¡¡¡¡INTRODUCTION

¡¡¡¡Microbial keratitis is a serious ocular infectious disease that can lead to significant vision loss and ophthalmic morbidity[1]. Bacteria¬ðs are the most common infective organisms responsible for this morbidity. The severity of corneal infection depends on the underlying condition of the cornea and pathogenecity of the infecting bacteria[2]. It is rare in the absence of predisposing factors, and hence most commonly associated with ocular trauma or ocular surface disease. However the increasing prevalent with the use of contact lenses in the general community has resulted well established association between keratitis and contact lens[3].

¡¡¡¡The spectrum of bacterial keratitis can also be influenced by geographic and climatic factors. Many differences in keratitis profile have been noted between populations living in rural or in urban areas in western, or in developing countries[4]. Gram positive bacterial species are more frequently recovered in temperate zones, and Gram negative species in tropic climates. Untreated, infective keratitis may lead to opacification and, ultimately, to perforation of the cornea. The associated morbidity is the result of several factors and is directly affected by difficulties in patient¬ðs management because of a lack of diagnostic facilities and appropriate treatment. Specific treatment requires prompt and accurate identification of causative microª²organisms[5]. This study is an effort to analyze the epidemiologic features, predisposing factors and the main causative organisms for bacterial corneal ulcer in this part of Asia to provide a useful guide for the practicing ophthalmologists. This two years Quasiª²experimental study (from April 2006 to March 2008) of bacterial corneal ulcer was conducted at Liaquat University Eye Hospital, Hyderabad, a Tertiary Referral Center in Southern Pakistan.

¡¡¡¡MATERIALS AND METHODS

¡¡¡¡Subjects  Patients above 15 years of age presenting with suspected corneal ulceration and having symptoms of pain, redness, watering, photophobia and decreased vision were registered for the study. Patients written consent was obtained and a standardized proforma was used to record the data. Detailed history and examination of the patients was taken regarding demographic features, time of onset of symptoms, preª²disposing factors including corneal injuries (agriculture, non agriculture, foreign bodies), contact lens wear, keratopathies (due to previous herpetic infection, corneal dystrophy or surgical procedure, as in bullous keratopathy), dry eye syndrome, eye lid abnormalities (blephritis, entropion, ectropion, lagophthalmos, and others). Visual acuity was measured with Snellen chart. All patients underwent through slit lamp examination to locate the site, size and depth of ulcer. Anterior chamber inflammation, when present, was scored, according to Hoagan and associates, a 0+ to 4+ for Tyndall effect and cells.

¡¡¡¡After the instillation of local anesthetic 5g/L proparacaine hydrochloride, corneal scrapping was obtained aseptically with a sterile No.15 surgical blade from the base and edges of each ulcer. A portion of each scrapping was examined microscopically for the presence of bacteria, fungi or acanthamoeba by using Gram staining, 100g/L potassium hydroxide (KOH) and Giemsa staining methods. Another portion was inoculated on to blood agar, chocolate agar, Macª²Conkey agar, Sarboraud¬ðs agar, brain heart infusion broth respectively, in Cª²shaped streaks and cultured for the potential growth of, bacteria, fungi or acanthamoeba. Sarboraud¬ðs agar slants were incubated at 28¡æ while others at 37¡æ. All media were cultured for a period of seven days and observed daily. Isolated bacteria were tested by chemical reaction for identification. Further the bacteria were tested for their resistance against the following ocular antibiotics: cefuraxime, cefazolin, moxifloxacin, gentamycin, tobramycin, ceftazidime, norfloxacin, ofloxacin, levofloxacin, gatifloxacin. The resistance to antibiotics was evaluated with the standard disc diffusion method according to the modified test recommended by the NCCLS.

¡¡¡¡Treatment Protocol  Ninetyª²five (61%) patients were treated as an out patients department basis and 61 (39%) patients were hospitalized for treatment. The decision to admit patients and use of fortified antibiotics were influenced by the severity of the corneal ulcer and patients compliance. The standard fortified therapy consisted of topical cefuraxime 50g/L and fortified tobramycin 9g/L, where as commercially available antibiotics used were topical fluoroquinolones (Moxifloxacin). The antibiotic eye drops, administered alternately every fifteen minutes during the first 4 hours then every hour for the next 48 hours. Later, drops were progressively tapered according to the clinical response. Bottles of fortified antibiotics drops were freshly prepared and cefuraxime, was changed every 72 hours. This standard treatment protocol was started for every patient and modified on patients response and the bacterial susceptibility.

¡¡¡¡Statistical Analysis  Univariate analysis was used to evaluate the possible association between bacterial type, clinical characteristics, risk factors and clinical outcomes. Data was analyzed on SPSS version 10.0.

¡¡¡¡RESULTS

¡¡¡¡General Situation  Three hundred patients (300 eyes)  were enrolled with a corneal infiltration that was clinically compatible with the diagnosis of bacterial corneal ulcer during the two years study period. Of these 60 patients were lost in followª²up, excluded from study. Of the remaining 240 cases, bacterial corneal ulcer was identified in 156 (65.0%) patients. Among these, 60 (38.5%) patients were examined first time in the out patients department, where as 96 (61.5%) were previously treated by general practitioners and ophthalmologists and were already being treated with topical antibiotics, corticosteroids and antifungal eye drops. The age of patients ranged from 14 to 74 (mean age of 48) years. Majority of them were male 102 (65.4%) with male to female ratio of 1.9¡Ã1(Table 1). One hundred and two (69.2%) patients belonged to rural and 48 (30.0%) were from urban population. Trauma with vegetative material was by far the most common risk factor; this was encountered in 46 (29.5%) patients. History of nonª²vegetative trauma in 16(10.3%) patients(Table 2). In 18 (11.5%) patients, ocular surface disorder was observed, the keratitis was induced by foreign body in 24 (15.4%) patients. Eleven (7.1%) patients were affected by contact lenses. Keratopathies (including herpetic, bullous and post operative keratopathies) were presented in 17 (11.0%) patients. Blephritis was noted in 8 (5.1%) patients. While 16 (10.3%) patients had no significant prior history.

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