|Year : 1967 | Volume
| Issue : 2 | Page : 54-57
Bacteriology of corneal ulcer with special reference to hypopyon corneal ulcer
Eye Department, Medical College, Patna, India
|Date of Web Publication||18-Jan-2008|
J N Rohatgi
Eye Department, Medical College, Patna
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Rohatgi J N. Bacteriology of corneal ulcer with special reference to hypopyon corneal ulcer. Indian J Ophthalmol 1967;15:54-7
The two important factors in the causation, progress and prognosis of corneal ulcers are (1) virulence of the organism invading the cornea and (2) the inherent resistance of corneal tissue.
This resistance is afforded by three great barriers
(1) an intact corneal epithelium, (2) the microscopic film of tears and Meibomian secretion, and (3) the knife action of the upper eyelid.
With the exception of the gonococcus and bacillus diphtheria, the normal corneal epithelium offers an efficient barrier to the entrance of micro-organisms. Therefore, unless special circumstances exist which lower the resistance of the epithelium (like vitamin A deficiency in cases of xerosis and keratomalacia) or even cause its exfoliation (like neuro-paralytic keratitis, herpes and corneal oedema), the majority of corneal ulcers (including the hypopyon corneal ulcers) are traumatic in origin and involve an abrasion of the corneal epithelium and an infection of the cornea. Trauma can also bring with it organisms from outside, like fungi and aspergillus, or it can bring in some more potent poison or toxin.
As to the virulence of micro-organ ism-Browning (1927) said "Practically all organisms found in the conjunctival sac have been known to cause hypopyon corneal ulcer. The organism most frequently found associated with hypopyon ulcer is the pneumococcus and it would appear from statistics that the pneumococcus is almost always found in cases of true ulcus serpens, though we have found organisms other than the pneumococcus in such cases.
A review of literature shows that different authors have found in conjunctival sac organisms of various kinds and in varying proportions. Further, these organisms vary with the locality from which cases are drawn.
Again, indiscriminate local and systemic use of antibiotics and corticoids convert organisms, considered benign into viruent and resistant to treatment.
Therefore, this study of bacteriology of hypopyon corneal ulcer in 115 cases was preceded by
I. A study of Conjunctival flora in 50 healthy eyes-from patients attending the outpatients for refractive errors.
II. Conjunctival flora study in 75 cases of corneal ulcers other than hypopyon ulcers.
I. The findings of conjunctival swab in 50 normal eyes has been as follows.
No growth indicates either-(1) a non-culturable agent such as the Herpes virus, or (2) the patient may have used antibiotics before coming to the hospital.
While staphylococcus aureus is definitely pathogenic, those among the albus which give a + ve coagulase test and/or haemolysis in a blood-agar plate are also pathogenic. Some authors label the two as staphylococcus pyogenes.
Organisms like streptococcus haemolyticus, pneumococcus, B. Pyocyaneus, and Morax-axenfield were not isolated from cases of ulcers with hypopyon whereas these have been reported by various authors like Devorah Khorazo (1935), Wissman (1924), Keilty (1930), Rhodes (1939).
Agarwal and Khosla from All-India Institute of Medical Sciences, while studying 30 normal conjunctival flora, besides staphylococcus aureus, strepto-viridans, strepto-haemolyticus and pneumococcus have also isloated-
B. Pyocyaneus (1 case)
Foecalis alkaligenes (3 cases)
Klebsiella aerobacter (2 cases)
Proteus vulgaris (1 case)
B. Coli (2 cases)
Here again, it will be apparent that in majority of our cases, we could only isolate staphylococcus pyogenes and B. xerosis.
A review of literature demonstrates again how varying have been the findings of conjunctival flora and smear from the ulcer itself in different types of corneal ulcers with different authors.
Thus, Sorsby and Burn (1950) examining 30 cases of corneal ulcer with and without hypopyon got the following findings:
Hypopyon ulcer cases (25)
Pneumococci ... 36
Staph. aureus ... 4%
Morax-Axenfield ... 4%
Staph. albus with B. Xerosis... 40%
Sterile ... 16%
Corneal ulcer without hypopyon
B. Pyocyaneus... 1
B. Proteus B. subtilis... 1
B. Pneumococci and gram negative bacilli. ... 1
Staphy. albus, pneumococcus B. Xerosis. ... 1
Tulsidas and Chaddah got the following organisms in 100 cases of corneal ulcer: - cases.
1) Staphylococcus pyogenes ..31
2) B. Pyocyaneus ... 14
3) Pneumococci ... 8
4) Strepto-viridans ... 8
5) B. Proteus ... 3
6) Strepto-hxmolyticus ... 2
7) C. b. Xerosis ... 35
8) Staphylococci ... 22
9) M. Tetragenes ... 3
10) M. Catarrhalis ... 1
11) Streptococci non-haemolyticus ... 1
12) No growth ... 19
In 74 of these hypopyon ulcer cases scrapings from the ulcer margin was obtained by a platinum loop, smears prepared on a glass slide and stained with gram stain.
These showed gram + ve cocci, (pneumococci) + ve bacilli, + ve diplobacillus, Gram - ve diplococci (M. catarrhalis and Gram - ve bacilli. It was a quick method and sometimes the only method in the absence of a culture growth, of knowing the microorganisms responsible for or associated with hypopyon corneal ulcer.
There were 27 cases of hypopyon corneal ulcer with chronic dacryocystitis and clinically demonstrable regurgitation of mucoid or muco-purulent fluid on pressing over the lacrimal sac.
In these cases, the mucoid fluid from the lacrimal sac was cultured in broth and blood agar media with the following findings-
Pneumococcus is said to be the chief pathogenic flora in cases of hypopyon corneal ulcer so much so that these cases have been divided into two types:
(1) typical, caused by the pneumococcus, and
(2) atypical, caused by other organisms.
But the findings of Wright (37.2%), MacCallan (41%), Rhodes (11.1%) and Sorsby (36%) have given the pneumococcus a lower figure varying from 11.6 to 41%- indicating that they are not the predominating organisms in hypopyon corneal ulcer as described by Browning.
(a) This has also been our finding. We could isolate pneumococcus in only 23 cases (20%),-by itself in 16 cases and associated with C. b. diphtheroids and staph. albus in 7 cases.
(b) Further, they were also not predominant in the group of hypopyon ulcers associated with chronic dacryocystitis.
(c) This series demonstrated the presence of a higher percentage of Streptococcus viridans (24.9%) in case of hypopyon ulcers which is not mentioned by others.
(d) Staphylococcus albus hemolyticus with positive coagulese test is a definite pathogenic organism and can produce a corneal ulcer including hypopyon corneal ulcer. It frequently plays a dormant part due partly to the low temperature of the conjunctival sac, partly to the action of lysozyme of the tears and partly to the mechanical action of blinking and the sluicing action of lacrimal secretion. The exotoxin produced by it has been blamed for ulcer production. This damages the epithelium and then the organism itself, or some other organism found associated in the conjunctival sac, gains access to the corneal substance to bring about a corneal abscess or a hypopyon ulcer.
We have not been able to record in our series of hypopyon ulcers a single case of aspergillosis, or streptothrix.
| Summary|| |
A bacteriological study of the flora of 50 normal conjunctival smears, 75 smears from corneal ulcer cases without hypopyon and 115 cases of corneal ulcer with hypopyon has been carried out and the results are analysed and compared with those of other authors.
| References|| |
Agarwal, L. P. and Khosla (1963). Oriental Archieves of Ophthalmology. 1, 145.
Browning (1927), Transac. of Ophth. Society of United Kingdom, page 38.
Devorah Khorazo (1935), Am. Journ. of Ophthal. 18, 1114.
Keilty, Robert A. (1930), Am. Journ. of Ophthal. 13, 876.
MacCallen, A. F. (1927). Trans. of Ophthal. Soc. U.K. p. 159.
Sorsby Arnold and Burn R. A. (1950). Brit. Journ. of Ophthal. 34, 16.
Tulsidas et al (1955). Brit. J. of Ophthal. 39, 26.
Wissman, R., (1924), Zeit f. Aug. 53 255, Quoted by Lucic, H., Am. Journ. of Ophthal. 10, 829.
Wright, R. E. (1927), Tran. of Ophthal. Society of United Kingdom, page 73.
[Table - 1], [Table - 2], [Table - 3], [Table - 4]