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An epidemiologic analysis of staphylococcus aureus‐associated keratitis in Boston
Author(s) -
BEHLAU I,
HEIMER SR,
LEONARD EM,
MARTIN JN,
DOHLMAN CH,
GILMORE MS
Publication year - 2009
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2009.4359.x
Subject(s) - keratitis , staphylococcus aureus , microbiology and biotechnology , multilocus sequence typing , biology , ciprofloxacin , medicine , genotype , antibiotics , gene , genetics , bacteria
Abstract Purpose S. aureus is a normal commensal of the human skin and nasopharynx. It is therefore of interest to determine whether S. aureus keratitis is caused by a subset of these organisms. In this study, the phenotypic and genotypic characteristics of S.aureus keratitis isolates were analyzed. Methods All S. aureus clinical isolates were prospectively collected over a 24 month period at the MEEI (2006‐2008). The diagnosis of clinical keratitis and associated risk factors was by medical record review. Keratitis‐associated S. aureus strains were assessed for: 1) antibiotic susceptibility, 2) biofilm robustness by gentian violet staining using an in vitro microtiter plate assay, and 3) genetic lineage by multi‐locus sequence typing (MLST). Results 26 cases of keratitis were identified from the 600 S. aureus clinical isolates. Risk factors associated with S.aureus keratitis included trauma, prior surgery, soft contact lens wear, and the presence of a foreign body. Ocular surface disease does not appear to be an independent risk factor. All 26 isolates were tetracycline‐ and trimethoprim‐sulfamethoxazole‐ sensitive. All the MRSA strains were found to be ciprofloxacin‐resistant (10/26). Nearly one‐half of all the S.aureus keratitis‐associated isolates were caused by a single clone, ST5. Both methicillin sensitive and resistant S. aureus strains were represented within ST5. Conclusion These results suggest that there may be specific S.aureus lineages which possess phenotypic and genotypic characteristics that enable S. aureus to more effectively cause sight‐threatening keratitis. Future work will examine their virulence traits and a comparison to commensal S.aureus strains.