Abstract
Purpose: :
To characterize and identify associated microbial agents and risk factors for infectious keratitis at a teaching hospital in South Texas.
Methods: :
We reviewed medical records of patients who presented to the hospital between January 1, 2005 and December 31, 2006 with corneal ulcers that were cultured. Targeted data included patient demographics, contact lens wear, corneal infiltrate size, and initial culture growth. The statistical analyses used were Chi-square and t-tests.
Results: :
Eighty five eyes of 85 patients met the inclusion criteria. Of those, 51% (n= 43) were female. Seventy six percent (n= 65) were Hispanic, 8% (n=7) were Caucasian, 5% (n=4) were African American and 11% (n=9) were unknown. Contact lens use was present in 60% (n=51) of the patients. At presentation measured infiltrate size was < 1 mm in 34%, 1.1-2.0 mm in 28%, 2.1 -3.0 mm in 8% and >3mm in 14 % of affected eyes. Cultures were positive for 56% (n=48) of total eyes. Cultures were positive for 63% (n=32) of contact lens wearers (n=51). Chi-square analysis demonstrated an association between contact lens wear and culture positive independent of size, (p=0.006, with a medium effect size. Initial cultures grew pseudomonas aeruginosa (n=16), coagulase negative staphylococcus (n=19), Staphylococcus Aureus (n=6), Serratia (n=5) and fungus (n=4), and polymicrobial growth (n= 12 eyes). A t-test demonstrated that negative cultures were associated with smaller size ulcers (mean=1.6 mm, SD=1.16), whereas positive cultures tended to show larger ulcers (mean=2.6 mm, SD=1.95), p=0.005 and medium effect size.
Conclusions: :
The microbial spectrum of corneal ulcers at a South Texas teaching hospital included a high frequency of pseudomonas aeruginosa, coagulase negative staphylococcus, and polymicrobial growth including fungus. The likelihood of positive growth was related to ulcer size and contact lens wear independent of culture size.
Keywords: cornea: clinical science • keratitis • microbial pathogenesis: clinical studies