Rosacea is a chronic inflammatory dermatological condition that has been reported to affect at least 3% of the population in Ireland. Symptoms are concentrated around the center of the face and include chronic inflammation, telangiectasias and inflammatory lesions (papules, pustules and plaques). Up to 50% of those suffering from rosacea have symptoms that manifest in the periocular region, including irritation, inflammation of the eyelids (blepharitis), increased vascularisation of the ocular surface and in severe cases inflammation of the cornea (keratitis) can develop leading to sterile ulcers and visual impairment. Individuals with rosacea often have an elevated presence of Demodex mites in their skin follicles and eyelashes. Bacillus oleronius is a gram negative bacterium isolated from a Demodex folliculorum mite from the face of a rosacea patient. Antigens associated with the bacterium (62 and 83 kDa) were isolated and shown to cause immunoreactivity in the serum of papulopustular rosacea patients. A collaboration with Dr. Scheffer Tseng (Ocular Surface Research Centre, Miami) lead to the publication of work that proved a strong correlation has between serum reactivity to these B. oleronius antigens and eye lid margin inflammation (p = 0.04), and ocular rosacea (p = 0.009). Proteomics techniques were used to investigate the environmental conditions which lead to antigen production in the bacterium. Another area of focus was the effect of Bacillus proteins on Neutrophils and Corneal epithelial cells. Neutrophils are known to play a part in the development of inflammation in rosacea. Our studies showed that there was an increase in neutrophil degranulation, migration and cytokine production following exposure to the bacterial antigens. Corneal epithelial (hTCEpi) cells responded to the bacterial antigens by increasing motility and migration, decreasing proliferation and altering protein production. This work provides strong evidence for the role of Demodex associated Bacillus proteins in the development of facial and ocular symptoms of rosacea.