OR037
   
 

Clinical Factors Associated With Positive Corneal Culture In Suspected Microbial Keratitis

1. Matthew Green¹
2. Andrew Apel¹
3. Thomas Nadivulath3,4
4. Fiona Stapleton2,3,4

¹Princess Alexandra Hospital, Brisbane, Australia
²Vision CRC, Sydney, Australia
³Brien Holden Vision Institute, Sydney, Australia
4School of Optometry and Vision Science, University of New South Wales, Australia

Purpose: Determine demographic and clinical characteristics associated with positive culture in suspected microbial keratitis.

Methods: Retrospective audit of all patients that had corneal scraping between October 1999 - September 2004 at Princess Alexandra Hospital. Clinical information was gathered from medical records and smear and culture results from local microbiology database. Variables associated with positive cultures were analysed in a univariate and multivariate analysis and population attributable risk percentage (PAR).

Results: Univariate analysis showed that positive cultures were associated with patients over 60 years old (> 60 years 81% vs < 60 years 55%; p<0.001), VA of 6/24 or worse on presentation (74% vs 57%; p=0.012) or contact lens-related keratitis (CLK 77% vs 62%; p=0.08). Analysis of patients' clinical presentation showed that positive culture was associated with a central epithelial defect (74% vs 57%; p=0.012), anterior chamber reaction of 2+ cells or worse (73% vs 56%; p=0.03), epithelial defect 2mm or more in diameter (71% vs 50%; p=0.006) or no prior treatment with antibiotics (68% vs 56%; p=0.053). Multivariate analysis showed the independent variables associated with positive cultures were contact lens-related keratitis, age greater than 60 years, VA of 6/24 or worse on presentation, an anterior chamber reaction of 2+ cells or worse and no prior treatment with antibiotics. The factor with the strongest association (PAR%) for a positive corneal culture was an entering VA of 6/24 or worse (21%).

Conclusions: Positive cultures were associated with CLK, older age, poor presenting VA, anterior chamber reaction and no prior treatment with antibiotics.

 
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