A process comprises (a) providing (1) at least one sample suspected of comprising at least one coliform strain, (2) at least one culture device comprising at least one culture medium that is hydrated or hydratable, and (3) at least one particulate concentration agent that is substantially optically transparent when in contact with the culture medium in the culture device when the culture medium is hydrated; (b) placing the particulate concentration agent in contact with the sample such that at least a portion of the coliform strain is bound to the particulate concentration agent to form coliform-bound particulate concentration agent; (c) placing the coliform-bound particulate concentration agent in contact with the culture medium; (d) incubating the culture device comprising the coliform-bound particulate concentration agent in contact with the culture medium, the culture medium being hydrated; and (e) optically detecting the presence of the coliform strain without separating the coliform strain from the particulate concentration agent.