is common

If there is a history of anaphylaxis, then consider a macrolide or a fluoroquinolone

Question 22

Is fluoroquinolone narrow or broad spectrum?

Answer 22

Broad spectrum

Question 23

What is fluoroquinolone reserved for?

Answer 23

When there is penicillin allergy

Question 24

Give an example of a fluoroquinolone and the dosage.

Answer 24

Ciprofloxacin

500mg q.i.d for a week

Question 25

Are macrolides typically a first-line antibiotic?

Answer 25

No

Question 26

List two cases where macrolides are generally used.

Answer 26

Chlamydial infections | Pregnancy

Question 27

How do macrolides work? Are they bacteriostatic or bactericidal?

Answer 27

Inhibit protein synthesis | Mainly bacteriostatic but can be bactericidal in higher concentrations

Question 28

What properties do macrolides have at low doses?

Answer 28

Anti-inflammatory

Question 29

What is the alternative when tetracyclines are contraindicated?

Answer 29

Macrolides

Question 30

What antibiotic (name specifically) is commonly used as a second choice and in what population is it a common choice in?

Answer 30

Erythromycin | Common choice in pregnancy

Question 31

What is azithromycin good against?

Answer 31

Chlamydial infections

Question 32

What is the dose for azithromycin for chlamyia? What about erythromycin and doxycycline?

Answer 32

Azthromycin - 1gm p.o single dose Erythromycin - 500mg q.i.d for a week Doxycycline - 1000mg b.i.d for 1 to 3 weeks

Question 33

Are the use of tetracyclines common or limited? Explain why.

Answer 33

Limited due to resistance

Question 34

What tetracycline is the most effective in ocular disease? Explain why.

Answer 34

Doxycycline, it has the fewest potential side effects

Question 35

What does doxycycline decrease the bioactivity of?

Answer 35

Major inflammatory cytokines

Question 36

How does doxycycline affect lipid metabolism?

Answer 36

Modifies and enhances it

Question 37

How does doxycycline affect the eyelid glands (2)?

Answer 37

Alters gland and tear film function

Question 38

How does doxycycline treat surface ocular disease (2)?

Answer 38

Inhibits the formation of cytokines | Damages the enzyme MMP

Question 39

What is MMP implicated in?

Answer 39

Corneal damage (such as recurrent erosion)

Question 40

In what 4 cases are tetracyclines prescribed?

Answer 40

When topical medication is ineffective Needs repeat topical anti-inflammatory treatment Severe inflammation of the ocular surface Significant lid disease

Question 41

List 3 potential side effects of doxycycline. What is it minimised by?

Answer 41

GI disturbance (drink with water) Yeast infections Photosensitivity Minimised by a low dose

Question 42

Doxycycline is ineffective when taken by what two other products? Explain why and how long one should wait between taking the two.

Answer 42

Ineffective when taken with dairy products or antacids Calcium chelates the medication Wait 2 hours between the two

Question 43

In what four cases is doxycycline contraindicated?

Answer 43

Children <8 years Osteoporosis Pregnant or nursing women Poor renal function

Question 44

What may doxycycline do to bone and teeth?

Answer 44

May discolour teeth and hinder bone development