The present disclosure provides an assembly for preparing a sample for analysis. The assembly comprises a hollow body comprising first opening, an outlet with a second opening, and a fluid pathway extending therebetween; a filter element operatively interposed in the fluid pathway; and a closure comprising a third opening and a chamber, the closure being slideably engaged with the outlet. The chamber and the outlet are dimensioned so that the outlet is sealingly engaged with the chamber. A method of using the assembly to detect a microorganism is also provided.