An apparatus (150) comprises a first detection chamber (130) for receiving microorganisms and configured to allow detection of the microorganisms via detection of scattered light from the first detection chamber (130); a medium (120) configured to permit passage of microorganisms from a sample (110) through the medium (120) into the first detection chamber (130); and at least one second detection chamber (140) configured to allow detection of the microorganisms via detection of scattered light from the at least one second detection chamber (140).