wk6:AED - Antibacterial 2

Question 1

Name 5 antibiotics that can be given orally

Answer 1

penicillin
cephalosporin
macrolides
fluorooquinolones
tetracyclines

Question 2

How commonly is penicillin used in eye care?

Answer 2

rarely

Question 3

How does penicillin work?

Answer 3

inhibits bacterial cell wall synthesis

Question 4

Is penicillin bacteriostatic or cidal?

Answer 4

bactericidal

Question 5

Are most staphylococci sensitive or resistant to penicillin?

Answer 5

resistant (they produce an enzyme penicillinase that degrades the clinical efficiency of penicillins)

Question 6

What is special about dicloxacillin (in relation to penicillins)?

Answer 6

penicillinase resistant

Question 7

What is amoxycillin?

Answer 7

is a classic synthetic penicillin

Question 8

How can we improve the spectrum of activity of amoxycillin?

Answer 8

Combine with potassium clavulanate (a beta lactase inhibitor)

Question 9

How does the spectrum of activity of amoxycillin-clavulanate compare with amoxycillin?

Answer 9

Extended coverage of gram positives, some gram negatives

Question 10

How good of a choice is amoxycillin-clavulanate for common eye and eyelid infections?

Answer 10

excellent choice

Question 11

What is the standard dosage of diicloxacillin treatment? Why?

Answer 11

250mg qid. due to short half life.

Question 12

Is dicloxacillin taken with meals?

Answer 12

Doesn’t have to be

Question 13

What are the standard doses for amoxycillin-clavulanate treatment? (3)

Answer 13

Depends on severity.
Mild = 500mg
Most = 875mg
Severe = 1000mg

Question 14

List 6 potential side effects of penicillins

Answer 14

Hypersensitivity reactions
Up to 20% reported
Most limited to skin rashes
Severe anaphylaxis (uncommon)
May also alter normal flora in resp. tract (super infections)
Gastrointestinal upset

Question 15

What 3 alternative antibiotics might you use if your patint is allergic to pnicillin?

Answer 15

Cephalosporin
Macroliides
Fluoroquinolone

Question 16

Name a common first choice ophthalmic antibiotic

Answer 16

Cephalosporin

Question 17

What part of bacteria is targeted with cephalosporin tx?

Answer 17

Bacterial cell wall synthesis (so similar to penicillins)

Question 18

Do cephalosporins contain a beta lactam group?

Answer 18

yes, but derived from different amino acids than the penicillin beta lactam group

Question 19

How long is a standard course of cephalexin (a type of cephalosporin, also known as keflex)?

Answer 19

1 week (lenght can change based on severi or condition)

Question 20

What is the usual dosage of cephalexin?

Answer 20

500mg bid or 500mg qid

Question 21

Why are cephalosporins contraindicated in hemophiliacs?

Answer 21

Because they can destroy intestinal bacteria which are necessary for the synthesis of vitamin K which can result in impaired blood clotting

Question 22

What is the primary adverse reaction to cephalosporins?

Answer 22

hypersensitivity

Question 23

What percentage of patients allergic to penicillin are also allergic to cephalosporin?

Answer 23

5-10%

this is known as cross sensitivity

Question 24

Under what circumstances would cephalosporin be a suitable alternative for a penicillin allergy?

Answer 24

Only if minor adverse reaction to penicillin

Question 25

What suitable alternatives can be used if a patient has a hx of penicillin anaphylaxis? (2)

Answer 25

Macrolides or Fluoroquinolones

Question 26

Do fluoroquinolones have a broad or narrow spectrum?

Answer 26

broad

Question 27

When are fluoroquinolones mainly used?

Answer 27

mainly reserved for when penicillin allergy

Question 28

What is norfloxacin used for? (1)

Answer 28

tx of UTI

Question 29

Provide an example fluouroquinolone, dose, and duration?

Answer 29

ciproflaxacin 500mg qd x 1 week

Question 30

Are macrolides used as first line antibiotics?

Answer 30

usually NOT

Question 31

Name 2 uses for macrolides

Answer 31

chlamydial infections | pregnancy

Question 32

What part of bacteria do macrolides target?

Answer 32

inhibit protein synthesis

Question 33

Are macroliides bacteriostatic or cidal?

Answer 33

mainly bacteriostatic but can be bactericidal in higher concentrations

Question 34

What gram stain of bacteria are macrolides active against?

Answer 34

Gram +ve and some gram -ve

Question 35

What properties do macrolides possess at low doses?

Answer 35

anti inflammatory properties

Question 36

When might macrolides be used by clinicians?

Answer 36

As an alternative when tetracyclines are contraindicated

Question 37

When is erythromycin (a macrolide) commonly used? (2)

Answer 37

Commonly used as a second choice antibiotic | Common choice in pregnancy

Question 38

What is the ideal use for azithromycin?

Answer 38

excellent against chlamydial infections

Question 39

What are the standard options when considering tx with macrolides? Outline procedure

Answer 39

``` Lab test azithromycin 1gm p.o single dose alternative or if unresponsive erythromycin 500mg qid, 7 days doxycycline 100mg bid 1 to 3 weeks ```

Question 40

Out of the different tetracyclines, which one has the fewest potential side effects?

Answer 40

doxycycline

Question 41

Describe how doxycycline affects cytokines?

Answer 41

reduces bioactivity of major inflammatory cytokines

Question 42

In terms of the anti-inflammatory action of doxycycline, describe its effects (2) and describe at what dose (1)

Answer 42

at sub-optimal antibiotic doses modify and enhance lipid metabolism alter gland function, tear film function

Question 43

How does doxcycline interact with MMPs?

Answer 43

inhibits theme

Question 44

How do MMPs relate to eye problems? (1)

Answer 44

mmp is an enzyme implicated in corneal damage including recurrent erosion

Question 45

Name 3 conditions where mmp is inhibited

Answer 45

mgd, dry eye, RCES

Question 46

When would you prescribe doxycycline? (4)

Answer 46

topical medications ineffective need repeat topical anti-inflammatory tx severe inflammation ocular surface significant lid disease

Question 47

List 3 potential side effects of doxcycline

Answer 47

GI (drink full glass of water) Yeast infections Photosensitivity

Question 48

How can we minimise the potential side effects of doxycycline?

Answer 48

use low dose

Question 49

Describe 1 important interaction that doxycycline has that affects the medication

Answer 49

Ineffective when taken with dairy products or antacids because calcium chelates the medication do not take for at least 2 hours after dairy products

Question 50

When is docycyline contraindicated? (3)

Answer 50

children under 8 years (may discolour teeth or hinder bone development) pregnant or nursing women renal function problems

Question 51

What factors should you consider when deciding what antibiotic to prescribe to a patient? (8)

Answer 51

``` Age Weight General Health Mental status Allergy Hx Liver+Kidney function Current medications Pregnancy status ```

Question 52

What are the 2 most important things to remember about doxycycline?

Answer 52

Function dependent on dose. One is antibiotic and other is MMP-9 inhibitor