Concurrence of ocular infection with Demodex folliculorum

Abstract Background: The ectoparasite Demodex spp. is the most common human parasite detected in skin lesions such as rosacea, lichen, and keratosis. It is also an etiological factor in blepharitis. As Demodex spp. is involved in the transmission of pathogens that can play a key role in the pathogenesis of demodecosis, the aim was to assess the concurrence of Demodex folliculorum and bacterial infections.Methods: The study involved 232 patients, including 128 patients infected with Demodex folliculorum and 104 non-infected patients. The ophthalmological examination consisted of examining the vision of the patient with and without ocular correction, tonus in both eyes) and a careful examination of the anterior segment of both eyes with special emphasis on the appearance of the eyelid edges and the structure and appearance of eyelashes from both eyelids of both eyes. The samples for microbiological examination were obtained from the conjunctival sac. The bacterial culture was obtained by inoculating the samples on chocolate agar and agar with 5% sheep blood. After 24-48 h of incubation at 37 °C, the growth of various colonies of bacteria was identified based on morphological evaluation of the colonies on the media and preparations stained by the Gram method. Species identification was performed biochemical examination ex. coagulase test or VITEK Compact (bioMerieux, Poland).Results: Physiological flora was found in all patients infected with D. folliculorum and 9 (8.7%) participants from the control group.Only in patients infected with D. folliculorum we isolated Staphylococcus aureus (9 patients, 7%), Acinetobacter baumannii (one patient, 0.8%), Streptococcus pneumoniae (one patient, 0.8%), Klebsiella oxytoca (one patient, 0.8%), and Bacillus spp. (one patient, 0.8%) in the conjunctival sac.Conclusions: The occurrence of symptoms: dryness and burning sensation in the eye, tearing, conjuctival redness, foreign body sensation, eyelash loss, blockage of the Meibomian glands, cylindrical dandruff, and chalazia may suggest infection with Demodex spp. Patients infected with Demodex spp. should also undergo microbiological examination of conjunctival swabs. The treatment of each patient should be individualized, adapted to the clinical condition, and in cases of bacterial co-infection. Furthermore, daily hygiene of the eyelid margins should be recommended.