Corneal scraping is an important diagnostic tool for infectious keratitis that allows identification of the infectious agent, such as bacteria, fungi, or Acanthamoeba. Identification of the agent guides selection of targeted antibiotic or antifungal treatment and improves recovery chances. Corneal scraping should be performed before starting antibiotic therapy, on central or deep ulcers, or in young or immunosuppressed patients. It has a high rate of positive results and identification of agents including Staphylococcus, Pseudomonas, Candida, and Fusarium. Targeted topical or systemic therapy is selected based on agent identified, with close follow-up of patients required.

1. THE ROLE OF CORNEAL SCRAPINGTHE ROLE OF CORNEAL SCRAPING
IN THE MANAGEMENT OFIN THE MANAGEMENT OF
INFECTIOUS KERATITISINFECTIOUS KERATITIS
Dr. Luca AvoniDr. Luca Avoni
Dr. Andrea VoliniaDr. Andrea Volinia
““Santa Maria delle Croci” Hospital, RavennaSanta Maria delle Croci” Hospital, Ravenna
Department of OphthalmologyDepartment of Ophthalmology
Head of Department: Dr. Domenico D’EliseoHead of Department: Dr. Domenico D’Eliseo

2. INFECTIOUS ETIOLOGIESINFECTIOUS ETIOLOGIES
• Bacterial KeratitisBacterial Keratitis
• Herpes KeratitisHerpes Keratitis • Fungal KeratitisFungal Keratitis
• AcanthamoebaAcanthamoeba
KeratitisKeratitis

3. BACTERIAL KERATITISBACTERIAL KERATITIS
MOST COMMON INFECTIOUS AGENTS
Gram – 10-50%
• Pseudomonas aeruginosa 5-45%
S. marcescens 1-8%
P. mirabilis 1-5%
Others 1-10%
• Coccobacillus
H. influenzae 1-6%
Moraxella 1-5%
• Neisseria 1%
Gram + 50-90%
• Staphylococcus aureus 11-30%
Staphylococcus coagulasi – 5-40%
Staphylococcus pneumoniae 5-25%
Staphylococcus viridans 1-15%
• Corynebacterium 1-5%
Propionibacterium 1-5%
Mycobacterium 1-2%

4. FUNGAL KERATITISFUNGAL KERATITIS
 Yeasts:Yeasts: CandidaCandida
( C. albicans, C. tropicalis, C. parapsilosis, C. famata)( C. albicans, C. tropicalis, C. parapsilosis, C. famata)
CryptococcusCryptococcus
 Filamentous Septate Fungi:Filamentous Septate Fungi:
 Non-pigmentedNon-pigmented ( Fusarium, Aspergillus, Acremonium,( Fusarium, Aspergillus, Acremonium,
Paecilomyces, Penicillium, Pseudallescheria )Paecilomyces, Penicillium, Pseudallescheria )
 PigmentedPigmented ( Curvularia, Alternaria, Phialora, Bipolaris,( Curvularia, Alternaria, Phialora, Bipolaris,
Exserohilum, Cladosporium )Exserohilum, Cladosporium )
 Dimorphic fungiDimorphic fungi::
Blastomyces, Coccidioides, Histoplasma, SporothrixBlastomyces, Coccidioides, Histoplasma, Sporothrix

5. DIAGNOSIS WITH CORNEALDIAGNOSIS WITH CORNEAL
SCRAPINGSCRAPING
WHEN:
 Central Corneal Ulcer
 Corneal Ulcer of great proportions (thickness > 6
mm) or deep (which affects more than 50% of
corneal thickness)
 Young patients or immunosuppressed patients
If possible before starting antibiotic therapy!

6. Our experience: 44 corneal scrapings in 2 years…
• Stafilococco species
• Enterococcus faecalis
• Actinomyces naeslundii
• Pseudomonas aeruginosa
• Moraxella catarrhalis
• Candida species
• Fusarium species
• Aspergillo fumigatus
• Acanthamoeba
Gram positive
bacteria
(n = 24 ; 54,63%)
Gram negative
bacteria
(n = 6 ; 13,42%)
Fungi
(n =12 ; 27,41%)
{
{
(n =2 ; 4,54%)
{
All corneal scrapings have been positive!!!

7. Corneal ScrapingCorneal Scraping
 If possible, suspend the use of antimicrobial agents for 24 hours prior to sampling
 Apply anaesthetic drops that do not contain preservative
 Corneal scraping must be performe at the edge of corneal lesion
 If fungal infection is suspected, it is preferable to sample material from the deeper
stromal layer of the cornea
 Take a sample for Gram positive and Gram negative bacteria and an other for fungi
 If it is possible, susceptibility testing must be performe on contact lens, too
 To take the sample must to use a sterile and thin spatula
 Before to performe the corneal scraping, we must remove all debris which hold
corneal ulcer

8. PROBLEMS IN THE MANAGEMENT OFPROBLEMS IN THE MANAGEMENT OF
INFECTIOUS KERATITISINFECTIOUS KERATITIS
 11 Choice of eye drops to useChoice of eye drops to use
 2 Routes and method of administration2 Routes and method of administration
 3 Follow-up of patients3 Follow-up of patients

9. TREATMENTTREATMENT
Features of eye drops:Features of eye drops:
 Broad-spectrum of activityBroad-spectrum of activity
 Failure to develop resistant micro-organismsFailure to develop resistant micro-organisms
 Good intraocular penetrationGood intraocular penetration
 Absence of local and systemic toxicityAbsence of local and systemic toxicity

10. FORTIFIED EYE DROPSFORTIFIED EYE DROPS
 To use after the results of corneal scrapingTo use after the results of corneal scraping
 They should be retained in the fridge (3°-7°) and must to useThey should be retained in the fridge (3°-7°) and must to use
within 7 days after preparationwithin 7 days after preparation
 At these concentrations, eye drops may have effects on theAt these concentrations, eye drops may have effects on the
ocular surface, so these patients should be seen frequentlyocular surface, so these patients should be seen frequently

11. ANTIBACTERIAL AGENTSANTIBACTERIAL AGENTS
Cefazolina* eye drops 5% (50mg/ml): cephalosporin with
broad spectrum against gram-positive bacteria and minimal
toxicity
Cephalosporin is not commercially available, but it isCephalosporin is not commercially available, but it is
prepared by our hospital pharmacyprepared by our hospital pharmacy
CefazolinaCefazolina

12. ANTIFUNGAL DRUGSANTIFUNGAL DRUGS
CLASSIFICATIONCLASSIFICATION
POLYENESPOLYENES
LARGELARGE
POLYENESPOLYENES::
Amphotericin BAmphotericin B
SMALLSMALL
POLYENES:POLYENES:
NatamycinNatamycin
AZOLESAZOLES
IMIDAZOLES:IMIDAZOLES:
Miconazole,Miconazole,
KetoconazoleKetoconazole
ClotrimazoleClotrimazole
TRIAZOLES:TRIAZOLES:
FluconazoleFluconazole
ItraconazoleItraconazole
VoriconazoleVoriconazole

13. TOPICAL (0,2 %): penetrates well into the corneaTOPICAL (0,2 %): penetrates well into the cornea
SYSTEMIC: good absorption following taking oral,SYSTEMIC: good absorption following taking oral,
few side effects, penetrates well into the corneafew side effects, penetrates well into the cornea
FluconazoleFluconazole
TRIAZOLESTRIAZOLES

14. TOPICAL (2 %): well tolerated, penetrates well intoTOPICAL (2 %): well tolerated, penetrates well into
the cornea and into anterior chamberthe cornea and into anterior chamber
SYSTEMIC: high bio-availability (96%), penetratesSYSTEMIC: high bio-availability (96%), penetrates
well into intraocular tissueswell into intraocular tissues
VoriconazoleVoriconazole
TRIAZOLESTRIAZOLES

15. POLYENESPOLYENES
TOPICALTOPICAL (0.15%): may penetrate in vitreous humour and(0.15%): may penetrate in vitreous humour and
corneal scraping may facilitate the penetration in the corneacorneal scraping may facilitate the penetration in the cornea
SYSTEMICSYSTEMIC :: contraindicated in infectious keratitis for itscontraindicated in infectious keratitis for its
systemic toxicity and its poor penetration in intraocular tissuessystemic toxicity and its poor penetration in intraocular tissues
Amphotericin BAmphotericin B

16. POLYENESPOLYENES
NatamycinNatamycin
TOPICAL (5%)TOPICAL (5%): especially effective against Aspergillus and: especially effective against Aspergillus and
Fusarium corneal infectious keratitis, but also against CandidaFusarium corneal infectious keratitis, but also against Candida
SYSTEMICSYSTEMIC :: contraindicated in infectious keratitis for itscontraindicated in infectious keratitis for its
systemic toxicity and its poor penetration in intraocular tissuessystemic toxicity and its poor penetration in intraocular tissues
Only antifungal commercially available for topicalOnly antifungal commercially available for topical
administration in US, but not available in Italy!!administration in US, but not available in Italy!!

17. DOSAGE OF MAIN ANTIFUNGALDOSAGE OF MAIN ANTIFUNGAL
AGENTSAGENTS
AGENT TOPICAL SUBCONJUNTIVAL* SYSTEMIC*
Natamycin 50 mg/ml (5%) _ _
Amphotericin B
0,5 - 2,5 mg/ml
(0,05 - 0,25%)
_ _
Miconazole 10 mg/ml (1%) 5 mg 30 mg/kg/day (IV)
Fluconazole 2 mg/ml (0,2%) 1 mg 200-400 mg/day (oral)
Voriconazole 20 mg/ml (2%) _ 400-600 mg/day (oral)
*Reserved for severe keratitis
The Cornea II Ed. - Kaufman et al

18. CORTICOSTEROIDCORTICOSTEROID
 Contraindicated in the early treatment of fungal keratitisContraindicated in the early treatment of fungal keratitis
 Promote the growth of yeasts and filamentous fungiPromote the growth of yeasts and filamentous fungi
 Suppress neutrophil’s capacity to destroy hyphae and sporesSuppress neutrophil’s capacity to destroy hyphae and spores
 Can be used to reduce the inflammation, after the infection is goneCan be used to reduce the inflammation, after the infection is gone

19. OUR RESULTSOUR RESULTS

20. TAKE HOME MESSAGETAKE HOME MESSAGE
 Wherever possible, microbiological investigations should beWherever possible, microbiological investigations should be
performed in all patients presenting with suspectedperformed in all patients presenting with suspected
infectious keratitisinfectious keratitis
 Once the organism has been identified by culture, theOnce the organism has been identified by culture, the
therapeutic regimen may be modified to improve thetherapeutic regimen may be modified to improve the
chances of recoverychances of recovery
 Therapeutic surgery may be required for clinical cases ofTherapeutic surgery may be required for clinical cases of
infectious keratitis that respond poorly to medical therapyinfectious keratitis that respond poorly to medical therapy