Indian Journal of Ophthalmology (Jan 2007)
Comparison of clinical and microbiological profiles in smear-positive and smear-negative cases of suspected microbial keratitis
Abstract
Purpose: To examine the hypothesis that initial smear examination results have a significant bearing on the management and outcome of suspected microbial keratitis. Materials and Methods: One hundred and seventy consecutive patients with suspected microbial keratitis were included in a prospective nonrandomized comparative study and their detailed clinical and microbiological data (smears and cultures of corneal scrapings) were captured on a predesigned corneal ulcer database. Patients were divided into two groups: Group 1 included 68 patients with corneal scrapings negative in smears while Group 2 included 102 patients with corneal scrapings positive in smears. The two groups were compared for their clinico-microbiological profile, management and clinical outcome. The outcome was noted at three months. Fisher′s exact test was applied for statistical analysis. Results: Cultures were sterile in 57.3% of patients in Group 1 compared to 17.6% in Group 2. Scrapings that grew S. pneumoniae , gram-negative organisms, fungi and Acanthamoeba were more often positive in smears (18.6%, 11.8%, 19.6% and 2.9% respectively). While data on duration of prior treatment was not available, prior medication made no significant difference to smear results. More (79.3%) patients of Group 1 had small infiltrate size (< 25 mm[[2]]) compared to Group 2 (49%). Significantly more patients in Group 2 than in Group 1 were treated with antifungals (5.4% vs. 41%) and fortified antibiotic combination (12.7% vs. 27%). Broad-spectrum antibiotic (ciprofloxacin) was started more often in Group 1 than Group 2 (60% vs. 15% respectively). The corneal infiltrate resolved in 33.3% of cases in Group 2, which was significantly more than in Group 1 (33.3% and 7.3% respectively). Conclusions: Initial smear examination helps in instituting specific therapy thereby improving the outcome in cases of microbial keratitis. Positive smears indicate greater severity of disease and prior medication may not be a significant cause of smear negativity.
