Risk factors for treatment outcome of suspected microbial keratitis

Abstract

Background-Primary treatment for suspected microbial keratitis is generally successful. Although risks such as contact lens use are well recognised as causative factors for microbial keratitis, little is known about the risk factors that influence treatment outcome. The present study evaluates the risk factors assessed at diagnosis as prognostic indicators of primary treatment failure. Methods-Patients were prospectively enrolled in the ofloxacin treatment trial and data concerning symptoms, treatments, past and concurrent eye disease were collected along with the measurement of corneal ulcer size at the slit lamp. All patients were scraped for microbiological investigation, and treated with either ofloxacin (0.3%) or standard therapy of fortified cefuroxime and gentamicin drops. Treatment success was complete healing of the ulcer with zero dimensions of the epithelial defect within 2 weeks of start of treatment.The important prognostic indicators were selected by comparison among those who failed treatment, had delayed healing, or were culture positive with other patients using univariate and stratified analysis. These were then used in a Poisson model for multiple regression analysis to estimate the relative risk of the main prognostic variables. Results-Of the 118 patients enrolled in the study, 14 were identified as primary treatment failures, 17 had slow healing, and 15 indolent ulcers. There were 49 culture positive patients. The multivariate analysis identified that large culture positive ulcers in patients 60 years or older had 5.5 times the risk of primary treatment failure (p<0.001). Significant predictors of slow healing were previous ocular disease and a positive culture; significant predictors of indolent ulceration were previous ocular disease and steroid use at diagnosis; the main predictor of a culture positive result was ulcer size. Conclusions-Elderly patients with large ulcers were more likely to be culture positive, fail primary therapy, and require surgical intervention. A positive microbial culture provided prognostic information regardless of the organism isolated. However, this information was of less value for those with small ulcers and for younger patients.

Simplifying Collection of Corneal Specimens in Cases of Suspected Bacterial Keratitis

“…In the present study, 61% of patients were on treatment with topical antimicrobials at presentation; although the overall isolation rate was 33%, the isolation rate was 27% for those on treatment and 42% for those not on treatment. This effect of pretreatment may account in part for the isolation rate being lower than that reported in previous studies (20,22). For example, Morlet et al (22) reported an isolation rate of 41.5% for a group of patients of whom only 22% were receiving topical antimicrobial medications, while McCleod et al (20), having excluded patients who had had prior treatment, obtained an isolation rate of 69.1% (56/81).…”

Microbiological findings and predisposing risk factors in corneal ulcers

“…At least one of these predisposing factors was detected in 35% of the patients in this study. WCL, associated ocular disease, and corneal trauma were seen as the main local risk factors [9][10][11][12]. Most notably, WCL has frequently been associated with severe forms of microbial keratitis [13].…”

Clinical review of corneal ulcers resulting in evisceration and enucleation in elderly population

“…In our hospital, the most common indications for enucleation and evisceration in this age group were nonresolving severe keratitis (30 patients, 64%) and corneal perforation (17 patients 36%). The variables found to be associated with adverse outcomes in cases of microbial keratitis in the past include severe infection [12][13][14][15], advanced patient age [13,16,17], poor visual acuity at presentation [13,15,17], associated herpetic keratitis [14,18], ocular surface disease [12], associated systemic disease [12], prior treatment with steroids [19], and a delay in seeking treatment [20]. Failure to use fortified antibiotics has also been found to be associated with poor prognosis in cases with microbial keratitis [20].…”