Seasonal, Geographic, and Antimicrobial Resistance Patterns in Microbial Keratitis: 4-Year Experience in Eastern Pennsylvania.
Ni, Nina MD; Nam, Enoch M. MD; Hammersmith, Kristin M. MD; Nagra, Parveen K. MD; Azari, Amir A. MD; Leiby, Benjamin E. PhD; Dai, Yang MS; Cabrera, F. Abigail MPH; Ma, Jenny F. BA; Lambert, Calvin E. Jr BA; Honig, Stephanie E. BA; Rapuano, Christopher J. MD
34(3):296-302, March 2015.
(Format: HTML, PDF)
Purpose: The aim of this study was to review the demographics, causative organisms, seasonal and geographic variation, and antimicrobial resistance patterns of microbial keratitis at our institution over a 4-year period.
Methods: Electronic medical records of all patients with microbial keratitis who underwent corneal culturing at a single institution in eastern Pennsylvania between January 1, 2009 and December 31, 2012 were reviewed.
Results: A total of 311 patients representing 323 instances of infectious keratitis were analyzed. The most frequently implicated organisms in contact lens-related infections were Pseudomonas aeruginosa for bacteria and Fusarium species for fungus, compared with Staphylococcus aureus and Candida species in non-contact lens-associated bacterial infections. Bacterial keratitis occurred most frequently in spring and least frequently in winter (P = 0.024). Patients who live in large fringe metro (suburban) areas accounted for the highest proportion of infectious keratitis cases. P. aeruginosa and methicillin-sensitive S. aureus isolates were highly susceptible to fluoroquinolones, whereas 32% of coagulase-negative staphylococcus isolates tested were resistant to moxifloxacin and gatifloxacin, and all methicillin-resistant S. aureus organisms tested were resistant to these 2 fluoroquinolones. No organisms tested were resistant to tobramycin, gentamicin, or vancomycin. No fungal infections tested were resistant to voriconazole.
Conclusions: Most infectious keratitis occurred in nonwinter months and in patients from suburban counties. Although fluoroquinolones were effective against the most common bacteria, staphylococcal species exhibited a high rate of resistance, representing a therapeutic challenge given the increasing use of fluoroquinolones as first-line monotherapy. No organisms tested were resistant to tobramycin, gentamicin, vancomycin, or voriconazole.
Copyright (C) 2015 Wolters Kluwer Health, Inc. All rights reserved.