Virulence factors in Pseudomonas aeruginosa keratitis

Abstract

 

Purpose:

 

To identify virulence factors in cases of P. aeruginosa keratitis that can be used for prognosis and personalising treatments.

 

Methods:

 

Clinical outcome data and isolates were collected from cases of P. aeruginosa keratitis from six centres around the UK from two time periods, 2003-4 and 2009-10. Isolates were genotyped utilising a novel array tube system to generate a clone type. Presence of genes coding specific exotoxin production (exoS or exoU) as well as clonal type clustering was investigated in the two time periods. Population genomic analysis between groups of isolates with related genotypes was performed using eBurst software. An association was then sought between clonal type, the presence and type of exotoxin and clinical outcome.

 

Results:

 

123 cases of P. aeruginosa keratitis over the two time periods were included. 75% and 82% of keratitis isolates respectively fell into one main cluster in the eBurst analysis, compared to 40% of non-keratitis isolates (see Figure). Exotoxin gene type (exoS or exoU) clustered with clonal type. Clinical outcome data available from 41 out of 123 isolates showed clone A, serotype O11 and the presence of exoS were was associated with larger corneal ulcers, prolonged healing time and gentamicin resistance.

 

Conclusions:

 

The identification of clonal type and the virulence factor exoS are of prognostic significance. The presence of these factors in patients with P. aeruginosa keratitis may help target treatment and potential future therapies.  

 

Keywords: pseudomonas • keratitis