High prevalence of Legionella and multidrug-resistant Pseudomonas in portable hemodialysis RO systems: Implications for infection control.

BACKGROUND

This study was investigating bacterial contamination, particularly Legionella pneumophila and multidrug-resistant Pseudomonas aeruginosa, in outlet water of stationary and portable reverse osmosis (RO) systems used in hemodialysis. Antibiotic resistance, and biofilm-related risks were compared to assess their implications for infection control in clinical settings.

METHODS

This study was performed across 3 leading hospital hemodialysis units in Yazd City. Water samples were analyzed for the presence of Staphylococcus aureus, P aeruginosa, L pneumophila, and heterotrophic plate count bacteria.

RESULTS

The output water from 36.11% of RO systems tested positive for L pneumophila, while 15.28% contained P aeruginosa and 6.94% contained heterotrophic bacteria. Portable RO systems showed significantly higher contamination levels of Legionella and heterotrophic bacteria compared to stationary units (P-value = .002). Antibiotic susceptibility testing demonstrated concerning resistance patterns among P aeruginosa isolates: 72.73% were resistant to piperacillin, 63.64% to piperacillin-tazobactam, and 45.46% to imipenem. Notably, 52.2% of isolates exhibited multidrug-resistant profiles.

CONCLUSIONS

Portable RO systems demonstrated significantly greater Legionella contamination than stationary units, likely due to biofilm formation. This poses serious infection risks for hemodialysis patients, potentially leading to extended hospitalizations and increased mortality. Mandatory quarterly microbiological monitoring and biofilm-targeted disinfection protocols are recommended for portable systems.