Commensal microflora in human conjunctiva; characteristics of microflora in the patients with chronic ocular graft-versus-host disease

Purpose: To investigate the transformation in the composition of ocular surface microflora. Evidence shows that microbial diversity correlates with autoimmune disorders. Chronic ocular graft-versus-host disease (GVHD) is the lethal complication after hematopoietic stem cell transplantation (HSCT) which influences patients' quality of life. It has a similar pathophysiology to autoimmune disorders but the relation of the microbial status especially in the ocular surface and chronic ocular GVHD is still unknown. Methods: We prospectively harvested conjunctival microorganism with a cotton swab from following 3 groups, 32 eyes/20 ocular GVHD patients (9 males, 11 females), 28 eyes/20 nonGVHD cases (10 males, 10 females) which defined as post hematopoietic stem cell transplantation and without ocular GVHD, and 20 eyes/11 controls (7 males, 4 females). Conventional culture-based methods were performed to examine the microbial community. Results: Ocular surface microbes in the GVHD patients was more complex in diversity compared with in the nonGVHD patients and the control. Staphylococcus species, Alpha-haemo Streptococcus, Corynebacterium species, Propionibacterium Acnes, Aerobic gram-positive cocci, Haemophilus Influenzae, and Aerobic gram-positive rod were observed in the GVHD patients, whereas only a few species detected in the other groups. Conclusions: We found that ocular surface microbes in the GVHD patients is more diverse than that in the nonGVHD patients and the controls. These results suggest the alternation of microbes are involved in the pathogenic process of the chronic ocular GVHD. Further examination using state-of-the-art methods will be needed to gain greater insights into the diversity of microflora on the chronic GVHD-affected ocular surface.