Week 2.05 Anti Infective Pharmaceuticals

Question 1

What are the two main reasons we need anti-infective pharmaceuticals

Answer 1

• prophylactic use - prevent an infection developing
• therapeutic use - treat an existing infection

Question 2

Viral bacteria

Answer 2

Redness, swelling of lid, watery discharge, highly contagious

Question 3

Bacterial conjunctivitis

Answer 3

Mucus discharge shown, lids being stuck together in morning

Question 4

Why might someone get eye infection

Answer 4

Immunosuppression - immense system compromised
- diabetes
- corticosteroid use
- elderly
- HIV/AIDS
Trauma
Co existing infections
Contact with contagious individual

Question 5

What are antibiotics used for

Answer 5

Chemical substances produced by, or derived from a micro-organisms which have the capacity, in dilute solution, to inhibit bacterial growth or destroy bacteria

Question 6

What’s difference of gram positive and gram negative

Answer 6

Thick cell wall - gram positive
Thin cell wall - gram negative

If put iodine and it stains purple its thick cell wall i.e gram positive

If pink stain then its gram negative I.e. gram negative

Question 7

Antibacterial drugs can be classified as what two things

Answer 7

Bacteriostatic - slow down or stop the replication of bacteria
Bactericidal- actively kill bacteria

Question 8

What are aminoglycosides

Answer 8

• type of antibacterial drug
• irreversibly bind to 30s ribosome sub-unit
• causes mis reading of mRNA - stops the ability of the ribosome to make the protein
• broad spectrum - meaning they work over a wide range of bacterial cells

Highly effective against GRAM NEGATIVE bacteria - useful for bacterial keratitis

Question 9

What is an example of aminoglycoside and what’s it used for

Answer 9

Gentamicin
Reserved for treatment of severe infections
Highly effective against pseudomonas aeruginosa (gram negative)
Used to treat bacterial keratitis
Preserved with Benzalkonium chloride

Question 10

Pseudomonas aeruginosa is a…

Answer 10

…gram negative bacteria

Question 11

What is another less effective aminoglycoside

Answer 11

Neomycin
- Less effective against pseudomonas aeruginosa
- May produce an allergic eyelid reaction
- Not available as a stand alone product
- Used as prophylactic antibacterial after cataract surgery
Preserved with Benzalkonium chloride

Question 12

Tetracycline

Answer 12

• have a bacterostatic action (stop/slow)
• bactericidal action at high conc
• bind to 30s ribosome sub-units
• block tRNA binding to A site
• broad spectrum of antibacterial activity
• highly effective against clamidiya

Question 13

When would you use oral tetracycline

Answer 13

Chlamydial conjunctivitis
Chronic Blepharitis
Can discolour teeth
Can produce photosensitivity reaction

Question 14

Chloramphenicol

Answer 14

• Most commonly prescribed antibacterial pharmaceutical in optometric practice
• Bacteriostatic action – slows down or stops bacteria replicating
• Binds to 50s ribosome sub unit
• Inhibits ‘peptidyl transferase’ enzyme – stops proteins
• This enzyme critical to process of linking amino acids to form protein

Question 15

When would you use chloramphenicol

Answer 15

• superficial eye infections
  Blepharitis
  Bacterial conjunctivitis
  Corneal abrasions (prophylactic use - prevent infection developing)
• Broad spectrum of antibacterial activity
• gram POSITIVE & NEGATIVE
• NOT pseudomonas - not used for bacterial keratitis
  Grey baby syndrome if used in pregnancy

Question 16

What is chloramphenicol licensed for

Answer 16

Bacterial conjunctivitis only

Question 17

Chloramphenicol POM version

Answer 17

Exempted POM to all optometrists
Sell and supply in an emergency
Otherwise (if not emergency) written order to pharmacist

Licensed for bacterial conj, Blepharitis, corneal abrasions

Question 18

When would you prescribe P or POM chloramphenicol

Answer 18

P for bacterial conjunctivitis
POM for Blepharitis, corneal abrasions and bacterial conj

Question 19

Chloramphenicol: ointment

Answer 19

• either as a P med or exempted POM
• longer retention
  Smeary effect on vision

Question 20

What is fusidic acid

Answer 20

• alternative method to chloramphenicol
• bacteriostatic action
• inhibits translocase enzyme which assembles amino acids into a peptide chain

Question 21

When to use fusidic acid

Answer 21

• superficial infections of lid and conjunctiva
  Blepharitis
  Bacterial conjunctivitis
• narrow spectrum of antibacterial activity
• gram POSITIVE bacteria only
• no need to refrigerate
• doesn’t need to put in more frequently
  Can be used in pregnancy

Question 22

Fusidic acid as a POM

Answer 22

Available as an exempted POM
Sell/supply in an emergency
Otherwise: written order

Question 23

Nucleic acid inhibition

Answer 23

DNA required to produce new cells
Inhibiting DNA synthesis prevents bacteria replication - bacteriostatic effect
Bacteria require DNA to manufacture key components of the cells surface - bactericidal effect

Question 24

Fluoroquinolones

Answer 24

• broad spectrum action
• effective against both gram POSITIVE and gram NEGATIVE bacteria
• inhibit action of enzyme DNA gyrase
• DNA gyrase is critical to the process of unzipping the DNA double helix during cell replication

Question 25

What’s 2 examples of fluoroquinolone

Answer 25

Ofloxacin: - Antibacterial not antibiotic - reserved for treatment of moderate-severe infections of conjunctiva or cornea - only available as POM - often used by opthalmologists to manage bacterial keratitis - sometimes used in combination with gentamicin Ciproflaxcin: Alternative to ofloxacin Only available POM (IP)

Question 26

Trimethoprim

Answer 26

- broad spectrum action - effective against gram positive and gram negative bacteria - not pseudomonas - inhibits production of folic acid - needed to make components for DNA synthesis

Question 27

Polymyxin B

Answer 27

- broad spectrum action - bactericidal against gram NEGATIVE bacteria - poor against gram POSITIVE Due to differences in cell wall structure

Question 28

When to use polymyxin B

Answer 28

- on its own to treat bacterial keratitis caused by gram NEGATIVE bacteria (e.g. pseudomonas) - combination with other drugs to treat milder bacterial eye infections - combining with a drug which effective against gram positive bacteria (e.g. trimethoprim) increases the spectrum of antibacterial activity

Question 29

Diamadines

Answer 29

Antibacterial drug Effective against gram POSITIVE not gram negative Inhibit ability of plasma membrane to uptake molecules which are required for vital functions Can be used to treat minor bacterial eye infections - Blepharitis, conjunctivitis

Question 30

What’s the main thing diamadines is used to treat

Answer 30

To manage acanthamoeba keratitis - sight threatening infection by Protozoa

Question 31

What are the two types of herpes simplex virus

Answer 31

HSV-1 - eyes and lips HSV 2 - below waist Most infected during childhood

Question 32

Aciclovir

Answer 32

- commonly used antiviral - used to treat HSV - pro-drug: inactive until metabolised by body - action of enzyme ‘thymidine kinase’ within virus-infected cell transforms drug into its active form - active drug inhibits viral DNA synthesis - thymidine kinase in healthy human cells is poor at activating aciclovir - selective toxicity

Question 33

What’s an alternative to aciclovir

Answer 33

Ganciclovir Same mode of action