The role of syringe filters in harm reduction among injection drug users

Objectives. Three filters were tested for in situ efficacy in reducing bacterial contamination associated with injection drug use. Methods. Ina self-method control design with blinded laboratory testing, injection drug users were asked to use 3 filters in random succession when loading their syringes with drug solute. Results. The 0.22-mu m filter proved significantly better than both the cigarette filter (relative risk [RR] = 18.0) and the 20-mu m filter (RR = 4.5) in rendering syringes bacteria-free. Conclusions. The 15- to 20-mu m syringe filter currently provided injection drug users in Switzerland does not significantly reduce contamination associated with common bacterial infections among users. Filters with pore width 1/100th as large are recommended.