Abstract:ObjectiveTo explore the retrograde contamination of drainage bag outlets, and provide basis for the formulation of related guideline for healthcareassociated infection(HAI) management. MethodsOn October 14, 2016, with sterile manipulation, urine, 5% glucose solution, glucose normal saline, sterile water, and 0.9% normal saline were injected into antireflux drainage bags (antireflux group) and common drainage bags (common group) respectively, entrances of bags were sealed and bags were hung in two ways: outlets were 10 cm away from the ground (suspended group) and touched the ground (groundtouching group) respectively, specimens were collected from bag outlets to perform bacterial culture every 3 days, a total of 10 times of cultures were performed, retrograde contamination of drainage bag outlets was observed dynamically. ResultsRetrograde contamination rate of drainage bag outlets of antireflux group was significantly lower than common group (7.7% vs 46.0%, P=0.000); suspended group was significantly lower than groundtouching group (17.9% vs 35.8%, P=0.000). Retrograde contamination rates of outlets of drainage bags filled with different properties of liquid were as follows: urine (54.3%)＞5% glucose solution (34.5%)＞glucose normal saline (24.3%)＞0.9% normal saline (10.8%)＞sterile water (10.5%), pairwise comparison showed a significant difference(P=0.000). The initial occurrence time of contamination in antireflux group and common group was on the 13th day and 7th day respectively, two group was significantly different on the 7th day(P=0.041). There was a medium intensity correlation between the types of drainage bags and liquid properties（Pearson C=0.5）. ConclusionDifferent types of drainage bags, retention time, and liquid property can impact retrograde contamination of drainage bag outlets, regular urine culture during the use of drainage bags should be paid attention in clinical practice, so as to use antimicrobial agents rationally and guide replacement time of drainage bags.