Abstract: Apparatus for isolating and identifying microorganisms in blood or the like which comprises a tubular collection vessel which is sealed at both ends but includes means at one end for permitting the removal of fluid therein by the application of vacuum when the seal at that end is broken, a multisection filtration unit comprising a first section provided with means for receiving said one end of the collection vessel, means in said section for breaking the seal in said one end of the vessel when it is received by said first section, a second section of said filtration unit nested against the bottom of the first section, a filter membrane positioned between the nested first and second sections of said filtration unit, said filter membrane being in open communication with said one end of the collection vessel which is received by said first section, a third section of said filtration unit nested against the second section on the opposite side of the filter membrane from the nested first and second sections, and m