Abstract
Purpose :
Cultures of corneal swabs, contact lenses and contact lens cases are frequently obtained in management of patients with microbial keratitis (MK). Our retrospective, observational clinical study evaluates similarities between microorganisms found on corneal and contact lens related (CLR) cultures in patients with MK.
Methods :
MK patients who had diagnostic laboratory cultures performed on both corneal and CLR specimens were identified in the University of Michigan electronic health record from August 2012 to April 2022. Test results were classified as lab-positive infections (bacterial, fungal, viral, Acanthamoeba, or polymicrobial) or lab-negative. The degree of microbiological agreement between the corneal and CLR cultures was investigated. Snellen visual acuity (VA) was converted to logMAR equivalent. The trends of VA over time based on their first and subsequent lab results were assessed using linear regression (Group 1, first lab-negative and later lab-negatives; Group 2, first lab-negative and later lab-positives; and Group 3, first lab-positive and later lab-positives).
Results :
Of 50 MK patients identified, patients were on average 49 years old (SD=20.9), 56% were female, 90% White, and 100% non-Hispanic. The agreement rate between corneal and CLR culture results was 30% (n=15/50), including 7 lab-negative cases, 6 bacterial infections, 1 fungal, and 1 polymicrobial. The disagreement rate was 70% (35/50). Of these 35 patients, 13 patients were negative on corneal cultures but positive on CLR cultures and 11 were positive on corneal cultures but negative on CLR cultures. The most common isolates were Pseudomonas aeruginosa (n=16), Staphylococcus aureus (n=10), and Coagulase-negative Staphylococcus (n=11). Since the patients received their first lab results, logMAR VA improved over time for all 3 groups (Group 1: slope estimate=-0.1 per 10 days, Group 2: -0.13, Group 3: -0.18; p=0.5655).
Conclusions :
Cultures from contact lenses and contact lens cases can aid in clinical management of microbial keratitis, particularly when the corneal cultures are negative. This additional result can provide clinicians guidance on appropriate antimicrobial selection, especially in challenging cases.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.