Dear Editor,

We read with great interest the article published by Pate JC (1) in your journal and the editorial (2), regarding polymicrobial infection of cornea. Our centre is a tertiary level eye care centre in northern India and also the apex centre for eye care of the country. We, in our country come across a large number of fungal keratitis cases compared to that reported in western studies. Though the authors rightly state that the findings reported by them may not be generalized to populations like ours, we would like to share our view. As a part of a recent project on fungal keratitis, we studied 76 eyes of presumed fungal keratitis in the last 1 year duration prospectively. The pattern of polymicrobial infection was analyzed as well.

The criteria mentioned for diagnosing the co-infection by Pate JC (1) were similar in our study. Of a total 76 eyes only 20 (26%) were proven to have fungal keratitis by culture. Of these 20, pure fungal infection was detected only in 5 (25%) and the remaining 15 had bacterial co-infection (75%). The isolation of yeast is much less in our country in contrast to that of western literature. Also there is intracountry variation in geographical distribution of filamentous fungi such as Aspergillus and Fusarium. At our center, in northern India, the isolation of Aspergillus heads the list. While the authors reported bacterial co-infection in 10% and 20% of Moniliaceous and Dematiaceous filamentous fungi respectively, we found 66% and 100%. However, we feel that high percentages of co- infection in our study could be attributed to small sample size.

The authors have also commented that the prevalence may be due to a number of factors such as nonconformity in microbial co- isolation, climatic effect, history of trauma, ocular surface integrity, and prior therapy. The first factor was ruled out in our study as the microbial co-isolation was carefully evaluated in our microbiology lab. The climatic effect did not show any correlation. It is not possible to comment on ocular surface as a negligible number of eyes with ulcer had associated ocular surface abnormalities. Though, 60% & 86.6% of eyes with polymicrobial co-infection revealed a history of trauma and prior drug therapy respectively the same could not be compared with that of growth without co-infection as the number of eyes was only 5. We are in concurrence with our earlier reports (3,4) and that of the authors (1,2) that coexistence of Staphylococcal infection is most commonly found along with fungal infection . The authors have expressed their view that there may be a mutual alliance for the co-pathogens. Tuft (2) has commented about the super infection with a second organism which is attributed to the inhibition of the local immune response by the topical corticosteroid. This is an important aspect to note as the patients with keratitis when referred to the tertiary center with extensive and non responsive infection are found to be on topical corticosteroid sometime or other during course of the disease.

At the end, we congratulate the authors for bringing this important issue to light so that clinicians may effectively manage polymicrobial co-infection.

Table 1.

Isolate	Proven fungal case	Bacterial co-infection
Moniliaceous filamentous fungi	15	10 (66%)
Dematiaceous filamentous fungi	5	5 (100%)
Total	20	15

References

1. Pate J C, Jones DB, Wilhelmus KR. Prevalence and spectrum of bacterial co-infection during fungal keratitis. Br J Ophthalmol 2006; 90:289-92.

2. Tuft S. Polymicrobial infection and the eye- Has important management implications. Br J Ophthalmol 2006; 90:57-58.

3. Satpathy G, Vishalakshi P. Ulcerative keratitis: microbial keratitis and sensitivity pattern-a five year study. Ann Ophthalmol 1995; 27:301-6.

4. Khanal B, Deb M, Panda A, et al. Laboratory diagnosis in ulcerative keratitis. Ophthalmic Res 2005; 37:123-7

Dear Editor,

We read with great interest the clinical report by Pate et al. in which bacterial conifection in keratomycosis was reported by smear, culture or both. We have seen in our own practice in a series of 110 cases of infectious keratitis (unpublished data) between year 2001-2005, six cases of bacterial co infection in keratomycosis. Five of them were smear positive and one case was only culture positive for bacteria. In all these cases, the mycotic element was septate fungus - Fusariunm sps and not yeast as reported by these authors. We had suspected polymicrobial keratitis clinically in all these cases due to certain distinctive features at presentation. The typical raised dry infiltrate with hyphate margins which is so characteristic of keratomycosis was modified into wet looking necrotic infiltate in some areas; epithelial defect overlying the infiltrate showed extension beyond the infiltrate in some areas. Treatment in all these cases is incomplete if thorogh microbiological work up is not done. Clinical judgement does suffice to treat microbial keratitis in many cases, rather we advocate laboratory support.