Co-occurrence of Free-living Amoebae and Amoebae-resisting Bacteria in Hospital Drinking Water System: Evaluation and Comparative Analysis

Aims: Conventional routine water analysis does not search for free-living amoebae (FLA) and Amoebae-Resisting Bacteria (ARB) in spite of their morbid impact on human health especially towards patients in health care services. In Egypt, very limited data are available in FLA, existing in the treated drinking water and the ARB naturally inhabits them. Therefore, this study was to elucidate the obscure side of this problem trying to find their actual co-occurrence and strength of such relations in nature.

Study Design: Cross-sectional study.

Place and Duration of Study: This study was conducted between June and December 2014 at six of Assiut University Hospitals (AUH) buildings.

Methodology: A total of 54 samples (27 water and 27 biofilms) were collected from the drinking water system (DWS) of AUH. The samples were filtered and processed to Fluorescent In-situ Hybridization (FISH) using specific oligonucleotide probes for Legionella spp., Legionella pneumophila, Parachlamydiaceae, and eukaryote-specific probes for Hartmannella spp. and Naegleria spp.

Results: Forty-four out of 54 samples (81.4%) were positive for FLA, 45% Hartmannella species, 27.27% Naegleria spp. and 27.27% (co-occurrence of both amoebae). Legionella spp. was the most detected ARB within their FLA host 84% (37/44) in contrast to 54% (24/44) Parachlamydiaceae. Co-existence of Legionella spp. and Parachlamydiaceae in both amoebae within the same sample was observed. The number of Hartmannella harboring Legionella spp. was higher than Naegleria spp., but the number of FLA decreased when both amoebae coexisted and harboring Parachlamydiaceae.

Conclusion: It is worth mentioning it could be the first comparative study in Egypt pointing to the relation between FLA and ARB in their natural environment and not from in vitro culture using FISH. New strategies are to be implemented for efficient infection prevention and control to restrict the spread of nosocomial infections through hospital water systems.