Pseudomonal Type Three Secretion System and Contact Lens Associated Microbial Keratitis

This study is currently recruiting participants. (see Contacts and Locations)
Verified April 2014 by National Taiwan University Hospital
Sponsor:
Information provided by (Responsible Party):
National Taiwan University Hospital
ClinicalTrials.gov Identifier:
NCT01925846
First received: August 16, 2013
Last updated: April 14, 2014
Last verified: April 2014
  Purpose

Microbial infection of the cornea, also known as microbial keratitis, causes severe corneal inflammation that could result in permanent visual loss. Contact lens wear is the strongest risk factor related to microbial keratitis in developed countries. The most commonly isolated pathogen of contact lens associated microbial keratitis (CLMK) is Pseudomonas aeruginosa, which accounts for over one third of the cases. Among the various virulence factors involved in the pathogenesis of pseudomonal keratitis, a secretion system known as type three secretion system (T3SS) secretes toxins that damage the host cells. ExoS is a bifunctional exotoxin with GTPase-activating protein (GAP) activity and ADP ribosyl transferase (ADPRT) activity. It results in an invasive phenotype of P. aeruginosa causing a relatively slower host cell death with intracellular invasion and possibly proliferation of bacterium. In contrast, ExoU expressing strains carries a cytotoxic phenotype that causes rapid host cell lysis due to its phospholipase activity. Previously, cytotoxic strains were reported to be more commonly found in patients with pseudomonal keratitis and were highly correlated with multidrug resistance.

In order to understand the pathogenesis of CLMK, especially pseudomonal related CLMK, we proposed to recruit 180 volunteers who will wear different contact lens materials. We then collect the used contact lens and analyze 1) the microbiota on the used contact lens; 2) the bacterial-contact lens adhesion of wild strains, pscC mutant strains (T3SS needle-comples mutant), cytotoxic strain, and invasive strain P. aeruginosa; 3) the effect of shearing forces on bacterial-contact lens adhesion; 4) the bacteriocidal effect of multipurpose solution on different strains of P. aeruginosa.


Condition
Keratitis; Infectious Disease (Manifestation)

Study Type: Observational
Study Design: Observational Model: Cohort
Time Perspective: Retrospective
Official Title: Association of Type Three Secretion System (T3SS) of Pseudomonas Aeruginosa With Pathogenesis of Contact Lens-Associated Microbial Keratitis (CLMK)

Resource links provided by NLM:


Further study details as provided by National Taiwan University Hospital:

Primary Outcome Measures:
  • bacterial adhesion assay [ Time Frame: after co-culture for two hours ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • Identification of bacterial colonization to worn contact lenses [ Time Frame: after the CL been worn for 6 hours ] [ Designated as safety issue: No ]

Estimated Enrollment: 180
Study Start Date: January 2013
Estimated Study Completion Date: July 2015
Estimated Primary Completion Date: January 2015 (Final data collection date for primary outcome measure)
Detailed Description:

Subject recruitment

The inclusion criteria includes:

  1. age 20-35 years old
  2. myopia less than -6.00D and astigmatism less than -1.50D
  3. previous soft contact lens wear discontinued for at least 2 weeks.

Exclusion criteria includes:

  1. subjects with previous RGP wear
  2. any ocular inflammation or infection, proved dry eye syndrome, glaucoma, ocular trauma or surgery, and topical medication instillation
  3. diabetic mellitus
  4. pregnancy
  5. status post corneal refractive surgery

The aim and purpose of this study will be thoroughly explained to the potential participants. Informed consent will be obtained from all enrolled subjects. This study will be approved by our Institutional Review Board and adheres to the tenets of the Declaration of the Helsinki. A minimal of 12 subjects per group is required to show a difference in the microbiota for one classification level or more at a significance level of 0.05 and a power of 90%. Thus, the goal is to recruit 15 volunteers to wear each type of contact lens and 180 subjects totally for this study.

The recruitment will be divided into three stages. At the first stage, we will test 4 types of silicone hydrogel contact lenses, followed by testing 5 types of color-tinted hydrogel lenses at the second stage and 3 types of hydrogel lenses at the third stage. (T = types of lenses, which equals 4,5 and 3 at stage one, two and three).

At each stage, we will recruit subjects to certain amount (M) each time (M=N×T , N equals 1,2,3…to 15). M subjects will then be randomized, equally distributed to wear T types of lenses by the random number method. Until the required case numberis achieved at the first stage, we will proceed to the second and the third stage with the same stratified randomization methods.( required case number, ΣM, equals 60, 75 and 45 at stage one, two and three).

Subjects are fitted with the soft contact lenses and are expected to wear the lenses for at least 6-8 hour per day. Standardized hand hygiene and lens care regimen are thoroughly explained to each subject to insert the contact lens. Each subject enrolled will be provided with the soft contact lenses without charge. After wear each day, the contact lenses must be returned and collected for material analysis.

  Eligibility

Ages Eligible for Study:   20 Years to 35 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Sampling Method:   Probability Sample
Study Population

In order to understand the pathogenesis of CLMK, especially pseudomonal related CLMK, we proposed to recruit 180 volunteers who will wear different contact lens materials. We then collect the used contact lens and analyze 1) the microbiota on the used contact lens; 2) the bacterial-contact lens adhesion of wild strains, pscC mutant strains (T3SS needle-comples mutant), cytotoxic strain, and invasive strain P. aeruginosa; 3) the effect of shearing forces on bacterial-contact lens adhesion; 4) the bacteriocidal effect of multipurpose solution on different strains of P. aeruginosa.

Criteria

Inclusion Criteria:

  1. age 20-35 years old
  2. myopia less than -6.00D and astigmatism less than -1.50D
  3. previous soft contact lens wear discontinued for at least 2 weeks. -

Exclusion Criteria:

  1. subjects with previous RGP wear
  2. any ocular inflammation or infection, proved dry eye syndrome, glaucoma, ocular trauma or surgery, and topical medication instillation
  3. diabetic mellitus
  4. pregnancy
  5. status post corneal refractive surgery -
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01925846

Contacts
Contact: Fung-rong Hu, Professor 02-23123456 ext 65189 fungronghu@ntu.edu.tw
Contact: Hsiao-sang Chu, Professor +886-928-980736 einahpets18@gmail.com

Locations
Taiwan
Department of Ophthlamology, National Taiwan University Hospital Recruiting
Taipei, Taiwan, 10002
Contact: Fung-rong Hu, MD    +886-2-23123546 ext 65819    fungronghu@ntu.edu.tw   
Contact: Hsiao-sang Chu, MD    +886-928-980736    einahpets18@gmail.com   
Principal Investigator: Fung-rong Hu, MD         
Sponsors and Collaborators
National Taiwan University Hospital
Investigators
Study Chair: HU FR Hu, professor
  More Information

No publications provided

Responsible Party: National Taiwan University Hospital
ClinicalTrials.gov Identifier: NCT01925846     History of Changes
Other Study ID Numbers: 201212003RINC
Study First Received: August 16, 2013
Last Updated: April 14, 2014
Health Authority: Taiwan: Institutional Review Board

Keywords provided by National Taiwan University Hospital:
Pseudomonas aeruginosa
type three secretory system
contact lens associated microbial keratitis

Additional relevant MeSH terms:
Communicable Diseases
Infection
Keratitis
Corneal Diseases
Eye Diseases

ClinicalTrials.gov processed this record on August 18, 2014