Abstract
Purpose: :
Diversity and dynamics of the ocular microbiota directly impacts the pathology of the ocular surface in health and disease. Identifying and comparing these microbial communities and their interactions at the ocular surface will lead to improved detection, management and prevention of common surface disorders. We implemented a pilot study to begin to decipher the incidence and diversity of the ocular surface microbiota comparing routine culture and metagenomics.
Methods: :
Samples from tears, tarsal conjunctiva and cornea of four healthy volunteers were collected for routine cultures and genomics using a cotton swab and or cytology brush. Samples for culture were plated directly onto chocolate, blood and thioglycollate and incubated at 35 C in CO2. Samples for genomic analysis were placed in extraction buffer, DNA extracted and bacterial populations determined using universal bacterial 16S rRNA primers and pyrosequencing
Results: :
On average 3 bacteria species (coagulase negative staphylococci- (75%), Corynebacterium species (Corsp-100%), and Propionibacterium species (100%) were recovered from routine culture methods versus an average of 224 different species obtained via metagenomic analysis. The isolates recovered from culture constituted 33% of the genomics species and ranged from 3.9% (staphylococci) to 18% for Propionibacterium. Incidence of Corynebacterium species via genomics was (11%). Recognized common ocular pathogens-Pseudomonas species (phylum Pseudomonadales-avg 2.27%) and Acinetobacter (phylum Moraxellaceae- avg-5.65%) were documented from all 4 volunteers. Rare ocular pathogens (Mycobacterium, Nocardia, Enterobacter and Stenotrophomonas species) were recovered from at least one volunteer. Forty percent (22/55) of the recovered species in this sample have never been reported as ocular commensals or pathogens.
Conclusions: :
The ocular surface is populated by a diverse consortium of microorganisms. Little is known how these organisms interact with each other and the resultant influence on the ocular surface ecosystem. Deciphering these interactions and impact can lead to improved ocular surface health and vision in compromised and noncompromised patients.
Keywords: bacterial disease • microbial pathogenesis: experimental studies • conjunctiva