Abstract: A process for detecting microorganisms present in a biological fluid including a) contacting a sample of the biological fluid with a reaction environment comprising a marking agent that is a derivative of cyanines and at least one reactant of cellular penetration of the membrane of the microorganisms, b) filtering the sample on a filter capable of retaining the marked microorganisms present in the sample, and c) detecting the marked microorganisms retained in the filter in stage (b).

Abstract: A method for detecting contaminating microbes possibly present in a blood product including blood cells including a) subjecting a sample of the blood product to an aggregation treatment of the blood cells, b) substantially eliminating aggregates formed in step (a) by passage of the sample over a first filter allowing passage of contaminating microbes, but not cell aggregates, c) selectively lysing residual cells of the filtrate obtained in step (b), d) recovering the contaminating microbes by passage of the lysate from step (c) over a second filter allowing passage of cellular debris, e) adding a marker agent of the contaminating microbes either during step (a) or step (c), and f) analyzing material on the second filter to detect labeled contaminating microbes possibly retained by the second filter; and a device for concentrating contaminating microbes possibly present in a blood product including blood cells including a first watertight, sterile tank containing at least one blood cell aggregation agent and,