Study of the Microbiological Quality of Water for Hemodialysis After Implementation of a New Treatment System at the University Hospital of Yaoundé

Abstract

Controlling the microbiological quality of water in hemodialysis centers is essential to avoid complications in hemodialysis patients that may be caused by microorganisms. The aim of this study was to determine the microbiological quality of water after the installation of a new water treatment system in the hemodialysis department of the Yaoundé University Hospital Center. A total of sixteen (16) samples were taken every two weeks at sites A (network inlet), B (filter outlet/osmosis inlet), C (osmosis outlet) and D (loop return) between May and July 2023. Microorganisms were isolated after filtration of 100 ml of water through a nitrocellulose membrane, microporosity 0.22 µm, then deposited on Tryptone Glucose Extract Agar (TGEA) medium and incubated at room temperature between 17 and 22°C for 7 days. After subculturing on different media, the pure microorganisms were identified by their cultural characteristics and marketed biochemical galleries. The compliance threshold was below 100CFU/ml. Of the samples analyzed, 56% (9/16) were declared non-compliant (>100UFC/ml) versus 43% (7/16) compliant (<100CFU/ml). Only samples from the fourth series were all compliant at points A, B, C and D. Of the microorganisms identified, five (5) species were Gram-negative bacilli, including <i>Acinetobacter baumanii</i>, <i>Pseudomonas luteola</i>, <i>Burkholderia cepacia</i>, <i>Pseudomonas aeruginosa </i>and <i>Stenotrophomonas maltophilia</i>. Gram-positive cocci were all coagulase-negative Staphylococcus and yeasts were Candida spp. The most frequently isolated bacterial genera were Pseudomonas (29.17%), Staphylococcus (25%), Acinetobacter (16.67%), Stenotrophomonas (12.50%), Candida (12.50%) and Burkholderia (4.17%). In this study, although the samples from the fourth series of sampling were all compliant at the various sampling points, the high rate of non-compliance and the detection of a variety of microorganisms demonstrate the need to reinforce the disinfection system in the hemodialysis water treatment circuit.