A device (1) comprising an optical apparatus (2) for monitoring
bacterial growth of a
drug-dosed liquid biological sample. A sample
container port for receiving a sample container (6), in use, is provided in the device, the sample container (6) having at least one detection chamber (20) for containing the
drug-dosed sample. The optical apparatus (2) comprises a
light source (22) configured to emit light along an
incident beam axis that, in use, intersects with at least one detection chamber (20) of the sample container (6), and to illuminate the
drug-dosed sample contained within the detection chamber (20). The optical apparatus (20) comprises a first
photodetector (26) configured to receive light scattered by
bacteria in the sample. The optical apparatus (2) comprises a light collection arrangement (24) configured to collect light exiting the detection chamber (20) that has been scattered in a forward direction by
bacteria in the sample, in a range of scattering angles between about + / -4 and + / -20 degrees relative to the
incident beam axis, and to direct the collected
scattered light to the first
photodetector (26); and prevent non-
scattered light travelling parallel to the
incident beam axis and exiting the detection chamber (20) from reaching the first
photodetector (26). The optical apparatus (2) comprises at least one processor configured to: measure an intensity of the
scattered light received by the first photodetector (26); determine a corresponding representative amount or concentration of
bacteria present in the sample based on the intensity of the scattered light; repeat the measuring and determining steps at a series of pre-determined intervals to determine changes in the representative amount or concentration of
bacteria present in the sample as a function of time; and determine a corresponding susceptibility of the bacteria in the sample to the respective drug.