Diseases Commons^™

Human Tear Fluid Reduces Culturability Of Contact Lens-Associated Pseudomonas Aeruginosa Biofilms But Induces Expression Of The Virulence-Associated Type Iii Secretion System, Yvonne T. Wu, Connie Tam, Lucia S. Zhu, David J. Evans, Suzanne M. J. Fleiszig

Faculty Publications & Research of the TUC College of Pharmacy

Purpose

The type III secretion system (T3SS) is a significant virulence determinant for Pseudomonas aeruginosa. Using a rodent model, we found that contact lens(CL)-related corneal infections were associated with lens surface biofilms. Here, we studied the impact of human tear fluid on CL-associated biofilm growth and T3SS expression.

Methods

P. aeruginosa biofilms were formed on contact lenses for up to 7 days with or without human tear fluid, then exposed to tear fluid for 5 or 24 h. Biofilms were imaged using confocal microscopy. Bacterial culturability was quantified by viable counts, and T3SS gene expression measured …

Cytotoxic Clinical Isolates Of Pseudomonas Aeruginosa Identified During The Steroids For Corneal Ulcers Trial Show Elevated Resistance To Fluoroquinolones, Durga S. Borkar, Nisha R. Acharya, Chelsia Leong, Prajna Lalitha, Muthiah Srinivasan, Catherine E. Oldenburg, David J. Evans

Faculty Publications & Research of the TUC College of Pharmacy

Background: To determine the relationship between type three secretion genotype and fluoroquinolone resistance for P. aeruginosa strains isolated from microbial keratitis during the Steroids for Corneal Ulcers Trial (SCUT) and for two laboratory strains, PA103 and PAO1.

Methods: Confirmed P. aeruginosa isolates from the SCUT were divided into exoU(+) or exoU(−). The exoU(+) strains contained the gene encoding ExoU, a powerful phospholipase toxin delivered into host cells by the type three secretion system. Isolates were then assessed for susceptibility to fluoroquinolone, cephalosporin, and aminoglycoside antibiotics using disk diffusion assays. Etest was used to determine the MIC of moxifloxacin …