This document discusses principles of antibiotic therapy in ophthalmology. It outlines different classes of antibiotics including penicillins, cephalosporins, aminoglycosides, macrolides, chloramphenicol, and fluoroquinolones. It describes how each class works and common pathogens they target. Dangers of antibiotic overuse like bacterial resistance and toxicity are also covered. The document provides guidance on selecting antibiotics based on the organism, disease severity, and patient factors. It concludes by describing various methods of antibiotic administration for ophthalmic conditions like topical, subconjunctival, intracameral, and systemic delivery.

1. Principles of
antibiotic therapy

2. Outline
• Introduction
• Pathogens
• Danger of overuse
• Selection and administration of antibiotics
• Methods of administration of antibiotics

3. Introduction
Chemical substances produced by microorganism that has the capacity to inhibit
growth or destroy bacteria
Chemical substances produced by microorganism that has the capacity to inhibit
growth or destroy bacteria
BactericidalBactericidal BacteriostaticBacteriostatic

4. • Inhibits cell wall synthesis
• Inhibits protein synthesis
• Inhibits nucleic acid synthesis
• Inhibits cell membrane synthesis

5. Bactericidal Bacteriostatic
Penicillins Chloramphenicol
Cephalosporin Erythromycin
Vancomycin Clindamycin
Gentamicin Sulfonamides

6. Pathogens
Gram positive and Gram negativeGram positive and Gram negative Aerobic and anaerobicAerobic and anaerobic
Gram positive cocci Gram negative rods
Penicillins, cephalosporins and
Vancomycin
Aminoglycosides, cephalosporins
Erythromycin, clindamycin
,chloramphenicol and tetracycline
Chloramphenicol and tetracycline

7. Chloramphenicol
• First line treatment of bacterial
conjunctivitis(broad spectrum)
• Bacteriostatic antibiotic which inhibits
protein synthesis
• Streptococci, Pneumococci and
Corynebacteria
• 0.5% drops and a one percent ointment

8. Fluoroquinolones
• Ciprofloxacin, ofloxacin(2nd
generation)
• Levofloxacin( 3rd
generation)
• Moxifloxacin, Gatifloxacin( fourth generation)
• Efficacious against Gram positive and Gram
negative bacteria, particularly staphylococci
• Low toxicity
• Enzymic inhibition of bacterial DNA
production( DNA gyrase)
• Deposit of whitish material in the base of corneal
ulcers which can make monitoring of the progress
of the disease more difficult.

9. Penicillins
• Benzylpenicillin,Procaine penicillin,
Benzathine penicillin ,Phenoxymethyl
penicillin, Cloxacillin,Ampicillin/amoxicillin
• Bactericidal and inhibit cell wall synthesis
• Low toxicity

10. Cephalosporins
• 1st
generation: cefazolin, cephalexin( gram
positive cocci)
• 2nd
generation: cefaclor, cefuroxime
sodium( gram positive and negative)
• 3rd
generation: cefotaxime sodium,
ceftizoxime(gram negative bacilli)
• Bactericidal and Inhibit cell wall synthesis
• Allergic reaction, neutropenia and
thrombocytopenia

11. Aminoglycosides
• Gentamicin(0.3%), Kanamycin,
Neomycin(0.3-0.5%), Streptomycin,
Tobramycin(1%), amikacin
• Bactericidal and inhibit protein synthesis
• Oto-toxicity and nephrotoxicity

12. Macrolides
• Erythromycin, Clarithromycin,
Azithromycin
• Inhibits protein synthesis

13. Danger of overuse
1.Hypersensitivity
• Skin eruptions
• Painful swollen joints, asthma and
fever
• Anaphylactic shock
2. Drug toxicity
• Aplastic anemia
3. Bacterial resistance 4. Alteration of normal bacterial flora

14. Selection and administration of
antibiotics
1. Nature of the offending organism and its
sensitivity to antibiotic
2. Nature of the disease, seriousness and
location
3. General health, sensitivities and allergies
of the patient

15. Methods of administration of
antibiotics
• Topical
• Subconjunctivally
• Intracamerally
• Systematically

16. Topical
• Conjunctivitis
• Superficial corneal ulcers

17. Systematic antibiotics
• Intraocular infections
• Infections of the orbit
• Severe conjunctivitis
• Severe corneal ulcers

18. Subconjunctival injections
• Severe intraocular infections
• Severe corneal ulcers

19. Intracamerally
• Bacterial endophthalmitis

20. Summary
• Introduction
• Pathogens
• Danger of overuse
• Selection and administration of antibiotics
• Methods of administration of antibiotics

21. Thank you