Exploring the efficacy of combination of point-of-use filters and peracetic acid disinfection in reducing total viable counts in final rinse water of endoscopes.

The final rinse water pollution of endoscopes in medical institutions is a severe growing problem, posing a latent risk to nosocomial infection. This study aimed to explore the efficacy of combination of point-of-use (POU) filters and peracetic acid (PAA) disinfection in reducing total viable counts (TVCs) in final rinse water of endoscopes. Eight final rinse water faucets of endoscope centers were randomly selected and none of the faucets had POU filters prior to the study. Four faucets were assigned to experimental group and had POU filters installed, the other four faucets were set as control group and did not have POU filters installed. During monitoring, both the experimental and control groups were used 0.3% PAA to disinfect the purified water system twice. TVCs in final rinse water was monitored weekly for 13 weeks. 231 final rinse water samples were collected, of which 111 and 120 samples were in the experimental and control groups, respectively. The mean TVCs and positive rate of samples for experimental group were both significantly lower than that of control group [10 vs. 50,450 colony-forming units (CFU)/100 mL, and 27.7% vs. 98.3%, P < 0.001]. The TVCs in control group was from 2.0 × 10 to 2.5 × 10 CFU/100 mL, and the positive rates of samples were almost 100%. However, the TVCs and positive rates of samples in experiment group were always at a low-level, with a maximum TVCs of 47 CFU/100 mL, corresponding to a maximum positive rate of 50%, by the 13th week of monitoring. Our findings demonstrated that PAA disinfection alone exhibited limited efficacy in controlling TVCs in final rinse water of endoscopes, whereas its combined application with POU filters significantly enhances the control effect of TVCs.