Abstract
Purpose:
To document and correlate the presence of quorum sensing (QS) proteins/genes and their role in the selection of Pseudomonas aeruginosa as a preferential corneal pathogen from contaminated contact lens cases.
Methods:
We used a combination of Proteomics, RT-PCR and plate biosensor bioassays to detect the presence of Pseudomonas aeruginosa quorum sensing proteins (lasI/lasR, rhlI/rhlR and rpoD) and signaling molecules (acyl homoserine lactones) in 15 randomly selected contaminated contact lens cases recovered from patients with keratitis (N=26, Jan2011-June 2012). Results were correlated with cultures and number of microbial communities members. Contact lens cases were retrieved from storage at 4 C, refreshed with 2 ml trypticase soy broth and incubated at room temperature for 24-48 hours. 1 ml aliquots were retrieved and used for the study.
Results:
Pseudomonas aeruginosa emerged as the cornea pathogen from 76.9% (20/26, N=83 species) of all matched ctl/cornea cultures. There was an average of 3.8 species per well. P. aeruginosa quorum sensing and or metabolic proteins including protease IV, elastase, and elastase B were recovered in 10/22 (45.4%) of the proteins identified by mass spectrometer in sample 1 of three samples. No proteins were recovered that correlated with any of the other community members (Acanthamoeba species, Klebsiella oxytoxca, Mycobacteria chelonae). Proteins specific for S. marcescens (#2) was documented in 5/44 (11.4%). Neither proteins from P. aeruginosa or S. marcescens were recovered in the 37 proteins from sample #3. No proteins were recovered from the tsb control. Both quorum sensing systems (las and rhl) were expressed in aliquots from at least one well in 8 of the 15 evaluated contact lens cases. Pseudomonas aeruginosa was recovered in 5/8 (62.5%) in the presence of at least 2 other community members (N=21). Acyl homoserine lactones production from case aliquots was evident in 3/15 (20%) of C. violaceum screening vs 6/15 (40%) for A. tumefaciens.
Conclusions:
The production and expression of quorum sensing genes and signaling molecules in contact lens case ecosystems may allow for the preferentially selection of P. aeruginosa as a corneal pathogen. Deciphering this mechanism can lead to solutions to reduce and or neutralize the advantage.
Keywords: 477 contact lens •
663 proteomics •
594 microbial pathogenesis: experimental studies