Oculomycosis modified

occulomycosis- infections of eye and its related structures by various fungal agents.
3 broad category
1.keratomycosis
2.fungal endophthalmitis
3.fungal infections of occular adnexa

1. OCULOMYCOSIS BY SENI MB Msc . MLT MICROBIOLOGY

2. OCULOMYCOSIS Fungal disease of eye denoting manifestations related to external and internal structures of the eyeball. To be more precise Keratomycosis - fungal infection of cornea Endophthalmitis - fungal inf. When posterior chamber involved.

3. Clinical descriptions of fungal inf. Of eye and adnexa are divided into 3 broad categories . Keratomycosis Fungal Endophthalmitis Fungal inf. Of Ocular Adnexa

4. KERATOMYCOSIS Defined as invasive infection of corneal stroma caused by variety of fungal spp. Other names- mycotic keratitis or simply fungal keratitis or fungal corneal ulcer. [ It is exclusevely inf. Of cornea, not to the keratinised layers of skin.] Majority cases occur amoung agricultural workers following corneal trauma with vegetative matter contaminated by the fungi. These are opperchunistic orgm – when natural defences of eye abrogated , topical corticosteroid use, predisposing factors,

5. HISTORY Leber described fungal keratitis caused by A spergillus spp for the first time in 1879 in germany . Upto 1951 only 63 cases were reported bez of the awareness of corticosteroid use . And calcofluor white stain in mid 1980 s as diagnostic tool . Considered as a neglected tropical disease.

6. EPIDEMIOLOGY Causative fungi of keratomycosis are ubiquitous orgm . Responsible for 6- 53% of al corneal infections world wide. Resulting in visual diability , particularly in tropical countries. Due to large agrarian population and environmental factors, keratomycosis is common in india . Keratomycosis occurs with Frequently after corneal trauma by vegetative matter. Rarely following keratoplasty Also found in contact lens weares .

7. Topical use of corticosteroids and antibacterial agents for external ocuular disease. Males are commonly affected than females incidence high in middile age. In north india Aspergillus is commonest cause., south india its fusarium . In india 113 cases per 100000 of population

8. MYCOLOGY Causative agents of keratomycosis is long and varied. There is substantial fungal flora in normal eye and even greater in diseased eye. Infection substantiated by demonstration of fungal elements in debrided materials as well as culture. causative fungi belong to 70 species from 40 genera. These include hyaline or phaeoid hyphomycetes and yeast- like fungi. Majority of cases caused by Aspergillus ., Fusarium and phaeoid fungal spp.

9. Apergillus , Fusarium resposible for one- third of all traumatic infectious keratitis. A. flavus >A. fumigatus > A.niger >A. glaucus are order of freequency Phaeoid fungi are now considered as the third major group of fungi after Aspergillus and Fusarium . In india Aspergillus genus is the commonest fungal a=gent followed by other genera. Ke ratomycosis caused by dimorphic fungi is rarely encountered in their respective area of endemicity .

10. Common agents of keratomycosis

11. PATHOGENESIS AND PATHOLOGY Keratomycosis occur due to interaction between different agent factors such as 1. invasiveness and toxigenicity of fungal strains 2. host factors 3. hypersensitivity reaction 4. underlying defects of neutrophils Predisposing factors include 1. trauma 2. administration of corticosteroids. 3. antibacterial antibiotics.

12. Fungi are unable to penetrate intact corneal epithelium hence trauma , with organic matter facilitate penetration of fungal element into corneal stroma . Fungal hyphae invade from corneal ulcer bed to stroma Coagulation necrosis associated with loss of keratocytes anmd edematous changes of collagen fibers occur. Satellite lesions are formed around main site of involvement.

13. Late in the course of disease process, hyphae may be seen to penetrate Descemet’s membrane, encased in dense neutrophilic exudate of Hypopyon .

14. Leucocyte infiltrate with feathery borders in corneal stroma is characteristic of fungal keratitis.

15. Fusarium is more aggressive and less responsive to treatment than Aspergillus . Phaeoid fungi are low virullance but produce protracted infections. Stronal keratitis caused by candida spp may be more localised in contrast to filamentous fungi and have collar- button apperance .

16. CLINICAL FEATURES PATIENT FEEL Gritty, foreign body sensation in eye, burning and stinging along with ocular discomfort. After few days pain becomes intense and associated with photophobia. Usually presented unilatarally eye becomes red and vision is blurred. Slit lamp examination- breach in corneal epithelium and bowman’s membrane. Classical signs are central , shaggy- edged ulcers with satellite lesions, marked hypopyon , and endothelial plaque. Surrounding corneal stroma edematous.

17. Candida albicans – more localised , small ulceration with expanding but discreate stromal infiltration. Contact lens weares – candida spp and cryptococcus laurentii (1 case). Curvularia - mild and not associated with much corneal sloughing . Presence of pigmented infiltrate – diagnostic tool for phaeoid fungus . Filamentous fungi- severe ocular reaction and folds in Descemet’s membranehypha margin extend beyond edge of ulcer.

18. Elevated slough firm in consistancy:endothelial plaques of whitish material and presence of an immune ring Wessely’s ring along with corneal abscesses. The satalite lesion around central wound are called ‘ ring- abscesses’

19. DIFFERENTIAL DIAGNOSIS Difficult to identify from bacterial, viruses, Acanthamoeba . Dense stromal infiltrate, early commencement of hypopyon , satallite lesions suggest keratomycosis , but lab confirmation is essential.

20. LAB DIAGNOSIS Difficult to diagnose Slit lamp examination of eye Sample collection Diagnostic material harvested by experienced ophthalmologist. Scraping of cornea with no.15 Bard-parker surgical blade from the base and margins of ulcer aseptically using local anesthetics (4%xylocaine ) drops. Kimura’s platinum spatula is an alternative particularly to get material from base and borders of the ulcer. The base should be thoroughly scraped to remove all necrotic tissue. Biopsy from lesion with 4mm or larger trephine can be taken.

21. DIRECT EXAMINATION 10% KOH wet mount Examination of corneal scrapings Septate hyphae are easily visible in KOH wet film .

22. 2 . Gramstain More useful when etiological agent is a yeast although hyphal elements are also stained . 3. Fluorescent stained smears For tissue sections and cytopathologic preparation non specific flouroscent stain like calcofluor white , blankophor and Uvitex 2B are used. calcofluor white stained smears examined under fluorescent microscope and barrier filter (300-412nm) It is superior to conventional staining techniques for detection of fungi in clinical specimens particularly where no. of fungal agents scanty . Acridine orange- early diagnosis of keratomycosis . PAS and GMS- fungal identification in corneal tissues.

23. Fungal corneal ulcer showing septate hyphae in histology section

24. Fungal culture 2 sets of SDA with antibacterials but without actidione are inoculated and incubated at 25oC and 37oC over a period of 4 weeks. One set BHIA containing antibiotics and cycloheximide is incubated at 37oC for same period. Specimens also inoculated on blood agar as well. For corneal scraping- inoculated on agar plates on a special manner to differentiate the growth over inoculum from fungal contaminants found prevalent in lab, Make ‘ C’ or ‘S’ streak on plate . Fungal growth from streak ensures that the growth from inoculum .

25. All cultures are checked every day during first week Twice a week during next three weeks. Mycelial isolates are identified by their colony characteristics and microscopic morphology in LCB stained mount and finally by slide culture. Yeast isolates identified by standard tests *germ tube test * reduction of tetrazolium . * chlamydospore production on corn meal agar * urease test, sugar fermentation, assimilation etc.

26. Fusarium spp Colony- pluffy to cottony owing to extensive mycelium. Sometimes diffusable pigment is produced in the reverse. Conidiophores are singly or grouped into sporodochia , a compact mass of interwoven conidiophores( coloured red, pink, purple etc.) Macroconidia faiciform or bean – shaped. Diff. diagnosis- colletotrichum spp having bean shaped conidia. But it has setae in addition to bean shaped conidia.

27. 2. Colletotrichum species Phylum – Ascomycota Having setae in addition to bean shaped macroconidia .

28. Curvularia species Colonies- rapidly growing, floccose and brown with black reverse. Conidiophore simple bearing conidia, Conidia transversely septate and cylindrical or slightly curved with one of the central cells being largewr .

29. IMMUNODIAGNOSIS No specific test for confirmatin of keratomycosis . Diagnosis based on demonstration of the organbism in direct smear and culture confirmation. ANIMAL PATHOGENICITY Experimental animals corneal ulcer produced by interlamellar injection of fungal spore suspension in eyes of previously immunosuppressed albino and black wild rabbits.

30. TREATMENT AND PROPHYLAXIS Topical antifungal preparation are mainstay of therapy. Pimaricin ( natamycin ) as 5% suspension is used for tratment of keratomycosis . Amphotericin B , flucytosine , and nystatin lavage can be tried. Frequent drug administration for prolonged period needed for successful treatment. Penetrating keratoplasty or lamellar keratectomy for patient who are not responding to medical treatment.

31. 2. FUNGAL ENOPHTHALMITIS It’s is a suppurative inflamation of the inner occular coats and their adjacent structures with the involvement of vitreous fluid. Caused by variety of fungal agents either from external (exogenous) or internal source through hematogenous route. HISTORY Fungal endophthalmitis used to be rare entity during first half of 20 th century. In 1914 Dimmer reported choroidoscleritis presumably caused by Aspergillus fumigatus . In same yr Churchil et al found blastomycosis from vitreous of patient having systemic infection. first histologically proven case of endophthalmitis resulting from systemic candidiasis was reported by Milae in 1943.

32. EPIDEMIOLOGY Fungal endophthalmitis accounts for about 4-11% of all cases of culture- proven endophthalmitis . Usually acquired from an endogenous source via hematogenous spread. Or it may be secondary to intraocular surgery, corneal ulceration, o r even trauma. Candida spp most frequently encountered cause of both type of fungal endophthalmitis . The other fungi may be Aspergillus spp , Histoplasma capsulatum , Coccidioides immitis , B.dermatitidis , Cryptococcus spp , Sporothrix schenckii and fusarium spp.

33. PATHOGENESIS AND PATHOLOGY This clinical entity arises out an interaction between different agent factors such as Invasiveness and toxigenic nature of causative fungi. Host factors and other predisposing factors. Sustained fungemia with even saprophytic fungi may lead to endophthalmitis . Patient with exogenous endophthalmitis are usually healthy and immunocompetent . In endogenous type of endophthalmitis they are invariably found to be immunocompromised .

34. CLINICAL FEATURES Classical apperance with Progressive granulomatous uveitis, diffuse retinitis , and deep vitreous abscess. Time to make diagnosis from onset of symptoms- 3 days to 4 months during which bilateral ocular disease may cause severe morbidity.(especially debilitated ) Candida spp are most common cause of fungal endophthalmitis and may present in a similar ,manner to chronic bacterial endophthalmitis .

35. Fungal endophthalmitis is clinically of 2 types depending upon mode of infection. EXOGENOUS ENDOPHTHALMITIS ENDOGENOUS ENDOPHTHALMITIS EXOGENOUS ENDOPHTHALMITIS It occurs by introduction of organisms into eye from external source. patients do not have any immunodeficiency. This clinical entity develops after occular surgery, trauma by intaocular spread from f ungal keratitis or therapeutic keratoplasty for keratitis. Also found in found in patients taking contaminated intravenous fluids.

36. It maybe as a result of pre-existing keratitis Cataract removal followed by placement of prosthetic lens and corneal transplantation are surgical procedures associated with post operative endophthalmitis . Candida are common spp of exogenous endophthalmitis . Other spp include Aspergillus , Fusarium , Paecilomyces,Curvularia and mucormycete .

37. ENDOGENOUS ENDOPHTHALMITIS Incidence increased in 2 nd half of outgoing 20 th century bez of advent of antibiotics and indwelling catheters. Patients are generally immunocompromised . Granulomatous intraocular inflammation in patients with one or more of risk factors should raise suspicion of fungal endophthalmitis . Aspergillus is seen more in organ transplant recipients with granulocytopenia or in cardiac surgery patients as compared with candida endophthalmitis .

38. Histoplasma - ocular manifestation of histoplasmosis are rarely described at the time of initial infection. Late sequelae of subclinical H istoplasma capsulatum inf. Called Presumed Ocular Histoplasmosis Syndrome(POHS). It is common , bilateral multifocal chorioretinal scarring. The punched out chorioretinal scars , Histo spots. Candida , dimorphic fungi ( less frequently occur )

39. CHORIORETINITIS Inflamation of choroid ( thin pigmented vascular coat of eye.) and retina of eye. Cryptococcal chorioretinitis is recognized cause of permanent visual impairment. Associated with disseminated disease like meningitis . Primary choroidal involvement helps to distinguish cryptococcal choriorectinitis from that due to other opperchunistic pathogen.,(CMV, T.gondii ) On histopathological examination of choroid- granulomatous inflammation with microabscesses and giant cells centered around the capsule.

40. DIFFERNTIAL DIAGNOSIS Bacterial, viral , parasitic LAB DIAGNOSIS Detailed examination of affected eye. Difficulty to diagnose. SAMPLES Intraocular specimens(vitreous fluid). Vitreous biopsy. DIRECT EXAMINATION For demonstration of hyphae, pseudohyphae , 10%KOH Calcofluor white stain- rapid diagnosis of mycotic inf. Gramstain PAS & Giemsa - vitreous biopsy

41. FUNGAL CULTURE Material like vitreous fluid inoculated on 2 sets of SDA with antibiotics are inoculated and incubated at 25oC and 37oC for 4 weeks. 1 set of BHIA with cycloheximide and antibiotics incubate 37oC( dimorphic fungi) After culture identification procedure same used in conventional lab. IMUNODIAGNOSIS PCR Molecular typing methods. ANIMAL PATHOGENICITY The rabbit model of Candida albicans endogenous endophthalmitis .

42. TREATMENT 3 modes of treatment. Systemic administration of antifungal agents. Amphotericin B or an azole derivative. Intravitreal injection of antifungal agent, voriconazole , amphotericin B Vitrectomy (bulk infection)

43. 3. MYCOSES OF OCULAR ADNEXA Conjunctiva, eyelids, and lacrimal sac. Eyelids- Sporothrix schenkii ,(chronic ulcerative lesions) Blastomyces dermatitidis , P.brasiliensis Eyelashes- Microsporum canis , Malassezia furfur, candida spp Lacrimal duct- infection and obstruction of lacrimal duct system or dacryocystitis caused by candida spp. Acute dacryocystitis - Sporothrix braziliensis . Chronic dacryocystitis - Candida and Aspergillus spp. lab diagnosis- KOH , grams stain PAS, giemsa .

44. Histopathological section from a cyst of eyelid showing Aspergillus spp

45. References Text book of mycology jagdish chander .