The classification of bacteria is generally based on their morphology and biochemical reactions. However, using these methods is time consuming, and require training and expertise. Infrared (IR) spectroscopic measurements of bacteria followed by a formal chemometric analysis could offer advantages including speed and consistency. Such an analysis was first carried out in the late 1950s, with some success, but with limitations imposed both by the instrumentation and by the post-processing tools available. Modern tools, however, allow quick and consistent results.