|Year : 1967 | Volume
| Issue : 1 | Page : 1-10
Mycotic keratitis (experimental & clinical study)
LP Agarwal, PK Khosla
Department of Ophthalmology, All India Institute of Medical Sciences, New Delhi, India
|Date of Web Publication||18-Jan-2008|
L P Agarwal
Department of Ophthalmology, All India Institute of Medical Sciences, New Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Agarwal L P, Khosla P K. Mycotic keratitis (experimental & clinical study). Indian J Ophthalmol 1967;15:1-10
In a tropical country like India, conjunctival and corneal conditions present one of the major ophthalmic problems.
Keratitis, apart from traumatic, is directly related to the conjunctival flora which varies according to the environment of the population. Indiscriminate local use of antibiotics and corticoids, at least in the urban regions of this country, effectively represents a change in the environment. Many workers have reported the increase of fungal infections of eye and adnexa after the advent of corticoids.-Thygeson (1953), Paulter (1955), Anderson (1959), Barsky (1959), Fine (1959), Makley (1961), Wolter (1961), Currie (1963), Puttanna et al (1963). Change in conjunctival fungal flora has been postulated by many workers (Fazakas 1953, Mitsui and Hanabusa 1955, Agarwal and Khosla 1963) which they think is intimately connected with corneal ulceration.
Recently we have seen some cases of corneal ulcers with a clinical picture quite different from those described in the literature. These ulcers also failed to respond to usual antibiotic and supportive therapy, but progressed relentlessly and either ended in deep lamellar keratoplasty to save the eye or in blindness. In view of this we undertook to explore the experimental and clinical aspects of mycotic ulcers.
| Material and Methods|| |
The study has been divided in three parts
A. Conjunctival flora.
B. Experimental mycotic keratitis.
C. Clinical cases of mycotic keratitis.
A. Conjunctival flora
(i) 100 cases were selected from the refraction unit for conjunctival swab examination. The following criteria were employed in the selection.
(a) Not suffering from conjunctival, corneal or sac infection.
(b) No history of use of antibiotics or corticoids in the eye for at least six months before study. Smear and culture examination was done for bacteria and fungi.
(ii) 10 human volunteers out of the above were given hydrocortisone Ointment l% to be put regularly three times a day for one month. Care was taken to select a volunteer about whom we were sure that he will use the drug regularly. At the end of this period conjunctival swab examination was undertaken.
[Table - 1] shows the type of conjunctival organisms isolated from normal persons of rural and urban areas. 20% cases showed no growth, while many showed the isolation of more than one organism. [Table - 2] shows the growth of flora before and after treatment with Hydrocortisone ointment for one month.
The usual per cent of positive cultures of fungi from normal conjunctiva are 70% (Hammake 1960) 18.5% (Mitsui 1955) and 24.3% (Fazakas 1935). According to Hammake (1960) more positive results are from rural areas, but in our series most of them were isolated from urban cases. This difference seems to be due to indiscriminate prescription of corticoid and antibiotic ointments for eye diseases, to urban population to whom such medical aid is available. Mitsui (1955) showed an increase in the fungal culture from 18.5% to 67% in cases where topical cortisone was administered. He also showed appearance of fungus in 50% cases which showed no fungus before treatment showing a definite increase or appearance of fungi after local corticoid therapy. Our findings are in close agreement with those of Mitsui (1955) and it seems that cortisone suppresses the bacterial flora and allows the fungi to grow.
Our studies on human volunteers show the appearance of fungi in 2 of 10 volunteers who had sterile conjunctival sacs. These fully support the contention that there has been a real increase in the incidence of the fungus flora of the conjunctival sac and infections of the cornea.
Preparation of Suspension for inoculation in Experimental groups:
Aspergillus fumigatus and Candida albicans isolated from normal conjunctival sacs were grown on Sabovraud's medium. Aspergillus terreus was obtained from a case of proptosis secondary to mycotic granuloma of maxillary antrum (Agarwal et al 1962). When there was profuse growth, a gross suspension in normal saline was made. Staphylococcus aureus grown on blood agar was used. A suspension of the organisms was made in normal saline conforming to Naphelometer tube 3 i.e. 900 million organisms per C.C.
Intracorneal injections of 0.1 c.c. of suspension was given in the left eye by the technique of Ley (1956), the right eye receiving similarly 0.1 c.c. sterile normal saline as a control. 1-mega unit penicillin dissolved in I c.c. normal saline was given sub-conjunctivally daily for a week in group III while group IV in addition to penicillin received 12.5 mgm hydrocortisone in 0.5 c.c. suspension on alternate days for a week.
The production of ulcers, presence of hypopyon, presence of slough, ciliary congestion, vascularization, iritis and recovery of pathogens were observed.
B. Experimental Mycotic Keratitis
45 albino rabbits (approx. 3 lbs. weight) were divided into groups as follows:
Group 1: Intra-corneal injection of fungi without any treatment- 15 rabbits (5 each for Aspergillus terreus, Aspergillus fumigatus and Candida albicans)
Group II: Intra corneal injection of fungi and pencicillin sensitive coagulase positive Staphylococcus aureus without any treatment- 10 rabbits (5 each for Aspergillus fumigatus and Candida albicans).
Group III: Intracorneal injection of fungi and penicillin sensitive coagulase positive Staphylococcus aureus treated with penicillin-10 rabbits (5 each for Aspergillus fumigatus and Candida abicans).
Group IV: Intra-corneal injection of fungi and penicillin sensitive coagulase positive Staphylococcus aureus treated with penicillin and corticosteroids-10 rabbits (5 each for Aspergillus fumigatus and Candida albicans).
The clinical picture produced by Aspergillus fumigatus and Candida albicans was not very different while Aspergillus terreus produced a severer picture always showing mycotic corneal ulcer associated with slough, iritis and hypopyon. The wheal raised by the intracorneal injection remained for about 2 days after which the epithelium broke down resulting in ulceration (2-6 days) in 4 out of 10 cases. Mild conjunctival congestion and discharge was present. Vascularization was absent in all the cases and hypopyon was present in 2 cases (1 each of 5 rabbits). Organisms could be recultured from all the cases showing ulceration. From the observations recorded it would be evident that fungi when given intracorneally are capable of producing corneal ulcers. Group I experiments show that non-pathogenic fungi (those isolated from normal conjunctival sacs) may sometimes produce corneal ulcers in favourable circumstances, but pathogenic fungus (from a case of orbital granuloma) always produced a corneal ulcer and these showed no vascularization. These findings do not support Conant (1954) who found that only pathogenic fungi produce corneal ulceration and also contradict Ley (1956) and Montana (1958) that corneal ulceration can be produced in each case with non-pathogenic fungi. The absence of hypopyon in most of our experiments with nonpathogenic fungi differs from the findings of Barsky (1959) and Byers (1960) that fungi aways produce a dense purulent keratitis and hypopyon. Stern and Kulvin (1950) suggested that in some instances a plaque consisting of mycelial threads mixed with necrotic corneal fibres is cast off quite easily and the ulcer heals rapidly. In our series, although the lesion produced by the fungi was mild, the fungus could be recultured from the ulcer margin which shows that all the fungal mass is not cast off and the treatment of choice is excision of the ulcer area including its margins. This is also supported by the clinical case (No. 6) where fungus was only cultured from the margins of the ulcer.
All the rabbits in this group developed sloughing corneal ulcer between 3-7 days with marked conjunctival congestion, ciliary congestion and discharge. Hypopyon was more marked than seen in the first group. Culture from the hypopyon was sterile. An important finding was the early vascularization of the cornea which probably tried to contain the ulceration. The lesion was progressive and ultimately all these eyes were lost. Staphylococcus aureus was recovered from all of them but the fungus could only be re-cultured from seven eyes. When the fungus is given along with pathogenic bacteria, a severe sloughing ulcer with hypopyon is the result. The ulcers showed vascularization which was thought to be due to addition of bacteria in this group. We, however, do not support the contention of Fazakas (1950) that in some cases, no keratitic reaction may appear due to antibiosis between the fungi and the bacteria.
The clinical picture in this group was deceptive. The clinical course was severer than in group I while milder as compared to group II. All eyes showed corneal ulceration, conjunctival congestion and ciliary congestion. Hypopyon and iritis developed in Aspergillus infection. There was some corneal vascularization evidenced by dilatation of the limbal capillaries although the ulcer area was not invaded. The fungus was recovered from all ulcers but no Staphylococcus could be cultured from 8 of them. The hypopyon was sterile in most eyes, but fungus was recovered from two.
Staphylococcus seems to activate the fungi which in turn produce severer keratitis-this may be termed as a form of symbiosis and may support Fazakas (1950) and Paulter (1955). In later stages the Staphylococcus is removed from the scene by intensive penicillin therapy, the activated fungus grows unfettered producing keratitis which is always associated with hypopyon.
This group showed the severest clinical picture of all. Within 3-5 days of the intra-lamellar corneal injection, the epithelium broke down giving rise to corneal ulceration in all the cases. Although the conjunctival and ciliary congestion was not very much marked, yet there was profuse discharge so that the eyelashes were matted together. The slough increased considerably and nearly all cases showed marked posterior corneal abscesses. Severe iritis and hypopyon was present in all the cases. There was no attempt at vascularization of the cornea. The clinical course was progressive, the ulcers perforated rapidly and eyes were lost. Fungus was isolated from all the eyes and Staphylococcus aureus from one. The clinical course in both the fungi was similar.
The clinical course in group IV was very violent. The only addition from group III is cortisone which seems to increase the virulence of activated fungus as already described. This confirms the belief that corticoids are generally contra-indicated in cases of corneal ulcers specially if fungal ulcer is suspected.
Our experimental work has enabled us to record the clinical picture of corneal ulcer produced by fungi and bacteria with or without treatment with antibiotics and corticoids. The ulcer is usually produced by a pathogenic or a potentially pathogenic fungus. Corticoids probably activate the non-pathogenic fungi and potentiate the pathogenic ones. In pure fungal ulcers the inflammatory reaction is mild and lesion may become static though it is usually progressive. There is infilteration and oedema of the margins with colliquative necrosis forming a sharply defined greyish ulcer with overhanging oedematous margin. The central area becomes laminated. There is mild conjunctival and ciliary congestion. The eye looks surprisingly quiet with hardly any vascularization. Iritis and hypopyon are present in most cases especially so if the fungus is pathogenic and if the infection is a mixed bacterial and fungal one. In the latter case vascularization is the rule. The antibiotics and corticoids have an adverse effect on the course of fungal ulcers leading even to perforation. Simple fungal ulcers even without treatment are usually static, but secondary infection leads to perforation and pan-ophthalmitis.
C. Clinical cases:
Case No. 1 R., 20 years, male, clerk had history of sore of left eye for 2 months for which the patient had been using various indigenous and modern medicines (including corticoid ointment) with occasional relief. There was intense lacrimation and photophobia for the last 7 days. A peripheral sloughing corneal ulcer 2 mm x 2 mm round was seen with little infiltration and no vascularization. No hypopyon was seen. Culture yielded Candida albicans and no bacterial growth.
Case No. 2: R. K., 26 years, female, housewife, had history of occasional attacks of redness both eyes with sneezing and nasal discharge for the last 3 months. She has been using cortisone ointment off and on in the eyes for redness. She complained of photophobia in L.E. 7 days ago while pain and lacrimation started only 2 days back. A horizontally oval, 3 mm x 1 mm central, sloughing corneal ulcer with infiltration and no vascularization was seen. 2 mm hypopyon was present at the time of examination with marked iritis. Culture yielded Candida albicans and no bacterial growth.
Case No. 3 S.D., 25 years, female, housewife, had a history of injury 15 days back with a blunt object over the lids on right side. There was redness for which she used achromycin ointment with relief. Ten days back she got redness, pain and photophobia with foreign body sensation in the eye for which again she used the same ointment. A central corneal ulcer 3 mm x 2 mm round, was seen with marked infiltration and vascularization of the cornea, the vascularization not reaching the ulcer. A 3 mm hypopyon with marked iritis was seen. Culture yielded Aspergillus fumigatus and Staphylococcus aureus coaglase positive insensitive to achromycin.
Case No. 4. K., 23 years, male, shop keeper, came with the complaints of redness, irritation, swellings of the lids and mucopurulent discharge in the right eye with pain and photophobia of 4 days duration. History of using some indigenous medicines was present. A central sloughing corneal ulcer 3 mm x 3 mm round with marked infiltration and conjunctival congestion was seen. A 2 mm hypopyon with marked iritis was also present. Culture yielded Candida krusie and no bacteria.
Case No. 5. B. V.S., 40 years, male, farmer, gave history of foreign body sensation in right eye of 4 days duration with watering, redness and photophobia. History of rubbing the eyes violently was present. No history of any medication locally. A 3 mm x 3 mm sloughing corneal ulcer in the lower periphery with marked infiltration, iritis and 1 mm hypopyon was seen. No vascularization was evident. Culture yielded Aspergillus fumigatus. Cultures for bacteria were repeatedly negative.
Case No. 6. K.K., 40 years, female, housewife, gave history of feeling of foreign body in the eye 15 days back and came with the complaints of redness, watering, photophobia and central white opacity. On examination 4 mm x 4 mm central sloughing corneal ulcer was seen with chemosed conjunctiva, profuse mucopurulent discharge and 3 mm hypopyon. The usual ulcer regime was instituted which gave no relief. Repeated culture examination showed no growth but later on when scrapings from the margins of the ulcer were directly inoculated in Sabouraud's medium, Fusarium was grown.
The following fungi were isolated from the clinical cases of corneal ulcers as described:
(i) Candida albicans ... 2
(ii) Aspergillus Fumigatus 2
(iii) Candida krusie ... 1
(iv) Fusarium ... 1
It is important to note that 3 cases (case 1, 2, 4) gave a positive history of medication which was used by the general practitioners for irritation and redness of the eye. Appearance of pain and photophobia during the course of treatment were the factors which led the patients to come to the hospital. The ulcers showed whitish slough and complete lack of vascularization of cornea. Small hypopyon was present in two cases. The picture resembled that of experimental group I, but was severer, probably due to the fact that cortisone had been used which enhanced the pathogenicity of the fungi. Case No. 5 is probably an example of simple fungal ulcer by Aspergillus fumigatus where no other incriminating factor was present. Case No. 3 gives a history of injury over the lids only which may not have any relation to the causation. From the history of foreign body sensation, it may be concluded that the ulceration occured in the usual way. The usage of antibiotic ointment has probably activated the fungus, as in Group III, and the clinical picture quite resembled it. Case No. 6 is important from the fact that a lesson can be taken from this. It is suggested that scrapings from the margins of the ulcer should be inoculated in Sabouraud's medium for isolating the fungus in a case which is not responding to usual ulcer regime and presents the clinical features of a fungal ulcer as described earlier.
| Summary and Conclusions|| |
A. Conjunctival flora-
(i) Fungi were positive in 6% of normal conjunctival swab cultures.
(ii) The incidence of positive fungal cultures is more in urban cases than in rural cases which may be related to indiscriminate use of corticoids for minor eye complaints.
(iii) Long continued use of corticoids locally favours the propagation of fungi in normal conjuntival sacs.
B. Experimental Mycotic Keratitis
(i) Data on experimental production of mycotic corneal lesions is presented.
(ii) Corneal ulceration may be produced by non-pathogenic fungi. Those due to pathogenic fungi are more severe.
(iii) A mixed infection by fungi and pathogenic bacteria produces a severe corneal reaction and leads to vascularization of the cornea, the presence of bacteria increasing the pathogenecity of the fungus.
(iv) Corticoids further increase the virulence of the fungus.
(v) Clinical picture of corneal ulcers due to fungi alone and with bacteria is described. The effect of antibiotics and corticoids is brought out.
C. Clinical cases:
Records of 6 typical cases are reproduced.
(i) Antibiotics and corticosteroids should not be used indiscriminately in the treatment of corneal ulcers, lest they produce or potentiate a corneal ulcer.
(ii) If the clinical appearance of the ulcer is severe of a sloughing type with or without hypopyon and no vascularization, a possibility of fungus infection should be kept in mind. Scraping should be taken from the edge of the ulcer and planted on suitable media for detection and isolation of fungi.
| References|| |
Agarwal, L. P., Malik, S. R. K., Mohan, M., and Mahopatra, L. N. (1962), Brit. J. Ophthal., 46, 559.
Agarwal. L. P., and Khosla, P. K. (1963), Orient. A. Ophthal. 1, 145.
Anderson, B., Roberts, S., Jr. Gonzalez, C., and Chick, E. E. (1959), A.M.A. Arch. Ophthal., 62, 169.
Barsky, D. (1959), Ibid., 61, 547.
Byers, J. L., Holland, M. G. and Allen, J. H. (1960) Amer. J. Ophthal., 49, 267.
Conant, M. R., Smith, D. T., Baker, R. D., Callaway, J. L. and Martin, D. S. (1954). "Manual of Clinical Mycology." 2nd ed. Saunders, Philadelphia.
Currie, D. (1963), A. M. A. Arch. Ophthal.. 70, 335.
Fazakas, A. (1935), Ophthalmologica, 126, 91.
Fazakas, S. (1950), Ibid., 120, 418.
Fine, B. (1959), Brit. J. Ophthal. 43, 753.
Hammeke, J. C., Ellis, P. P. (1960), Amer. J. Ophthal., 49, 1147.
Ley. A. P. (1956), Amer. J. Ophthal.. 42, p. 59.
- and Sanders, T. E. (1956), A.M.A. Arch. Ophthal.. 56, 257.
Makley, T, (1961), A.M.A. Arch. Ophthal., 66, 456.
Mitsui. Y., and Hanabusa, J. (1955), Brit. J. Ophthal., 39, 244.
Montana, J. A. and Sery. T. W. (1958), A.M.A. Arch. Ophthal. 60, 1.
Pautler, E. E. Roberts, R. W. and Beamer, P. R. (1955), A.M.A. Arch. Ophthal.. 53, 385.
Puttanna, S. T., Rao, G. R., Sirsi, M. & Swaminathan, M. (1963), Orient. Arch. Ophthal. 1, 191.
Stern. S. G., and Kulvin. M. M. (1950), Amer. J. Ophthal.. 33. 111.
Thygeson, P. Hogan, M. J., and Kimura. S. J. (1953), Trans. Amer. Acad. Ophthal. Otolaryng. 57, 64.
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8], [Figure - 9], [Figure - 10], [Figure - 11], [Figure - 12], [Figure - 13]
[Table - 1], [Table - 2]