**9. Immunodeficiency**

In dialysis-associated CRS, infection is severe, both induced by thrombosis of sclerosed AVF or not associated with vascular access. Pneumonia risk factors in dialysis CRS with malnutrition include immune deficiency with activation of opportunistic infections and Staphylococcus carrying in the nasopharynx, CHF with chronic hyperhydration and hypoxia of lung tissue, hydrothorax, hyperparathyroidism with lung tissue calcification, obstructive night apnea syndrome, and epoetin-resistant anemia.

Pathogens of acute pneumonia on dialysis include staphylococcus, opportunistic bacteria (*E. Coli*, Haemophylis influenzae, Klebsiella, Pseudomonas, Listeria, Legionella), and pathogenic fungi (Aspergillus, Candida, Cryptococcus, Mucormyces). In dialysis CRS, the mortality is extremely high from pneumonia caused by the association of influenza virus with *Staphylococcus aureus* [107] or superinfection with pneumocysts in MIA syndrome patients infected with cytomegalovirus. At the advanced stage of CRS in diabetic patients, purulent complications of obliterating atherosclerosis of lower limb arteries and diabetic foot typically cause high mortality from gangrene and sepsis. Risk factors for infectious endocarditis in dialysis CRS are vascular access infection, calcinosis of valves in severe hyperparathyroidism, their myxomatous degeneration, thrombotic deposits, or severe anemia [108].

Antibiotic therapy is carried out after removal of the infected fistula with the formation of a new AVF or with transfer to PD [109]. Treatment with broad-spectrum antibiotics should be started immediately and corrected by the blood culture results. Antibiotic therapy is ineffective in CHF, recurrent

thromboembolism, fungal endocarditis, tricuspid or pulmonary artery valves lesions (frequent in HD patients). In these cases, surgery is necessary to replace the affected valve [108].
