A screening device intended to be installed within a suction system and which has a membrane pore size small enough to retain bacterial pathogens, thus preventing the environment from becoming infected and decreasing the risk of cross-infection to subsequent patients. It is typically directly connected to the suction system collection bottle/canister, or as a common filter serving more than one bottle/canister through a switching mechanism, or in a tubing line between the suction bottle/canister and the suction pump, or at the suction pump exhaust where driving gases are discarded. This is a single-use device.