Occurrence of fungi in dialysis water and dialysate from eight haemodialysis units in central Italy.
Fungal contamination of dialysis fluids may be a serious problem in therapy, particularly due to the debilitated immune system of haemodialysis patients. To investigate the occurrence, distribution, and diversity of fungi in dialysis water and dialysis solution of eight haemodialysis units in a region of central Italy. Samples were collected over a one-year period from different points of the haemodialysis circuits in accordance with the guidelines of the Italian Society of Nephrology. Isolation and identification of fungi was performed according to the ISTISAN method Reports (2007/05 and 2008/10). Of the 976 samples analysed, 96 grew filamentous fungi, 28 were positive for yeast, and six samples contained both mould and yeast. A wide variety of filamentous fungi (26 genera, of which 15 identified at species level, and 'mycelia sterilia') were recovered, many of which are known as opportunistic pathogens. Cladosporium spp. were most frequently found (39%), followed by Alternaria spp. and Tricophyton spp. Fungal counts in treated water and standard dialysate solution were always below the threshold (<10 cfu/mL), and thus are in agreement with the Italian guidelines for dialysis fluid quality, whereas 10.9% of the samples of ultrapure dialysate solution were contaminated by one or several fungi types, in contravention of the guidelines. The large variety of opportunistic fungi recovered in the haemodialysis circuits proves the importance of including an analysis of fungi to check the microbial quality of dialysis water and dialysate.