Comparison of clinical and microbiological profiles in smear-positive and smear-negative cases of suspected microbial keratitis.

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 (

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.