Ocular infection & inflammation pharmacology Flashcards
Infection considerations
- barriers (skin & mucous membranes)
- Immune status
- organisms (bacteria, virus, fungi)
Gram positive Cocci
- staph aureus
- staph epidermidis
- strep pneumonia
- strep pyogenes
- strep faecalis
Gram negative Rods
- Haem Influenzae
- Pseudomonas aeruginosa
- Serratia Marcescens
Gram negative Cocci
- Neisseria gonorrhoeae
Bacteria def
- single celled
- subdivided by shape and gram stain
Gram Stain
- pos = violet = thick peptidoglycan layer in cell wall
- neg = red = thinner petidoglycan layer
unique structural bacteria
- Rickettsia (gram - found in ticks, fleas & mammals)(zoonotic)
- Chlamydia (mimic virus)
- Treponema palladium (syphilis - the masqarader)
- Mycobaterium tuberculosos
- Actinomyces (anaerobic - resemble fungal hyphae)
Bact uniqueness
- Peptidoglycan Cell wall (penicillin vulnerability)
- Ribosome cell membrane
Bactericidal
- destroys cell wall - peptidoglycan - Penicillin
Bacteriostatic
- inhibit cell growth - Tetracycline
Selective toxicity
Bact vs human
- Bact has cell walls - antibacterial inhibits synthesis of cell wall
- Cell membranes are similar
- Ribosomes - diff size and composition
- inhibit bact protein synthesis
Selective toxicity
Drugs
- biosynthetic pathways (intermediary metabolism)(Folic acid - bact produce/synthesize)
- Enzyme DNA gyrasee (prevents supercoiling of DNA during replication & transcription)
Mechanisms of Resistance
- Bact produces enzymes that degrade/inactivate antibiotics
- pump mechanisms (pump out) or decrease permeability of antibiotics
- resistance genes
- alteration for bact ribosomes
- chromosomal mutation
Cross resistance
- Misuse/overuse/non-compliance - SYSTEMIC mostly
- excess from animal feed
- leads to resistance to similar groups of antibiotics
- penicillin vs cephalosporins (similar drug structure)
Indications for oral antibiotics
- Meibomianitis
- Internal Hordeolum
- Ocular Rosacea
- Dacryocystitis
- Preseptal Cellulitis
- Chlamydial Conj
- Prophylaxis (fractures, sinusitis)
Topical Anti-biotics Use
- Ant Segment infection
- Conjunctivitis
- Corneal Ulcer
- Blepharitis
- Prophylaxis
Drug considerations
- selective toxicity
- spectrum of activity (narrow vs broad)
- resistance
Guideline for effective therapy
- accurate dx
- microorganism sensitivity to anti-infective
- least toxic drug
- adequate drug level
- optimum route of admin
- appropriate dosage
- appropriate tx time
- augment with physical procedures
Antimicrobial Failure - why?
- inaccurate Dx
- resistance (drug)
- inadequate dosage
- noncompliance
- inadequate suppl physical procedures
- inadequate immune system response
Drugs affecting Cell Wall
- Penicillins
- Cephalosporin
- Vancomycin
- Bacitracin (ung)
Vancomycin
-think = last line for MERSA
Chloramphenicol
- think = aplastic anemia
Penicillins
- Augmentin (Amoxicillin + clavulanate)
- Dicloxacillin
Cephalosporins
- Cephalexin (Keflex)
- Cefaclor (Ceclor)
B-Lactam antibiotics
- Penicillins & Cephalosporins
- B-lactam ring (similarity)
- resistant bact produces enzyme to disrupt B-lactam ring
Penicillins use
systemic
- Hordeolum
- Preseptal cellulitis
- Dacryocystitis
- Dacryoadenitis
Penicillin adverse reaction
- Hypersensitivity response (type 1 - 4) (2%)
- GI irritation (nausea, vomit, diarrhea)
- diarrhea is common - kills normal flora
- Superinfection (Tx but gets worse)
Penicillin vs Cephalosporin
- if Penicillin hypersensitive less than 2% cross-react to cephalosporin
- less likely in 3rd + 4th gen Cepalos
clavulanate mechanism (Augmentin)
- B-Lactamase inhibitor
- protects penicillin from penicillanse
- weak anti-microbial activity
Cephalosporins
- B-lactam ring (similar to Penicillin)
- addition of acyl side chains (1-4 gen)
- Broad spectrum
- Bactericidal
- Resistance (B-lactamase)
Cephalosporin Use
- same as Penicillins
- other (ophthalmically fortified use)
Bacitracin
- Gram +
- Bactericidal
- Ointment (unstable in sol)
- Combo = Polycin (Bacitracin + Polymyxin B)(for Gram - )
- Blepharitis
- Dose - QD > TID