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2017 OMIG Abstract 10

Increasing frequency of sheen isolates among Pseudomonas aeruginosa keratitis isolates
Robert M.Q. Shanks1, Jake Z. Callaghan1, Kateryna Czuczman1, John Romanowski1,
Michael E. Zegans2, Regis P. Kowalski1
1The Charles T. Campbell Laboratory, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; 2Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire


Purpose: Pseudomonas aeruginosa causes vision-threatening keratitis.  Approximately 20% of keratitis Pseudomonas aeruginosa isolates from the SCUT demonstrated a colony sheen appearance, and these sheen positive isolates correlated with a worse clinical outcome.  These sheen isolates were found in India between 2006 and 2010.  The basis of the sheen phenotype was a build up of 4-hydroxy-2-heptylquinoline due to mutation of the lasR gene.  It is not known whether North American P. aeruginosa keratitis isolates have this sheen phenotype.  Here we screened keratitis isolates from 1988-2015 for a sheen phenotype and sequenced the lasR gene from a subset of the sheen positive isolates.

Methods: 103 P. aeruginosa keratitis isolates were streaked out on blood agar plates and analyzed for colony sheen phenotypes.  The lasR gene was cloned and sequenced from a subset of these isolates.

Results: Sheen positive isolates were found in 18% of isolates in the Campbell Laboratory collection of keratitis isolates.   There is an increasing trend in the frequency of sheen positive isolates with 7.7% from isolates from 1988-1997 (n=36) and 26.5% from isolates between 2008-2015 (n=25).  The majority of tested sheen positive isolates had mutations in the lasR gene.

Conclusions: P. aeruginosa sheen isolates which were previously isolated from North American keratitis patients with a similar overall frequency to those observed in India.  There is a trend for increasing sheen isolates that is concerning given the likely increased pathogenesis of these strains.

Disclosure: N



2017 Agenda and Abstracts | < Previous Next >