An optical measurement instrument is an integrated instrument that includes an optical cavity with a light source, a sample cuvette, and an optical sensor. The light source and sensor are on a bench that is on a translational or rotational mechanical platform such that optical beam can be moved to multiple sample containers. The instrument can be used for taking measurements of organism concentration in multiple samples as a production tool for microbiology. Preferably, the instrument holds multiple, individually-loaded, independent fluid samples and determines bacteria concentration via a forward-scattering signal. The instrument can incorporate onboard incubation to promote bacterial growth in the samples during the test. In another aspect, the instrument can be a part of a network for medical diagnostic testing data where data is stored in a manner that is inherently untainted by patient identifiable information.