Isolation and Identification of Bacterial and Fungal Agents in patients with Corneal Ulcer in a Tertiary Care Ophthalmic Hospital.

INTRODUCTION : Eyes are our main contact with the world. Eyesight is the sense that everyone values more than all the rest. Light waves from an object enter the eye first through the cornea, the transparent dome which serves as the outer window of the eye. Corneal ulceration is defined as a loss of corneal epithelium with underlying stromal infiltration and suppuration associated with signs of inflammation. Corneal blindness is a major public health problem worldwide and infectious keratitis is one of the predominant preventable cause. In south East Asia according to an estimate, 6.5 million people are affected with, and 1.3 million eyes become blind due to corneal ulcer every year. Corneal ulceration is common in South India, and most often occurs after a superficial corneal injury with organic material. Any known organism can cause microbial keratitis and corneal ulceration, given the appropriate conditions and predisposing risk factors. A wide spectrum of microbial organisms like bacteria, fungi, viruses and parasites can produce infectious corneal ulcer. The most commonly encountered aetiological agents involved show tremendous geographical variance. AIMS AND OBJECTIVES : 1. To isolate and identify the fungal and bacterial aetiological agents of Infectious corneal ulcer. 2. To find a correlation between aetiological agents of corneal ulcer and age, sex and occupation of the patients. 3. To identify the predisposing factors for fungal and bacterial corneal ulcer. 4. To evaluate the sensitivity pattern of bacterial isolates from all cases to the commonly used antibiotics. 5. To study the sensitivity pattern of fungal isolates to the commonly used antifungal drugs. MATERIALS AND METHODS : This is a cross sectional study undertaken over a period of one year from May 2007 to May 2008. This study was carried out at the Institute of Microbiology, Madras Medical College, Chennai and Regional Institute of Ophthalmology, Government Ophthalmic Hospital, Chennai. All patients presenting to the Outpatient Department of the Regional Institute of Ophthalmology Government Ophthalmic Hospital (RIOGOH), with signs and symptoms of infectious corneal ulcer such as pain, redness, watering of the eye, dimness of vision and photophobia were included in the study. RESULTS : In this study, a total of 140 cases of corneal ulcers were studied. 107 cases were culture positive, in which 6 cases had mixed infections, thus bringing the isolates to 113. The cases were analysed under the following parameters: The age and sex distribution of corneal ulcers were analysed. 77.5% cases were found to be in the 10 – 60 years age group and 26% of corneal ulcer cases were in the 51 – 60 years age group. Extremes of age group ( 71) showed a low prevalence. A high prevalence of infectious corneal ulcer cases was seen among males, contributing to 62.6% of cases. The urban rural distribution of cases showed higher prevalence of corneal ulcers in rural population accounting for 65.4%. CONCLUSION : In conclusion, the infectious corneal ulceration was predominant in adult males of rural background, with vegetative matter induced ocular trauma as the major predisposing factor. A simple KOH preparation was highly beneficial as a rapid screening test for diagnosis. Fungal corneal ulcers were more common than bacterial ulcers. Aspergillus spp. and Staphylococcus aureus were the most common fungus and bacteria causing corneal ulcers respectively. From the present study, the vital role of microbiological evaluation in the management of infectious corneal ulcer is clearly evident, since the clinical features alone are not adequate to confirm infection. It is important to create awareness among people especially from rural background with regard to trauma as a major predisposing factor for corneal ulcers. Precise identification of the causative organisms and timely institution of appropriate antimicrobial therapy based on the prevailing sensitivity pattern of the fungal and bacterial isolates could save the eye from this preventable cause of blindness.