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Bacterial corneal ulcer
1. Dr. K. Vasantha M.S., F.R.C.S., Edin
Director RIO Chennai (Rtd)
2. Bacterial keratitis implies any form of corneal
inflammation either superficial, interstitial or
deep caused by bacteriae
When this inflammation is accompanied by a
loss of epithelium, it is termed a Corneal Ulcer.
4. Pseudomonas aeruginosa
Neisseria species
Haemophilus species
Moraxella species
Serratia marcescens
Proteus sp., Acinetobacter sp., Enterobacter sp, E.
coli,
Klebsiella sp., Eikenella sp.
Pasteurella multocida, Xanthomonas sp.,
5. Aerobic, nonfermenting gram negative rods
Achromobacter xylosoxidans and Stenotrophomonas
maltophilia are important causes for contact lens
induced keratitis. These are resistant to fluoroquinolones
and aminoglycosides
Actinomycetes including Nocardia are common in
developing countries
With orthokeratology lenses Pseudomonas, S.aureus,
Acanthamoeba and Stenotrophomonas are found
6. Normally the epithelium protects the cornea from getting infected.
But these bacteriae can penetrate the epithelium
Neisseria gonorrhoeae, Neisseria meningitidis
Corynebacterium diphtheriae
Haemophilus aegypticus
Listeria species
7. Ulcers can occur as secondary infection from the
conjunctival commensals, from the lids or from the sac
when it is inflamed. This will happen when there is an
abrasion. This is the reason why when there is a chronic
dacryocystitis it must be immediately dealt with
Diabetes and immuno suppressives will also predispose
the person to infection
Contact lens wear
8.
9. Watering, pain and redness usually following injury.
Defective vision. More if the ulcer is in the center
Lid edema, muco purulent discharge
Circum corneal congestion, sometimes conjunctival
congestion also. Chemosis if there is severe
inflammation
Opacity in the cornea which will take up fluorescein stain
as the epithelium will be abraded.
10. Pupil will be constricted and sluggishly reactive due to
irritation to the iris.
This toxic reaction can produce hypopyon which will be
sterile in bacterial ulcer.
In fungal ulcer fungal hyphae may be present.
Injury with vegetative matter should make one suspect
fungal etiology
If chronic dacryocystitis is present Pneumococcal
infection must be thought of
11. Stage of progressive infiltration
Stage of active ulceration
Stage of regression
Stage of cicatrization
12. Characteristics
• Suppuration is the hallmark
•Yellow – white, oval, densely opaque ulcer with relatively clear
surrounding cornea with or without hypopyon
•Two types of stromal infiltration:
•- small, discrete, peripheral anterior stromal infiltrates (free of
replicating bacteria)
•- large, severe, central stromal infiltrates (replicating bacteria
present)
•Tissue damage irreversible and leads to permanent scarring
13.
14. Often seen when chronic dacryocystitis is present
Suppuration and cicatrization are seen together. Ulcer
progresses on one side when the other side is healing.
Hypopyon will be present as this causes severe
iridocyclitis
See the sutures made for sac
excision
15.
16.
17. Irregular ulcer with thick greenish mucopurulent
exudate and ground glass appearance of surrounding
cornea (mushy/soupy stroma)
Presence of hypopyon
Rapid course – liquefactive necrosis, Descemetocoele
and perforation in 1 or 2 days
Most common pathogen in bacterial keratitis
associated with contact lens wear
18. This is a commensal organism present on the skin and
conjunctiva
Opportunistic infection
Usually causes secondary infection on HSV keratitis, or
on bullous keratopathy
Here the ulcer is on a
leucoma
19. Usually uniocular, mild, paracentral or perilimbal
Central grey infiltrate – ulcer with grey membranous
base
Second area of infiltration around it in the deep layers
of stroma with clear area in between
Infiltrated margin lacking and remaining cornea
relatively clear
20.
21. Commonest cause is Streptococcus viridans
Other etiologic agents: like
Staph. epidermidis, Pseudomonas, Mycobacteria,
Enterococci , Strep. pneumoniae , Peptostreptococcus
and Haemophilus also can rarely cause crystalline
keratopathy
Serratia marcescens also will give raise to satellite
lesions
22. Corynebacterium also can cause ulcer in preexisting
corneal lesions
Bacillus species will cause a rapidly progressing ulcer.
There will be a ring infiltrate remote from the site of
injury
Enterobacteriaceae will give raise to a shallow ulcer
with grayish white pleomorphic suppuration opaque
stroma and ring infiltrates -> ->
23. When you see an ulcer the following tests must done to
find the causative organism
Smear
KOH suspension
Culture
Detection of antigens, antibodies and endotoxins
Immunoglobulins
PCR
Confocal microscopy – not possible to see bacteriae as
they are only 0.5 microns in size
24. Apply topical anesthetic and wait for 3 – 5 mins for the
anesthetic to drain off
Remove the purulent material with a cotton swab and
discord
Use a Kimura’s spatula or a surgical blade to take the
sample. This is preferably done under a slit lamp. The
spatula can be sterilized with flame or 70% alcohol.
Contamination by eye lashes is avoided by using a
speculum
Immediate transfer needed due to small sample
25. Gram stain: for bacteria, yeasts, cysts of Acanthamoeba.
Can detect 60 – 70% of bacteriae. Fungal hyphae are
Gram negative or faintly stained walls with unstained
protoplasm
Giemsa: viral and Chlamydia inclusion bodies,
polymorphs and mononuclear cells besides the above
microbes
Ziehl-Neilson: Mycobacteria and Nocardia
Acridine orange: bacteria, fungi and Acanthamoeba
cysts
26.
27. Blood agar: for aerobic bacteriae and fungi esp.
Fusarium
Chocolate agar: Haemophilus, Neissaria and Moraxella
Sabouraud’s dextrose agar: fungus
Thioglycollate broth: both aerobic and anaerobic
Non nutrient agar with E. coli – Acanthamoeba
Thayer Martin agar: to isolate Neisseria
Brain heart infusion: filamentous fungi and Yeast
Lowenstein Jenson for Mycobacteria
28. Not satisfactory because of
Small sample
Prior antibiotic use
Many organisms are difficult to grow – Streptococci and
Propionibacterium
Polymicrobial keratitis can occur. It is difficult to
differentiate this from contamination
So while specificity is satisfactory sensitivity is poor
29. Elisa for detecting different antigens
Serological tests for IgG and IgM to detect viruses and
Microsporidia
Limuluslysate test: to detect endotoxins
Eubacterial PCR is done for all bacteriae
30. A DNA sequence determination is coupled with
bioinformatic analysis to detect matches between the
sample and a data base of reference genome sequence.
Rapid and highly accurate identification is possible
31. Aim of the treatment
To reduce the number of organisms as much and as
quickly as possible
To reduce the detrimental changes to the cornea caused
by the inflammation
32. Atropine eye drops are given to cause dilatation and
cycloplegia. This will reduce pain as ciliary spasm which
is the cause for the pain is relieved
Dilatation will break any synechiae and also prevent
further synechiae from forming
Atropine reduces the tear secretion and there by
increases the lysozomal content of the tears
It also separates the corneal lamellae and helps in
penetration of the drops applied
33.
34. If chronic dacryocystitis is present sac excision has to
be done
As diabetes may predispose to infection and delay
healing, this must be checked for
History must be taken regarding use of
immunodepressants and immunosuppression
35. Broad spectrum fortified antibiotic drops like
Gentamycin and Tobramycin for gram negative
organisms
Cefuroxime 500 mg in 2 ml if mixed with 8 ml of tear
substitute will give a fortified i.e. 50 mg in one ml
solution
Loading dose for the first half an hour or so and then
every hour initially
Once healing starts it can be tapered a little but not like
steroids as tapering might cause resistance
36. Has a broad spectrum – even against penicillin and
methicillin resistant bacteriae
Acts against anaerobes and atypical mycobacteriae
Has a higher solubility than the earlier antibiotics
Minimum concentration needed is low
It is bactericidal
Toxicity and allergenicity are low
37. Moxifloxacin is less active against Pseudomonas but
more active against Mycoplasma than Gatifloxacin. It is
less likely to give raise to resistance as two mutations
are needed. Moxifloxacin is self preserved and hence
preservatives are not needed
Since it reaches a higher concentration in the anterior
chamber development of mutation are prevented
Gatifloxacin acts against even Chlamydia and
Mycoplasma
38. Recommended drugs Alternative drugs
No organism Cefuroxime +
Tobramycin
or
Ciprofloxacin
Bacitracin
Gentamicin
Ofloxacin
Gram positive cocci Cefuroxime Bacitracin
Vancomycin +
Tobramycin
Gram negative
cocci
Cefuroxime Ciprofloxacin
Fortified Ceftriaxone
Gram negative
bacilli
Tobramycin
or
Ciprofloxacin
Gentamicin
Ofloxacin
Gram negative
diplobacilli
(Moraxella sp.)
Cefuroxime
or
Ciprofloxacin
Fortified Ceftriaxone
Ofloxacin
43. Symptoms will be less
Congestion will be less
The ulcer will stop progressing
The edges will become rounded
Hypopyon will disappear
The cornea around the ulcer will become clearer as the
edema comes down
44. Compliance must be checked
Change the antibiotics if it is different as per the culture
report
It must be remembered that with the small sample we get
with ulcers the results may not be accurate
Resistance to even fluoroquinolones are developing
Decision regarding therapeutic keratoplasty must be
taken before the ulcer reaches the peripheral cornea
45. Even when an ulcer heals a scar is produced which will
cause defective vision
A small peripheral scar may not affect vision .
If the scar is central mechanical obstruction to vision is
caused.
A nebular opacity or a peripheral opacity especially one
with iris adherence can cause astigmatism and affect
vision
46.
47.
48.
49.
50. An ulcer may perforate as the stroma dissolves due to
infection and by the action of neutrophils
If the perforation is in the periphery the iris plugs the
leak and the ulcer may heal with an adherent leucoma
If the perforation is in the center a fistula will form. When
this ulcer heals an anterior polar cataract may form
Sometimes if a small ulcer perforates it may help in
healing as it acts like a paracentesis
51. Before the ulcer perforates the Descemet’s membrane
will with stand for some time as it is elastic. This will
cause the membrane to bulge forward giving raise to
Descemetocoele
At this stage and for small perforations glue with either
bandage or bandage contact lens can be used to seal the
perforation
Glue has a mild antibiotic activity
It also blocks the neutrophils which causes further
necrosis
52.
53. If the ulcer progresses further it will become a total ulcer.
A therapeutic keratoplasty must be done if the ulcer is
progressing fast. A rim of normal cornea will give a
better result. So TKP should be done before the ulcer
progresses to involve the peripheral cornea
Since the eye is inflamed the chances for getting a clear
graft is poor. There is a danger of the infection occurring
in the graft also
Since large grafts will be needed rejection and glaucoma
are more common
54. If the infection involves all the layers of the eye it is
called panophthalmitis. Once this happens the eye may
have to be eviscerated. If the infection is controlled at
this stage the eye will become phthisical.