Abstract
Purpose :
The human ocular surface (HOS) is exposed to surrounding environments and thus various types of microorganisms are present. However, it is unclear whether there are normal microbial communities in HOS and which factors cause the changes in HOS microbial communities. The present study aims to identify the major (core vs variable) genus in HOS. This study also compared the ocular surface microbial communities of humans with and without diabetic retinopathy to identify the specific microbial community related to the diabetic retinopathy.
Methods :
Diversity and distribution of the bacterial community in HOS was characterized using 16S rRNA deep sequencing analysis. Amplicon libraries of 16S rRNA gene were constructed from total conjunctival swab DNA samples (19 healthy and 30 diseased). Amplicons were sequenced using the Illumina MiSeq platform. Sequence classification and diversity analysis were conducted using a MOTHUR pipeline and tools available through Ribosomal Database Project.
Results :
Proteobacteria, Firmicutes, Actinobacteria, Cyanobacteria and Bacteroidetes were the dominant taxa present in HOS. Further taxonomic assignment at the genus level revealed that core genus presented in all samples were Bradyrhizobium, Staphylococcus, Streptococcus, Corynebacterium, Acinetobacteria, Pseudomonas, and Ralstonia, while genus of Cyanobacteria, Burkholderia, Bradyrhizobium, Massilia, Neisseria, and Micrococcus were variable among each sample. Diversity index and rarefaction analysis showed that healthy HOS has the higher bacterial diversity than diseased HOS. In addition, relative abundance of the microbial community in diseased HOS (diabetic retinopathy subjects) indicated a decrease of Bradyrhizobium(13.2 to 3.1%), Staphylococcus(10.7 to 0.7%), Corynebacterium(4.5 to 1.9%), Pseudomonas(4.3 to 1.3%) and a huge increase of Acinetobacter(2.3 to 39.6%).
Conclusions :
HOS include both core and variable microbial community and the community compositions are highly variable among individual HOS. However, the microbial community composition and diversity of diseased HOS are significantly different and lower than those of healthy HOS. High abundance of Acinetobacter in diseased HOS suggests that the presence of Acinetobacter is closely related to diabetic retinopathy or local hospital environment. Further studies are needed to understand the role or the high abundance of this microorganism in diseased HOS.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.