use of antibiotics in ocular disorders ,

1. ANTIBIOTICS IN OPHTHALMOLOGY
Dr.M.Sudheer kumar

2.  The term “antibiotic” is refer to drugs,,, natural
or synthetic, used to treat bacterial infections.
 Selective toxicity of anti microbial agent ,which
is harmful only to bacteria, and not to host is
because of the presence of a specific receptor
in the bacteria or different metabolic pathway
that is not present in host.

3. DEPENDING ON MODE OF ACTION , THEY
DIVIDED INTO 5 GROUPS.
1)Anti biotics acting by inhibition of cell wall
synthesis..
eg; penicillins
cephalosporins
bacitracin
vancomycin
2)Alteration in the permeability of cell
membrane
eg; amphotericin b
colistin
nystatin
polymixin

4. 3)Inhibition of protein synthesis
eg; chlormphenicol
erythromycin
tetracyclin
streptomycin
4)Inhibition of nucleic acid synthesis..
eg; rifampicin
pyrimrthamine
novobiocin
nalidixic acid

5.  5)interference with bacterial metabolism….
eg ; sulfonamide
trimethoprim
aminosalicylic acid

6.  Based on antibacterial activity….
Bactericidal Bacteriostatic
Penicillins Chloramphenicol
Cephalosporin Erythromycin
Vancomycin Clindamycin
Gentamicin Sulfonamides
 Based on spectrum of activity
- broad spectrum
- narrow spectrum

7. BETA LACTAM ANTIBIOTICS
 The first beta lactam antibiotic, penicillin, was
discovered by Sir Alexander Fleming in 1928.
 Bactericidal in nature.
 Resistance ,mechanism is associated with
enzymatic hydrolysis of the beta lactam ring by
the bacterial enzymes, beta lactamases or
penicillinases

8.  This mechanism of beta lactam resistance is
very common in Gram-negative bacteria
such as E. coli, Klebsiella species, Proteus
species, Pseudomonas aeruginosa .
 These are having beta lactam ring.
 Eg; penicillins
cephalosporins
carbapenem
monobactam

9. PENICILLINS

10. ANTIBACTERIAL ACTIVITY
Natural Penicillins
 The natural penicillins are narrow spectrum
antibiotics primarily effective against
Grampositive and a few Gram-negative
bacteria.
 The spectrum of antibacterial activity of
penicillin includes:
ƒƒ- Gram-positive cocci (Staphylococcus
species and Streptococcus species)

11.  ƒ-ƒGram-negative cocci
Neisseria gonorrhoeae,
Neisseria meningitidis
 -ƒƒGram-positive bacilli
Bacillus anthracis,
Corynebacterium diphtheriae,
Clostridium tetani
ƒƒListeria species
ƒƒ Spirochetes
Treponema pallidum,
Leptospira

12.  Majority of Gram-negative bacilli are
insensitive to natural penicillins.
 most strains of S. aureus and N.
gonorrhoeae are resistant to penicilli
 Penicillins penetrate well into all parts of the
ocular tissue such as the lid margins,
conjunctival sacs, corneae and lacrimal
sacs but not the ocular muscles.

13. Aminopenicillins ..
 They have enhanced ability to penetrate
Gramnegative organisms thus they have
greater activity against,
-ƒƒEnterobacteriaceae (E. coli, Shigella species,
Salmonella spp., Proteus mirabilis)
ƒƒ- Haemophilus influenzae
ƒƒ- Helicobacter pylor .
Antipseudomonal Penicillins
 They active against Pseudomonas
aeruginosa and other Gram-negative bacteria
such as Enterobacter species, Klebsiella
species,
 but they have no Gram-positive activity

14.  Currentlymost strains of Pseudomonas
aeruginosa produce different types of beta
lactamase.
 As such antipseudomonal penicillins are
generally used in combination with beta
lactamase inhibitors for the treatment of
pseudomonal infections .
Beta Lactamase Inhibitors …
clavulanic acid,
sulbactam
tazobactam.
-These drugs are not antibiotics.

15. The combination of clavulanic acid and
ticarcillin is known as timentin .
 Given parenterally.
 The combination increases the spectrum of
activity of ticarcillin to include,,
Gramnegative aerobic organisms,
Staphylococcus aureus
Bacteroides
Clavulanic acid is also
combined with amoxicillin,
and the combination is known as augmentin.
given orally

16.  Effectively treats infection by beta lactamase
producing organisms that include
Haemophilus influenzae
Staphylococcus species
Escherichia coli
Neisseria gonorrhea .
Administration …
Besides oral and parenteral routes, penicillins
can be administered by
-topical,
-subconjunctival
-intravitreal routes for the treatment of
ophthalmic infections

17. THERAPEUTIC USES
 Penicillins are useful in the treatment of many
acute ophthalmic bacterial infections and are
suited for surface application in the form of
drops.
 can be used for subconjunctival injections as
well intravenous or intramuscular injections.
 Organisms commonly found in ocular
infections, which are susceptible to the action of
penicillin are Staphylococcus pyogenes, the
hemolytic Streptococcus, the Gonococcus and
the Pneumococcus.

18.  Types of Ocular Infection Suitable for
Treatment by Penicillins …..
 Acute conjunctivitis, blepharitis and
canaliculitis.
Penicillin G potassium ophthalmic solution has
been used, however, currently not a favored
choice in clinical practice due to its narrow
spectrum and instability.
 Chronic blepharitis due to S. aureus.
Oxacillin subconjunctival injections
 Keratitis and corneal ulcers caused by S.
aureus.
Oxacillin subconjunctival injections

19.  Canaliculitis… blepharitis



20. TREATMENT OF BLEPHARITIS
 Lid hygiene can be carried out once or twice daily
initially by…
- A warm compress should frst be applied for
several minutes to soften crusts at the bases of the
lashes.
- Lid cleaning is subsequently performed to
mechanically remove crusts and other debris,
scrubbing the lid margins with a cotton bud or clean
facecloth dipped in a warm dilute solution of baby
shampoo or sodium bicarbonate.

21.  Antibiotics
○ Topical sodium fusidic acid, erythromycin,
bacitracin, azithromycin or chloramphenicol is used
to treat active folliculitis.
 Oral antibiotic regimens include doxycycline (50–
100 mg twice daily for 1 week
and then daily for 6–24 weeks) .

22.  Gonococcal conjunctivitis and gonococcal
corneal ulcer
 Ocular syphilis.
 Acquired syphilis with
ocular involvement should be treated as
neurosyphilis with intravenous penicillinG.
 The dose is 18–24 million units (MU)
daily for 10 to 14 days, followed by procaine
penicillin, intramuscular, 2.4 MU weekly
for three weeks


23. ADVERSE EFFECTS
 Penicillins are among the least toxic drugs
known.
 The most common side-effect of penicillins
is diarrhea. Nausea, vomiting, and epigastric
discomfort are also common.
 Penicillins can cause immediate and delayed
allergic reactions -specifcally, skin rashes,
fever, and anaphylactic shock.

24. CEPHALOSPORINS
 The cephalosporins are beta lactam antibiotics
 cephalosporins more resistant to penicillinase
compared to penicillins
 These drugs were frst obtained from
Cephalosporium acremonium, a fungus.
 The cephalosporins structures have now been
modified to include various substitutions of their
side chains (R1 and R2) and have proliferated
to four “generations”.

26.  In general Gram positive activity decreases from
frst generation to the fourth and Gram negative
activity increases in a reverse order. Stability to
beta lactamase also increases from the frst to
fourth generations.
 Pharmacokinetics
Besides oral and pareteral administration,
cephalosporins can be administered by topical,
subconjunctival and intravitreal route for the
treatment of ophthalmic infections.
 The formulations of cefazolin sodium, ceftazidime
and ceftriaxone available for ophthalmic use.
 These drugs are widely distributed to most body
tissues fluids including aqueous humor.

27.  Overall, cephalosporins do not undergo
metabolism and are excreted unchanged by
glomerular filtration and tubular secretion
in urine
 Cefoperazone and ceftriaxone undergo billiary
secretion, which makes them both, the choice
in patients with renal impairment.


28. THERAPEUTIC USES
 Types of Ocular Infection Suitable for
Treatment by Cephalosporins
 Acute conjunctivitis and blepharitis caused by
Gram-positive flora (S. aureus, Streptococcus
species): Topical frst generation
cephalosporins (cefazolin)
 Gonococcal conjunctivitis and gonococcal
corneal ulceration: Basic third generation
cephalosporins (ceftriaxone, cefotaxime)
intramuscularly or intravenously.


29.  Bacterial keratitis and corneal ulceration
due to Gram-positive flora: First generation
cephalosporins (cefazolin) by subconjunctival
injections
 Pseudomonal keratitis and corneal ulceration:
Third and fourth generation cephalosporins
with antipseudomonal activity (ceftazidime,
cefipime), subconjunctival
injections or systemic
injection in case of
corneal perforation.
Pesudomonal keratitis

30.  Dacryocystitis and dacryoadenitis: Second
and third generation cephalosporins
intravenously .
 Bacterial endophthalmitis: Usually combination
therapy of ceftazidime and vancomycin
intravitreal.
 Pre-operative prophylaxis of post-operative
endophthalmitis: Second generation
cephalosporins (cefuroxime) intracameral
injection.

32. TREATMENT OF ENDOPHTHALMITIS
 Intravitreal antibiotics are the key to management
because levels above the minimum inhibitory
concentration of most pathogens are achieved, and
are maintained for days.
 Antibiotics commonly used in combination are
ceftazidime, which will kill most Gram-negative
organisms (including Pseudomonas
aeruginosa) and vancomycin to address Gram-
positive cocci (including methicillin-resistant
Staphylococcus aureus) .
 ceftazidime 2 mg in 0.1 ml
vancomycin 2 mg in 0.1 ml;

33. CARBAPENEMS
 This class of beta lactam antibiotics include,,,
 imipinem/cilastatin,
 meropenem,
 etarpenem,
 doripenem,
 panipenem,
 biapenem,
 razupenem
are derived from thienamycin, naturally obtained
from Streptomyces cattleya .

34.  The antibacterial activity of the carbepenems
includes both, Gram-positive and Gram-negative
organisms such as Streptococcus,
Staphylococcus, Listeria, Pseudomonas
andAcinetobacter.
 They are also effective against anaerobes,
including Clostridium diffcile and Bacteroides
fragillis
 Pharmacokinetics …
- Carbapenems are administered intravenously
and are not absorbed orally
- They penetrate well into aqueous humor and
vitreous

35. ADVERSE EFFECTS
 Imipenem causes thrombophlebitis on
intravenous administration.
 It can also cause nausea and vomiting.
 Some metabolites of imipenem are neurotoxic
with effects such as tremor, seizure and
confusional state,


36. THERAPEUTIC USES
 Carbapenems are administred intravenously
and are used in the treatment of severe ocular
infections such as bacterial endophthalmitis.
 They are also may be used as pre-operative
prophylaxis of post-operative endophthalmitis and
in the treatment of orbital cellulitis .

37. TREATMENT OF ORBITAL CELLULITIS
 Hospital admission is mandatory, with urgent
otolaryngological assessment and frequent
ophthalmic review.
 Antibiotics are given intravenously, with the
specifc drug depending on local sensitivities;
-ceftazidime is a typical choice, supplemented
by oral metronidazole to cover anaerobes.
 Intravenous antibiotics should be continued until
the patient has been apyrexial for 4 days,followed
by 1–3 weeks of oral treatment.

38. MONOBACTAMS
 Mechanism of action is similar to other beta
lactams.
 It is beta lactamase resistant and is highly effective
against most Gram-negative aerobes, including
Pseudomonas aeruginosa, Escherichia coli,
Klebsiella, and Enterobacter .
 The clinical uses of aztreonam include severe
ocular infections such as bacterial endophthalmitis
caused by Gram-nagative bacteria including
Pseudomonas aeruginosa resistant to other beta
lactam antibiotics.

39. NON BETA LACTAM ANTIBIOTICS
Chloramphenicol ….
 Chloramphenicol’s spectrum of activity covers
the majority of ocular pathogens.
 In a study of 738 patients with acute bacterial
infections of the external eye, there was an overall
resistance rate of only 6% to chloramphenicol,
compared to 9% with tetracycline and around 20%
to the aminoglycosides tested .

40. Mechanism of Action …
 Chloramphenicol is a bacteriostatic antibiotic. It
inhibits bacterial protein synthesis. It binds to the
50S ribosomal subunit and inhibits the activity of
the enzyme, peptidyl transferase.
Antibacterial Spectrum …
 Chloramphenicol exerts bacteriostatic effect on a
wide range of Gram-positive and Gram-negative
organisms
 and is active against Rickettsia species, Chlamydia
species and Mycoplasma species.
 It is particularly effective against H. influenzae,
S. pneumoniae, S. typhi, Neisseria meningitidis,
Neisseria gonorrhoeae, Brucella species and
Bordetella pertussis.

41.  Pharmacokinetics
 penetrates well into the aqueous humor after
topical application
 Chloramphenicol is approximately 60%
protein bound. It is widely distributed in the
body.
 An important aspect of chloramphenicol’s
distribution is that it is able to penetrate blood
ocular barrier.
 The drug crosses the placenta and is distributed
into the breast milk.

42. TYPES OF OCULAR INFECTIONS SUITABLE FOR
TREATMENT BY CHLORAMPHENICOL
 1. Acute bacterial conjunctivitis and blepharitis.
2. Gonococcal conjunctivitis and gonococcal
corneal ulcer. Chloramphenicol is used as
an alternate for the treatment of gonococcal
infection when the cephalosporins or penicillin
are not suitable.
3. Bacterial keratitis and corneal ulceration.
4. Dacryocystitis and dacryoadenitis .
 risk of aplastic anemia due to topical application of
chloramphenicol is not well
founded, it is very important to monitor the blood
count during the chloramphenicol treatment.

43.  Optic and peripheral neuritis have been
reported, usually following long-term therapy.
If this occurs, the drug should be promptly
discontinued
 Fever, macular and vesicular rashes, angioedema
and urticaria may
occur, especially
after topical use.

44.  Contraindications
As chloramphenicol readily crosses
the placenta, it should be used with caution in
pregnant women although birth defects in humans
have not been documented.
 However, it should not be used in pregnancy at term or
during labor because of
potential toxicity in premature
or full-term infants, including
gray baby syndrome

45. QUINOLONES AND
FLUOROQUINOLONES
 They are derivatives of quinolones which
have a fluorine atom attached to the central ring,
Classification
 Quinolones and fluoroquinolones are divided into
four generations.


46. First Generation…
 the oldest and least often used quinolones. they are
more susceptible to the development of bacterial
resistanc
Second Generation…
 increased Gram-negative activity, as well as some
Gram-positive and atypical pathogen coverage.
 Ciprofloxacin is the
most potent fluoroquinolone
against P. aeruginosa.

47. Ciprofloxacin and ofloxacin are the
most widely used second generation
quinolones because of their availability
in oral, intravenous and topical formulations
Third Generation …
 They have expanded activity against Gram-positive
organisms, particularly penicillin-sensitive and penicillin-
resistant S. pneumoniae, and atypical pathogens such
as Mycoplasma pneumoniae and Chlamydia
pneumoniae.
 Less active than ciprofloxacin
against Pseudomonas species.

48. Fourth Generation…
 signifcant antimicrobial activity against anaerobes
while maintaining the Gram-positive and
Gramnegative activity of the third generation drugs.
 They also retain activity against Pseudomonas
species.

49. Mechanism of Action
 Fluoroquinolones are the only class of
antimicrobial agents in clinical use that are
direct inhibitors of bacterial DNA synthesis.
 Fluoroquinolones inhibit two bacterial enzymes,
DNA gyrase (topoisomerase II) and
topoisomerase IV .
 fluoroquinolones are bactericidal agents
Pharmacokinetics…
Fluoroquinolones penetrate well into the
aqueous humour after topical application.
Moxifloxacin 0.5% has better corneal
penetration compared to gatifloxacin 0.3% .

50.  So Moxifloxacin 0.5 % achieves highest level in
aqueous humor.
 Levofloxacin 0.5% has better ocular penetration.

51. TYPES OF OCULAR INFECTION SUITABLE FOR
TREATMENT BY FLUOROQUINOLONES
 Second generation fluoroquinolones are very
effective in the treatment of acute bacterial
conjunctivitis and blepharitis
 Power et al. investigated the
effcacy of ciprofloxacin and chloramphenicol
in 57 culture-positive patients and reported
that the difference between the groups was
not significant
 Both antibiotics were highly effective and
signifcantly superior to placebo .

53. TREATMENT OF ACUTE BACTERIAL
CONJUNCTIVITIS
 About 60% resolve within 5 days without
treatment.
 Topical antibiotics, usually four times daily for
up to a week ,but sometimes more intensively,
are frequently administered to speed recovery
and prevent re-infection and transmission.
 There is no evidence that any particular antibiotic
is more effective.
 Ointments and gels provide a higher
concentration for longer periods than drops but
daytime use is limited because of blurred vision.

54.  Some practitioners, particularly in the United
States, believe that chloramphenicol should not
be used for routine treatment because of a
possible link with aplastic anaemia.
 Topical steroids may reduce scarring in
membranous and pseudomembranous
conjunctivitis, although evidence for their use is
unclear.
 A broad-spectrum antibiotic with good Gram-
positive coverage such as a third- or
fourthgeneration fluoroquinolone, 10% sodium
sulfacetamide, or trimethoprim-polymyxin may
be used for 7–10 days

55.  Irrigation to remove excessive discharge may
be useful in hyperpurulent cases.
 Contact lens wear should be discontinued until
at least 48 hours after complete resolution of
symptoms
 Risk of transmission should be reduced by
hand-washing and the avoidance of towel
sharing

56.  Gonococcal conjunctivitis and gonococcal
corneal ulcer. Second generation fluoroquinolones
(ciprofloxacin) are used topically and parenterally in the
treatment of gonococcal conjunctivitis and keratitis


57.  Bacterial keratitis and corneal ulceration. The
common pathogens causing bacterial keratitis
are Pseudomonas aeruginosa, Pneumococcus,
Moraxella species, and Staphylococci.

Fluoroquinolones such as levofloxacin
0.5%, ofloxacin 0.3%, norfloxacin 0.3%, or
ciprofloxacin 0.3% are commonly used as frstline agents
to treat this condition as long as
local prevalence of resistant organisms is low.

59. TREATMENT OF BACTERIAL KERATITIS
 fluoroquinolone is the usual choice for empirical
monotherapy and appears to be about as effective
as duotherapy .
 Ciprofloxacin instillation is associated with white
corneal precipitates that may delay epithelial
healing.


60.  Antibiotic duotherapy may be preferred as frst-
line empirical treatment in aggressive disease.
 Empirical duotherapy usually involves a
combination of two fortifed antibiotics, typically a
cephalosporin and an aminoglycoside, in order to
cover common Grampositive and Gram-negative
pathogens.
 Mydriatics are used to prevent the formation of
posterior synechiae and to reduce pain.
 Steroids reduce host inflammation, improve
comfort, and minimize corneal scarring.

61.  -Epithelialization may be retarded by steroids and
they should be avoided if there is signifcant thinning
or delayed epithelial healing .
 Many people do not commence topical steroids
until evidence of clinical improvement is seen with
antibiotics alone, typically 24–48 hours after starting
treatment .


62.  If the pathogen identifed is Mycobacteria,
the fourth-generation fluoroquinolones
(moxifloxacin 0.5% and gatifloxacin 0.3%) are
indicated
 Bacterial endophthalmitis
 Fluoroquinolones are the
drug of choice in the prophylaxis of
postoperative endophthalmiti

63. ADVERSE EFFECTS
 Local adverse effects following ocular administration of
fluoroquinolones include pain or discomfort in the eye,
swelling,
 foreign body sensation, itching, conjunctival hyperemia
and transient burning .
 white crystalline precipitate, commonly located in the
superfcial portion of the corneal defect i.e. the area of
inflammation.

64.  Phototoxicity …..The degree of phototoxic
potential of fluoroquinolones is as follows:
lomefloxacin > sparfloxacin > ciprofloxacin >
norfloxacin = ofloxacin = levofloxacin =
gatifloxacin = moxifloxacin
 nausea, vomiting, diarrhea, constipation, and
abdominal pain, which occur in 1 to 5% of patients.
 Contraindications … previous allergic
reaction to ciprofloxacin or other quinolones.


65.  certain disorders that predispose to arrhythmias
such as QT-interval prolongation, uncorrected
hypokalemia or hypomagnesemia.
 Fluoroquinolones are approved for use only
in people older than 18 years of age. They are
contraindicated in children and in pregnant
women because they may cause cartilage lesions
if growth plates are open
 potential to cause teratogenic orembryocidal effects
.
 also excreted in breast milk and
should be avoided during breast-feeding

66. TETRACYCLINES
 Tetracycline is a group of broad spectrum
antibiotics that inhibit bacterial protein synthesis
and are bacteriostatic.

 Gram-positive cocci (Staphylococcus species
and Streptococcus species)
ƒƒGram-negative cocci (Neisseria gonorrhoeae)
Gram-positive bacilli (Bacilus anthracis

67.  Gram-negative bacilli (Haemophilus influenzae,
Helicobacter pylori)
 Atypical bacteria (ChlamydiaspeciesMycoplasm
species, Legionella species, Ureaplasma)
 Spirochetes (Treponema pallidum, Borrelia
recurrentis, Borrelia burgdorferi)
 Rickettsiae, Listeria,Vibrio choler ƒƒ,Anaerobes
 Tetracyclines penetrate into
most body tissues and fluids and tetracycline
particularly penetrates well into the ocular tissue
 Tetracycline is available as eyedrop and ointment

68. THERAPEUTIC USES …
 1. Acute conjunctivitis and blepharitis.
2. Ophthalmia neonatorum. Tetracycline ointment
1% is used in prevention and treatment of
gonococcal and chlamydial ophthalmia neonatorum
(neonatal conjunctivitis).
3. Trachoma. Doxycycline and tetracycline are
the frst line drugs in the treatment of trachoma.
4. Bacterial keratitis and corneal ulceration due to
Gram-positive flora (Staphylococcus species).
 trachoma

69.  5. Dacryocystitis and dacryoadenitis. Tetracyclin is
used as alternative to other antibiotics.
6. Bacterial endophthalmitis
 Adverse Effects…
 burning sensation of the stomach, diarrhea, sore
mouth or tongue.
 Tetracyclines should not be used in children under
the age of 8 years, and specifcally during periods of
tooth development.
 Tetracyclines are classed as pregnancy categoryD
 Minocycline commonly causes vestibular
dysfunction.

70. MACROLIDES
 Macrolides are usually administered orally.
Erythromycin is also available as ophthalmic
ointment .
 After systemic administration, macrolides
enetrate well into all tissues including ocular
tissues.
Therapeutic Uses…
 Bacterial conjunctivitis and blephritis
 adult inclusion conjunctivitis (AIC) and
neonatal inclusion conjunctivitis (NIC)
 Trachoma

71. Adverse Effects
 nausea, vomiting, abdominal pain, diarrhea and
anorexia. (Azithromycin and clarithromycin have
fewer gastrointestinal side-effects than
erythromycin )
 pseudomembranous colitis
 QT prolongation and ventricular arrhythmias,

72. AMINOGLYCOSIDES
 Bactericidal action
 1st gen are effective against M. tuberculosis . streptomycin
is still the first line drug in the treatment of tuberculosis.
 second generation…Tobramycin is more active than
gentamicin against Pseudomonas aeruginosa ,whereas
gentamicin is usually more active against Serratia .
Pharmacokinetic…
 Topically applied aminoglycosides are primarily
absorbed through conjunctiva due to their hydrophilic
nature
 After parenteral administration, aminoglycosides are
primarily distributed within the extracellular fluid. They do
not penetrate well into the aqueous humor and vitreous
fluid of the eye.

73.  The commercially available topical ocular
aminoglycosides include gentamicin, neomycin,
framycetin and tobramycin.
 Gentamicin is also administered subconjunctivally
and intravitreally
Therapeutic Uses
 Gentamicin and tobramycin (in fortifed form) has
been a “go to” agent for the treatment of Gram-
negative ocular infections, especially
Pseudomonas aeruginosa .
 1. Conjunctivitis, blepharitis and
blepharoconjunctivitis.
2. Bacterial keratitis and corneal ulceration.

74. 3. Dacryocystitis and dacryoadenitis.
4. Bacterial endophthalmitis
Adverse Effects…
 Nephrotoxicity, which is usually reversible.
 Ototoxicity is irreversible,

75. SULFONAMIDES
 sulfonamides inhibit the biosynthesis
of folic acid, which is essential for the synthesis of
purine nucleotides for DNA and RNA.
 Trimethoprim is a potent inhibitor of the bacterial
enzyme dihydrofolate reductase and interferes
competitively with the conversion of dihydrofolic acid to
tetrahydrofolic acid .
 Cotrimoxazole is a combination of a sulfonamide
(sulfamethoxazole) and trimethoprim. Combined
administration of both exerts synergistic antimicrobial
activity leading to bactericidal effect.


76.  Sulfonamides generally are used in the oral
form, though parenteral preparations are also
available
 Commercially available 30% ophthalmic solutions of
sulfacetamide sodium are present.
 Use..Treatment of conjunctivitis, corneal ulcers, and
other superfcial infections of the eye caused by
susceptible Staphylococcus aureus, Streptococcus
pneumoniae, Streptococcs viridans, Haemophilus
influenzae .
 S/E; irritation, stinging, and burning. Conjunctivitis,
conjunctival hyperemia

77. BACITRACIN
 Derived from the cultures of Bacillus subtilis,
 Bacitracin has a narrow antibacterial spectrum.
Gram-positive bacteria such as Staphylococcus
species and Streptococcus species are susceptible.
Therapeutic Uses
-Bacitracin is never used as a systemic agent
because it causes serious nephrotoxicity.
-It is usually used in combination with polymixin B
and neomycin, to treat superfcial infections of
conjunctiva, eyelids and cornea.

78. POLYMYXIN B
 Not used systemically as it causes
neurotoxicity and nephrotoxicity.
 Topically, it is used in combined preparations with
other anti-infectives such as bacitracin .
 Trimethoprim/polymixin B ophthalmic
preparation is available as ointment and solution.
 Polymixin B is also available for subconjunctival
injections
USES;
 1. Conjunctivitis, blepharitis and
blepharoconjunctivitis due to Gram-negative infection.
2. Keratitis and corneal ulcers.

79. Thank you