POINT-OF-USE FILTERS TO PREVENT FUNGAL CONTAMINATION OF HOSPITAL WATER A. Onken 1* , P. Gaustad 1 3 , T.G. Abrahamsen 2 3 , A. Warris 4 1 Dep. of Microbiology and 2 Div of Paediatrics, Rikshospitalet, University Hospital, Oslo, Norway; 3 University of Oslo, Norway; 4 Paediatric Dep., Radboud University, Nijmegen Medical Center, Nijmegen, The Netherlands *Present address: Dep. of Microbiology, Hospital Asker Bærum, Rud, Norway, email: annette.onken@sabhf.no Abstract Hospital water has been suggested as a route for transmission of invasive lamentous fungal infection and preventive measures are needed to protect immunocompromised patients. The installation of point-of-use lters could retain the fungal contamination of the hospital water. Our ndings at the Rikshospitalet, University Hospital, Oslo, Norway, indicate that point-of-use lters might be useful, unless the water contains much organic material blocking the lters. Introduction and Purpose To investigate whether the installation of point-of-use lters could retain the fungal contamination of the hospital water at the Rikshospitalet, University Hospital, Oslo, Norway. Previously, we showed that the hospital water of the paediatric oncology ward was contaminated by fungal organisms (1). Furthermore, hospital water has been suggested as a route for transmission of invasive lamentous fungal infection (2,3) and preventive measures are needed to protect immunocompromised patients. Methods In April 2005 water samples were taken from 10 showers (hot water) and 10 sink taps (cold water) at the paediatric oncology ward, including four BMT units. The samples were collected in sterile glass bottles on three different days during an 8-day period. Then, point-of-use lters (Pall Corporation®) were installed on the taps and showerheads. Sixty water samples were taken from showers and sink taps before installation, and 20 samples were taken with the lters in place. The collected water was ltered through sterile lters, pore size 0.45 m. The lters were deposited on Sabouraud glucose agar and incubated for 7 days. Fungal species were identied by macroscopic and microscopic characteristics. Aspergillus isolates were identied to the species level. Results Filamentous fungi were recovered from 97% (58 of 60 samples) of the water samples before installation of the point-of-use lters. Aspergillus fumigatus was isolated in 21 of 60 samples (35%). On average, 2.9 colony forming units / 500 ml of lamentous fungi were recovered, Aspergillus spp. 0.7 cfu/500 ml, A. fumigatus 0.6 cfu/500 ml. After the installation of local lters no moulds were recovered (20 samples), but the lters were rapidly occluded within 1 or 2 days. Electron microscopy showed that the surface of the occluded lters was completely covered with large amounts of particulate colloidal material. Percentage of positive water samples and level of contamination Before point-of-use lters With point-of-use lters Sink taps (n=30) Showers (n=30) Sink taps (n=10) Showers (n=10) Filamentous fungi 100 % (3.4 cfu/500mL) 93 % (2.3 cfu/500mL) 0 0 Aspergillus spp. 53 % (1.0 cfu/500mL) 17 % (0.2 cfu/500mL) 0 0 A. fumigatus 53 % (1.0 cfu/500mL) 17 % (0.2 cfu/500mL) 0 0 Conclusions The installation of point-of-use lters retained the fungal contamination of the hospital water completely and is an easy to implement preventive measure to protect immunocompromised patients. References 1. Warris A, Gaustad P, Meis J F G M et al. Recovery of lamentous fungi from water in a paediatric bone marrow transplantation unit. J Hosp Inf 2001; 47:143- 48. 2. Warris A, Klaassen C H W, Meis J F G M et al. Molecular epidemiology of Aspergillus fumigatus isolates recovered from water, air, and patients shows two clusters of genetically distinct strains. J Clin Microbiol 2003; 41: 4101-06. 3. Anaissie E J, Stratton S L, Dignani M C et al. Pathogenic molds (including Aspergillus species) in hospital water distribution systems: a 3-year prospective study and clinical implications for patients with hematologic malignancies. Blood 2003; 101:2541-46. Acknowledgement We thank Amanada Stephens, Pall Corporation , Pall Europe Limited, Portsmouth, England, for providing the lters. 0 10 20 30 40 50 60 70 80 90 100 A. fum. Asp. spp. mold total tap shower total