/ /

  • linkedin
  • Increase Font
  • Sharebar

    Ocular surface unfriendly to pathogenic bacteria

    Seattle—Whether or not the ocular surface hosts a live microbiome has been an unresolved question, but findings of a study presented at ARVO 2016 provide further insight on this issue.

    Presented by Suzanne M. Fleiszig, OD, PhD, and colleagues, the research was conducted in a mouse model and evaluated whether stable bacterial colonization of the ocular surface could be established after deliberate inoculation.

    Using a novel method to detect live bacteria, the results indicated that the ocular surface does not host a stable, metabolically active microbiome, noted Dr. Fleiszig, professor of optometry and vision science, Infectious Diseases and Immunity, and Microbiology, Berkeley Optometry, University of California.

    Related: What physicians need to know about bacterial resistance

    The investigators acknowledged, however, that the study does not rule out the possibility that non-metabolically active bacteria were present on the ocular surface.

    In designing their experiment, the researchers noted that findings from previous studies using high-throughput sequencing of the microbial 16s ribosomal gene indicated an abundance of microbes resides on the ocular surface.

    More from ARVO: Anti-VEGF shows benefits for CNV with rare diseases

    However, that particular analytical method does not distinguish between living and non-viable organisms because it is based on the detection of bacterial nucleic acid.

    To overcome that limitation, the investigators used alkyne functionalized D-alanine as a novel marker to identify live microbes because it incorporates into the cell wall of only metabolically active bacteria.

    SPONSORED: Join us for dinner and diabetes management tips! Click here if you’re attending ASCRS!

    After the performance of this novel labelling technique was confirmed, animal eyes were inoculated with bacteria, including Pseudomonas aeruginosa, Staphylococcus aureus, and a gram-positive commensal organism isolated from the mouse dermis.

    Then, groups of animals were sacrificed after 24 or 72 hours for analyses to detect metabolically active bacteria in tear fluid, cornea, and conjunctiva.

    Whether inoculated with a high or low bacterial load (~108 or ~104 CFU, respectively), the ocular surface was found to be an inhospitable environment for supporting bacterial colonization, either by the pathogenic organisms or the commensal bacterium.

    In eyes assessed at 24 hours after inoculation, clearance rates were >99.99% when the inoculum contained ~108 CFU and >99.75% with the smaller inoculum.

    Related: Photoactivation holds promise for keratitis treatment

    The results were similar when the analyses were conducted 3 days post-inoculation, and metabolically active bacteria were sparsely found on the cornea (mean 0.50 bacteria/image), they reported.

    Investigators from Touro University, Vallejo, CA, and Stanford University, Stanford, CA, collaborated in the project.

    New Call-to-action


    You must be signed in to leave a comment. Registering is fast and free!

    All comments must follow the ModernMedicine Network community rules and terms of use, and will be moderated. ModernMedicine reserves the right to use the comments we receive, in whole or in part,in any medium. See also the Terms of Use, Privacy Policy and Community FAQ.

    • No comments available


    View Results