Week 9 - Antiinfectives

Front 1

Defence mechanisms against ocular infections

Back 1

-Skin and mucosal membranes act as barriers
-Tear anti-microbial agents eg. lysozyme (dissolves cell wall of bacteria-> esp. gram +ve), beta-lysin (affects cell membrane)
-Beta-Lysin in aqueous humour
-Immune system, tear immunoglobulins IgA, IgG, IgM

Front 2

Factors and situations that increase risk of ocular infections

Back 2

-Corneal abrasions (CL wear), trauma, depressed immune system
-Increased risk areas: farming, gardening, 3rd world countries

Front 3

Biological Processes in Tears

Back 3

-64 Proteases (enzyme that breaks down proteins and peptides)
-18 Anti-oxidant enzymes

-Most involved in defence of eye -> immune response against external agents, wound healing, blood coagulation.

Front 4

Antimicrobial Activity of Tears

Back 4

Tear components with antimicrobial activity (mainly from lacrimal gland, cells of ocular surface)
-AMPS= Antimicrobial Peptides
-slgA= Secretory immunoglobulin A
-sPLA2= Secretory phosopholipase A2
-SLPI= Secretory leukocyte protease inhibitor
-SP-D= Surfactant protein D

Front 5

Cellular Classification of Organisms

Back 5

Prokaryotes= Cells without nuclei (bacteria)
Eukaryotes= Cells with nuclei (fungi, protozoa, helminths)
Viruses= Don't really have cells but take over the host biochemical machinery

Front 6

Bacteria Classification and Examples

Back 6

Single-celled, produce own energy + components, gram dividing on shape
Gram +ve -> simple cell wall structure, easy passage of +vely charged compounds, layered peptidoglycan cell wall, Purple stain
Gram -ve -> more complex cell wall, thin peptidoglycan cell wall, outer membrane outside cell wall
Eg.
Gram +ve Cocci= Staphylocci-> lives in skin, Streptococci-> sore throat
Gram -ve Cocci= Neisseriae-> ophthalmia neonatorum (conjunctivitis at birth)
Gram +ve rods= Corynebacteria-> membranous conjunctivitis
Gram -ve rods= Pseudomonas Aeruginosa-> water contaminant (green pus), Haemophilus

Front 7

Virus Examples

Back 7

Herpes Viruses= Zoster, Simplex, cytomegalovirus
Adenovirus 8= EKC-> common cause of acute conjunctivitis
Rubella= Microphthalmia, Cataracts, Glaucoma
HIV

Front 8

Fungi Examples

Back 8

Candida
Aspergillus

Front 9

Chlamydia Examples

Back 9

Trachoma

Front 10

Amoeba Examples

Back 10

Acanthomoeba

Front 11

Choice of Agent

Back 11

Intelligent guess on type of organism and most effective agent for that
Base treatment on cultures (time issue)
Least toxic drug
Surface Infection-> absorption characteristics not important
Internal infection-> drug penetration/ injection
Drops easiest to use
Ointments longer action but smear vision, good for children, lid infections

Front 12

Choice of Dosage

Back 12

Concentration high enough for bacterial effect-> higher than minimum inhibitory concentration (MIC)
Increase frequency to increase dose
Antibiotics half life ~8min, little left after 1hr-> hourly admin may be ok
Compromise between what is required and what Px compliance
Treat for right length of time
Addition to physical procedures

Front 13

Resistance and Cross Resistance

Back 13

Bacteria are resistant if growth is not stopped by maximum level of antibiotic tolerated by host
Bacteria are resistant to one antibiotic will be resistant to the whole class (cross-resistance)
Genetic changes in bacteria (many generations in short periods)

Front 14

Mechanisms of Bacterial Resistance

Back 14

-Drug inactivation or modification
-Alteration of target site
-Alteration of metabolic pathway
-Reduce drug accumulation

Front 15

Multidrug Antibiotic Resistance Examples

Back 15

Staphylococci-> resistant to nearly all available
Mycobacterium-> resistant to most antituberculosis agents = death
Staphylococcus-> Methiciliin resistance

Front 16

Prescribing for Microbial Resistance

Back 16

-Do not use antibiotics if not necessary
-Appropriate use (antibiotic, dose, duration)
-Avoid chronic use
-Reserve newer antibiotics for corneal disease
-Less likely for ocular drugs

Front 17

Microbial Resistance OBA Guidelines

Back 17

Avoid:
-Inappropriate drug selection
-Insufficient therapeusis
-overuse
-Inappropriate dosage
-Don't use fluoroquinolones where older drug can be used
-Consider specialist opinion if requires long term use

Front 18

Antimicrobial Failure Reasons

Back 18

Inaccurate diagnosis
Resistant microorganism
Inadequate drug dosage
Patient noncompliance
Inadequate patient immune response

Front 19

Sensitisation and Examples

Back 19

Reaction when Px applies more of drug in attempt to decrease problem -> red eyes, contact dermatitis
Eg
-Neomycin
-Penicillin
-Streptomycin
-Gentamycin
-Some sulphonamides

Front 20

5 Differences between Bacterial and Human cells

Back 20

-Bacteria have a cell wall without which the bacteria undergoes lysis and dies (contain peptidoglycan)
-Slight differences in cell membranes (no sterols)
-Different size and structure of ribosomes
-Some different biosynthetic pathways (bacterial cells synthesis of their own folic acid)
-Differences in DNA gyrase (enzyme mediating coiling of DNA)

Front 21

5 Antibacterial Drug Mechanisms

Back 21

-Affect Cell Wall Structure
-Affect Cell Membrane
-Affect DNA Synthesis
-Affect Protein Synthesis
-Affect Intermediate Metabolism

Front 22

Penicillin (Beta-lactam)

Back 22

-antibacterial drug-> Inhibit cell wall synthesis
-Effective against gram +ve
-Acquired resistance (drug deactivating enzymes produced by bacteria)
-Allergic reaction problem
-Alter normal microflora of body
-25+ types (pneumonia, STDs, meningitis, tissue infections, UTIs, Bronchitis, Pharyngitis

-CAUTION OF HYPERSENSITIVITY REACTIONS-> CROSS SENSITIVITY

Front 23

Cephalosporins (Beta-lactam)

Back 23

-antibacterial drug-> Inhibit cell wall synthesis
-Similar structure to penicillins (action and resistance)
-Good against gram +ve bacteria, modest against gram –ve
-Broad spectrum, bactericidal, poor oral activity-> IV
-First, second, third generation compounds
-Septicaemia, pneumonia, meningitis, UTI, Sinusitis

Front 24

Beta-Lactam (penicillin and cephalosporin) Action

Back 24

Interferes with cross-linking of peptide chain (final step in bacterial cell wall formation)
Peptide chains give cells wall strength

Front 25

Polymixin B

Back 25

-Antibacterial drug-> affects cell membrane
-Cationic surfactant that interacts with cell membranes, increases permeability and causes cell leakage
-Effective against some gram –ve bacteria, some pseudomonas strains
-Popular for Tx of infections of the conjunctiva and lids
Risks: Neurotoxicity, nephrotoxicity

Front 26

Gramicidin

Back 26

-Antibacterial drug-> affects cell membrane
-Ineffective against gram –ve bacteria

Front 27

Propamidine (Brolene)

Back 27

-Action: Divalent cationic surfactant, affects cell membranes
-Activity: Active against Stap aureus, Streptococcus pyogenes, not active against Pseudomonas, some antifungal properties, action not inhibited by pus
-Use: Minor conjunctivitis blepharitis, acanthamoeba
-Adverse: Sensitization
-Pack: Eye drops 0.1%, 10mL bottle, ointment
-Dose: 2-3 times daily for ~1 week
-Available over the counter without Rx, S2

Front 28

Drugs Affecting Intermediate Metabolism Action

Back 28

Synthesis of folic acid in bacterial cells only (not human)
-Folate required for DNA synthesis -> humans obtain from diet
-Sulfonamides inhibit folic acid synthesis-> contains sulfanilamide -> competes with p- aminobenzoic acid (PABA) for the enzyme involved in folate synthesis
(diagram in notes)

Front 29

Sulfacetamide (Bleph-10 Allergan)

Back 29

-Action: Sulfonamide, bacteriostatic
-Use: Conjunctivitis, trachoma, generally replaced by other agents, superseded
-Adverse: Allergic reactions common
-Pack: eye drops 10%, 15mL bottle
-Dose: every 2-3 hours during the day for ~1 week
-Available OTC
-S3, ask about sulphur allergies
-Irritant, avoid

Front 30

Drugs Affecting Bacterial Protein Synthesis Action

Back 30

-Takes place in ribosomes, differ eukaryotes and prokaryotes, sub-units in bacterial cells are 30S and 50S, human cells are 40S and 60S
-Some can interact with human mitochondrial ribosomes causing group toxic effects

Front 31

Chloramphenical (Chloromycetin, Clorsig)

Back 31

-Antibacterial drug-> affects bacterial protein synthesis
-Bind to 50S
-Action: Broad Spectrum (corynebacterium, E.coli, Haemophilus, streptoccoi), not effective against Pseudomonas, low toxicity (limits use), binds to bacterial ribosomes, inhibits protein synthesis
-Use: Prescribed for topical therapy, effective against gram +ve and –ve bacteria, chlamydia, mycoplasma, rickettsia and spirochetes, rarely used systemically (< resistance)
-Adverse: Toxicity, Anaemia, Optic neuropathy, bone marrow depression, fear of possible aplastic anaemia (may be fatal) limits use in some countries (USA), low systemic absorption, gray baby syndrome (child inability to excrete drug⇒ only in inappropriate dosing)
-Pack: eye drops 0.5%, 10mL bottle, fridge
minims, 20 per box
ointment 1%, 4g
-Dose: eye dorps 1-2 drops every 2-6 hrs for 2-3 days then reduce frequency
-S3, PBS

Front 32

Tetracyclines (Optycin, Latycin)

Back 32

-Antibacterial drug-> affects bacterial protein synthesis
-Bind to 30S
-Action: Broadest spectrum (gram +ve and –ve), bacteriostatic, resistance develops slowly, not effective against pseudomonas, poor corneal penetration
-Use: Ocular infections, chlamydial infection
-Adverse: Few side-effects topically, local reactions in isolated cases, oral tetracyclines can permanently yellow teeth and slow bone growth in children
-Pack: ointment 1%, 5g now compound pharmacy product (largely superseded by oral azithromycin for trachoma)
-Dose: Apply into lower conjunctival sac every 2 hrs, treatment duration depends on severity of condition

Front 33

Macrolides

Back 33

-Antibacterial drug-> affects bacterial protein synthesis
-Alternative to penicillins, similar effect
-Treat pneumonia, genital infections, legionnaires disease, chlamydial infections
-Resistant organisms
-Ear damage, GI disturbance
-Azithromycin, Erythromycin

Front 34

Azithromycin

Back 34

-Antibacterial drug-> affects bacterial protein synthesis
-Bind to 50S
-Action: Broad spectrum macrolid antibiotic with anti-inflammatory properties, inhibits protein synthesis, inhibits macrophage activity
-Use: Ocular infections, chlamydial infections, toxoplasma, STDs, malaria, respiratory infections
-Adverse: GI, HA, bitter taste, hypersensitivity
-Pack: 1.5% drops, compound pharmacy product (superseded by azithromycin)
-Dose: apply daily, treatment duration depends on severity of infection, long half life (68hrs)⇒ one high oral dose Tx, Oral 1g for adults, 20mg/kg for children

Front 35

Erythromycin

Back 35

-Antibacterial drug-> affects bacterial protein synthesis
-Bind to 50S

Front 36

Aminoglycosides Action and Examples

Back 36

-Antibacterial drug-> affects bacterial protein synthesis
-Bind to 30S unit of bacterial ribosome preventing protein synthesis
-Active against aerobic gram –ve and some gram +ve bacteria
-Rapid action, bacrtericidal
-If oral can cause nephrotoxicity (kidney damage) and otoxicity (ear damage)
-Not for systemic use
-Streptomycin, Framycetin, Gentamicin, Neomycin, Tobramycin

Front 37

Framycetin

Back 37

-Antibacterial drug-> affects bacterial protein synthesis
-Aminoglycoside

-Action: Isomer of neomycin, broad spectrum effective against gram-positive and –negative bacteria
-Use: Conjunctivitis, blepharitis, abrasions, styes, topical application, poor ocular penetrance
-Adverse: Kidney, ears affected, contact allergies
-Pack: eye drops 0.5%, 8mL bottle
-Dose: eye drops 2 drops every 1-2 hours decreasing to 3/times per day

Front 38

Gentamicin

Back 38

-Antibacterial drug-> affects bacterial protein synthesis
-Aminoglycoside

-Action: Broad Spectrum antibiotic, some resistant gram-positive organisms, bactericidal, poor ocular penetration when applied topically
-Use: Treatment of external eye and adnexal infection (bacterial conjunctivitis), prophylaxis following surgery or trauma (abrasions), suspected pseudomonas
-Adverse: Transient irritation, damage ears, kidneys, sensitisation reduced
-Pack: 0.3% 5mL bottle & minums
-Dose: 1-2 drops q4h, if severe 2 drops hourly
-1.3% fortified for bacterial keratitis

Front 39

Neomycin

Back 39

-Antibacterial drug-> affects bacterial protein synthesis
-Aminoglycoside

-Action: Broad spectrum antibiotic, some resistance from gram-positive organisms, bactericidal, not effective against pseudomonas
-Use: Bacterial infection, rarely used systemically, used prophylactically with steroid after surgery or for inflammation cover
-Adverse: ears, kidneys affected, hypersensitivity
-Pack: 0.5% minims, Neosporin drops, ointment, compound product

Front 40

Tobramycin

Back 40

-Antibacterial drug-> affects bacterial protein synthesis
-Aminoglycoside

-Action: Broad Spectrum, some resitance from gram +ve organisms, bactericidal
-Use: Treatment of external eye and adnexal infection (bacterial conjunctivitis), prophylaxis following ocular surgery or surface trauma, suspected pseudomonas
-Adverse: Ocular and systemic toxicity, superinfection ⇒ retarded corneal wound healing
-Pack: eye drops 0.3%, 5mL bottle
ointment 0.3%, 3.5g
-Dose: eye drops 1-2 drops every 4 hours
-Severe infection: 2 drops hourly until improvement
-1.3% fortified for bacterial keratitis

Front 41

Drugs Affecting Bacterial DNA Synthesis

Back 41

-New generation quinolones and fluorinated quinolones (fluoroquinolones)
-Broad Spectrum, little resistance
-Use only for microbial keratitis, extremely severe conjunctivitis
-Active against Pseudomonas & Staphylococcus
-Cause: Kidney stones, headache, nausea
-Not for use in children under 8yrs (cartilage damage)

Front 42

Fluoroquinolones

Back 42

-Antibacterial drug-> affects bacterial DNA synthesis
-Newest group, major area for new drugs
-Inhibit DNA synthesis during bacterial replication, unique mechanism means cross-resistance with other antibiotics less likely
-Well absorbed orally
-Inhibit DNA-gyrase, preventing supercoiling of DNA molecule
-Ciprofloxacin, Ofloxacin

Front 43

Ciprofloxacin (Ciloxan, Ciloquin)

Back 43

-Antibacterial drug-> affects bacterial DNA synthesis
-Action: Active against broad spectrum of gram+ve and –ve ocular pathogens
-Use: Bacterial keratitis, severe bacterial conjunctivitis, effective, safe, limit use to prevent resistance
-Adverse: Super infection, discomfort, burning, itching, hyperaemia, precipitates on corneal ulcers
-Pack: 0.3% 5mL bottle
-Dose:
-Corneal Ulcers= day 1: 2 drops every 15min for 6 hours then every 30min, Day 2: 2 drops every hour, Days 3-14: 2 drops every 4 hours
-Bacterial Conjunctivitis = Days 1-2: 1 drop every 2 hrs while awake, days 3-7: 1 drop every 4hrs while awake

Front 44

Ofloxacin (Ocuflox)

Back 44

-Antibacterial drug-> affects bacterial DNA synthesis
-Action: Active against broad spectrum of gram+ve and –ve ocular pathogens
-Use: Bacterial keratitis, severe bacterial conjunctivitis
-Adverse: Super infection, transient eye pain, hyperaemia,  risk of corneal perforation
-Pack: 0.3% 5mL bottle
-Dose:
-Bacterial conjunctivitis= Days 1-2: 1 drop every 4hrs while awake, Days 3-10: 1 drop every 6hrs
-Corneal Ulcers= Day 1: 2 drops every 15min for 6hrs then every 30min, Day 2: 2 drops every hour, Days 3-14: 2 drops every 4hrs

Front 45

Antibacterial use for:
BACTERIAL CONJUNCTIVITIS

Back 45

-Resolves in 10-14 days
-Staphylococcus aureus, staph. Epidermidis, Streptococcus pneumonia, hemophilus influenza
-Microbiological investigations (swabs) rarely needed
-Hygiene
-Topical antibiotics shorten course
-Broad spectrum antibiotic (gram+ive and –ve)
-4 times/day for 1 week

Front 46

Antibacterial use for:
BACTERIAL KERATITIS

Back 46

-Sight threatening
-CL wear and pseudomonas
-Microbial work up
-Broad spectrum antibiotic (immediately)
-Monotherapy with fluoroquinolone or dual therapy with fortified cephalosporin and aminoglycoside
-Drops hourly
-Ineffective corneal ulcers: Day1: 2 drops every 15min for 6hrs, then 30min, Day 2: 2 drops every hr, Days 3-14: 2 drops every 4hrs

Front 47

Antibacterial use for:
CORNEAL ABRASION

Back 47

-Heals spontaneously within few days
-Ice packs and oral analgesics for pain
-Subepithelial lesions referred immediately
-Broad-spectrum topical antibiotic used 4 times per day until epithelial healing

Front 48

Antibacterial use for:
ANTERIOR BLEPHARITIS

Back 48

-Anterior eye lid margin
-Chronic recurrent nature
-Lid hygiene, tear supplements
-Weak corticosteroids and antibiotics (chloramphenicol, erythromycin, gentamicin) ⇒ short term

Front 49

Antibacterial use for:
POSTERIOR BLEPHARITIS

Back 49

-Meibomian gland dysfunction
-Chronic recurrent nature
-As above treatment
-Systemic tetracyclines (doxycycline 100mg per day for 1 mth, then 50mg for 2 mths)
-Mild topical steroid (FML) and topical antibiotic 1-2 weeks to reduce inflammation and bacterial load
-Optimel antibacterial honey

Front 50

Antibacterial use for:
CHLAMYDIAL CONJUNCTIVITIS

Back 50

-Refer
-Oral doxycycline 100mg per day for 10-14 days
-one or two 1gm doses of azithromycin
-topical treatment ineffective

Front 51

Antibacterial use for:
DACRYOCYSTITIS

Back 51

-Bacterial or fungal infection of lacrimal sac and tear drainage system
-Oral broad-spectrum antibiotics
-Refer for aspiration if painful, surgical reconstruction

Front 52

Antibacterial use for:
GONOCOCCAL KERATOCONJUNCTIVITIS

Back 52

-Acute bilateral sight threatening disease caused by gram-ve diplococcus infection, Neisseria gonorrhoea ⇒ corneal perforation
-Lytic Enzymes in mucopurulent discharge must be washed away
-Systemic infection requiring systemic antibiotics
-Penecillin, 1gm ceftriaxone intramuscularly daily for 5 days, oral doxycycline, topical gentamycin 1.3% hourly

Front 53

Antibacterial use for:
HORDEOLUM INTERNAL/ EXTERNAL

Back 53

-Abscess of sebaceous gland
-Internal (acute staph infection of meibomian gland)
-External (acute staph infection of lash follicle and zeiss or moll gland)
-Resolve spontaneously
-Warm compresses, lid hygiene
-Broad-spectrum antibiotic 1 week course (external)
-1 week course of oral antibiotic if sig. cellulitis
-Epilation or curettage may assist drainage

Front 54

Antibacterial use for:
PRESEPTAL CELLULITIS

Back 54

-Infection of subcutaneous eyelid tissue anterior to orbital septum
-Requires urgent systemic treatment
-Haemophilus influenza, streptococcus pneumonia cause?
-Oral antibiotics for ~10days ⇒ penicillin, cephalosporin
-IV application may be required in children or if oral response does not occur

Front 55

Antibacterial use for:
ROSACEA KERATITIS

Back 55

-Inflammatory skin condition
-Butterfly rash of cheeks and nose
-Posterior blepharitis, corneal involvement
-Oral tetracycline(doxycycline 100mg/day for 1mth, 50mg/day for 2mths), erythromycin, or azithromycin
-Tear supplements and weak topical steroids helpful

Front 56

Viruses

Back 56

-Smallest infectious organisms
-Infect humans, animals, plants and bacteria
-Obligate intracellular parasites
-Depend on host cells for multiplication
-Invades metabolic machinery
-Acute disease limited by immune system
-Some can be latent (recurrent)
-Difficult to destroy without hurting host
-Immunisation only option (mostly)

Front 57

Anti-Virals

Back 57

-Target specific enzymes
-Difficult to develop (selective toxicity for viruses)
-Aciclovir, Vidarabine, Idoxuridine
-Many virus specific (in notes)

Front 58

Aciclovir (Zovirax)

Back 58

-ANTIVIRAL
-Zovirax, HSV, IV, tablets, ointment
-Analogue of guanosine
-Inhibits multiplication of herpes simplex virus, varicella zoster virus
-Activated by viral thymidine kinase (viral selectivity)
-Virus thinks it is a nucleotide
-Activated form inhibits DNA polymerase
-Minimal side effects
-Action: Antiviral agent, sig more effective than older agents
-Use: Herpes simplex keratitis
-Adverse: Transient mild stinging upon application, superficial punctate keratopathy
-Pack: Ointment 3% 30mg/g, 4.5g
-Dose: 1cm inside lower conjunctival sac 5 times daily for 14 days or minimum 3 days after healing
-Cold sore cream skin lesion versions available over the counter

Front 59

Vidarabine (adenine arabinoside)

Back 59

-ANTIVIRAL
-Action: Antiviral agent, nucleoside stops growth of nuclear chain, superseded by acyclovir
-Use: Herpes simplex virus
-Pack: Compound pharmacy product, 3% ointment
-Dose: 1 cm inside lower conjunctival sac 5 times daily for 14 days or minimum 3 days after healing
-First drug to become generally available for treatment of herpes simplex virus infections (1980s)

Front 60

Idoxuridine

Back 60

-ANTIVIRAL
-HSV, not for ocular use

Front 61

Antiviral use for:
HERPES SIMPLEX

Back 61

-Leading cause of corneal opacification and infection related visual loss
-Stromal keratitis or iritis can be present in serious forms
-Avoid triggers (sunglasses)
-Prompt presentation on recurrence of disease (Px education)
-Limit corneal scarring
-Topical antiviral agent, acyclovir ointment
-90% dendrites healed in 1 week

Front 62

Antiviral use for:
HERPES ZOSTER

Back 62

-Varicella zoster virus of trigeminal nerve (shingles)
-Treatment within 72hrs
-Early treatment reduces risk of post-herpetic neuralgia
-Irreversible ocular damage
-Contagious when vesicular lesions present
-Oral acyclovir 800mg 5x/day for 7 days
-reduces time for lesion healing
-reduces duration of viral shedding and new lesion formation
-Reduces duration of pain and incidence of other complications
-Poor oral bioavailability (poor water solubility)
-Valaciclovir 1g 3x/day for 7 days
-Enhanced bioavailability (prodrug of acyclovir)
-decreased duration of pain
-Greater effectiveness
-Topical antivirals have little effect
-Topical steroids, tear supplements, anti-glaucoma meds may be used to manage long term complications (virus never leaves)

Front 63

Antiviral use for:
ADENOVIRAL CONJUNCTIVITIS (EKC)

Back 63

-Broad range of adenoviruses causing it
-Upper respiratory tract infection
-Preauricular lymphadenopathy signals viral infection
-Gritty, watery, inflamed eyes, photophobia
-No effective treatment
-progression to viral keratitis
-AdenoPlus (diagnostic test)
-Highly contagious (hygiene)
-Resolution occurs within 2-4 weeks
-Antiviral agents ineffective
-Tear supplements to improve comfort
-Cold packs every 3-4 hours
-Topical steroids for early stages when opacities are inflammatory (not scars yet)
-Aspirin helpful if sig discomfort
-Povidone Iodine (betadine) wash suggested (limited evidence of effectiveness- stings)

Front 64

Antiviral use for:
CYTOMEGALOVIRUS RETINITIS

Back 64

-Inflammation of retina caused by human cytomegalovirus
-Occurs in immunocompromised individuals (AIDs)
-Cidofovir/ ganciclovir/foscarnet used intraveniously (or injected into eye) if active
-Intraocular ganciclovir device
-Inhibits viral DNA polymerases at concentrations too low to affect human DNA polymerases
-Discontinuation of use is common (Toxic!)

Front 65

Antiviral use for:
MOLLUSCUM CONTAGIOSUM

Back 65

-Localised skin infection caused by pox-wart-like viral skin infection
-Self-limiting (3-12mths)
-Raised, shiny, white-pink nodules
-Around eye can cause follicular conjunctivitis
-Good hygiene to avoid reinfection
-Treatment is excision not antiviral agents, upon removal lesion resolves

Front 66

Antifungals

Back 66

-No topical antifungal available
-Difficult to produce
-Ocular antifungal infections are rare
-Occur most after surgery or depressed immune system
-Fungal spores in farming areas can cause (doesn’t have to be from abrasion)
-Causes severe ocular damage
-Prompt and effective treatment to avoid loss of eye
-Fungal toxins cause damage after fungus eliminated
-Tablets and ointments (external)

Front 67

Polyenes

Back 67

-Antifungal agent
-Alter fungal cell membrane permeability, bind to sterol moiety of membrane
-Poor penetration, intravitreal for endophthalmitis
-Highly toxic⇒ retinal damage, renal toxicity, reversible anaemia, fevers, chills, hypotension
-Amphotericin B, Nystatin

Front 68

Pyrimidines

Back 68

-Antifungal agent
-Flucytosine

Front 69

Imidazoles Azoles and Triazole Azoles

Back 69

-Antifungal agent
-Alter fungal cell membrane permeability
-Miconazole, ketoconazole (IAs)
-Itraconazole, fluconazole (TAs)

Front 70

Fungal Infections

Back 70

-Uncommon ocular pathogens
-May be hard to distinguish from bacterial infections (won’t respond to antibiotics)
-Occurs in already compromised eye (ocular surface disease, long term steroid use)
-Slow, relentless infection

Front 71

Antifungal use for:
FUNGAL KERATITIS

Back 71

-Antibiotics inactive
-Ulcer with posterior corneal involvement
-pearls on back of cornea
-Refer to corneal specialist
-Send corneal scrape to lab
-Treat with antifungal agents when diagnosed (drugs are toxic to cornea)
-Topical and oral antifungal agents
-Amphotericin B, Ketoconzole, fluconazole, itraconozole, flucytosine
-Frequent administration for prolonged period (12 weeks at least)
-Topical corticosteroids are contraindicated

Front 72

Antifungal use for:
ENDOPHTHALMITIS

Back 72

-Ocular emergency, urgent referral
-Bacteria cause, unusual for fungi
-Entry to eye via wound (surgery, penetrating injury)
-Reduce post-operative risk by treating infections before surgery
-instil povidine iodine immediately post surgery (reduce risk)
-Intravitreal injection of antibiotics (vancomycin, ceftazidine) and steroid (dexamethasone)
-Topical, oral and IV antibiotics are ineffective on their own

Front 73

Antifungal use for:
ACANTHAMOEBA KERATITIS

Back 73

-Ubiquitous protozoan that rarely infects cornea
-Cease contact lens wear immediately (reintroduce after 6mths)
-Lab identification (scraping)
-Commence treatment using anti-amoebic drugs after confirmation (propamidine, neomycin and 0.02% polyhexamethylene-biguanide (PHMB) or topical chlorhexidine)
-Refer, reviewed weekly until clinical improvement seen