Comparative evaluation of filters for sustained bacterial control in endoscope reprocessing final rinse water.

BACKGROUND: Filter performance is critical for maintaining endoscope final rinse water quality, however comparative data on different filter types remain limited. METHODS: Brominated polystyrene hydantoin (BPSH), polyethersulfone (PES), polypropylene (PP) filters were challenged with water containing ~10⁶ CFU/mL E. coli, P. aeruginosa, and S. aureus. Performance was assessed under dynamic (3.6 L/min flow, 6 h/day) and static (8-day stagnation) conditions. RESULTS: Under dynamic conditions, the BPSH filter consistently maintained effluent bacterial concentrations ≤10 CFU/100 mL for all three organisms throughout the 64-day study. In contrast, the PES and PP filters showed progressive deterioration in performance. Under static conditions, BPSH maintained <1 CFU/100 mL for all organisms over 7 days, whereas PES and PP exceeded the limit from day 2 for P. aeruginosa and E. coli, and from day 6 for S. aureus. DISCUSSION: The sustained efficacy of BPSH under both dynamic and static conditions is attributed to the continuous release of active bromine. This release kills retained bacteria and offers a significant advantage over conventional physical filters. CONCLUSION: BPSH provides consistent, high bacterial removal under both conditions, ideal for clinical settings with intermittent downtime.