[Study on antibacterial property of silver loaded titanium dioxide antibacterial coated endotracheal intubation tube]

To study the antibacterial property of silver loaded titanium dioxide (TiO2) antibacterial coated endotracheal intubation tube, and to determine the minimum effective antibacterial concentration.

Intubation tubes coated with different concentrations of antibacterial agents were prepared with sol gel method. Polyethylene endotracheal intubation tubes were used as substrate, and silver loaded TiO2 was used as the antibacterial agent. According to the different antibacterial concentrations of the antibacterial agent, the tubes were divided into nine groups: 10.0% group, 5.0% group, 2.0% group, 1.5% group, 1.0% group, 0.8% group, 0.6% group, 0.2% group, and control group. They were respectively immersed in three standard bacteria suspensions with 1.0×10(5) cfu/mL: Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. Together with standard bacteria liquid group, there were 10 experimental groups. They were kept overnight for 24 hours. 10 μL of respective culture medium was smeared on blood agar culture medium. After being cultured overnight in 35 centigrade, the number of bacteria colonies was respectively counted.

In 1.0×10(5) cfu/mL of three standard bacteria liquids with antibacterial agent concentration ≥1.0%, three bacterial colonies had un-obviously growth rate. Almost the same strong antibacterial effects to achieve sterilizing rates of more than 98% was shown in each group of the antibacterial coating endotracheal intubation tubes (all P>0.05). As the antibacterial agent concentration decreased, three bacterial colonies were increasing gradually. Intermediate antibacterial effects were shown in tubes of 0.8% group, with significant statistic difference as compared with 1.0% and 0.6% groups [Pseudomonas aeruginosa: 7.300 (4.050, 8.350) vs. 0.200 (0.050, 1.200), 9.700(9.000, 10.000); Staphylococcus aureus: 4.100 (3.300, 4.650) vs. 0.000 (0.000, 0.150), 5.800 (5.350, 7.650); Escherichia coli: 1.400 (0.750, 3.750) vs. 0.050 (0.025, 0.050), 9.500 (8.500, 9.800), all P<0.01].

Silver loaded TiO2 antibacterial coated endotracheal intubation tube had definite antibacterial properties, which were related to the antibacterial concentration. Strong antibacterial effects were shown when antibacterial concentration was above 1.0%, with bacteria almost completely killed in the immersing liquid.