About Anti-Biotics in eye care

1. Drugs Used in Ophthalmology
Anti-Biotics
𝑷𝒓𝒂𝒕𝒚𝒖𝒔𝒉 𝑫𝒉𝒂𝒌𝒂𝒍 DOA,FO
Optometrist
Advanced Eye Hospital and Institute
Sanpada,Navi Mumbai

2. Definition
• Type of antimicrobial used specifically against
bacteria, and are often used in medical treatment
of bacterial infections.
• They may either kill or inhibit the growth of
bacteria.
• Several antibiotic agents are also effective against
a number of fungi, protozoans and some are toxic
to humans and animals
• Antibiotics are not effective against viruses such
as the common cold or influenza, and may be
harmful when taken inappropriately.

3. Anti-Biotics
• Broad classifications
• Bacteriostatic and Bactericidal
• Narrow/intermediate/Broad spectrums
• Tab/cap/syr/ed/eo/iv/im/ivit
• Gram-Negative and Gram-Positive

4. Gram Positives
• Gram-positive bacteria are those that are
stained dark blue or violet by Gram staining.
The examples for gram-positive bacteria are
Bacillus, Nocardia, Clostridium,
Propionibacterium, Actinomyces,
Enterococcus, Cornyebacterium, Listria,
Lactobacillus, Gardnerella, Mycobacterium,
Mycoplasma, Staphylococcus, Streptomyces,
and streptococcus

5. • Gram-negative bacteria are bacteria that do not
retain crystal violet dye in the Gram staining
protocol and The examples for Gram-negative
bacteria are Escherichia coli (E.coli), Helicobcater,
Hemophilus, Neisseria, Cyano bacteria, Klebsiella,
Acetobacter, Enterobacter, Chlamydia, Vibrio,
Pseudomona, Salmonella, Thiobacter, Borrelia,
Burkholderia, Serratia, Treponema

6. 6 groups of Anti-Biotics
• Sulfonamides:In bacteria, antibacterial
sulfonamides act as competitive inhibitors of the
enzyme dihydropteroate synthetase (DHPS), an
enzyme involved in folate synthesis. Sulfonamides
are therefore bacteriostatic and inhibit growth and
multiplication of bacteria, but do not kill them.
Humans, in contrast to bacteria,
aquire folate (vitamin B9) through the diet.
• E.g Sulfadizine, Sulfacetamide, Sulfadimidine
etc

7. Beta-lactam antibiotics
• These antibiotics have a beta-lactam ring. The
two important groups are penicillins, and
cephalosporins.All beta-lactam antibiotics act by
interfering with the synthesis of bacterial cell
wall.
• A. Penicillins. These are produced by growing one
of the penicillium moulds in deep tanks. These
may be categorised as: natural penicillins and
semisynthetic penicillins.

8. PENICILLIN
• Benzyl penicillin
• Procaine penicillin
• Methicillin, cloxacillin and flucloxacillin
• Carbenicillin.
• Ampicillin Its dosage is 0.25-2 g oral/i.m./i.v. depending
upon the severity of infection every 6 hours. Paediatric dose
is 25-50 mg/kg/day
• Amoxycillin

9. cephalosporin's
• 1.First-generation (narrow spectrum) cephalosporins.These
are very active against grampositive cocci and thus have
useful antistaphylococcalactivity. These include
cefazolin,cephradine, cephalexin and cephadroxyl.
• 2. Second-generation (intermediate spectrum)
cephalosporins. These have antistaphylococcal activity and are
also effective against certain gram-negative organisms. They
comprise cefuroxime, cefamandole and cefoxitin.
• 3. Third-generation (wide spectrum) cephalosporins.
These are mainly effective against gramnegative organisms but
not against staphylococci.These include: cefotaxime, cefixime
and cefotetan.

10. Aminoglycosides
• These are bactericidal and act primarily against gramnegative
bacilli. These are not absorbed orally, distributed mainly
extracellularly and are excreted unchanged in the urine. These are
ototoxic and nephrotoxic. Certain aminoglycosides are too toxic
for systemic use and hence used only topically.
• Commonly used preparations are as follows:
• 1. Streptomycin. It is used mainly in tuberculosis.
• 2. Gentamicin. It has become the most commonly used
aminoglycoside for acute infections. It has a broader spectrum of
action and is effective against Pseudomonas aeruginosa. It is
nephrotoxic, therefore, its dose must be precisely calculated
according to body weight and renal function. For an average adult
with normal renal function, the dose is 1-1.5 mg/kg
intramuscularly 8 hourly. Topically, it is used as 0.3% eyedrops.

11. • 3. Tobramycin. It is 2-4 times more active against
Pseudomonas aeruginosa and Proteus as compared to
gentamicin. Topically, it is used as 1% eyedrops.
• 4 Amikacin. It is recommended as a reserve drug for
hospital acquired gram-negative bacillary infections where
gentamicin resistance is increasing.
• 5. Neomycin. It is a widespectrum aminoglycoside,active
against most gram-negative bacilli and some gram-positive
cocci. However, Pseudomonas and Streptococcus pyogenes
are not sensitive to it. It is highly toxic to internal ear and
kidney and hence used only topically (0.3-0.5%).

12. • 6. Framycetin. It is very similar to neomycin. It is also too toxic
for systemic use and hence used only topically. It is available
as 1 percent skincream; 0.5 percent eye ointment and
eyedrops.
• Tetracyclines
• These are broad-spectrum bacteriostatic agents with a
considerable action against both gram-positive and gram-
negative organisms as well as some fungi,rickettsiae and
chlamydiae. This group includes tetracycline, chlortetracycline
and oxytetracycline.

13. • Chloramphenicol
• It is also a broad-spectrum antibiotic, primarily bacteriostatic, effective
against gram-positive as well as gram-negative bacteria, rickettsiae,
chlamydiae and mycoplasma.Its molecule is relatively small and lipid
soluble.Therefore, on systemic administration, it enters the eye in
therapeutic concentration. Topically it is used as 0.5% eyedrops.
Polypeptides
• These are powerful bactericidal agents, but rarely used systemically due to
toxicity. Clinically used polypeptides are polymyxin B, bacitracin, colistin
and tyrothricin.
• 1. Polymyxin B and colistin. These are active against most gram-negative
bacteria, notably Pseudomonas.
• 2. Neosporin (neomycin-polymyxin-bacitracin). It is an effective broad-
spectrum antimicrobial but suffers the disadvantage of a high incidence
(6-8%) of sensitivity due to neomycin.

14. Fluoroquinolones
• Fluoroquinolones are potent synthetic agents
having broad spectrum of activity against
gram-positive and gram negative-organisms.
• Mechanism of action. Fluoroquinolones are
bactericidal drugs. These inhibit the bacterial
DNA synthesis.

16. Common use in Eyes
• To treat Bacterial Conjunctivitis
• Prophylactic pre-operatively
• Bacterial and Fungal keratitis
• To prevent secondary infections