Free-living amoebae (FLA): detection, morphological and molecular identification of Acanthamoeba genus in the hydraulic system of an haemodialysis unit in Tunisia.

UNLABELLED The free-living amoebae (FLA) are ubiquitous and opportunistic protozoa. They can induce human and animal diseases. The aim of our study was to detect the FLA and Acanthamoeba genus in the hydraulic system of an hemodialysis unit. It was a prospective study of 46 water samples. The first collect (23) was before cleaning and after the haemodialysis sessions and the second (23) after cleaning and before the hemodialysis sessions. RESULTS the morphological study enabled us to detect morphotypic diversity. The predominant morphotypes were the acanthopodial forms (29%). At the entrance of hemodialysis unit there were acanthopodial (44%) and monotactic (25%) forms; at the outlet, acanthopodial and fan-shaped forms (25% each). In addition, Acanthamoeba genus was present in 39% (1st collect) and 18% (2nd collect). The amplification of the FLA 18S rDNA gene was negative in only one sample localized in the last stage of water treatment unit (WTU). The amplification of the 18S rDNA (ASA.A1) Acanthamoeba gene was positive in 15 samples. CONCLUSIONS we noted that, in the hemodialysis unit, the purification techniques used in the WTU were effective, but there is a problem of water stagnation in the drain, which constitutes an appropriate condition for the biofilms formation. It is then necessary to use a filter with a low porosity (0.2 microm) at the entrance of the hemodialysis unit and if possible to change the drain.