1. Department of Medical Biology, Faculty of Medicine, Medical University of Plovdiv, 4000 Plovdiv, Bulgaria
2. Department of Dialysis Treatment, St George University Hospital, 6000 Plovdiv, Bulgaria
3. Department of Medical Microbiology and Immunology “Prof. Dr. Elissay Yanev”, Faculty of Pharmacy, Medical University of Plovdiv, 4000 Plovdiv, Bulgaria
4. Laboratory of Microbiology, St George University Hospital, 6000 Plovdiv, Bulgaria
5. Research Institute at Medical University of Plovdiv, 4000 Plovdiv, Bulgaria
6. Laboratory of Clinical Immunology, St George University Hospital, 6000 Plovdiv, Bulgaria