Identification of culturable bacteria present in haemodialysis water and fluid

Water used to prepare haemodialysis fluid is not sterile, and its microbiological control is important for the prevention of haemodialysis-associated illness. Bacterial populations inhabiting a distribution system for haemodialysis water were studied over an 18-month period. 203 planktonic bacteria isolated on R2A medium were identified by restriction analysis and sequencing of 16S rRNA gene. A diverse bacterial community was detected, containing predominantly Gram-negative members of the Alphaproteobacteria and Betaproteobacteria, as well as representatives of the genus Mycobacterium. Ecological and clinical consequences are discussed: bacteria from the genera Novosphingobium, Pseudomonas and Sphingomonas have been described in the build-up of biofilms, and others like Acinetobacter, Mycobacterium or Brevibacterium may represent a health risk to patients under haemodialysis treatment.