Microbiota Analysis and Standard Culture Identify Bacteria in Ophthalmic Trypan Blue Solution Commonly Used During Canine Cataract Surgery.

Abstract

OBJECTIVE: To identify bacterial communities and quantify endotoxin within different lot numbers and brands of commercially available sterile ophthalmic trypan blue solution commonly used during canine cataract surgery; with the ultimate goal of improving our understanding of possible factors associated with post-operative fibrin web (FW) formation. PROCEDURES: Five samples from two production lots of three different brands of trypan blue (30 samples total) and reagent controls were collected for deoxyribonucleic acid (DNA) extraction, 16S ribosomal ribonucleic acid (rRNA) sequencing, sequence analysis, and classification. All samples underwent conventional aerobic and capnophilic bacterial culture. Assays for endotoxin quantification included fluorogenic, kinetic chromogenic, and turbidimetric methods. Statistical analysis assessed DNA concentration, microbial richness, and alpha (α) and beta (β) diversity. RESULTS: an-blue (4/10), VisionBlue (3/10), and MONOBLUE Saf-R (3/10) all cultured at least one organism in each lot number from the enrichment broth. Genera cultured included Staphylococcus spp., Lysinibacillus spp., Bacillus spp., and Micrococcus spp. Analysis of sequencing data revealed no significant difference in α-diversity but significant differences in weighted and unweighted measures of β-diversity (Bray-Curtis and Jaccard distances) between an-blue and VisionBlue samples. Differential abundance testing found Halomonas and Saccharofermentans to be genus-level biomarkers. Dominant families recovered from sequencing included Bifidobacteriaceae, Christensenellaceae, Clostridiaceae, Erysipelotrichaceae, Lachnospiraceae, Lactobacillaceae, Oscillospiraceae, Propionibacteriaceae, WCHB1-41, and Streptococcaceae. Endotoxin quantification could not be performed at clinically relevant dilutions. CONCLUSIONS: Significant brand-specific differences in relative abundance of shared bacterial taxa were noted between an-blue and VisionBlue. Halomonas and Saccharofermentans were identified as genus-level biomarkers.