1691 Midterm material Flashcards
Other anti-infectives on board list: Miconazole
Fungal skin infections (ex. Athlete’s foot)
Combination drugs: Polytrim
Polymyxin B, trimethoprim; drops
Other anti-infectives on board list: Nystatin
Fungal infections of skin, intestinal tract, orifices
Pink bottle cap
Steroid drop
Why are ‘old’ drugs still used sometimes when there are newer antibacterials?
Old drugs are good for cover (prevention) vs. actual treatment. Serious infections require new drug as there will be less resistance to newer drugs, however overuse of the new drugs leads to quicker development of resistance to them too
Also patient compliance and cost of drug can make old drug a better choice
Which oral antibacterial drug has a black box warning on Z-pack for fatal arrhythmia? (47/1M courses)
Azithromycin (Zithromax brand)
Combination drugs: Neosporin and Polysporin
Polymyxin B, neomycin, bacitracin; ointment
Polysporin is w/o neomycin
uncompetitive antagonism
stabilizes binding of ligand-receptor complex, prevents re-stimulation of receptor by fresh agonist
cardinal signs of inflammation
PRISH: pain, redness, immobility (loss of function), swelling, heat
inflammation often goes with infection but can also occur by itself*
Why is a steroid used (in combination) for infections and what should be considered?
Steroid is used to limit damage from an infection caused by the immune response itself. Combined steroid/antibiotic treatment should be started AFTER treatment with antibiotics alone has gotten the infection under control
Abrasion signs and symptoms
Sharp pain, photophobia, FBS, tearing, discomfort w/blinking, hx of trauma, epithelial defect that stains w/fluorescein
solid drug delivery systems
collagen shields soaked in drug, inserts in lower fornix, paper strips (ex. fluorescein strip), cotton pledget
Morgan lens
large CL with opening in center attached to tubing for continuous irrigation
enteral
by mouth, p.o., oral, sublingual, etc
Topical treatment for blepharitis/MGD…
Bacitracin (ing, 1/2”, qhs) CWI, cidal, sustained release
Azithromycin 1% (1 drop BID for 2 days, then once a day for 12d) macrolide, PSI, static, also has anti-lipase activity and improves quality of meibum
Treatment for fungal keratitis
Natamycin 5%* gtts q1-2hr around the clock, taper over 4-6 wks
In addition: fluconazole 200-400mg loading dose then 100-200mg po QD
(Amphoteracin gtts or Voriconazole 200mg po BID or topical)
Subconj injection of fluconazole possible
Or intrastromal voriconazole for more serious cases
Topical antibiotics: gentamycin and tobramycin are…
Aminoglycosides
Lincosamide (clindamycin)
Protein synthesis inhibitor (50S), bacteriostatic, gram + and - , anaerobes, Protozoa, acne, MRSA, diarrhea
Km
the concentration of substrate that produces half of the maximum rate of processing
Other anti-infectives on board list: Foscarnet
Antiviral (CMV)
Topical hordeolum tx:
Bacitracin or erythromycin ointment
For external - apply ung to lid margin to reduce bacterial load
For internal - apply ung to cul-de-sac as prophylaxis against following conjunctivitis
(Older drugs fine as resistance not as important)
Sulfonamides
Folate metabolism inhibitors (sulfacetamide, sulfadiazine, sulfamethoxazole, *sulfisoxasole) bacteriostatic, gram + and - , widespread resistance (oldest antibacterial drugs). Primary ocular use is for treating toxoplasmosis, many side effects including nephrotoxicity and hypersensitivity (stevens Johnson)
Topical antibiotics: besifloxacin, ciprofloxacin, gatifloxacin, levofloxacin, moxifloxacin, ofloxacin are…
Fluoroquinolones
Common infecting organisms causing bacterial keratitis
Staph aureus, Staph epidermidis, Staph pneumoniae, Strep viridans, Moraxella, Propionibacterium acnes, Klebsiella, Proteus, Serratia, Haemophilus, Nisseria, Pseudomonas aeruginosa (in CL wearers)
partial agonist
same effect as agonist but to a lesser degree, reduces effect of natural ligand or full agonists to its own level of effect (ex. buspirone is a serotinergic partial agonist)
competitive antagonism
can be reversed by increasing concentration of agonist; agonist and antagonist are competing for the same site of action
Preseptal cellulitis tx:
Mild cases, oral tx - Augmentin
- Keflex 250-500mg QID 10-14d
- Trimethoprim/sulfamethoxazole (Bactria) 400mg/80mg BID po
- moxifloxacin 400mg q24hr po (bone, joint, tendon effects)
Treatment for community acquired MRSA
Sulfamethoxazole + trimethoprim DS 800mg/160mg BIDx10d
Clindamycin 300-600mg TID x10d
Doxycycline 100mg BID x10d
ED50
dose that produces the desired effect in 50% of subjects
receptors: desensitization vs. supersensitization
desensitization is caused by extended prescence of an agonist (ex. opioids). supersensitization is caused by prolonged absence of agonists or extended presence of antagonist (ex. pilocarpine in Adie’s pupil, or apraclonidine in Horner’s syndrome)
What is rosacea?
Long term skin condition that typically affects nose, cheeks, forehead, chin, involving redness, pimples, swelling, small and superficial dilated blood vessels, possibly rhinophyma
Cause is unknown, symptoms worsen due to triggers such as heat, exercise, sunlight, cold, spicy food, alcohol, menopause, stress, or steroid face creams
Can use brimonidine gel to treat redness
Macrolides
Azithromycin*, clarithromycin, neomycin
Protein synthesis inhibitor (50S), bacteriostatic, mostly gram + some - , high strep resistance to older drugs (erythromycin), hypersensitivity, GI effects, reversible hepatitis
Efficacy
the size of the effect of a drug
Which oral antibacterial should not be used in young children or nursing mothers?
Tetracyclines, has anti-inflammatory (matrix metaloproteinase inhibition) and bacterial lipase inhibiting activities (good for MGD)
Doxycycline
Polymyxin B*, Polymyxin E
Membrane disruptors, bactericidal, gram - . Polymyxin B is used with other drugs such as trimethoprim (Polytrim), can cause nephro and ototoxicity
What are the common pathogens that can cause blepharitis/MGD?
Most common by far is Staph aureus. Also can be Strep epidermidis, Propionibacterium acnes, and Moraxella spp. (mostly gram +, but minor contribution from gram - )
Other anti-infectives on board list: Cidofir
Antiviral (CMV)
Penicillins
amoxicillin*, dicloxacillin, CWI, bactericidal, gram + to extended spectrum, some gram - , beta lactamase sensitive (unless giving with beta lactamase inhibitor like clavulanate), considerable resistance developed for older drugs, very low toxicity, but common allergy
Oxervate (cenegermin-BKBJ ophthalmic solution)
rhNGF, helps neurotrophic keratitis infection but does not get sensation back
1 drop 6x/d at 2hr intervals for 8wks
~$100k :(
barriers to absorption of drugs in eye
corneal epithelial and endothelial cells, and the relative impermeability of cornea and sclera
What to look at to distinguish infective inflammation from sterile inflammation
exposure to infective sources, duration (viral is slower), presentation, appearance of discharge, health history, culturing
Which oral antibacterial drug can be used if patient has penicillin allergies?
Macrolides (Azithromycin, erythromycin)
Bacitracin
CWI, bactericides, primarily gram + coverage, some gram - , usually topical administration due to nephrotoxicity
Empirical approach vs. pragmatic approach
empirical - treat and observe effect
pragmatic - treat both, leads to overuse of antibiotics
Gramicidin
Cell membrane disruptor, bactericidal (depending on bacterial growth phase, may also be basteriostatic), gram + coverage, used with other drugs, topical only (hemolysis)
Abrasion with no infection should still be treated for cover, how?
Erythromycin, bacitracin, polysporin ung Q2-4h, or Polytrim gtts QID
If secondary to vegetable matter or fingernails - fluoroquinolone gtts QID or ung Q2-4h to slow possible fungal growth
CL wearers must also have antipseudomonal coverage (tobramycin, ciprofloxacin, other floxacins ung Q2-4h or gtts QID)
Other anti-infectives on board list: Rifampin
TB
At risk populations for community acquired MRSA:
Children, toddlers, babies, prison inmates, athletes, pts known to be colonized
therapeutic index ratio:
LD50/ED50
What is dacryocystitis and what commonly causes it?
Infection of lacrimal sac usually secondary to nasolacrimal duct obstruction. Most common infective organisms are Staph, Strep, also H. Influenzae, pseudomonas, enterobacteriacaea
(Use broad spectrum drugs!)
Viral conjunctivitis includes three main types/viruses
Herpes simplex (HSV), herpes zoster (HZV), adenovirus
Vancomycin
CWI, bactericides, gram + coverage, used for MRSA, nephro and ototoxicity :(
Other anti-infectives on board list: Metronidazole
Ocular rosacea (facial lesions not in eye)
IC50
concentration that inhibits the effect by 50% (or dose that inhibits the effect in 50% of subjects)
Turquoise bottle cap
Prostaglandin analogs
LD50
concentration that kills 50% of the treated subjects (lethal dose)
parenteral
directly across body’s barrier defenses: intravenous, intramuscular, subcutaneous, intrathecal (subarachnoid)
Oral antiviral drugs:
Acyclovir, valacyclovir, famcyclovir
HZV signs and symptoms
Dermatomal pain, parasthesias, skin rash, blurred vision, red eye, eye pain, Hutchinson sign, SPK, pseudodendrite (raised instead of excavated in staining, with no end bulbs like HSV)
Antifungal drugs - oral:
Fluconazole* (also can be injected subconjunctival), voraconazole, used for deep, stromal infections
types of injections into the eye
subconjunctival, lesional (intralesional), intravitreal, intracameral, sub-tenon’s (graft rejection, or severe uveitis), retrobulbar (behind the eye), peribulbar (outside the EOMs)
antagonist (inhibitor)
no action by itself, blocks action of natural ligand or agonist (ex. tropicamide is a cholinergic antagonist)
Red bottle cap
Mydriatic and cycloplegic drops
Associations for Bacterial conjunctivitis
Not as common as viral conjunctivitis, more rapid progression, injection “meaty red”, mucopurulent discharge, FBS, grittiness
Bacteria commonly involved: staph aureus, strep pneumoniae, n. Gonorrhoeae, haemophilus sp. (gram + and -)
Aminoglycosides
Gentamycin, tobramycin*
Protein synthesis inhibitor (30S), bacteriostatic or bactericidal, gram + and - , anti-pseudomonal
Given topical or parental, poor oral absorption, nephro and ototoxicity
Tx for acanthamoeba keratitis - topical:
Propamide isethionate (Brolene) 0.1% drops q1h Dibromoprooamidune isethionate (Brolene ung) 0.15%
Povidone-iodine wash regimen steps
Anesthetize, treat with 5% betadine ophthalmic solution for 1 minute, wash with saline for 1 minute, re-anesthetize
Best if done earlier in infection
Supplementary treatments for blepharitis/MGD:
Lid scrubs to decrease bacterial burden, warm compresses to decrease the viscosity of meibum to encourage outflow, and/or expression of meibomian glands to renew meibum
Fluoroquinolones
Oflaxacin, ciprofloxacin, levofloxacin, moxifloxacin, gatifloxacin, besifloxacin
DNA synthesis inhibitors (inhibit topoisomerase) bactericidal, gram - with improving gram + coverage in successive generations, antipseudomonal
Low toxicity when used topically, but side effects can include destructive arthropathy, tendinitis, tendon rupture
Collagen cross linking (CXL)
Used in cases of tx-resistant microbial keratitis, CXL inhibits enzymatic digestion of the cornea started by bacteria and fungi, enhances rigidity
Effective against Staph, MRSA, Strep, pseudomonas, Candida, Acanthaomeba, fusarium
Capacity (Vmax or Bmax)
the receptors or enzymatic sites available for binding
Orange bottle cap
Carbonic anhydrase inibitors (CAIs)
emulsions
small droplets of water in oil (w/o) or oil in water (o/w) - o/w is preferred for ophthalmic uses (less irritation, better tolerance), used for drugs w/low aqueous solubility. sustained release, and improved corneal residence time and penetration, also do not need to shake like suspensions
types/forms of eye drops and what they can be used for
solutions (fully dissolved liquid), suspensions, emulsions, liposomes. can be used for diagnostics, anesthetics, anti-glaucoma, anti-allergy, artificial tears, etc.
barriers to absorption of drugs in the circulatory system
blood-aqueous barrier in the ciliary body, blood-retinal barrier in the RPE/choroid, and capillary/pericyte membranes
Other anti-infectives on board list: Efanvirenz-emtricitabine-tenofovir (Atripla)
HIV
Fungal keratitis signs and symptoms
Pain, photophobia, tearing, discharge, FBS, often assoc. w/CL wear or trauma involving vegetative matter
Grey-white corneal infiltrate w/feathery border, epithelium may be elevated or ulcerated
Light green bottle cap
Adrenergic agonist plus CAI
HSV tx:
- trifluridine 1% drops q2h (9x/d) until ulcer heals and then q4h (5x/d) for 7d
- gancyclovir 0.15% gel 5x/d until ulcer heals then TID for 7d
- Acyclovir ung 1cm ribbon 5x/d until ulcer heals then TID for 7d; or 400mg po 5x/d 10d
Other anti-infectives on board list: Ethanbutol
TB
How do you make a decision between using topical vs systemic administration?
Depends on tissue depth and seriousness of infection (ex. eyelid abrasion vs. preseptal cellulitis)
Bacterial conjunctivitis treatment:
- Fluoroquinolones (besifloxacin, moxifloxacin, gatifloxacin) topical, TID or QID, 3-7d ; loading doses
- Polytrim, topical QID 7d
- Azithromycin topical BID to QID 7d or oral (for chlamydia) single dose 1000mg or 3 or 5 day dosing (remember black box warning)
inverse agonist
has the opposite effect of the natural ligand or its agonists, neural systems related to anxiety and appetite, no approved drugs in US
Other anti-infectives on board list: Lamivudine
HIV
Green bottle cap
Miotic drops
Oral hordeolum tx:
Cephalexin (cephalosporin, CWI, cidal), Augmentin (penicillin w/clavulanate, CWI, cidal), Dicloxacillin (penicillin, CWI, cidal) for cases that don’t respond to topical treatment
-focus on gram + (don’t want to kill gram - systemically)
Potency
dosage at which a given level of effect is achieved
Anti fungal drugs - topical:
Natamycin*, also amphoteracin (off label), disrupt membrane, best for surface infections as penetration of the cornea not very good
HSV signs and symptoms
Red eye, pain, photophobia, tearing, decreased vision, vesicular rash on eyelid, conj injection w/follicles
Macropunctate keratitis, dendritic keratitis, geographical ulcer
Topical antibiotics: azithromycin and erythromycin are…
Macrolides
liposomes drops
lipid vesicles with aqueous core, can encapsulate hydrophilic or lipophilic drugs and create good penetrability for them since the lipid vesicles are membrane-like on the outside, sustained release
Ethambutol
CWI, bacteriostatic, effective against TB bacteria
treatment considerations
type of infecting organism, location of the infection, the natural course of the infection, patient’s immune status (age, pregnancy, allergies, etc), likelihood that organism is drug-resistant
Suprachoroidal injection
injection into suprachoroidal space (SCS), less likely to have IOP spikes, with concentration 10-fold greater than IVT
intracameral
route of administration directly into the anterior chamber of the eye, mostly used in cataract surgery
Dacryocystitis prophylaxis tx for neonates…
Topical trimethoprim/Polymyxin B (Polytrim)
affinity (Kd)
the concentration of ligand that produces binding to half of the receptors. lower concentration (Kd) = the higher the affinity
also lower affinity = tighter binding
Bacterial keratitis signs and symptoms
Conjunctival injection, FBS, pain, decreased VA, photophobia, discharge (purulent or mucopurulent), focal white opacity in corneal stroma, may have overlying ulcer, often seen in CL wear
Subconjunctival injections
injection of drug into space bw anterior conj and Tenon’s capsule. Usually used to treat severe corneal disease, anterior uveitis or scleritis
CXL tx regimen
Anesthetize cornea, riboflavin in dextran (0.5-1%) is instilled over 30m at intervals of 2-3m, cornea is irradiated with UVA (365nm, total dose 5.4J/cm2), topical antibiotics can be given
Topical antivirals:
Trifluridine (Viroptic)
Gancyclovir (Zinfandel)
Acyclovir (Avaclr) new
Tx for acanthamoeba keratitis- oral:
Itraconazole 400mg loading dose, then 100-200mg QD
Ketoconazole 200mg QD
Voriconazole 200mg QD to BID
Trimethoprim
Folate metabolism inhibitor, bacteriostatic, gram + and - , primarily used in combinations, toxicities associated w/folate deficiency, (used mostly in combination with sulfonamide)
Which oral antibacterial drug is better in pediatric patients due to its effectiveness against H. influenza in ocular/adnexal infections?
Penicillins (ex. Augmentin - amoxicillin with clavulanate)
Infectious agents for fungal keratitis…
Fusarium, Aspergillus, Candida, pseudomonas in CL wearers
-incorrect dx 55% of the time, smears and cultures are gold standard, also can be seen on confocal microscopy or ant. seg OCT
What causes blepharitis/MGD and what can it lead to?
Due to bacterial colonization of lid margin, lid glands, or cilia follicles. Can lead to lid changes (thickening, telangiectasia), bacterial toxins can cause conjunctivitis, SPK, corneal infiltrates, and phlyctenules
noncompetitive antagonism
can’t be reversed by increasing concentration of agonist; antagonist acts on a different site from the agonist but prevents the agonist’s action (steric or allosteric inhibition)
bacterial ocular infections include:
blepharitis, hordeolum, dacryocystitis, cellulitis, conjunctivitis, keratitis, retinitis, endophthalmitis
Other anti-infectives on board list: Lopinavir
HIV
Purple bottle cap
Adrenergic agonist
What are the common sizes for topical antibacterial? Drops, ointments…
5mL for a bottle of drops, 3.5G for a tube of ointment
Other anti-infectives on board list: Ribavirin
Hepatitis C
Acanthamoeba (protozoan) keratitis signs and symptoms
Severe ocular pain out of proportion to early clinical findings, redness, photophobia, symptoms persisting for wks, cornea shows pseudodendrites, inflammation, SEIs, usually assoc. w/improper CL wear (ex. in hot tub)
normal volume of eye drop compared to normal tear volume
volume of drop = 50-70uL
tear volume = 3-11uL
agonist
same effect as natural ligand (ex. phenylephrine is an adrenergic agonist)
Cephalosporins
ceftriaxone, cephalexin, CWI, bactericidal, gram + in 1st gen to extended spectrum in 4th gen, resistance for the older drugs, major side effect of allergic response. 1st gen cross-sensitize w/penicillin
Intravitreal injection/implants
drug injected into vitreous, risk of infection
Blue and yellow bottle caps
beta blocker (blue are lower dose), and beta blocker combinations
EC50
concentration that produces 50% of the maximum effect
Chloramphenicol
Protein synthesis inhibitor (50S), bacteriostatic, broad spectrum, including non-bacterial microorganisms, aplastic anemia
Other treatments for neurotrophic keratitis besides Oxervate…
Antibiotic cover, BCL, tarsorrhaphy, amniotic membrane transplantation
What is hordeolum and what causes it?
Infection of sebaceous glands associated with cilia (external) or meibomian glands (internal)
The most common pathogens are Staph aureus and Staph epidermidis (gram +)
HZV tx:
Acyclovir (800mg po 5x/d) famciclovir (500mg po q8h) valcyclovir (1000mg po QID)
Erythromycin ung BID as antibiotic cover
Non-drug hordeolum tx:
Warm compresses 10m QID with light massage over the hordeolum, to get lesion to point and drain
What is preseptal cellulitis?
Infection that causes tenderness, redness, swelling of eyelid and periorbital area. May have hx of abrasion, insect bite, sinusitis, can cause mild fever. Infecting organism is usually staph aureus, strep, h influenzae (gram + and -)
Oral treatment for blepharitis/MGD:
Doxycycline (100 or 50mg QD; 20mg BID), tetracycline (250mg po QD), PSI, static, treat for 1-6 months primarily for anti-lipase activity
Azithromycin (500mg/day for 3 days/wk for 1 mo… or 500mg day 1, then 250mg for next 4 days) macrolide, PSI, static, may be better than doxy for hard to treat MGD
Lesional injections
injected into or through a lesion (ex. chalazion), similar to subcutaneous injection
antibacterial drugs (antibiotic) mechanisms
- cell wall inhibitors
- cell membrane disruptors
- protein synthesis inhibitors (attack bacterial ribosomes)
- folate metabolism inhibitors (anti-metabolic)
- DNA synthesis inhibitors
ointments and gels
hydrocarbon (ointment) or water (gel) based, supplied in a small tube with dosage specified as a length of ribbon squeezed from tube (ex. 1cm) usually qhs
Other anti-infectives on board list: Zidovudine (AZT)
AIDS
Tetracyclines
Tetracycline, doxycycline, protein synthesis inhibitor (30S), bacteriostatic, broad spectrum, high resistance in common bacteria, many toxicities, discolouration of developing teeth
What does orbital cellulitis infection look like and what causes it?
Red eye, pain, blurred/dbl vision, nasal/sinus congestion/pain, tooth pain, orbital pain, eyelid edema, warmth tender, conjunctival chemosis and injection, proptosis, pain on eye movement, restricted EOMs
Caused by same as preseptal, staph, strep, h. influenzae, also sometimes fungi in immunocompromised pts
At what point or which groups of pts should you refer a preseptal cellulitis case to the hospital/imaging?
Children <5yrs, patient who appears toxic, patient who doesn’t improve on oral antibiotics
Admit to hospital for IV antibiotics: ampicillin/sulbactam, ceftriaxone, moxifloxacin, vancomycin
Adenovirus (EKC) treatment…
Infection is self-limiting but can do a povidone-iodine wash regimen (off-label) or gancyclovir ophthalmic gel 0.15% (zirgan)
What ocular symptoms differentiate preseptal cellulitis from orbital cellulitis?
Proptosis, optic neuropathy, restriction of eye movement, pain on eye movement - all indicate orbital cellulitis and are not seen in preseptal
Gray bottle cap
NSAID drop
Dacryocystitis treatment:
Oral due to deep infection: -Cephalexin 250-500mg QID 10-14d
- Amoxicillin w/clavulanate 400mg po q8h or 500-875mg BID for 5-7d for ADULTS, 20-40mg/kg/day po 10d for kids
- IV cefaxolin or cefuroxime for serious adult infections
Tan bottle cap
Antibiotic drop
What is 4-3-2-1 DREW for administering a drop rx?
4 times a day (QID), 3ml, for 2 eyes (OU), for 1 week
normal regimen, a bit less for anti-glaucoma drops (2.5ml/wk qid ou)
suspension drops
liquid dispersion of finely divided insoluble drug (drugs w/low aqueous solubility), drug dissolves after instillation of drop and can have improved absorption. container must be shaken before use it is also possible for suspension to clog tip of dropper
